Dissertations / Theses on the topic 'Blood loss'

"May 2002" Includes bibliographical references (leaves 229-251) Describes the investigation of the alteration of ABH antigen expression on the surface of red blood cells in patients with haematological malignancies.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "December 2006" Includes bibliographical references.

Introduction Peri-operative blood loss and blood transfusions are associated with poorer short- and long-term outcomes in patients undergoing hepatectomy. Various techniques are utilised to decrease blood loss though these may also cause an Ischaemia-Reperfusion Injury (IRI). The aim of this thesis was to identify factors which predispose to intra-operative bleeding during liver surgery and to identify methods to decrease blood loss without increasing the likelihood of post-operative liver dysfunction Methods In order to address the aim of this thesis, several studies are performed: 1. A systematic review examining non-surgical methods to decrease blood loss. Primary outcome measures included peri-operative blood loss and transfusion requirements. The secondary outcome measure was occurrence of IRI. The review was performed according to the PRISMA guidelines for systematic reviews. 2. A retrospective database analysed the association between blood transfusion and survival. . Uni- and multivariate analysis were performed. 3. A pilot single blinded, randomised control trial (RCT) was undertaken comparing the Pringle manoeuvre (standard) versus Portal Vein clamping. Results 1. Seventeen studies were included in the systematic review. In 8 studies (n=894) pharmacological methods and in another 9 studies (n=679) anaesthetic methods to decrease blood loss were investigated. In 3 trials potential benefits of anti-fibrinolytics were demonstrated. Six anaesthetic trials demonstrated potential roles for low central venous pressure, acute normovolaemic haemodilution, autologous blood donation techniques and choice of inhalational anaesthetic agent employed. 2. Six hundred and ninety patients were included in this study. Median follow-up was 33 months. Sixty-four (9.3%) patients required a peri-operative RBCT. Red cell transfusion was a predictor for decreased OS (median 41 vs 49 months, p=0.04). However, on multivariate regression analyses pre-operative chemotherapy, post-operative complications and Clinical Risk Score (CRS) were independently associated with reduced overall survival, though RBCT was not. There was no association between RBCT and recurrence free survival ( median 15 vs 17 months, p=0.28) 3. The main findings of the RCT were that it was technically feasible to perform isolated portal vein clamping in patients and to recruit patients into the trial. However, a larger RCT will be needed to obtain definitive evidence on the role of PVC in hepatic resections in the future Conclusions There is potential for use of non-surgical techniques to decrease peri-operative bleeding in liver surgery. RBCT is not independently associated with poorer survival although it may be a surrogate marker for more advanced disease. The RCT confirms that isolated portal vein clamping is technically feasible and it was possible to recruit into the trial; a multi-centre RCT is required to assess the role of isolated portal vein clamping surgery for colorectal liver metastases.

Obstetric hemorrhage is one of the most common causes of maternal morbidity and mortality. The measurement of quantitative blood loss (QBL) at delivery prevents clinicians from failing to recognize hemorrhage in healthy obstetric patients who initially compensate for excessive blood loss. The purpose of this project was to improve the compliance of labor and delivery nurses in a community hospital with consistent QBL measurement. Key theories that formed the basis for the project were Lewin’s theory of planned change and homeostasis. The project question addressed was: Is the use of weekly scorecards to provide feedback to nurses with both blinded individual data and aggregate unit data associated with an increase in the percent of patients with blood loss at delivery documented as a QBL measurement over a 12-week period of time? A blinded scorecard of the percent of deliveries attended by each nurse that had QBL documented and an aggregate run chart of the percent of all deliveries with QBL documented were posted in the unit weekly. The postings included discussions of means to enhance facilitators of and decrease barriers to QBL measurement. Over 12 weeks, the percent of deliveries with QBL documented increased from 22.7% to 80.0%. This result is consistent with previous reports that clear and objective feedback from scorecards is associated with improvement in performance. Scorecard feedback may be explored to determine if it is associated with improvement of other nursing practices. This project has implications for positive social change as it may contribute to a reduction in preventable maternal deaths. Decreasing maternal morbidity and mortality supports the health of women in a population and influences the health of the next generation.

"May 2002"
Includes bibliographical references (leaves 229-251)
xv, 251 leaves : ill. (some col.) ; 30 cm.
Describes the investigation of the alteration of ABH antigen expression on the surface of red blood cells in patients with haematological malignancies.
Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2003

The object of this thesis is to investigate the value of analysis of WGLF in the assessment of Gl pathology, specifically in the measurement of blood and protein loss from the gut. The method for haemoglobin measurement was selected on the basis of a need for sensitivity and the need to detect metabolites of haemoglobin as well as the parent molecule. The measurement of haemoglobin in WGLF has been assessed in a series of patients with clinical conditions known to result in anaemia and which may be related to blood loss from the gut. The relationship between the subjective assessment of inflammatory bowel disease activity and the measurement of WGLF proteins arising by leakage from plasma has been examined with a view to establishing more objective activity indices. The specificity of WGLF protein measurements for the diagnosis of active inflammatory bowel disease has been assessed in a large group of patients with a variety of gastrointestinal pathologies. Gut clearance measurements of plasma proteins and haemoglobin have been undertaken to evaluate quantitative protein and blood loss in normal and pathological groups. Many workers have used alpha-1-antitrypsin in faeces as an indicator of inflammatory bowel disease, and different molecular weight forms have been described. The molecular weight of alpha-1-antitrypsin in WGLF has been investigated in controls and patients with inflammatory bowel disease. Hyaluronic acid, a structural glycoprotein found in the submucosa of the intestine has been determined in WGLF in control and patient groups in an attempt to find a direct index of tissue disruption during active disease process in the gut.

Delayed control of haemorrhage or blood loss has been recognised as a major contributor to preventable trauma deaths, but early detection of internal bleeding is difficult due to unreliability of heart rate (HR) and blood pressure (BP) as markers of volume status. This thesis explores a novel method of early blood loss detection using a noninvasive finger photoplethysmographic (PPG) pulse oximetry waveform that is normally utilised in pulse oximeters for estimating arterial oxygen saturation. Graded head-up tilt (n = 13) and blood donation (n = 43) in human volunteers were selected as experimental models of mild to moderate blood loss. From the tilt study, a novel method for automatically detecting left ventricular ejection time (LVET) from the finger PPG waveform has been developed and verified by comparison with the LVET measured from aortic flow velocity. PPG waveform derived LVET (LVETp) and pulse transit time (PTT) were strongly correlated with aortic LVET and pre-ejection period respectively (median r = 0.954 and 0.964) and with the decrease in central blood volume indicated by the sine of the tilt angle (median r = -0.985 and 0.938), outperforming R-R interval (RRI) and BP in detecting mild central hypovolaemia. In the blood donation study, progressive blood loss was characterised by falling LVETp and rising PTT (p < 0.01). A new way of identifying haemorrhagic phases by monitoring changes and trends in LVETp, PTT and RRI has been proposed based on the results from the two studies. The utility of frequency spectrum analysis of PPG waveform variability (PPGV) in characterising blood loss has also been examined. A new technique of PPGV analysis by computing the coherence-weighted cross-spectrum has been proposed. It has been shown that the spectral measures of finger PPGV exhibited significant changes (p < 0.01) with blood donation and were mildly correlated with systemic vascular resistance in intensive care unit patients (r from 0.53 to 0.59, p < 0.0001), therefore may be useful for identification of different haemorrhagic phases. In conclusion, this thesis has established finger PPG waveform as a potentially useful noninvasive tool for early detection of blood loss.

This research utilized a descriptive study to establish a relationship between educational background and accuracy of estimating blood loss. The null hypothesis, that the educational background of health care providers in the operating room has no effect on the accuracy of estimating blood loss , was tested. Ten nurse anesthesia students, 8 certified registered nurse anesthetists, 16 operating room registered nurses, 12 anesthesiologists, and 9 surgeons were included in the sample population. A number of different protocols were utilized to assess the relative accuracy of blood volumes estimates. The study was separated into four stations. Station 1 consisted of three tables, each with different sizes and types of sponges with varying amounts of blood placed on them. Four estimates were required at each table, for a total of 12 estimates. Stations 2-3-4 contained different aggregates of blood-soaked materials, requiring a single estimate at each station. Repeated measures analysis of variance (ANOVA) revealed that the means across all groups in Station 1 reached statistical significance beyond p = .05 (< .001), and the hypothesis is rejected for equal group means. However, the results for Stations 2-3-4 for equal group means did not reach statistical significance ( p = .136), therefore, do not reject the null hypothesis of equal group means.

