Academic literature on the topic 'Alveolar recruitment'
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Journal articles on the topic "Alveolar recruitment"
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Baumgartner, William A., Eric M. Jaryszak, Amanda J. Peterson, Robert G. Presson, and Wiltz W. Wagner. "Heterogeneous capillary recruitment among adjoining alveoli." Journal of Applied Physiology 95, no. 2 (August 2003): 469–76. http://dx.doi.org/10.1152/japplphysiol.01115.2002.
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Pulmonary capillaries recruit when microvascular pressure is raised. The details of the relationship between recruitment and pressure, however, are controversial. There are data supporting 1) gradual homogeneous recruitment, 2) sudden and complete recruitment, and 3) heterogeneous recruitment. The present study was designed to determine whether alveolar capillary networks recruit in a variety of ways or whether one model predominates. In isolated, pump-perfused canine lung lobes, fields of six neighboring alveoli were recorded with video microscopy as pulmonary venous pressure was raised from 0 to 40 mmHg in 5-mmHg increments. The largest group of alveoli (42%) recruited gradually. Another group (33%) recruited suddenly (sheet flow). Half of the neighborhoods had at least one alveolus that paradoxically derecruited when pressure was increased, even though neighboring alveoli continued to recruit capillaries. At pulmonary venous pressures of 40 mmHg, 86% of the alveolar-capillary networks were not fully recruited. We conclude that the pattern of recruitment among neighboring alveoli is complex, is not homogeneous, and may not reach full recruitment, even under extreme pressures.
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Slutsky, A. S. "Barotrauma and alveolar recruitment." Intensive Care Medicine 19, no. 7 (July 1993): 369–71. http://dx.doi.org/10.1007/bf01724874.
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Hajari, A. J., D. A. Yablonskiy, A. L. Sukstanskii, J. D. Quirk, M. S. Conradi, and J. C. Woods. "Morphometric changes in the human pulmonary acinus during inflation." Journal of Applied Physiology 112, no. 6 (March 15, 2012): 937–43. http://dx.doi.org/10.1152/japplphysiol.00768.2011.
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Despite decades of research into the mechanisms of lung inflation and deflation, there is little consensus about whether lung inflation occurs due to the recruitment of new alveoli or by changes in the size and/or shape of alveoli and alveolar ducts. In this study we use in vivo 3He lung morphometry via MRI to measure the average alveolar depth and alveolar duct radius at three levels of inspiration in five healthy human subjects and calculate the average alveolar volume, surface area, and the total number of alveoli at each level of inflation. Our results indicate that during a 143 ± 18% increase in lung gas volume, the average alveolar depth decreases 21 ±5%, the average alveolar duct radius increases 7 ± 3%, and the total number of alveoli increases by 96 ± 9% (results are means ± SD between subjects; P < 0.001, P < 0.01, and P < 0.00001, respectively, via paired t-tests). Thus our results indicate that in healthy human subjects the lung inflates primarily by alveolar recruitment and, to a lesser extent, by anisotropic expansion of alveolar ducts.
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Albert, Scott P., Joseph DiRocco, Gilman B. Allen, Jason H. T. Bates, Ryan Lafollette, Brian D. Kubiak, John Fischer, Sean Maroney, and Gary F. Nieman. "The role of time and pressure on alveolar recruitment." Journal of Applied Physiology 106, no. 3 (March 2009): 757–65. http://dx.doi.org/10.1152/japplphysiol.90735.2008.
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Inappropriate mechanical ventilation in patients with acute respiratory distress syndrome can lead to ventilator-induced lung injury (VILI) and increase the morbidity and mortality. Reopening collapsed lung units may significantly reduce VILI, but the mechanisms governing lung recruitment are unclear. We thus investigated the dynamics of lung recruitment at the alveolar level. Rats ( n = 6) were anesthetized and mechanically ventilated. The lungs were then lavaged with saline to simulate acute respiratory distress syndrome (ARDS). A left thoracotomy was performed, and an in vivo microscope was placed on the lung surface. The lung was recruited to three recruitment pressures (RP) of 20, 30, or 40 cmH2O for 40 s while subpleural alveoli were continuously filmed. Following measurement of microscopic alveolar recruitment, the lungs were excised, and macroscopic gross lung recruitment was digitally filmed. Recruitment was quantified by computer image analysis, and data were interpreted using a mathematical model. The majority of alveolar recruitment (78.3 ± 7.4 and 84.6 ± 5.1%) occurred in the first 2 s (T2) following application of RP 30 and 40, respectively. Only 51.9 ± 5.4% of the microscopic field was recruited by T2 with RP 20. There was limited recruitment from T2 to T40 at all RPs. The majority of gross lung recruitment also occurred by T2 with gradual recruitment to T40. The data were accurately predicted by a mathematical model incorporating the effects of both pressure and time. Alveolar recruitment is determined by the magnitude of recruiting pressure and length of time pressure is applied, a concept supported by our mathematical model. Such a temporal dependence of alveolar recruitment needs to be considered when recruitment maneuvers for clinical application are designed.
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Ghadiali, Samir N. "Making “time” for alveolar recruitment." Journal of Applied Physiology 106, no. 3 (March 2009): 751–52. http://dx.doi.org/10.1152/japplphysiol.91652.2008.
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Cereda, Maurizio, and Yi Xin. "Alveolar Recruitment and Lung Injury." Critical Care Medicine 41, no. 12 (December 2013): 2837–38. http://dx.doi.org/10.1097/ccm.0b013e31829cb083.
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Kacmarek, Robert M. "Strategies to optimize alveolar recruitment." Current Opinion in Critical Care 7, no. 1 (February 2001): 15–20. http://dx.doi.org/10.1097/00075198-200102000-00003.
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Mancebo, J. "PEEP, ARDS, and alveolar recruitment." Intensive Care Medicine 18, no. 7 (July 1992): 383–85. http://dx.doi.org/10.1007/bf01694337.
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Lista, G., F. Castoldi, F. Cavigioli, S. Bianchi, and P. Fontana. "Alveolar recruitment in the delivery room." Journal of Maternal-Fetal & Neonatal Medicine 25, sup1 (March 5, 2012): 39–40. http://dx.doi.org/10.3109/14767058.2012.663164.