Background: Postpartum haemorrhage (PPH) is the leading cause of maternal death worldwide. For every woman that dies, 20 or 30 more will experience morbidity. Severe PPH is increasing and is the leading cause of severe maternal morbidity in the UK. Rapid recognition of PPH is essential, but concealed bleeding, underestimation of blood loss and a failure to appreciate the physiological effects of blood loss, lead to delays in recognition and treatment. Experts believe that most deaths from PPH could be avoided by earlier diagnosis, but there is a lack of evidence on how to achieve this. Aims: To explore the experiences of those involved in evaluating blood loss during childbirth; and to develop and test a theory of blood loss evaluation and PPH recognition, as a prerequisite to developing strategies to support earlier diagnosis. Study Design: A sequential, exploratory mixed methods design was used. Methods: Qualitative methods included 8 focus groups and 19 one-to-one semi-structured interviews, conducted with 50 participants. These included: women and their birth partners (recruited from Liverpool Women's Hospital); and health professionals (midwives and obstetricians recruited from Saint Mary's Hospital, Manchester). A purposive sampling strategy was used to recruit women, who had experienced vaginal birth with or without PPH, and health professionals, with varying levels of experience in blood loss evaluation and PPH management. A snowball sampling strategy was used to recruit the birth partners of women participants. Phase one was completed from June to September 2014. All discussions were audio-recorded and transcribed verbatim. Data were managed using NVivo 10 qualitative data analysis software, which also supported the Framework approach to analysis and interpretation. Quantitative methods were used in phase two and involved 10 midwives and 11 obstetricians, recruited from Liverpool Women's Hospital, during February and March 2015. Two scenarios, one of fast and one of slow blood loss, were presented to the sample using clinical simulation with the NOELLE® childbirth simulator, in a pilot, randomised, cross-over study. Participants also completed three questions about the use of the NOELLE® mannequin for these types of scenarios. IBM SPSS Statistics version 23 software was used for quantitative data management and to estimate descriptive statistics. Numerical crossover data were copied into StatsDirect software, to perform the crossover analyses. Results: Women and birth partners were very perceptive to blood loss but felt ill-prepared for the reality of bleeding, with many experiencing negative emotional responses to both PPH and the lochia. Non-verbal communication from staff was used by women and their birth partners to interpret the seriousness of their blood loss. Health professionals: Recognition of PPH mainly occurs as an automatic response to the speed of blood flow. Volume of blood loss is often ascertained and used retrospectively after a PPH diagnosis, to validate the intuitive response and to guide and justify on-going decisions. This was confirmed by the simulation studies, where treatment was initiated at 100ml or less in all blood loss scenarios. Fast blood loss was more likely than slow blood loss to elicit a PPH response, despite volumes in the two groups being similar. Formal quantification of blood loss is not used routinely in practice. When it is used, values are often unofficially normalised to reflect health professionals' perceptions of the woman's clinical condition. Tools introduced to aid diagnosis, such as blood collection bags, routine weighing and the use of early warning scores, are not routinely used in the immediate post-birth period, especially if the woman and her blood loss are perceived to be normal. The tools are again used to validate intuitive feelings about blood loss and maternal condition. When they are used, the values are often modified if they contradict professional judgement. Conclusions: Women and birth partners want more information, open communication, and on-going support, to minimise the emotional impact of blood loss. For health professionals, the speed of blood loss is the crucial factor in PPH recognition rather than an accurate assessment of the volume of blood loss. The amount of visible blood is generally not initially interpreted as a volume, but is used to compare current blood losses to those previously witnessed. Experience therefore plays a crucial role in the decisions of whether blood loss is considered normal or excessive. Formal quantification of blood loss and regular recording of physiological observations do not occur routinely in the immediate post-birth period. Therefore, women with insidious blood loss can have delayed PPH diagnosis because they have a normal blood flow and exhibit minimal physiological changes, due to the compensatory mechanisms of shock. Often such women need to exhibit outward signs of physiological compromise, such as fainting or feeling unwell, before their physiological observations and blood loss are formally re-evaluated. Education of health professionals should highlight the common errors of judgement made during blood loss evaluation and provide feedback on cases of delayed recognition. Future research should examine normal postnatal bleeding in the hours following birth, and create visual aids for women to self-diagnose insidious blood loss. Training should focus on the skills of PPH recognition, particularly those with insidious blood loss and postnatal physiological assessments. Novel tools such as the shock index should be considered and evaluated as tools of assessment.

Background: Postpartum haemorrhage (PPH) remains a major cause of maternal mortality and morbidity, and in recent years there has been a temporal increase in the incidence of PPH and associated morbidities in resource rich countries. Individual risk factors for PPH have long been identified but the relative importance of each has been under explored and thus the potential for preventative strategies is unknown. Aim: The aim of this study was to, i) ascertain the incidence of PPH at various thresholds in a South of England population, ii) identify the relative importance of predictor variables associated with PPH at different blood loss thresholds and iii) identify the independent and cumulative association of prepregnancy, pregnancy acquired and intrapartum variables on estimated blood loss following birth. Methodology: A prospective observational study was undertaken in two maternity services. Estimated blood loss data for all women (n=10,213) were imported from NHS electronic summary records. A representative sample of cases (n=1897) was selected for review, using a weighted sampling strategy. Univariate analysis identified variables associated with mean estimated blood loss and PPH at various thresholds. Multivariate regression modelling assessed the association of sequentially acquired variables with PPH ≥500 ml, ≥1000 ml, and ≥1500 ml. Results: The incidence of PPH ≥500 ml, ≥1000 ml ≥1500 ml ≥2000 ml and ≥2500 ml was 33.9% (95%CI 31.4 to 36.5), 9.4% (95%CI 8.5 to 10.4), 4.0% (95%CI 3.4 to 4.6), 2.0% (95%CI 1.6 to 2.4) and 0.8% (95%CI 0.7 to 1.0) respectively. Incidence of PPH ≥1000 ml was investigated by mode of birth. The incidence for spontaneous vaginal birth (SVD) was 4.75% (95%CI0.37 to 3.7) and instrumental vaginal birth, 12.1% (95%CI 9.3 to 14.6). The incidence following abdominal birth was 18.2% (95%CI 15.8 to 20.7); elective CS 11.8% (95%CI8.9 to 14.5), emergency CS 22% (95%CI18.6 to 25.4). Multiple regression analyses identified different independent variables associated with overall PPH at different thresholds. Novel independent variables resulting from this study associated with PPH at varying levels, were Black African ethnicity (≥500 ml and ≥1000 ml) OR 1.68 (95%CI 1.23 to 2.28) and OR 1.50 (95%CI1.13to 1.98), assisted conception (≥500 ml) OR 3.80 (95%CI1.69 to 8.57), antenatal attendance feeling ‘generally unwell’ (≥500 ml) OR 2.03 (95%CI1.18 to 3.49), antenatal steroid administration for fetal reasons (≥1500 ml) OR 2.00 (95%CI 1.17 to 3.41). In addition some previously known variables were confirmed. These were the impact per unit of BMI (Kg/m2) OR 1.04 (95%CI 1.01 to 1.04); previous PPH (≥500, ≥1000, ≥1500) 2.75 (95%CI1.40 to 5.44) 1.88 (96%CI 1.13 to 3.11) 2.39 (95%CI1.33 to4.28) multiple pregnancy (≥1000, ≥1500) 2.33 (95%CI1.23 to 4.41) 2.60(95%CI1.27 o 5.38) retained placenta (≥1000) 7.51 (4.08 to 13.8), interval to suturing (≥1000 ml) 1.74 (95%CI1.46 to 2.08). There was also a liner association with maternal temperature in labour and level of PPH. Conclusion: This study found higher rates of PPH at all thresholds and, with all modes of birth. Which is not fully explained by rising Caesarean section rates. Prepregnancy and pregnancy acquired variables are commonly mediated through intrapartum events, and previous pregnancy management can impact on blood loss in subsequent pregnancies. Novel variables found in this study require further investigation, particularly the impact of Black African ethnicity, assisted conception techniques, antenatal steroid administration, and, feeling “generally unwell”. Modifiable risk factors include preconceptual weight loss, expedient suturing of genital tract trauma and regular recording of maternal temperature in labour, which may alert staff to higher risk of PPH.

The current thesis examined whether sex-differences in local and whole-body heat loss are evident after accounting for confounding differences in physical characteristics and rate of metabolic heat production. Three experimental studies were performed: the first examined whole-body heat loss in males and females matched for body mass and surface area during exercise at a fixed rate of metabolic heat production; the second examined local and whole-body heat loss responses between sexes during exercise at increasing requirements for heat loss; the third examined sex-differences in local sweating and cutaneous vasodilation to given doses of pharmacological agonists, as well as during passive heating. The first study demonstrates that females exhibit a lower whole-body sudomotor thermosensitivity (553 ± 77 vs. 795 ± 85 W•°C-1, p=0.05) during exercise performed at a fixed rate of metabolic heat production. The second study shows that whole-body sudomotor thermosensitivity is similar between sexes at a requirement for heat loss of 250 W•m-2 (496 ± 139 vs. 483 ± 185 W•m-2•°C-1, p=0.91) and 300 W•m-2 (283 ± 70 vs. 211 ± 66 W•m-2•°C-1, p=0.17), only becoming greater in males at a requirement for heat loss of 350 W•m-2 (197 ± 61 vs. 82 ± 27 W•m-2•°C-1, p=0.007). In the third study, a lower sweat rate to the highest concentration of acetylcholine (0.27 ± 0.08 vs. 0.48 ± 0.13 mg•min-1•cm-2, p=0.02) and methylcholine (0.41 ± 0.09 vs. 0.57 ± 0.11 mg•min-1•cm-2, p=0.04) employed was evidenced in females, with no differences in cholinergic sensitivity. Taken together, the results of the current thesis show that sex itself can modulate sudomotor activity, specifically the thermosensitivity of the response, during both exercise and passive heat stress. Furthermore, the results of the third study point towards a peripheral modulation of the sweat gland as a mechanism responsible for the lower sudomotor thermosensitivity in females.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The production and export of ostrich meat from southern Africa, to especially the European Union, are increasing rapidly due to the healthy nature of ostrich meat. The European Union has very high standards when importing food products, and it is inevitable that more emphasis is being placed on the production of high quality ostrich meat. Another aspect also of concern to consumers, is the welfare of animals prior to slaughter, and this forces producers to look at ways to decrease stress of animals during the ante-mortem period. Research regarding the effect of stress during the ante-mortem period, and as a result, on meat quality, haematology and weight loss in ostriches, is lacking and thus the purpose of this study was to investigate the effect of various transport distances, travel conditions and different birds on these factors. Ante-mortem stress was measured using serum corticosterone levels (ng/ml), heterophil: lymphocyte (H:L) ratio, white blood cell (WBC) count, aspartate aminotransferase (AST) and creatine kinase (CK), as well as the rate and extent of pH decline in the M. gastrocnemius. Special emphasis was also placed on the meat quality parameters drip loss, cooking loss, colour and Warner-Bratzler shear force (kg/1.27 cm diameter). Live weight losses, as well as carcass weight and weight of bruises cut off from each bird were also recorded during various stages of the trials. The effect of transport distance on the meat quality of ostriches was investigated. Ultimate pHu measurements were taken at 24 hours post-mortem. The muscles of the ostriches from the control group (i.e. birds that were not transported prior to slaughter) had a lower mean pHu (5.77 ± 0.053) than birds that travelled 60 (5.93 ± 0.053) and 600 km (6.11 ± 0.053), respectively. Differences in meat drip loss percentage were also observed between the three treatments. The birds in the control group (0.40 ± 0.07 %) had the lowest meat drip loss percentage compared to the birds that travelled 60 km (treatment C) (1.36 ± 0.07 %) and 600 km (treatment B) (0.97 ± 0.07 %), respectively, to a commcerical ostrich abattoir. Ostriches that were transported for 600 km (8.13 ± 1.16 %) had a greater percentage live weight loss during the antemortem period than birds that travelled a distance of 60 km (2.4 ± 2.185 %) to the abattoir, although both groups were deprived of feed for the same period. When the haematology of the groups that travelled different distances was compared at various time intervals in the ante-mortem period, both groups of birds experienced significant increases in WBC, s-AST and s-CK. An increased H:L ratio from pre-transport to post-transport was only evident in the birds that travelled 600 km (treatment B). However, the birds that travelled 60 km were the only group of birds that had significant elevated serum corticosterone levels during the ante-mortem period. The increase in the various blood parameters indicates severe physical stress, which negatively affected meat quality. Another trial also investigated the effect of various farming systems and transport on meat quality and bruising of ostrich carcasses. Ostriches were raised in three different farming systems, i.e. feedlot -, semiintensive - and free range conditions. Other factors that could maybe impact on stress susceptibility, such as road conditions, floorspace and floor type were also investigated. A significant difference in meat pHu was found between ostriches that were raised in a feedlot (5.95 ± 0.018) and semi-intensive (6.04 ± 0.033) environment. The feedlot birds also had the greatest percentage of carcass weight removed due to bruising. The free range birds were the birds that had the lowest floor density per birds and also had the least amount of bruising on their carcasses. Incidently the other two groups (feedlot and semi intensive) were the birds that travelled on the same type of road (mountain pass) in a truck with rubber flooring whilst the free range birds travelled on a straight road in trucks with metal grid floors.The results indicate that the type of farming system didn’t have a significant influence on meat quality of ostriches, but that factors such as road conditions, flooring and bird density did play a significant role in the incidence of bruises and injuries obtained during transport.
AFRIKAANSE OPSOMMING: Die produksie en uitvoer van volstruisvleis vanuit suidelike Afrika, na veral die Europese Unie, is gedurig aan die toeneem as gevolg van die gesonde aard van volstruisvleis. Die Europese Unie het baie hoë standaarde wanneer dit kom by die invoer van voedselprodukte en dit is onvermydelik dat meer klem op die produksie van hoë gehalte volstruisvleis gelê word. ʼn Ander aspek wat ook kommer wek by verbruikers is die welstand van diere voor slagting en hierdie aspek noodsaak produsente om te kyk na maniere om stres te beperk tydens die periode voor slagting. Navorsing rakende die effek van stres tydens die ante-mortem periode, asook vleiskwaliteit, hematologie en gewigsverlies in volstruise as gevolg van vervoer, ontbreek. Die doel van die studie was dus om die invloed van verskillende vervoerafstande, vervoersomstandighede en tipe produksiesisteme op volstruise se stresrespons te ondersoek. Die omvang van ante-mortem stres is bepaal deur die serum-kortikosteroon vlakke (ng/ml), heterofiel: limfosiet (H:L) ratio, witbloedsel (WBS) telling, aspartaat aminotransferase AST en creatien kinase CK, asook die tempo en vlak van pH-daling in die M. gastrocnemius, te meet. Spesiale klem is gelê op die vleisgehalte parameters kookverlies, drupverlies, kleur en Warner-Bratzler-skeurwaardes (kg/1.27 cm deursnee). Gewigsverlies is aangeteken op verskillende stadiums tydens die proewe. Karkasgewigte en die hoeveelheid gewig afgesny van elke volstruiskarkas a.g.v. kneusings is ook bepaal. Die eerste studie het die invloed van vervoerafstand op vleiskwaliteit van slagvolstruise ondersoek. Vleis kwaliteit parameters soos pH, drip verlies, kook verlies, taaiheid en kleur is ondersoek. Die pHu metings is op 24 uur post-mortem geneem. Slagvolstruise in die kontrole groep (d.i. -volstruise wat nie voor slagting vervoer is nie) het ’n laer vleis pHu (5.77 ± 0.05) gehad as voëls wat onderskeidelik 60 km (5.93 ± 0.05) en 600 km (6.11 ± 0.05) ver vervoer is. Verskille in persentasie dripverlies is gesien tussen die vleis van die voëls wat nie vervoer is nie (0.40 ± 0.07 %) en die voëls wat 60 km (1.36 ± 0.07 %) en 600 km ver (0.97 ± 0.07 %) onderskeidelik vervoer is. Volstruise wat vir 600 km (8.13 ± 1.16 %) vervoer is, het ‘n groter persentasie lewende gewig tydens die ante-mortem periode as voëls wat 60 km (2.4 ± 2.19 %) ver vervoer is na die abattoir, verloor, al was beide groepe weerhou van voer vir dieselfde tydperk. Beide groepe wat vervoer is (60 en 600 km) het merkbare toenames in witbloedsel (WBS) tellings, s-AST’s en s-CK’s getoon tydens die ante-mortem periode. Daar is slegs ʼn toename in H:L ratio (ʼn indikator van stres) van voor vervoer tot na vervoer gesien in die voëls wat 600 km vervoer is. Daarteenoor was die voëls wat slegs 60 km vervoer is die enigste voëls wat ʼn toename in korticosteroon vlakke getoon het gedurende die ante-mortem periode. Die toenames is heel moontlik ‘n aanduiding van erge fisiese stres wat ‘n negatiewe effek op vleiskwaliteit het. Die tweede studie het die effek van verskillende produksiesisteme en die stress respons van die verskillende groepe slagvolstuise op vervoer ondersoek. Vleis kwaliteit parameters soos pH, drip verlies, kook verlies en taaiheid is ondersoek. Die hoeveelheid kneusings per volstruis is ook gemeet. Daar was ‘n beduidende verskil (P = 0.009) tussen die pHu van die voerkraal (5.95 ± 0.018) en semi- intensiewe (6.04 ± 0.033) volstruise. Die voerkraal volstruise se vleis het die grootste drip- en kookverliese gehad in vergelyking met die ander twee groepe (semi-intensiewe en ekstensiewe) terwyl die ekstensiewe volstruise die taaiste vleis gehad het. Die voerkraalvoëls het ook die grootste persentasie karkasgewig verloor a.g.v. kneusings wat afgesny is. Die ekstensiewe voëls het die laagste vloer digtheid per volstruis gehad asook die minste kneusings. Die ander twee groepe (voerkraal en semi intensief) was die groepe wat op dieselfde pad vervoer is (bergpas) in vragmotors wat rubber vloere gehad het terwyl die ekstensiewe voêls op ‘n reguit pad vervoer is in ‘n vragmotor met ‘n metaal oppervlakte. Die resultate van die studie is ‘n aanduiding dat die tipe plaassisteem nie ‘n groot impak op die hoeveelheid akute stres ervaar deur die voëls tydens vervoer gehad het of gevolglik op die vleiskwaliteit van die volstruise nie, maar dat faktore soos pad toestand, tipe vloer en voëldigtheid wel ‘n wesenlike rol speel in die voorkoms van kneusings en beserings opgedoen tydens vervoer.

Exercise and/or heat-induced dehydration is associated with decreases in plasma volume (hypovolemia) and increases in plasma osmolality (hyperosmolality), which are thought to stimulate peripheral baroreceptors and central osmoreceptors respectively. Independently, plasma hyperosmolality and baroreceptor unloading have been shown to attenuate sweating and cutaneous vasodilation during heat stress, and therefore, negatively impact body temperature regulation. However, to date little is known regarding the combined influence of plasma hyperosmolality and baroreceptor unloading on thermoefferent activity. Therefore, we evaluated the separate and combined effects of baroreceptor unloading (via lower body negative pressure, LBNP) and plasma hyperosmolality (via infusion of 3% NaCl saline) on heat loss responses of sweating and cutaneous vascular conductance (CVC) during progressive whole-body heating. We show that the combined nonthermal influences of plasma hyperosmolality and baroreceptor unloading additively delay the onset threshold for CVC, relative to their independent effects. In contrast, baroreceptor unloading has no influence on the sweating response regardless of osmotic state. These divergent roles of plasma hyperosmolality and the baroreflex on heat loss responses might serve to enhance blood pressure and body core temperature regulation during dehydration and heat stress.

Contact mechanics of rough surfaces and surface wear will be considered. Two types of failures are considered. The first involving rapidly growing failure and the second fatigue type surface failure as a result of repetitive application of load cycle. The first type of failure will be identified based on surface hysteresis energy loss in a load/unload cycle or examination of fracture toughness of the material near its rough surface. The above approach will be used to examine both types of failure in joint implants in the human body. These include consideration of implants for hip, ankle, spine and knee. In this case rapid and/or fatigue failures will be considered and related to anticipated implant life cycle based on implant recipient's tolerance level. Hence surface fidelity in terms of the biological host's tolerance of toxicity level due to wear will be used to develop life cycle prediction of an implant. The second application, rapid and fatigue wear will be examined in commonly used mechanical systems that include spur and helical gearing and rolling element bearings.