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Esquinas, Antonio M., and Luca S. De Santo. "Alveolar recruitment manoeuvres after cardiac surgery." European Journal of Anaesthesiology 35, no. 1 (January 2018): 61–62. http://dx.doi.org/10.1097/eja.0000000000000652.
Full textDissertations / Theses on the topic "Alveolar recruitment"
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Andrade, Felipe Silveira Rêgo Monteiro de. "Estudo clínico da mecânica respiratória em equinos sob ventilação com volume controlado durante cirurgia artroscópica." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-04092015-180239/.
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Sabe-se que a anestesia geral por si só já é capaz de causar substancial depressão cardiovascular e respiratória em equinos e tal característica pode ser potencializada ainda mais pelo posicionamento do paciente em decúbito dorsal e pela a administração de elevadas pressões intratorácicas durante as manobras de recrutamento utilizadas para reverter a hipoxemia. Sendo assim, o objetivo do atual estudo foi avaliar a mecânica respiratória e hemogasometria arterial após manobra de recrutamento alveolar e aplicação de PEEP para manutenção, em equinos ASA I e II submetidos à anestesia geral inalatória para cirurgia artroscópica, bem como qual o melhor valor da PEEP para manutenção do recrutamento alveolar. Para tanto foram utilizados 30 equinos, pesando em média 454 kg, submetidos a cirurgia artroscópica em decúbito dorsal, divididos aleatoriamente em 4 grupos, sendo eles: Controle; PEEP 7; PEEP 12; e PEEP 17. Os animais receberam xilazina (0,6 mg/kg) como MPA, seguida de indução anestésica (quetamina 2,2 mg/kg associado ao diazepam 0,05 mg/kg e EGG 10% 50 mg/kg) e anestesia inalatória com isofluorano. Os animais foram posicionados em decúbito dorsal e submetidos a ventilação com volume controlado (14ml/kg), FR de 7 mpm, relação I:E 1:3, PEEP 7 cmH2O e FiO2 de 0,7. Após período de instrumentação foi realizada MRA por titulação da PEEP a cada 5 minutos até alcançar PEEP de 22 cmH2O, sendo que os animais do grupo Controle não receberam MRA, apenas manutenção com PEEP de 7 cmH2O. Os animais dos outros grupos passaram pela MRA seguido de manutenção com suas PEEP de tratamento (7, 12 ou 17 cmH2O). Os parâmetros de mecânica respiratória e hemogasometria arterial foram avaliados imediatamente antes da MRA; e 5, 10, 15, 20, 40, 60 e 80 minutos após a MRA. Foram também avaliadas a FC, PAS, PAM e PAD, porcentagem de anestésico inalatório inspirado e expirado, ETCO2 e consumo de fármaco vasoativo. Os animais que receberam MRA apresentaram aumento na complacência estática e nos parâmetros de oxigenação após a manobra, nos animais do grupo PEEP 12 e 17 foi observada manutenção do incremento oriundo da MRA por pelo menos 80 minutos. Já os animais do grupo PEEP 7 apresentaram queda do incremento após 20 minutos da manobra, assim como o grupo Controle apresentou queda nos parâmetros de oxigenação e ventilação ao longo do tempo, ambos indicando uma provável fechamento pulmonar devido a PEEP insuficiente para manutenção dos alvéolos abertos. Não foram observadas alterações cardiovasculares nos animais do estudo, apenas leve taquicardia transitória no grupo PEEP 17 logo após a MRA. Portanto as PEEP de 12 e 17 cmH2O utilizadas após a MRA foram capazes de manter os alvéolos abertos, promovendo assim melhor trocas gasosas e o incremento na oxigenação e ventilação dos pacientes. Já os animais que receberam MRA e manutenção com PEEP de 7 cmH2O, foram capazes de manutenção dos alvéolos abertos por apenas 20 minutosIt is known that general anaesthesia by it’s self is capable of causing substantial cardiovascular and respiratory depression in horses and this characteristic can be enhanced even more by patient positioned in dorsal recumbence and the administration of high intrathoracic pressures during recruitment manoeuvres used to reverse hypoxemia. Therefore, the aim of this study was to evaluate the respiratory mechanics and arterial blood gas analysis after recruitment manoeuvre and PEEP for maintenance, in horses ASA I and II undergoing general isoflurane-anaesthesia for arthroscopic surgery and what is the best value PEEP to maintain alveolar recruitment. Therefore, we used 30 horses, weighing on average 454 kg, which underwent arthroscopic surgery in the dorsal recumbence, randomly allocated into one of the 4 groups, as follows: Control; PEEP 7; PEEP 12; and PEEP 17. Animals received xylazine (0,6 mg/kg) as pre anaesthetic medication followed by anaesthesia induction (ketamine 2,2 mg/kg associated to diazepam 0,05 mg/kg and EGG 10% 50 mg/kg) and maintenance with isoflurane-anaesthesia. The animals were positioned in dorsal recumbence and submitted the volume-controlled ventilation (14ml/kg), RR: 7 mpm, I:E ratio 1:3, 7 cmH2O of PEEP and FiO2 0,7. After instrumentation period was performed RM by PEEP titration every 5 minutes until reach 22 cmH2O of PEEP, and the animals of control group did not receive RM, only maintenance with PEEP 7 cmH2O. The animals of other groups went through the RM followed by maintenance with their treatment PEEP (7, 12 or 17 cmH2O). The respiratory parameters and blood gas samples were assessed immediately before the RM; and 5, 10, 15, 20, 40, 60 and 80 minutes after the manoeuvre. We also assessed the HR, SAP, MAP and DAP, percentage of inhaled anaesthetic: inhaled and exhaled, ETCO2 and vasoactive drug consumption. Animals receiving RM showed an increase in static compliance and oxygenation parameters after the manoeuvre, maintenance of the increase coming from the RM were observed in animals from PEEP 12 and 17 group, for at least 80 minutes. The animals in PEEP 7 group decreased the increase after 20 minutes of manoeuvre and the control group decreased the parameters of oxygenation and ventilation over time, both indicating a probable pulmonary closure due to insufficient PEEP to maintain the alveoli opened. Cardiovascular changes were observed in the study animals, only mild transient tachycardia in PEEP 17group soon after RM. Therefore, the PEEP 12 and 17 cmH2O used after RM were able to keep the lung opened, thereby performing better gas exchange and the increase in the oxygenation and ventilation of patients. The animals receiving RM and maintenance PEEP 7 cmH2O were able to maintain the alveoli open for only 20 minutes
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Mott, Lara Lopes Facó. "Avaliação de diferentes protocolos de recrutamento alveolar durante a ventilação mecânica em equinos submetidos a laparotomia." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-13042018-142412/.