ABSTRACTBackground: Determination of blood loss can be a crucial factor at surgical procedures, especially when the amount of blood is small and mixed with other fluids. The existing methods to measure this are still not supported with evidence enough.Aim: To validate the accuracy of the HemoCue® system (HemoCue, Ängelholm, Sweden) at estimation of blood loss in a setup where blood is mixed with saline and saliva.Materials and methods: The haemoglobin concentration of defibrinated horse blood was measured using the haematology analysers Hemocue® 201+ and Hemocue Plasma/Low Hb Photometer. Series of non-diluted blood (control) and blood diluted with saline and saliva (test) were conducted to mimic a clinical situation at oral and maxillofacial surgical treatment. Following each dilution, a new measurement of the haemoglobin concentration was performed using the appropriate haematology analyser to measure the blood loss.Results: There were no statistically significant differences regarding the measured Hb concentration in relation to the degree of dilution. The accuracy of measured blood volume in the diluted and non-diluted blood (control) was within a level of ± 11,5%.Conclusion: The measurement of haemoglobin concentrations in a mixture of blood, saline, and saliva, proved to be accurate when compared to non-diluted blood. It is suggested that the HemoCue® system can be applied in the field of oral and maxillofacial surgery to improve the accuracy of the blood loss measurement.

A blood transfusion may have important immunomodulatory effects and may carry certain risks which could be detrimental to the kidney transplant patient. The aim of this project is to examine the potential risks associated with post-transplant blood transfusions in kidney transplant recipients. We carried out a retrospective cohort study of all adult kidney transplant recipients at The Ottawa Hospital from 2002 to 2018 inclusive. We examined the risks for kidney transplant rejection, graft loss, death, infections and venous thromboembolic events (VTE) associated with the receipt of red blood cell transfusions (RBCTs) administered after kidney transplant. We calculated hazard ratios (HR) using Cox proportional hazards model with RBCT as a cumulative, time-varying exposure. Out of a total study population of 1,258 kidney transplants recipients, 37% received at least one RBCT. The receipt of a RBCT was not significantly associated with the risk for rejection, however it was associated with an increased risk for graft loss, death, infection and VTE. Important biases such as reverse causation and unmeasured confounding may account for some of these findings. That being said, our findings suggest clinicians should be judicious in their use of RBCT in kidney transplant patients.

This study sought to determine the independent influence of hypoxia on thermoregulatory responses to exercise in compensable and uncompensable hot conditions. Eight participants completed three experimental trials of cycling in either normoxia (21% O2) or hypoxia (13% O2) in order to manipulate relative exercise intensity (%VO2peak), since VO2peak was reduced by ~30% in hypoxia. When trials were matched for %VO2peak, changes in core temperature and local sweat rates (LSR) were significantly lower in the hypoxic trial as a result of a lower rate of metabolic heat production (Hprod) in order to maintain a similar %VO2peak compared to normoxia. However, when Hprod was fixed between normoxic and hypoxic trials the systematic differences in core temperature and LSR were eliminated. Conversely, at a fixed Hprod skin blood flow (SkBF) was greater in hypoxia compared to normoxia by ~40%. Despite improvements in SkBF, the potential for maximum heat loss was unaffected during an incremental humidity ramp protocol, resulting in no difference between normoxia and hypoxia in the critical ambient vapour pressures at which core temperature inflected upwards. These data further demonstrate, using a within-subjects design, that metabolic heat production, irrespective of large differences in %VO2peak, determines thermoregulatory responses during exercise. Furthermore, this study suggests that the influence of large differences in skin blood flow on heat dissipation may be lesser than previously thought.

A pressão sanguínea é responsável pela manutenção de importantes funções corpóreas. Uma perda de sangue que leve à queda brusca dessa pressão resulta em ineficiente perfusão tecidual e, consequentemente, em déficit de oxigênio e acúmulo de metabólitos. Quando em excesso, a perda sanguínea pode levar o paciente ao choque e a complicações anestésicas e cirúrgicas. O uso de um fármaco antifibrinolítico, como o ácido tranexâmico, pode minimizar o sangramento transoperatório, e é preferível à transfusão sanguínea. Este composto já é amplamente utilizado em cirurgias ortopédicas humanas, que apresentam alto grau de sangramento e geralmente requerem a transfusão sanguínea. O objetivo deste trabalho é avaliar a eficácia da utilização do ácido tranexâmico em cães submetidos a cirurgias com grande potencial de perda sanguínea. Foram incluídos 21 cães com ruptura de ligamento ou luxação de patela, com necessidade de osteotomia corretiva, distribuídos em 2 grupos. O primeiro grupo recebeu ácido tranexâmico em bolus, no momento da indução, na dose de 10 mg/kg seguido de infusão contínua na taxa de 1 mg/kg/hora já o segundo recebeu solução salina 0,9% no volume correspondente ao volume do fármaco. A estimativa da perda sanguínea foi feita através da pesagem dos campos cirúrgicos, compressas e gases quando secos e, posteriormente, quando embebidos em sangue, além disso foram dosadas a concentração sérica de lactato, tempos de coagulação, hemograma e hemogasometria, nos dados momentos: TB (basal), T1 (1 hora após a indução anestésica) e T2 (imediatamente ao final do procedimento cirúrgico). Utilizou-se análise de variância para medidas repetidas (ANOVA), seguido pelos testes de Tukey e t-Student, valores de p<0,05 expressam diferença estatística. Não houve diferença estatística entre os grupos em relação a nenhum dos parâmetros avaliados exceto as idades dos animais que foram significativamente mais velhos no grupo GSF quando comparados ao grupo GAT, também não houve diferença em relação à quantidade de sangue perdida nos diferentes grupos. Sendo assim, o ácido tranexâmico não foi eficaz em diminuir a perda sanguínea em cães submetidos a osteotomias corretivas.
Blood pressure is responsible for the maintenance of important body functions. A blood loss leading to low blood pressure results in ineffective tissue perfusion, oxygen deficit and accumulation of metabolites. When in excess, blood loss can lead to hypovolemic shock and surgical and anesthetic complications. The use of an antifibrinolytic drug, such as tranexamic acid, can minimize bleeding during surgery, and it is preferable to blood transfusion. This drug is widely used in human orthopedic surgery, with a high degree of bleeding wich often requires blood transfusion. The aim of this study is to evaluate the effectiveness of the use of tranexamic acid in dogs undergoing surgery with great potential of blood loss. 21 animals with ruptured cruciate ligament or patellar luxation, undergoing corrective osteotomy, were divided in 2 groups. The first group received tranexamic acid as a bolus, at the time of induction, at a dose of 10mg/kg followed by continuous infusion at the rate of 1mg/kg/hour. The second group, received saline solution 0.9% in volume corresponding to the volume of the drug. The estimation of blood loss was made by weighing the surgical drapes and gauzes when dry and then when soaked in blood, besides was dosed in addition serum lactate, coagulation times, blood count and blood gas analysis at three specific moments during the procedure: TB (baseline), T1 (1 hour after anesthesia induction) and T2 (immediatly before the end of procedure. Statistical analysis was performed by ANOVA for repeated measurements, followed by Tukey and t-Students test, values with p<0,05 were considered significant. There were no statistical difference between the groups regarding any of the parameters except the ages of the animals that were significantly older at the GSF group when compared to the GAT group. Regarding the blood loss, there were no difference as well. Therefore the tranexamic acid was not effective in reducing blood loss in dogs undergoing corrective osteotomies.

Introduction: Total knee replacement (TKR) is a common orthopaedic procedure, with 20-70% of patients needing 1-3 units of blood, although allogeneic transfusion is not risk free. Tranexamic acid (TXA) is a synthetic antifibrinolytic agent used intravenously to stop bleeding in TKR and other surgical procedures. Objectives: To determine whether intra-articular TXA is effective, safe and cost-effective in reducing blood loss and subsequent blood transfusion after TKR. Design: This thesis describes three research projects to address the objectives: 1. A systematic review and meta-analysis of the use of intravenous (IV) TXA in TKR; 2. A randomised controlled trial of the topical (intra-articular) use TXA in TKR; 3. A biomechanical study of the effect of local TXA on TKR materials. Outcome measures: The primary aim of intra-articular TXA was to reduce the blood transfusion rate. Secondary outcomes included reduced blood loss, length of stay, complications and cost and improved functional outcome measures. To explore whether TXA degrades TKR materials, tensile properties, wear rate and surface topographic profile were biomechanically tested. Results: The systematic review found that IV TXA reduced blood loss and transfusion significantly but there was significant heterogeneity between trials. A first trial of topical (intra-articular) TXA in TKR found TXA to be effective and safe in reducing blood loss and transfusion. Thirteen patients (16.7%) were transfused in the placebo group versus 1 (1.3%) patient in the TXA group (c2; P=0.001). Blood loss was reduced from 465 ml in the placebo group to 297 ml in the TXA group (t-test; P=0.00025). TXA use resulted in a net cost saving of £333 per patient (P=0.044). There was no adverse effect of TXA on the biomechanical properties of the joint materials. Conclusion: Topically Applied TXA in TKR is effective, safe and cost-effective in reducing blood loss and transfusion in TKR, and avoiding the potential complications of intravenous administration.