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A anestesia do paciente equino acometido por síndrome do abdômen agudo ainda é uma das situações mais desafiadoras enfrentada pelo médico veterinário anestesiologista na pratica clínica. Apesar dos inúmeros avanços alcançados na área de ventilação mecânica, monitoramento avançado do status volêmico e atendimento do paciente critico, o equilíbrio entre a melhor estratégia de ventilação, de modo a minimizar a ocorrência de shunt e espaço morto, e a otimização dos parâmetros de oxigenação e hemodinâmica para que a perfusão sanguínea para os tecidos periféricos seja mantida, ainda não foi determinada para cavalo afetado por síndrome cólica. O objetivo deste trabalho foi avaliar o impacto de dois valores diferentes de pressão positiva ao final da expiração (PEEP) sobre os parâmetros de ventilação, oxigenação, hemodinâmica e consumo de fármacos vasopressores em equinos submetidos a laparotomia exploratória em decorrência de quadros de abdômen agudo de diferentes etiologias. Para isso foram utilizados 20 animais, sendo 12 machos e 8 fêmeas, pesando 431±95 kg e encaminhados para o serviço de cirurgia de grandes animais da Faculdade de Medicina Veterinária e Zootecnia de Universidade de São Paulo (FMVZ/USP). Após avaliação pré-anestésica os animais foram pré-medicados com xilazina (0,6mg/kg-1) pela via intravenosa, decorridos 10 minutos realizou-se a indução da anestesia com cetamina (2,2mg/kg-1) associada a diazepam (0,05mg/kg-1). Os animais foram então posicionados em decúbito dorsal, mantidos em ventilação mecânica por volume controlado, com volume corrente de 14mL/kg e submetidos a manobra de recrutamento alveolar por escalonamento da PEEP, de maneira crescente a cada 5 minutos até 22 cmH2O, seguida do escalonamento decrescente, de forma que os animais foram então divididos sistematicamente em 2 grupos: PEEP constante de 12 cmH2O (Grupo PEEP12, n=10) ou PEEP constante de 17 cmH2O (Grupo PEEP17, n=10) durante todo o procedimento anestésico. O grupo PEEP12 apresentou valores de pressão arterial média (PAM) e pH significativamente maiores durante todo o período após a instituição do tratamento, bem como menor consumo de dobutamina e noradrenalina para a manutenção da PAM>60 mmHg. No grupo PEEP12 houve ainda uma tendência de valores maiores de base excesso após a instituição do tratamento. Não houve diferença entre os dois grupos para os valores dos parâmetros de oxigenação no período pós anestésico.The equine patient suffering from acute abdomen syndrome anesthesia remains one of the biggest challenges for the veterinary anesthesiologist. Despite many advances on mechanical ventilation, volemic status monitoring and critical care patient management it is still extremely difficult to achieve the balance between the best ventilation strategy to minimize the occurrence of ventilation mismatch and the optimization of cardiovascular parameters to keep blood perfusion to peripheral tissues within normal ranges. Therefore, the aim of this study was to assess the effects of a stepwise increase in airway pressure recruitment and two different values of positive end expiratory pressure (PEEP) on ventilatory, oxygenation and hemodynamics parameters as well as vasoactive drugs consumption on horses undergoing exploratory laparotomy. Thus, twenty client-owned horses, weighing 431± 95 kg, refered to the Large Animal Surgery Service of the Faculty of Veterinary Medicine and Animal Science, at the University of São Paulo were included on the study. The animals were premedicated with xilazine (0,6mg/kg-1) and after 10 minutes the anesthesia was induced with ketamine (2,2 mg/kg-1) and diazepam (0,05 mg/kg-1). The subjects were positioned in dorsal recumbence, maintained in volume controlled mechanical ventilation, with tidal volume of 14ml/kg. After 30 min of instrumentation the recruitment maneuver (RM) was performed by PEEP titration with increments of 5 cmH2O every 5 min up to a PEEP of 20 cmH2O followed by decremental PEEP titration until 12 cmH20 (Group PEEP12, n=10) or 17 cmH2O (Group PEEP 17, n=10) until the end of surgical procedure. The Group PEEP12 had significantly higher values of mean arterial blood pressure (MAP) and pH for 100 minutes after the RM was performed. The animals in this group also needed less vasoactive drugs (dobutamine and noradrenaline) to keep the MAP>60mmHg during the whole anesthesia time. There was no difference between group PEEP12 a group PEEP 17 regarding oxygenation parameters 30 minutes after the anesthesia was ended.
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Ambrósio, Aline Magalhães. "Estudo da influência das manobras de recrutamento alveolar sobre a mecânica, a ventilação e o parênquima pulmonar durante lesão aguda promovida pela instilação de ácido clorídrico: estudo experimental em porcos." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-29092006-201943/.