Background: Despite advances in the treatment of atherosclerosis, cardiovascular disease is the leading cause of death worldwide. With the population getting older and more obese, the burden of cardiovascular disease may further increase. Premenopausal women are relatively protected against cardiovascular disease compared to men, but the reasons for this sex difference are partly unknown. Redistribution of body fat from peripheral to central depots may be a contributing factor. Central fat is associated with hyperlipidemia, hyperglycemia, hypertension, and insulin resistance. Two possible mediators of these metabolic disturbances are tissue-specific production of the stress hormone cortisol and adipose tissue blood flow (ATBF). The aim of this thesis was to determine the adipose tissue production of cortisol by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and to investigate the regulation of ATBF. Materials and Methods: Cortisol release was estimated by labeled cortisol infusions and tissue-specific catheterizations of subcutaneous and visceral adipose tissue (VAT) in men. We investigated ATBF by 133Xe-washout and its relation to autonomic activity, endothelial function, adipose tissue distribution, and adipokines in different groups of women. We further investigated the effect of two diets and of weight loss on ATBF in women. Results: We demonstrated significant cortisol release from subcutaneous adipose tissue in humans. Splanchnic cortisol release was accounted for entirely by the liver. Cortisol release from VAT (to the portal vein) was not detected. ATBF decreased according to increasing weight and postmenopausal status, and the level of blood flow was associated with nitric oxide (NO) activity and autonomic activity. ATBF was also highly associated with leptin levels and both subcutaneous adipose tissue and VAT areas. After 6 months of diet and weight reduction, a significant difference in ATBF was observed between diet groups. Conclusions: Our data for the first time demonstrate the contributions of cortisol generated from subcutaneous adipose tissue, visceral tissues, and liver by 11β-HSD1. ATBF is linked to autonomic activity, NO activity, and the amount of adipose tissue (independent of fat depot). Postmenopausal overweight women exhibited a loss of ATBF flexibility, which may contribute to the metabolic dysfunction seen in this group. Weight loss in a diet program could not increase the ATBF, although there were ATBF differences between diet groups. The results will increase understanding of adipose tissue biology and contribute to the development of treatment strategies targeting obesity and obesity-related disorders.

Studies show that vasomotor and sudomotor activity is compromised in individuals with Type 1 Diabetes (T1DM) which could lead to altered thermoregulatory function. However, recent work suggests that the impairments may only be evidenced beyond a certain level of heat stress. We therefore examined T1DM-related differences in heat loss responses of sweating and skin blood flow (SkBF) during exercise performed at progressive increases in the requirement for heat loss. Participants were matched for age, sex, body surface area and fitness cycled at fixed rates of metabolic heat production of 200, 250, and 300 W•m-2 of body surface area, each rate being performed sequentially for 30 min. Local sweat rate (LSR), sweat gland activation (SGA), and sweat gland output (SGO) were measured on the upper back, chest and forearm while SkBF (laser-Doppler) was measured on the forearm and upper back only. We found that despite a similar requirement for heat loss, LSR was lower in T1DM on the chest and forearm only, relative to Control and only different at the end of the second and third exercise periods. Differences in chest LSR were due to reduced SGA whereas the decreased forearm LSR was the result of a decrease in SGO. SkBF did not differ between groups. The reduction in the sweating response in the T1DM group was paralleled by a greater increase in core temperature. We show that T1DM impairs heat dissipation as evidenced by reductions in LSR and not SkBF. A compromised thermoregulatory response during and following physical exertion is of considerable concern due to the associated increased risk of post-exertion heat-related injury.

The effect of comprehensive weight reduction program on selected blood parameters, body composition, and nutrient intake was investigated in 56 obese black women, 22 to 51 years old. Subjects attended nutrition and behavior modification classes once per week for 3 months. Twenty subjects participated in a low impact aerobics programs 3 times per week for 3 months. A 3.8 kg average weight loss was observed. A 2.6% significant reduction in body fat (BF) was observed in the exercise group. Total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) fell significantly from 198 to 175 mg/dL, and 130 to 109 mg/dL, respectively, in the exercise group. High density lipo-protein2-cholesterol (HDL2-C) was lowered significantly from 24 to 17 mg/dL in the non-exercise group. Triglycerides, HDL-C, TC/HDL-C ration, glucose, thyroxin, and insulin values were not significantly altered. Significant reductions in protein, fat, and cholesterol intake were reported. A comprehensive weight loss treatment promoted gradual weight loss, changes in body composition and food intake patterns, and significantly altered some blood lipid levels in obese black females.
Master of Science

Objective. To examine the effect of six months of Topiramate (TPM) supplementation use for weight loss on ambulatory blood pressure (ABP) in abdominally obese males. Methods. Sixty-eight abdominally obese males (Waist circumference >100 cm) with a BMI >27 and < 35 kg/m2 were assigned to the TPM or placebo group using a randomized pretest-posttest control group design with no behavioral modification. This was followed by a 12-week titration period and a 12-week stabilization period with a dosage up to 400 mg/d. Ambulatory blood pressure was monitored at baseline and at six months using the Spacelabs Medical Model 90207-31. Results. Topiramate supplementation group showed a significant decrease in systolic (5.2 +/- 9.79; p=0.006, -4.6 +/- 10.90; p=0.011 and -6.9 +/- 8.31; 0.003 mmHg) and diastolic (-3.7 +/- 6.13; p =0.006, -3.3 +/- 7.08; p=0.033 and -4.3 +/- 7.13; p=0.006 mmHg) 24-hr, daytime and nighttime ABP respectively. However, after performing an ANCOVA to control for the significant weight loss observed in the TPM supplementation group (-3.19 +/- 5.72 kg; p=0.006), systolic/diastolic 24-hr (p=0.233/0.147), daytime, (p=0.313/0.276) and nighttime (p= 0.108/0.187) changes in ABP were similar between the TPM and placebo group. Furthermore, change in systolic 24-hr ABP was significantly correlated to changes in % body fat (r=0.54; p=0.025), body fat mass (r=0.51; p=0.039) and total abdominal adipose tissue (r=0.46; p=0.043), whereas change in diastolic 24-hr ABP was significantly correlated to changes in total abdominal adipose tissue (c=0.51; p=0.043). Change in visceral adipose tissue (VAT) was not significantly related to changes in systolic/diastolic ABP (r=0.46/0.41; p=0.075/0.113) respectively. Discussion. These results suggest that the reduction in ABP observed in the TPM is mainly secondary to the reduction in body weight, especially the reduction in fat mass and total abdominal adipose tissue and not by the mechanistic abilities of the drug.

Blood-brain barrier breakdown is a common feature of neuroinflammatory diseases, such as multiple sclerosis (MS). Indeed, blood proteins may play a role in the pathology of the disease. Here we investigate the link between the presence of blood-borne components in the CNS parenchyma and the expression of neurological deficits. Male Sprague-Dawley rats were injected intraspinally with vascular endothelial growth factor (VEGF), which causes breakdown of the blood-brain barrier, or saline as control. The injection was made unilaterally at the T13 – L1 junction, namely the spinal level that controls hind limb movement. In VEGF-injected animals alone, hind limb motor and sensory deficits consistently appeared at day two after surgery, but not at days 1 or 3 (onwards), as assessed by behavioural and locomotor tests (horizontal ladder test, walking treadmill, von Frey hair test, inclined plane, burrowing). Histological examination revealed the presence of a blood-brain barrier leakage within the spinal cord as assessed by the presence of extravascular IgG and fibrinogen. Activated microglia/macrophages (ED1 + , MHC class II + and OX-42 + cells) were present at the injection site, peaking at day two, along with activated astrocytes. The mechanism responsible for the neurological deficit was investigated by attempting to antagonize specific VEGF signalling pathways, assessing a potential hypoxic state using immunohistochemical techniques, and characterizing neuronal excitability by electrophysiological methods. VEGF injection provokes opening of the blood-brain barrier which is temporally and spatially associated with neuroinflammation and loss of function. The findings indicate a potential mechanism underlying loss of function in inflammatory neurological diseases such as MS.

Introdução: A desmopressina, análogo sintético do hormônio hipotalâmico vasopressina, é utilizada em determinadas condições hematológicas hereditárias melhorando a função plaquetária e aumentando os níveis dos fatores de von Willebrand (FvW) e Fator VIII. Entretanto, sua administração na população geral é controversa, necessitando de mais estudos para elucidar sua eficácia como agente hemostático. Objetivo: O objetivo do presente estudo foi avaliar a coagulação sanguínea, clínica e laboratorialmente, após administração profilática da desmopressina em cirurgias cardíacas valvares. Métodos: Estudo clínico prospectivo e randomizado realizado no Instituto do Coração (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC-FMUSP). Foram incluídos 108 pacientes adultos submetidos à cirurgia cardíaca valvar, no período de fevereiro de 2015 a novembro de 2016. Os pacientes foram randomizados e alocados para a administração profilática da desmopressina ou para o grupo controle, na admissão hospitalar. Imediatamente após a reversão da heparina, administrouse a demopressina no grupo da intervenção ou solução placebo no grupo controle. O desfecho foi a análise da coagulação sanguínea e do sangramento perioperatório através dos exames laboratoriais, débito sanguíneo dos drenos cirúrgicos e do consumo de hemocomponentes em 48 horas. Resultados: Os níveis sanguíneos do Fator VIII no tempo 2h (236,5 ± 62,9 vs. 232,3 ± 66,7, P=0,015) foram estatisticamente significantes entre os dois grupos (DDAVP e controle), respectivamente. Os demais testes clássicos da coagulação, assim como a análise viscoelástica e de agregação plaquetária mantiveram-se homogêneos em todos os tempos de coleta entre os dois grupos. O débito dos drenos cirúrgicos, balanço sanguíneo e consumo de hemocomponentes não apresentaram diferenças significantes entre os grupos DDAVP e controle. O tempo de ventilação mecânica apresentou diferença relevante entre os grupos DDAVP e o controle [897 (820 - 1011) vs. 1010 (846 - 1268), em mim, P=0,031], respectivamente. Não houve diferença em relação à incidência de complicações, tempo de internação hospitalar e de UTI ou mesmo de mortalidade em 30 dias. Conclusões: A utilização profilática da desmopressina em cirurgias cardíacas valvares não se mostrou eficaz em exercer efeito hemostático em relação ao grupo controle no presente estudo
Introduction: Desmopressin, a synthetic vasopressin analogue, is used in certain hereditary hematologic conditions, improving platelet function and increasing the levels of von Willebrand factor and factor VIII. However, its use in general population is still controversial, requiring further studies to elucidate its efficacy as a haemostatic agent. Objective: To evaluate blood coagulation, through clinical and laboratorial analysis, after prophylactic use of desmopressin in heart valve surgeries. Methods: A prospective and randomized clinical study was performed in the Heart Institute (InCor) of Hospital das Clínicas, from the Faculty of Medicine, University of São Paulo (HC-FMUSP). A total of 108 adult patients undergoing heart valve surgeries were enrolled from February 2015 to November 2016. Patients were randomly assigned to the prophylactic use of desmopressin or to the control group at the time of hospital admission. Immediately after heparin reversal, demopressin was given in the intervention group or placebo solution in the control group. Blood samples were collected at three different times in all study participants. Blood coagulation and perioperative bleeding were analysed using laboratorial tests, blood flow through surgical drains and the consumption of blood components within 48 hours. Results: Blood levels of Factor VIII at Time 2h (236.5 ± 62.9 vs. 232.3 ± 66.7, P=0.015) were significantly different between the two groups (desmopressin and control), respectively. Classical coagulation tests, as well as viscoelastic and platelet aggregation tests, remained homogeneous at all collection times between the two groups. Flow rate of surgical drains, blood balance and consumption of blood components did not present significant differences between the DDAVP and control groups. Mechanical ventilation time presented a significant difference between the desmopressin and control groups [897 (820 - 1011) vs.1010 (846 - 1268), min, P=0.031], respectively. There was no difference in incidence of complications, length of hospital and ICU stay or even mortality in 30 days. Conclusions: The prophylactic use of desmopressin in heart valve surgeries was not effective in exerting haemostatic effect compared to the control group in this study