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Diversas estratégias de ventilação mecânica que estabelecem limites na pressão e volume intratorácicas têm sido propostas para pacientes com síndrome de angustia respiratória aguda (SARA). Estas recomendações são baseadas na observação de que a ventilação mecânica com volume corrente excessivo ou pressão positiva expiratória final (PEEP) insuficiente pode ocasionar lesões pulmonares graves, decorrentes de superdistensão de unidades alveolares. O objetivo do atual estudo foi aplicar manobras de recrutamento alveolar e PEEP em pulmões submetidos à lesão pulmonar aguda (LPA) através da administração de HCl . Foram utilizados 24 suínos Landrace - Largewhite, do sexo feminino, pesando entre 25 e 35 Kg. Após a anestesia os animais foram submetidos à ventilação com volume controlado (6 a 8 ml/Kg) e foram randomizados em 4 grupos: GI (6 animais não submetidos a LPA e tratados com PEEP progressivo de 5, 10, 15 e 20 cmH2O e regressivo de 20 a 5 cmH2O); GII (6 animais não submetidos a LPA e tratados com PEEP progressivo de 5, 10, 15 e 20 cmH2O e regressivo de 20 a 5 cmH2O associado a 3 manobras de recrutamento consecutivas, com pressão de 30 cmH2O antes de cada alteração do PEEP); GIII (6 animais submetidos a 1 hora de LPA por HCl e tratados como GI) e GIV (6 animais submetidos a 1 hora de LPA por HCl e tratados como GII). A mecânica respiratória e oxigenação foram avaliadas a cada 20 minutos, acompanhando cada alteração do PEEP. A LPA foi observada através de severas alterações na oxigenação e mecânica respiratória. A administração de MR associada a PEEP foi capaz de restaurar os valores controle, porém, os elevados valores de PEEP e CPAP foram acompanhados de significantes alterações hemodinâmicas quando comparadas com os animais que não foram submetidos a LPA. O derrecrutamento alveolar ocorreu provavelmente quando os valores de PEEP foram retornados para 5cmH2O. As lesões pulmonares foram uniformes nos animais que foram submetidos ao HCl, evidenciadas pela presença de necrose, hemorragia, congestão e infiltrado de células inflamatórias no interstício e nos alvéolos. O modelo experimental de lesão pulmonar aguda foi adequado para estudar MR seguidas por PEEP, pois apresentou importantes alterações dos valores de oxigenação e complacência, observado 1 hora após a instilação do HCl.Os valores de PEEP de 5cmH2O foram incapazes de manter o recrutamento no momento final do estudo, enquanto que os valores de PEEP de 10cmH2O foram suficientes para restabelecer a oxigenação com mínima alteração hemodinâmica. A complacência não melhorou após as manobras. Futuros estudos são necessários para confirmar os resultados obtidos, especialmente para mostrar que a manutenção do PEEP de 10cmH2O é suficientes para manter o recrutamento após as MRDifferent mechanical ventilation strategies which define limits of intrathoracic pressures and volumes are being proposed for patients with acute respiratory distress syndrome (ARDS). These recommendations are based on observations that mechanical ventilation with excessive tidal volumes or insufficient values of positive end expiratory pressure (PEEP) can cause severe lung injury due to overinflation. The aim of the present study was to apply recruitment maneuvers (RM) and PEEP in lungs submitted to acute lung injury (ALI) due to the administration of hydrochloride acid. Twenty four female Landrace Largewhite pigs, weighing 25 to 35 Kg were used. After anesthesia, animals were submitted to volume controlled mechanical ventilation (6 to 8ml/kg) and were randomly allocated in four groups of 6 animals each: GI animals without ALI and treated with progressive values of PEEP (5, 10, 15 and 20 cmH2O) or regressive (20 to 5 cm H2O); GII animals without ALI and treated with progressive values of PEEP (5, 10, 15 and 20 cmH2O) or regressive (20 to 5 cm H2O) plus 3 consecutive recruitment maneuvers with 30 cmH2O; GIII animals submitted to 1 hour of ALI and treated as GI; GIV animals submitted to 1 hour of ALI and treated as GII. Parameters of respiratory mechanics, ventilation and oxygenation were measured each 20 minutes according to the change of the PEEP values. ALI could be observed by the severe changes of oxygenation and respiratory mechanics noted. The use of RM and PEEP were able to restore control values. Nevertheless, application of high values of PEEP and CPAP were accompanied by significant hemodynamic changes which could be evidenced in animals without ALI. Derecruitment probably occurred when PEEP value reached 5 cmH2O. The lung lesions were uniform in the HCL-injured animals and consisted of necrosis, hemorrhage, congestion, and inflammatory cells infiltration that involved both the interstitium and the alveoli. The experimental model of lung injury was adequate to the study of RM followed by PEEP since significant changes of the oxygenation and compliance values could be observed 1 hour after acid instillation. PEEP values of 5cmH2O were incapable to maintain recruitment at the end of the observation period, while 10 cmH2O were sufficient to promote the reestablishment of oxygenation index with minimal hemodynamic changes. Compliance did not improve during the maneuvers. Further studies are necessary to confirm the results obtained, especially to show that the maintenance of a PEEP value of 10 cmH2O are sufficient to maintain recruitment after the RM
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Amaral, Ronaldo Alves do. "Origem f?sica das curvas sigmoidais respirat?rias press?o-volume: recrutamento alveolar e elasticidade n?o-linear." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/13248.
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Previous issue date: 2011-12-09An important unsolved problem in medical science concerns the physical origin of the sigmoidal shape of pressure volume curves of healthy (and some unhealthy) lungs. Such difficulties are expected because the lung, which is the most important structure in the respiratory system, is extremely complex. Its rheological properties are unknown and seem to depend on phenomena occurring from the alveolar scale up to the thoracic scale. Conventional wisdom holds that linear response, i.e., Hooke s law, together with alveolar overdistention, play a dominant role in respiration, but such assumptions cannot explainthe crucial empirical sigmoidal shape of the curves. In this doctorate thesis, we propose an alternative theory to solve this problem, based on the alveolar recruitment together with the nonlinear elasticity of the alveoli. This theory suggests that recruitment may be the predominant factor shaping these curves in the entire range of pressures normally employed in experiments. The proposed model correctly predicts the observed sigmoidal pressure volume curves, allowing us to discuss adequately the importance of this result, as well as its implications for medical practice
Um importante problema n?o resolvido na ci?ncia m?dica diz respeito ? origem f?sica da forma sigmoidal das curvas press?o-volume de pulm?es saud?veis (e de alguns n?o saud?veis). Tais dificuldades s?o esperadas tendo em vista que o pulm?o, a mais importante estrutura do sistema respirat?rio, ? extremamente complexo. Suas propriedades reol?gicas s?o desconhecidas, e parecem depender dos fen?menos que ocorrem a partir da escala alveolar at? a escala tor?cica. O modelo cl?ssico diz que a resposta linear, ou seja, a lei de Hooke, juntamente com a superdistens?o alveolar desempenha um papel predominante na formata??o dessas curvas, mas tais pressupostos n?o podem explicar a crucial forma emp?rica sigmoidal das curvas P-V respirat?rias est?ticas. Nesta tese de doutorado propomos uma teoria alternativa para resolver este problema, baseada no recrutamento alveolar, juntamente com a hip?tese do comportamento el?stico n?o-linear dos alv?olos. Esta teoria sugere o recrutamento alveolar como o fator predominante que modela as curvas press?o-volume em um completo intervalo de press?o normalmente utilizado nas experi?ncias. O modelo proposto prediz corretamente a forma sigmoidal observada nas curvas press?o-volume, nos permitindo discutir adequadamente a import?ncia deste resultado, assim como as suas implica??es para a pr?tica m?dica
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Rodrigues, Jéssica Corrêa [UNESP]. "Efeitos do pneumoperitônio e de uma manobra de recrutamento alveolar seguida por pressão positiva no final da expiração na função cardiopulmonar em ovinos anestesiados com isoflurano e fentanil." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/136391.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A realização da laparoscopia cirúrgica requer a insuflação de gás carbônico (CO2) na cavidade abdominal. O pneumoperitônio formado eleva a pressão intra-abdominal (PIA), deslocando o diafragma em sentido cranial, o que resulta em diminuição da complacência pulmonar e consequentemente formação de áreas atelectásicas. Este estudo objetivou investigar os efeitos do pneumoperitônio e de uma manobra de recrutamento alveolar (MRA) seguida por aplicação de pressão positiva ao final da expiração (PEEP) na função cardiorrespiratória em ovinos. Em um delineamento prospectivo aleatório cruzado, nove ovinos (36–52 kg) foram anestesiados com isoflurano e fentanil e submetidos à ventilação com volume controlado (volume corrente: 12 mL/kg) com o emprego do bloqueador neuromuscular atracúrio. Cada animal recebeu três tratamentos com intervalo de dez dias entre cada experimento: Controle (sem intervenção); Pneumo (pneumoperitônio mantido por 120 minutos sob PIA de 15 mmHg); Pneumo+MRA/PEEP (pneumoperitônio mantido por 120 minutos sob PIA de 15 mmHg e realização de uma MRA aos 60 minutos após insuflação abdominal seguida por 10 cmH2O de PEEP). A MRA consistiu em aumentos progressivos na pressão expiratória a cada minuto até alcançar o valor de 20 cmH2O de PEEP. As variáveis estudadas foram coletadas até 30 minutos após a interrupção do pneumoperitônio. A insuflação abdominal com CO2 diminuiu significativamente (P < 0.05) os valores de PaO2 de 435–462 mmHg (intervalo dos valores médios observados) no tratamento Controle para 377–397 mmHg e 393–413 mmHg nos tratamentos Pneumo e Pneumo+MRA/PEEP, respectivamente. A complacência estática (Cstat, mL/cmH2O/kg) diminuiu significativamente de 0,83–0,86 (Controle) para 0,49–0,52 (Pneumo) e 0,51–0,54 (Pneumo+MRA/PEEP) após a indução do pneumoperitônio. A MRA/PEEP elevou significativamente a PaO2 (429–444 mmHg) e a Cstat (0,68–0,72) quando comparada com o os animais sob pneumoperitônio que não receberam a MRA/PEEP (PaO2: 383–385 mmHg e Cstat: 0,48–0,49). A realização do pneumoperitônio aumentou significativamente a formação de “shunt” intrapulmonar; porém após a aplicação da MRA/PEEP houve uma diminuição significativa nos valores de “shunt”. Trinta minutos após a desinsuflação abdominal, a PaO2 e a Cstat encontravam-se significativamente menores e o “shunt” intrapulmonar significativamente maior no tratamento Pneumo quando comparado ao tratamento Controle. Durante os últimos 60 minutos de pneumoperitônio (Pneumo e Pneumo+MRA/PEEP), os valores médios de índice cardíaco (IC) foram 20–28 % menores (P < 0.05) que os valores observados no tratamento Controle. Após a MRA/PEEP, a pressão média da artéria pulmonar (PMAP) apresentou-se significativamente maior (47-56%) e a pressão arterial média (PAM) apresentou-se significativamente menor (16%) em relação ao tratamento Controle. Concluiu-se que a desinsuflação abdominal não foi suficiente para reverter os impactos negativos na função pulmonar associados à realização do pneumoperitônio e que a realização de uma MRA seguida por PEEP foi capaz de melhorar a complacência do sistema pulmonar e reverter o prejuízo na oxigenação ocasionados pela insuflação abdominal, sem, no entanto, induzir alterações hemodinâmicas inaceitáveis.