The principal objective of this study was to examine the effect of intense physical exercise on menstrual blood loss in women with Type I von Willebrand disease (vWD). First, we investigated the effect of exercise on the level of the von Willebrand protein (which is deficient in the disease) in a pre-test post-test quasi-experiment conducted on a single group of 40 healthy adult pre-menopausal female volunteers recruited from Sainte-Justine Hospital in Montreal between October and December, 2001. The von Willebrand protein (vWF:Ag), coagulation Factor VIII (FVIII:C), bleeding time (BT), coagulation time (aPTT) and several markers of exercise intensity (sweat sodium, lactate, noradrenaline, adrenaline) were measured before and after a standardized exercise session. The significance of the change in these values with exercise was assessed using a paired Student's t-test. The exercise markers were explored as potential predictors of the exercise-related change in vWF:Ag using multiple linear regression. Results showed that there was an absolute mean increase of 0.30 (95% confidence interval (95% CI) 0.23-0.37) and 0.60 (95% CI 0.44-0.76) in vWF:Ag and FVIILC, respectively, and a significant shortening of the BT and aPTT due to exercise. The change in the sweat sodium collected from patches applied to the forearm during exercise (a marker of exercise intensity) was found to be a significant predictor of the change in vWF:Ag induced by exercise (regression coefficient = 0.05 (95% CI 0.01-0.09). Changes of 1, 5 and 10 units in sodium were associated with average changes of 0.05, 0.26 and 0.52, respectively, in vWF:Ag from baseline (mean 0.83 U/ml). Next, we set out to assess the feasibility and acceptability of a 4-period randomized crossover trial in order to evaluate the effectiveness of exercise in reducing the menstrual blood flow in women with Type I vWD. The methods and protocol of this feasibility study are outlined in this thesis and issues related to patient recruitment, compliance and withdrawals are addressed. The strengths and pitfalls of the crossover design feasibility study are discussed and revisions for the definitive trial are recommended.

The current study evaluated whether NO synthase (NOS) contributes to cutaneous vasodilation and sweating during prolonged exercise in the heat. In addition, we determined if prolonged exercise-induced increases in reactive oxygen species (ROS) and activation of angiotensin II type 1 receptors (AT1R) impair heat loss responses. On two separate days, eleven young men completed 90-min of continuous cycling at ~600W of metabolic heat production followed by 40-min of recovery in the heat (40ºC). To evaluate the role of excess fluid loss via sweating, participants completed a second session of the same protocol while receiving fluid replacement (FR) determined during the first session (No-FR). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with either: (1) lactated Ringer (Control); (2) 10 mM NG-nitro-L-arginine methyl ester (L-NAME, NOS inhibition); (3) 10 mM ascorbate (non-selective anti-oxidant); or (4) 4.34 nM Losartan (AT1R inhibition). Ascorbate treatment increased CVC at 60- and 90-min of exercise versus Control during the FR (P < 0.02), but not the No-FR condition (P > 0.31). CVC was reduced at the L-NAME treated site (P < 0.02), but was not different relative to Control at the Losartan treated site (P > 0.19) irrespective of condition. LSR did not differ between sites or as a function of condition (all P > 0.10). We conclude that NO regulates cutaneous vasodilation but not sweating, irrespective of fluid replacement, and ascorbate sensitive ROS impair cutaneous vasodilation during prolonged exercise in the heat with FR.

Chemerin is a chemoattractant adipokine that regulates adipogenesis and may induce insulin resistance. Chemerin serum concentrations are elevated in obese, insulin-resistant, and inflammatory states in vivo. Here we investigate the role of omental (OM) and subcutaneous (SC) adipose tissue chemerin and CMKLR1 messenger RNA (mRNA) expression in human obesity. In addition, we test the hypothesis that changes in chemerin serum concentrations are primarily associated with reduced body fat mass in the context of 3 weight loss intervention studies. Chemerin serum concentration was measured in 740 individuals in a cross-sectional (n = 629) study including a subgroup (n = 161) for which OM and SC chemerin mRNA expression has been analyzed as well as in 3 interventions including 12 weeks of exercise (n = 60), 6 months of calorie-restricted diet (n = 19) studies, and 12 months after bariatric surgery (n = 32). Chemerin mRNA is significantly higher expressed in adipose tissue of patients with type 2 diabetes mellitus and correlates with circulating chemerin, body mass index (BMI), percentage body fat, C-reactive protein, homeostasis model assessment of insulin resistance, and glucose infusion rate in euglycemic-hyperinsulinemic clamps. CMKLR1 mRNA expression was not significantly different between the 2 fat depots. Obesity surgery–induced weight loss causes a significant reduction on both OM and SC chemerin expression. All interventions led to significantly reduced chemerin serum concentrations. Decreased chemerin serum concentrations significantly correlate with improved glucose infusion rate and reduced C-reactive protein levels independently of changes in BMI. Insulin resistance and inflammation are BMI-independent predictors of elevated chemerin serum concentrations. Reduced chemerin expression and serum concentration may contribute to improved insulin sensitivity and subclinical inflammation beyond significant weight loss.

Despite the increasing prevalence of obesity and the array of treatment modalities available, maintenance of reduced-weight in the long-term is uncommon. The reason(s) why weightregain is so commonplace remains contentious. The primary purpose of this dissertation was to determine the extent to which weight-loss in obese adults, when the intervention included an optimal exercise prescription, resulted in adaptations that may be considered aberrant and reflect risk of weight-regain. Unique to this investigation was the multifactorial approach to addressing the issue of adaptation through consideration of metabolic, physiological, and psychosocial factors. Accurate body composition assessment is a fundamental requirement upon which evaluation of adaptation to weight-loss is based. An additional purpose of the dissertation was to evaluate multi-frequency bioelectrical impedance analysis (MFBIA) as a technique for use in assessing body composition change of obese adults during weight-loss. Further, optimal weight management requires an incorporation of effective exercise prescription. Therefore, a final aim of the dissertation was to determine the optimal exercise intensity for weight management. Together the goals of this thesis were addressed through a series of studies, the first three relate to use of bioelectrical impedance analysis; the fourth and fifth studies were associated with exercise prescription for obese adults; and the final study, incorporating three components, dealt with adaptation to weight-loss in the obese. In the first study, twenty-nine young healthy adults, 17 males and 12 females (mean± SEM; 21.8 ± 0. 7 yrs and 20.3 ± 0.3 yrs) were recruited to assess the technical reliability (i.e., interinstrument and inter-operator reliability) of three MFBIA monitors. Technical reliability was assessed for both errors of measurement and associated analyses. In addition, intra-operator and intra-instrument variability was evaluated for repeat measures over a 4-hour period. The measured impedance values from a range of resistance-capacitance circuits were accurate to within 3 percent of theoretical values over a range of 50- 800 ohms. Similarly, phase was measured over the range 1 degrees-19 degrees with a maximum deviation of 1.3 degrees from the theoretical value. The extrapolated impedance at zero frequency was equally well determined (+/-3 percent). However, the accuracy of the extrapolated value at infinite frequency was decreased, particularly at impedances below 50 ohms (approaching the lower limit of the measurement range of the instrument). The inter-instrument/operator variation for whole body measurements were recorded on human volunteers with biases of less than +/-1 percent for measured impedance values and less than 3 percent for phase. The variation in the extrapolated values of impedance at zero and infinite frequencies included variations due to operator choice of the analysis parameters but was still less than +/-0.5 percent. The second study investigated the effect of moving from standing to lying supine on blood and plasma volumes, serum electrolyte concentrations, and measurements of whole-body impedance using MFBIA over a 60 minute period in 12 subjects (8 males, 4 females) 26.7 ± 5.5 yrs, 172.3 ± 6.9 em, and 71.0 ± 7.7 kg. While no significant differences were found in serum sodium, chloride or potassium concentrations as a function of the posture change, estimates of both blood and plasma volumes increased during the 60 minutes spent supine. Blood volume increased by 10.5 (4.2 to 16.4)percent and plasma volume increased 10.5 (5.0 to 17.6)percent. Similarly, whole-body resistivity measured at 50 kHz increased significantly by 24.1 (6.3 to 36.5) Q in absolute values across the hour supine, with the measurement at 60 minutes reflecting a 4. 7 ( 1.3 to 6. 7)percent increase in resistivity from the baseline measure. Although the weight lost across the hour was only 0.11 (0.05 to 0.15) kg, the change in total body water estimated from resistivity measures is likely to be significantly larger. The results from this study reflect the need for implementation of a standardised preparatory rest time prior to taking BIA measurements, and demonstrate the limitations associated with a single frequency, whole-body approach for assessing body-fluid distribution. The purpose of the third study was to validate the use of MFBIA to determine change in body composition of obese adults during weight reduction by direct comparison with total body water as measured by stable-isotope dilution. Specifically, the study had three parts. Firstly, from the data obtained on the total sample at baseline, the aim was to develop a prediction equation for the estimation ofTBW from MFBIA. The second aim was to validate the prediction equation in a subsample during (wk-5) and after the completion of a 12-wk weight-loss intervention. The final aim of the study was to determine whether intervention type influenced the accuracy of TBW predicted by MFBIA. Multiple regression analysis revealed that the MFBIA-derived prediction equation prior to weight-loss was able to determine TBW with a SEE of 1.9L by combining the impedance index (Ht2/R10o), age, gender, and body weight. However, during weight-loss, the comparison of TBW predicted by MFBIA and measured with deuterium dilution had a much larger bias than after completion of the weight-loss intervention. It was further revealed that the magnitude of the bias was influenced by the intervention mode, with those individuals on a very-low-energy diet recording greater measurement bias. These results raise concern for the accuracy of MFBIA during periods of weight-loss in obese adults. In particular, weight-loss elicited through severe restriction in dietary intake appears most problematic. In contrast, the post-intervention TBW measures determined from the MFBIAequation derived at baseline had a mean difference of only 0.9L relative to the group mean derived by deuterium dilution. Further, using the impedance index alone post-intervention, the mean TBW measures were within 0.5L of the mean reference measure. In the fourth study the relative and absolute levels of exercise intensity corresponding with the lactate threshold (LT) and ventilatory threshold (Tvent) were determined in forty-two sedentary obese adults, 23 females and 19 males (42.9±1.8 yrs; 36.8±0.9 kg.m-2 ). Subjects were obese but otherwise healthy and taking no medication known to modifY heart rate. Subjects were required to attend a testing session each week for three weeks scheduled for the same time of day, and day of the week. The three sessions involved: (1) a treadmill test to assist in subject familiarisation. The test enabled researchers to gauge working capacity and enable subjects to become accustomed with the treadmill and gas analysis apparatus; (2) a discontinuous graded treadmill test to assess cardiorespiratory function; and (3) assessment of body composition and resting metabolic rate. On two separate occasions subjects undertook a discontinuous graded treadmill walking test consisting of 4-minute work stages separated by 2-minute rest periods. During the last 30 seconds of each work stage, subjects rated perceived exertion (RPE) using the Borg 6-20 scale. Immediately on completion of each work stage, duplicate blood samples were collected by finger prick, haemolysed in 1 OO)ll of chilled perchloric acid, and stored for later blood lactate analysis. Throughout both tests HR was recorded and respiratory gases were collected and analysed. Resting metabolic rate was assessed by indirect calorimetry using a ventilated hood system. The major finding of this study was that corresponding with LT and Tvent respectively, the relative intensities defined as percentV02R (63.4±1.4 percent; 63.8±1.8 percent), percent HRR (65.2±1.6 percent; 66.6±1.5 percent) and percent HRpeak (78.2±1.0 percent; 79.2±1.0 percent), and the absolute intensity defined by METs calculated physiologically would be categorised as "hard" by the current guidelines. In contrast, at L T and T vent the relative intensity defined by RPE (12.6±0 .2; 12.8±0.3), and absolute intensity defined by METs calculated from mechanical parameters (4.8±0.2; 5.0±0.2), fall into the "moderate" intensity category. Therefore, there is a need to redefine the descriptors of exercise intensity for the obese population. Further, linear regression analysis revealed a relatively strong negative relationship (r=-0.58, P<0.001) between HRLT and age , and the addition of gender to the regression analysis improved the strength of the prediction equation (HRLr = 145.6- 0.623* Age(yrs) + 9.824*Gender (M=l, F=2) r=-0.70, P<0.001). Importantly, the intensity thresholds tested were at a level well tolerated by the obese population, and considered to be of moderate intensity. The purpose of the fifth study was to identify optimal aerobic exercise intensity for obese adults and to compare this with the relative and absolute intensity categories outlined in current guidelines provided by the Surgeon General (U.S. Dept. HHS, 1996) and American College of Sports Medicine (ACSM, 1995; 1998). In particular, the equivalence between submaximal markers of exercise intensity, challenged recently in studies of trained and recreational athletes and chronic obstructive pulmonary disease sufferers, was evaluated for the first time in obese adults. Using a testing procedure outlined in Study 4, data was assessed from 32 obese adults (15 males and 17 females), 42.1 ± 1.7 yrs and 37.4 ± 1.0 kg.m-2. The study showed that in the obese [1] the percent HRpeak-percent V02peak relationship was significantly greater than ACSM recommendations; [2] the percent HRR was equivalent with percent V02R not percent V02peak; and [3] exercise prescription at fixed percentages of V02peak or HRpeak corresponded with wide ranges of exercise intensities in relation to LT. These results together with those from Study 4 demonstrated for the first time that current exercise prescription guidelines for the obese are too conservative, particularly where optimising the exercise-induced benefits for weight management are concerned. The final study was based upon the hypothesis that weight-regain is attributed more to behavioural adaptations than to compensatory metabolic processes. The purpose of this randomised-control intervention was to ascertain the extent to which metabolic, physiological, and psychosocial factors adapt in obese adults during a period of weight decrement. Additionally, it was hypothesised that metabolic adaptation is related to the rate of weight-loss, the mode facilitating the energy deficit responsible for the weight-loss, and the tissue composition of the weight that is lost. In particular the study goal was to determine what evidence there is that loss of body weight results in metabolic, physiological, or psychosocial adaptations that are aberrant. Forty-eight obese adults (22 males and 26 females) on average 42.9 ± 1.8 years, 107.2 ± 3.4 kg, and 36.8 ± 0.9 kg.m-2 were recruited. Subjects were matched for gender, age, and BMI before being randomly assigned to very-low-energy diet plus exercise (VLED+Ex), low-fat diet plus exercise (LF+Ex), or control (C) groups. In the first two weeks, subjects undertook two treadmill tests to determine cardiorespiratory capacity and the relationship between submaximal markers of exercise intensity at increasing workloads. In the third week, all subjects underwent testing of baseline measures of resting metabolic rate, body composition, thyroid hormone function, blood lipid profile, body satisfaction and self-reported health. After this period, subjects followed the VLED+Ex, LF+Ex or C program for the following 12 weeks. For VLED+Ex and LF+Ex body composition and metabolic measures were repeated after the 4th and 8th week of the intervention. All measurements were repeated in the week following completion of the intervention, week 16 of the study program. Forty-two subjects completed the 16-week study. Collectively, the results from the weight-loss intervention do not support the notion that weightloss in obese adults results in aberrant changes in metabolic, physiological or psychosocial variables that would in turn place the reduced-obese adult at risk of weight regain. In particular, perception of size for both males and females post-intervention was strongly related with body weight (r = 0.71 and r = 0.89 for males and females respectively), relative weight (r = 0.81, r = 0.86), and BMI (r = 0.81, r = 0.84). While positive correlations were found between the magnitudes of change in body size and body satisfaction, self-reported health improved and limitations to daily physical activity were reduced in both intervention groups when compared with the control group at the completion of the intervention period. Overall, there was no evidence with respect to psychosocial factors that the intervention and concomitant change in body size was perceived negatively, and in many respects the greater the change in body size the greater the perceived benefit. In terms of physiological adaptation, participation in 12 weeks of aerobic endurance and resistance weight training was positively reflected in improvements in cardiorespiratory fitness, with an average improvement in maximal aerobic capacity (L.min-1 ) of 17.7 percent and 13.1 percent in the VLED+Ex and LF+Ex groups respectively. The energy-cost of exercise at LT did not change significantly with weight-loss and thus exercise prescribed at LT for the reduced-obese adult would as effective for increasing energy expenditure through physical activity as was shown at baseline. Although not reaching statistical significance, the time required to expend the energy suggested as necessary for weight maintenance was reduced by an average of 9 percent and 8 percent in the VLED+Ex and LF+Ex groups respectively. In terms of metabolic adaptation, the findings were somewhat conflicting depending upon the manner of comparing energy expenditure in people before and after a change in body size. Data was analysed via four different statistical approaches cited in the literature. Analysis of covariance with FFM (the variable most strongly explaining the variance in RMR measures) as the covariate revealed no significant differences in RMR between groups at any time point during the study. Comparing the actual RMR-FFM regression lines for each group before and after the intervention revealed that the slopes and intercepts of the RMR-FFM relationships did not alter significantly after weight-loss. In contrast, the third and fourth series of analyses in which predicted and observed measures ofRMR were compared pre and post intervention, and the change in FFM related to change in resting oxygen consumption were compared, were conflicting. However, it was proposed that these somewhat conflicting results may be explained by the influence of the energetic contribution of organ tissue to total FFM energetics. As would be expected, during the intervention changes in RQ reflected the nature of the dietary intervention. However, unexpectedly at the completion of the intervention the group that lost weight most rapidly had an RQ that was not significantly different from the values at baseline. The findings do not support the notion purported by previous research that weight-loss, and in particular rapid weight-Joss, increases the reliance on carbohydrate oxidation in the reduced-obese state and thus increasing the risk of weight regain. It may be concluded from the RMR and RQ data that as a function of endurance exercise training the adverse consequences cited in studies where weight is lost through dietary restriction alone are ameliorated. Finally, the VLED+Ex group had significantly reduced concentrations offT4, T4, T3 and IT3 at the completion of the intervention relative to baseline. However, the change in hormone concentration was not related to the change in body weight or FFM for any of the hormones. Further, all subjects were euthyroid throughout the intervention. Therefore, while rapid weightloss results in statistically significant reductions in thyroid hormones, determining whether this reflects clinically significant and persistent down-regulation of endocrine function, and thus reduced metabolic potential, requires further investigation.