Laparoscopic surgical procedures usually require carbon dioxide (CO2) insufflation into the peritoneal cavity. The pneumoperitoneum increases intra-abdominal pressure (IAP) displaces the diaphragm cranially, and decreases respiratory system compliance, leading to the development of atelectasis. This study aimed to investigate the effects of pneumoperitoneum and of an alveolar recruitment maneuver (ARM) followed by positive end-expiratory pressure PEEP on cardiopulmonary function in sheep. In a prospective randomized crossover study, nine sheep (36–52 kg) received 3 treatments with 10-day intervals during isoflurane-fentanyl anesthesia and volume-controlled ventilation (tidal volume: 12 mL/kg): Control (no intervention); Pneumo (120 minutes of CO2 pneumoperitoneum until achieving an intra-abdominal pressure of 15 mmHg); Pneumo+ARM/PEEP (same pneumoperitoneum protocol with an ARM after 60 minutes of abdominal inflation). The ARM consisted of stepwise increases in end-expiratory pressures every minute until 20 cmH2O of PEEP, followed by 10 cmH2O of PEEP. Data were recorded until 30 minutes after abdominal deflation. Abdominal inflation significantly (P < 0.05) decreased PaO2 from 435–462 mmHg (range of recorded mean values) in controls to 377–397 mmHg and 393–413 mmHg in the Pneumo and Pneumo+ARM/PEEP treatments, respectively. Static compliance (Cstat, mL/cmH2O/kg) was significantly decreased from 0.83–0.86 (Control) to 0.49–0.52 (Pneumo), and 0.51–0.54 (Pneumo+ARM/PEEP) after induction of pneumoperitoneum. The ARM/PEEP significantly increased PaO2 [429–444 mmHg and Cstat (0.68–0.72)] from values recorded during pneumoperitoneum alone [PaO2: 383–385 mmHg and Cstat: 0.48–0.49]. Pneumoperitoneum significantly increased intrapulmonary Shunt; while the ARM/PEEP significantly decreased the Shunt. Thirty minutes after abdominal deflation (Pneumo), PaO2 and Cstat were significantly lower and the Shunt was higher than in controls. During the last 60 minutes of pneumoperitoneum (Pneumo and Pneumo+ARM/PEEP), cardiac index values were 20–28 % lower than in controls. After the ARM/PEEP, mean pulmonary artery pressure was significantly higher (47-56%) and mean systemic arterial pressure was significantly lower (16%) than controls. It was concluded that abdominal deflation is not enough to reverse the impairment in pulmonary function associated with pneumoperitoneum and the ARM/PEEP may improve respiratory system compliance and reverse the oxygenation impairment induced by pneumoperitoneum with clinically acceptable hemodynamic changes.
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Kozian, Alf. "Pathophysiological and Histomorphological Effects of One-Lung Ventilation in the Porcine Lung." Doctoral thesis, Uppsala universitet, Klinisk fysiologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-108850.
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Thoracic surgical procedures require partial or complete airway separation and the opportunity to exclude one lung from ventilation (one-lung ventilation, OLV). OLV is commonly associated with profound pathophysiological changes that may affect the postoperative outcome. It is injurious in terms of increased mechanical stress including alveolar cell stretch and overdistension, shear forces secondary to repeated tidal collapse and reopening of alveolar units and compression of alveolar vessels. Ventilation and perfusion distribution may thus be affected during and after OLV. The present studies investigated the influence of OLV on ventilation and perfusion distribution, on the gas/tissue distribution and on the lung histomorphology in a pig model of thoracic surgery. Anaesthetised and mechanically ventilated piglets were examined. The ventilation and perfusion distribution within the lungs was assessed by single photon emission computed tomography. Computed tomography was used to establish the effects of OLV on dependent lung gas/tissue distribution. The pulmonary histopathology of pigs undergoing OLV and thoracic surgery was compared with that of two-lung ventilation (TLV) and spontaneous breathing. OLV induced hyperperfusion and significant V/Q mismatch in the ventilated lung persistent in the postoperative course. It increased cyclic tidal recruitment that was associated with a persistent increase of gas content in the ventilated lung. OLV and thoracic surgery as well resulted in alveolar damage. In the present model of OLV and thoracic surgery, alveolar recruitment manoeuvre (ARM) and protective ventilation approach using low tidal volume preserved the ventilated lung density distribution and did not aggravate cyclic recruitment of alveoli in the ventilated lung. In conclusion, the present model established significant alveolar damage in response to OLV and thoracic surgery. Lung injury could be related to the profound pathophysiological consequences of OLV including hyperperfusion, ventilation/perfusion mismatch and increased tidal recruitment of lung tissue in the dependent, ventilated lung. These mechanisms may contribute to the increased susceptibility for respiratory complications in patients undergoing thoracic surgery. A protective approach including sufficient ARM, application of PEEP, and the use of lower tidal volumes may prevent the ventilated lung from deleterious consequences of OLV.
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Namati, Eman, and eman@namati com. "Pre-Clinical Multi-Modal Imaging for Assessment of Pulmonary Structure, Function and Pathology." Flinders University. Computer Science, Engineering and Mathematics, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081013.044657.
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In this thesis, we describe several imaging techniques specifically designed and developed for the assessment of pulmonary structure, function and pathology. We then describe the application of this technology within appropriate biological systems, including the identification, tracking and assessment of lung tumors in a mouse model of lung cancer.
The design and development of a Large Image Microscope Array (LIMA), an integrated whole organ serial sectioning and imaging system, is described with emphasis on whole lung tissue. This system provides a means for acquiring 3D pathology of fixed whole lung specimens with no infiltrative embedment medium using a purpose-built vibratome and imaging system. This system enables spatial correspondence between histology and non-invasive imaging modalities such as Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET), providing precise correlation of the underlying 'ground truth' pathology back to the in vivo imaging data. The LIMA system is evaluated using fixed lung specimens from sheep and mice, resulting in large, high-quality pathology datasets that are accurately registered to their respective CT and H&E histology.
The implementation of an in vivo micro-CT imaging system in the context of pulmonary imaging is described. Several techniques are initially developed to reduce artifacts commonly associated with commercial micro-CT systems, including geometric gantry calibration, ring artifact reduction and beam hardening correction. A computer controlled Intermittent Iso-pressure Breath Hold (IIBH) ventilation system is then developed for reduction of respiratory motion artifacts in live, breathing mice. A study validating the repeatability of extracting valuable pulmonary metrics using this technique against standard respiratory gating techniques is then presented.
The development of an ex vivo laser scanning confocal microscopy (LSCM) and an in vivo catheter based confocal microscopy (CBCM) pulmonary imaging technique is described. Direct high-resolution imaging of sub-pleural alveoli is presented and an alveolar mechanic study is undertaken. Through direct quantitative assessment of alveoli during inflation and deflation, recruitment and de-recruitment of alveoli is quantitatively measured. Based on the empirical data obtained in this study, a new theory on alveolar mechanics is proposed.