Na+/K+-ATPase has been shown to regulate the sweating and cutaneous vascular responses during exercise; however, similar studies have not been conducted to assess the roles of the Na-K-2Cl cotransporter (NKCC) and K+ channels. Additionally, it remains to be determined if these mechanisms underpinning the heat loss responses differ with exercise intensity. Eleven young (24±4 years) males performed three 30-min semi-recumbent cycling bouts at low (30% VO2peak), moderate (50% VO2peak), and high (70% VO2peak) intensity exercise, respectively, each separated by 20-min recovery periods. Using intradermal microdialysis, four forearm skin sites were continuously perfused with either: 1) lactated Ringer solution (Control), 2) 6 mᴍ ouabain (Na+/K+-ATPase inhibitor), 3) 10 mᴍ bumetanide (NKCC inhibitor), or 4) 50 mᴍ BaCl2 (non-specific K+ channel inhibitor); sites at which we assessed local sweat rate (LSR) and cutaneous vascular conductance (CVC). Inhibition of Na+/K+-ATPase attenuated LSR compared to Control during the moderate and high intensity exercise bouts (both P˂0.01), whereas attenuations with NKCC and K+ channel inhibition were only apparent during the high intensity exercise bout (both P≤0.05). Na+/K+-ATPase inhibition augmented CVC during all exercise intensities (all P˂0.01), whereas CVC was greater with NKCC inhibition during the low intensity exercise only (P˂0.01) and attenuated with K+ channel inhibition during the moderate and high intensity exercise conditions (both P˂0.01). We show that Na+/K+-ATPase, NKCC and K+ channels all contribute to the regulation of sweating and cutaneous blood flow but their influence is dependent on the intensity of exercise.

Introduction An ageing population presents challenges to health care, such as the increasing prevalence of osteoporosis and associated low trauma hip fractures. These types of fractures are usually repaired surgically, which in turn presents risks. It is estimated that 35- 67% of patients with hip fractures have low haemoglobin levels on-admission, which is associated with increased length of hospital stay, morbidity and mortality. Background Patients who present with low trauma hip fracture at the study site have haemoglobin levels taken on-admission but not again prior to surgery. It is not known whether an additional haemoglobin level prior to surgery may reduce hospital length of stay and improve patient outcomes. Aims To investigate whether the implementation of a preoperative haemoglobin blood test immediately before surgery would improve patient outcomes. Primary aim: To reduce acute hospital length of stay. Secondary aims: To reduce post-anaesthetic care unit length of stay, complications and in-hospital mortality. Methodology Research design: A before and after cohort study. Participants were recruited into three groups: retrospective, interventional and observational. The retrospective group and observational groups received usual care. The observational group comprised prospective patients without capacity to make informed consent. The interventional group received an immediate preoperative HemoCue test to determine haemoglobin levels. Participants and setting: A large tertiary centre in metropolitan Western Australia. 150 participants >50 years, were recruited intro three groups of 50 each. Data analysis: The trend of haemoglobin taken across five timepoints in the interventional group was compared with a one-way repeated measures ANOVA. Hospital length of stay and post-anaesthetic care unit length of stay was compared using a generalised linear model negative binomial test with log link that adjusted for age, gender and other covariates. Results There was a statistically significant mean difference in haemoglobin between preoperative haemoglobin and on-admission haemoglobin in the interventional group. In the interventional group a preoperative drop in haemoglobin of -13.25g/L (95% CI: -21.25- - 5.25, p < 0.001) occurred. The preoperative drop in haemoglobin was more significant than the drop in haemoglobin observed intraoperatively or on any day postoperatively. An additional preoperative haemoglobin blood test taken immediately prior to surgery did not reduce hospital length of stay or post-anaesthetic care unit length of stay and was not associated with intraoperative use of tranexamic acid or packed red blood cells. Hospital length of stay was 30% shorter for participants who had a consultant perform the operation. Post anaesthetic care unit stay was 1.40 times longer if the patient was transfused with packed red blood cells intraoperatively; 1.23 times longer if the patient received a general anaesthetic; and 1.75 times longer if the patient experienced any complication in the post-anaesthetic care unit. Conclusions Patients with hip fractures experience significant drops in haemoglobin level prior to surgery, likely due to acute-fracture related blood loss. A haemoglobin blood test immediately prior to surgery did not improve patient outcomes. Larger studies are required to investigate if a preoperative haemoglobin test in hip fracture patients may identify preoperative blood loss and impact on patient outcomes.

This thesis sought to evaluate whether the increased risk of heat-related illness observed in black-African descendants stems from impairements in local- and whole-body heat loss responses in this ethnic group. To evaluate this, in separate studies local- (study 1) and whole–body (study 2) heat loss responses were compared in young men (18-30 y) of black-African (n=21) and Caucasian (n=21) descent, matched for physical characteristics and fitness and born and raised in the same temperate environment. In study 1, we compared nitric oxide-dependent skin blood flow and sweating responses in young men of black-African (n=10) and Caucasian (n=10) descent during rest, exercise, and recovery in the heat. Both groups rested for 10-min, and then performed 50-min of moderate-intensity exercise at 200 W/m2, followed by 30-min of recovery in hot-dry heat (35°C, 20% RH). Local cutaneous vascular conductance (CVC%max) and sweat rate (SR) were measured at two forearm skin sites treated with a) lactated-Ringer (Control), or b) 10 mM NG-nitro-L-arginine methyl ester (L‐NAME, NO synthase-inhibitor). L-NAME significantly reduced CVC%max throughout rest, exercise, and recovery in both groups (both p<0.001). However, there were no significant main effects for the NO contribution to CVC%max between groups (all p>0.500). L-NAME significantly reduced local SR in both groups (both p<0.050). The NO contribution to SR was similar between groups such that L-NAME reduced SR relative to control at 40 and 50 min into exercise (both p<0.050). In study 2, we assessed whole-body total heat loss (evaporative + dry heat exchange) in black-African (n=11) and Caucasian (n=11) men using direct calorimetry. Participants performed three, 30-min bouts of semi-recumbent cycling at fixed metabolic heat productions (and therefore matched heat loss requirements between groups) of 200 (light), 250 (moderate), and 300 W/m2 (vigorous), each followed by 15-min recovery, in dry heat (40°C, ~13% relative humidity). Across all exercise bouts, dry (p=0.435) and evaporative (p=0.600) heat exchange did not differ significantly between groups. As such, total heat loss during light, moderate and vigorous exercise was similar between groups (p=0.777), averaging ((mean (SD)); 177 (10), 217 (13) and 244 (20) W/m2 in men of black-African descent, and 172 (13), 212 (17) and 244 (17) W/m2 in Caucasian men. Accordingly, body heat storage across all exercise bouts (summation of metabolic heat production and total heat loss) was also similar between the black-African (568 (142) kJ) and Caucasian groups (623 (124) kJ; p=0.356). This thesis demonstrates that ethnicity does not influence NO-dependent cutaneous vasodilation and sweating in healthy, young black-African descent and Caucasian men during exercise in the heat. Furthermore, we extend upon these observations by showing no differences in whole-body dry and evaporative heat exchange and therefore body heat storage.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.
Objective The goal of this study was to investigate the effect of using a two attending surgeon approach on operative time, anesthesia time, and estimated blood loss in patients with neuromuscular scoliosis undergoing posterior spinal fusion surgery. Methods This was a retrospective chart review study of patients with neuromuscular scoliosis who underwent posterior spinal fusion surgery at Phoenix Children’s Hospital in 2011 and 2012. Results Results from 70 patients showed a significant reduction in operative and anesthesia times for patients with two attending surgeons as opposed to one. Mean operative time for the two surgeon group was 3 hours 30 minutes (SD = 49 minutes) and was significantly shorter than 4 hours 26 minutes (SD = 1 hour 22 minutes), the mean operative time for the one surgeon group, t (56) =3.44, p = .001. Mean anesthesia time for the two surgeon group was 5 hours 28 minutes (SD = 55 minutes) and was significantly shorter than 6 hours 9 minutes (SD = 1 hour 28 minutes), the mean anesthesia time for the one surgeon group, t (57) = -2.34, p = .023. There was no significant difference in estimated blood loss found between the groups. The mean blood loss for the two surgeon group was 1202.1 ml( SD = 1033.1) versus 1042.1 ml (SD = 959.41) for the one surgeon group, t(68) = .671, p = .50. This pattern of results remained the same in subgroup analysis designed to compare cases with similar severity of presentation. Significance Patients with neuromuscular scoliosis may benefit from a two attending surgeon approach to posterior spinal fusion. More studies are needed to determine modifiable risk factors for excessive blood loss in neuromuscular scoliosis patients as well as to investigate the effect of using a two surgeon approach on specific post-operative complications.