Finally, a longitudinal mouse lung cancer study utilizing the imaging techniques described and developed throughout this thesis is presented. Lung tumors are identified, tracked and analyzed over a 6-month period using a combination of micro-CT, micro-PET, micro-MRI, LSCM, CBCM, LIMA and H&E histology imaging. The growth rate of individual tumors is measured using the micro-CT data and traced back to the histology using the LIMA system. A significant difference in tumor growth rates within mice is observed, including slow growing, regressive, disappearing and aggressive tumors, while no difference between the phenotype of tumors was found from the H&E histology. Micro-PET and micro-MRI imaging was conducted at the 6-month time point and revealed the limitation of these systems for detection of small lesions ( < 2mm) in this mouse model of lung cancer. The CBCM imaging provided the first high-resolution live pathology of this mouse model of lung cancer and revealed distinct differences between normal, suspicious and tumor regions. In addition, a difference was found between control A/J mice parenchyma and Urethane A/J mice normal parenchyma, suggesting a 'field effect' as a result of the Urethane administration and/or tumor burden. In conclusion, a comprehensive murine lung cancer imaging study was undertaken, and new information regarding the progression of tumors over time has been revealed.
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Mori, Audie Rollin Roldan. "Impacto de duas estratégias de titulação da PEEP em modelo suíno de síndrome do desconforto respiratório agudo: guiada por pressão esofágica versus guiada por tomografia de impedância elétrica." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/5/5150/tde-27092017-114609/.
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INTRODUÇÃO: O uso de níveis elevados da pressão expiratória final positiva (PEEP) na Síndrome do desconforto respiratório agudo (SDRA), visando reduzir a quantidade de pulmão colapsado, tornando a ventilação mais homogênea, tem sido apontado por estudos clínicos randomizados e metaanálises como uma estratégia eficaz na melhora de alguns desfechos clínicos. Atualmente, não existe um método ideal para ajuste da PEEP na SDRA. Dois métodos distinguem-se pela racionalidade fisiológica e possibilidade de serem usados na prática clínica usual: ajuste da PEEP guiado por Pressão Esofágica (Pes) e ajuste da PEEP guiado por Tomografia de Impedância Elétrica (TIE). Os objetivos do estudo foram: (1) Avaliar, através de tomografia computadorizada de tórax (raios X), qual estratégia induz uma melhor aeração pulmonar: maior recrutamento pulmonar e menor hiperdistensão; (2) Avaliar as alterações da distribuição regional da ventilação, do volume pulmonar e da complacência regional medidos pela tomografia de impedância elétrica; (3) Avaliar as alterações na mecânica pulmonar e nas trocas gasosas produzidas por ambas as estratégias de titulação da PEEP. MÉTODOS: Dez porcos foram submetidos a um modelo de SDRA grave: depleção de surfactante mais lesão pulmonar induzida pelo ventilador. Após uma manobra de recrutamento (MR), duas estratégias de titulação da PEEP foram testadas em uma sequência aleatória: 1) Utilizando a tomografia por impedância elétrica para calcular a menor PEEP que mantem um colapso pulmonar menor de 1%; 2) Utilizando a pressão esofágica para calcular a PEEP necessária para atingir uma pressão transpulmonar final expiratória (PLexp) entre 5-6 cmH2O. Em seguida, os animais foram ventilados durante 1 hora com a PEEP ótima estimada por cada método. Foram registrados parâmetros fisiológicos e de tomografia computadorizada (TC) antes da MR (tempo basal) e após ventilação com a PEEP ótima (15 min e 60 min). RESULTADOS: Aos 60 min, ambas as estratégias reduziram o colapso pulmonar, mas com efeitos significativamente maiores (P < 0,05) no grupo TIE: tecido não-aerado (20,3 ± 11,8% vs. 38,6 ± 13,1%, TIE vs. Pes respectivamente), recrutamento cíclico (4,8 ± 3,7% vs. 8,7 ± 2,7%), PaO2/FIO2 (289 ± 78 vs. 209 ± 92 mmHg), pressão de distensão (14,5 ± 2,3 vs. 16,1 ± 2,3 cmH2O), e pressão de distensão transpulmonar (11,9 ± 1,7 vs. 13,6 ± 1,8 cmH2O). Apesar da escolha de uma maior PEEP ótima no grupo TIE, a pressão platô (33,2 ± 3,7 vs. 31,5 ± 3,1 cmH2O), a pressão transpulmonar inspiratória final (20,0 ± 2,8 vs. 19,2 ± 1,7 cm H2O) e a complacência das áreas não dependentes do pulmão medidas pela TIE (0,07 ± 0,04 vs 0,06 ± 0,05 unidades arbitrárias/cmH2O) ou TC (1,52 ± 0,90 vs. 1,41 ± 0,98 mL/cmH2O) variaram de forma semelhante nos dois grupos (P > 0,05). O tecido hiperaerado e a hipedistensão cíclica foram baixos em ambos os grupos. CONCLUSÕES: Neste modelo animal de SDRA grave o ajuste da PEEP guiado por TIE produz um maior recrutamento pulmonar e sinais fisiológicas de melhor proteção pulmonar quando comparado com o ajuste da PEEP guiado por PesINTRODUCTION: The use of higher levels of positive end-expiratory pressure (PEEP) in the acute respiratory distress syndrome (ARDS), aimed at reducing the amount of lung collapse, making the ventilation more homogeneous, has been pointed out by randomized clinical trials and meta-analysis as an effective strategy to improve some clinical outcomes. Currently, there is no ideal method for adjustment PEEP in ARDS. Two methods are distinguished by their physiological rationality and the possibility of being used in the clinical practice: PEEP titration guided by Esophageal Pressure (Pes) and PEEP titration guided by Electrical Impedance Tomography (EIT). The objectives of the study were: 1) To evaluate through computed tomography of thorax (X-ray), which strategy induces better pulmonary aeration: greater lung recruitment and less hyperdistension; (2) To evaluate changes in the regional distribution of ventilation, pulmonary volume and regional compliance, measured by electrical impedance tomography; (3) To assess changes in lung mechanics and gas exchange produced by both PEEP titration strategies. METHODS: Ten pigs were submitted to a two-hit model of severe ARDS: Surfactant depletion plus ventilator-induced lung injury. After a recruitment maneuver (RM), two strategies of PEEP titration were tested in a randomized sequence: 1) Using electric impedance tomography to calculate the lowest PEEP keeping recruitable-lungcollapse < 1%; 2) Using esophageal pressure to calculate the PEEP needed to achieve an end-expiratory transpulmonary pressure between 5-6 cmH2O. Then, animals were ventilated for 1 hour with the optimum-PEEP estimated by each method. Physiological and computed tomography (CT) parameters were recorded before RM (baseline) and after ventilation at optimum-PEEP (15 min and 60 min). RESULTS: At 60 min, both strategies reduced lung collapse but with significantly (P < 0.05) greater effects in EIT-group: nonaerated tissue (20.3 ± 11.8% vs 38.6 ± 13.1%, EIT vs. Pes, respectively), tidal recruitment (4.8 ± 3.7% vs 8.7 ± 2.7%), PaO2/FIO2 (289 ± 78 vs 209 ± 92 mmHg), driving-pressure (14.5 ± 2.3 vs 16.1 ± 2.3 cmH2O) and transpulmonary driving-pressure (11.9 ± 1.7 vs 13.6 ± 1.8 cmH2O). Despite the choice for a higher optimum-PEEP in the EIT-group; plateau pressure (33.2 ± 3.7 vs 31.5 ± 3.1 cmH2O), end-inspiratory transpulmonary pressure (20.0 ± 2.8 vs 19.2 ± 1.7 cmH2O) and compliance of non-dependent areas measured by EIT (0.07 ± 0.04 vs 0.06 ± 0.05 arbitrary units/cmH2O) or CT (1.52 ± 0.90 vs 1.41 ± 0.98 mL/cmH2O) varied similarly in both groups (P > 0.05). Hyperaerated tissue and tidal hyperinflation were very low in both groups. CONCLUSION: In this model, the choice of PEEP guided by EIT leads to higher lung recruitment and physiological signals of a better lung protection, when compared to the strategy guided by Pes
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Ya-i, Hsieh, and 謝雅宜. "Clinical Efficacy of Manual Hyperinflation on Alveolar Recruitment in Difficult Weaning Patients." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/01694989282061929660.
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碩士長庚大學
護理學研究所
90
Use of mechanical ventilator support through tracheostomy or intubation has been one of extremely important medical intervention to help support life for ICU patients. However, as the result of using current medical intervention for patients with lung collapse during mechanical ventilation is limited, manual hyperinflation helps alveolar recruitment that results in secretion clearance, ventilation improvement, lung collapse prevention, lung collapse re-inflation, dynamic compliance improvement, artery oxygenation improvement and work of breathing reduction according to certain clinic reports from foreign sources. This study seeks to verify success of sputum clearance and ventilation in giving manual hyperinflation to patients suffering from lung collapse who has been using mechanical ventilation for more than one week. The study takes the assumption that through manual hyperinflation to recruit alveolar, it will help patients sputum clearance and ventilation. A controlled, randomized, single blind, experimental design was used. Each patient was assigned a random number upon entering the research project, which allowed randomly allocation to two groups: experimental group and control group. The samples were collected in the ICU of a Medical Center in northern Taiwan and the Chronic Respiratory Treatment Center of the Regional Hospital under the cooperation program. A total of 28 patients joined the study in two groups, i.e., experimental group and control group, 14 patients in each group. Cases from the experimental group were treated with ventilation support and additional manual hyperinflation while cases from the control group were only treated with ventilation support. Patients in experimental group received the manual hyperinflation once of 20 minutes in 3 times per day for 5 days. Outcome measurement was evaluated by noting changes in the patient’s score in dry/wet ratio of sputum, sputum viscosity, tidal volume, maximal respiratory pressure, PaO2/FiO2, upper chest X-ray film, dynamic lung compliance and the index of rapid shallow breathing. Outcome measurements were assessed 3 times for all patients: at the day admitted to this study, the 3rd day, and 6th day. Upon giving the conclusions are as follows: (1)For the sputum clearance, patients from the experiment group indicate significant improvement than those from control group does depending on the time-point in terms of sputum viscosity (p=0.002); while patients from both group indicate no significant variance in dry/wet ratio of sputum; (2)For the ventilation, patients from the experimental group indicate significant improvement than those from control group does depending on the time-point in terms of improved tidal volume (p=0.033), maximal respiratory pressure (p=0.05), PaO2/FiO2 (p=0.016), upper chest X-ray film (p=0.069), the index of rapid shallow breathing (p=0.008); and while patients from both groups indicate no significant variance in terms of dynamic compliance.
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Herold, Susanne [Verfasser]. "Macrophage-epithelial interactions during influenza virus pneumonia : alveolar recruitment pathways and impact on epithelial barrier integrity / by Susanne Valerie Herold." 2008. http://d-nb.info/992276659/34.
Full textBooks on the topic "Alveolar recruitment"
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Muders, Thomas, and Christian Putensen. Pressure-controlled mechanical ventilation. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0096.
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Beside reduction in tidal volume limiting peak airway pressure minimizes the risk for ventilator-associated-lung-injury in patients with acute respiratory distress syndrome. Pressure-controlled, time-cycled ventilation (PCV) enables the physician to keep airway pressures under strict limits by presetting inspiratory and expiratory pressures, and cycle times. PCV results in a square-waved airway pressure and a decelerating inspiratory gas flow holding the alveoli inflated for the preset time. Preset pressures and cycle times, and respiratory system mechanics affect alveolar and intrinsic positive end-expiratory (PEEPi) pressures, tidal volume, total minute, and alveolar ventilation. When compared with flow-controlled, time-cycled (‘volume-controlled’) ventilation, PCV results in reduced peak airway pressures, but higher mean airway. Homogeneity of regional peak alveolar pressure distribution within the lung is improved. However, no consistent data exist, showing PCV to improve patient outcome. During inverse ratio ventilation (IRV) elongation of inspiratory time increases mean airway pressure and enables full lung inflation, whereas shortening expiratory time causes incomplete lung emptying and increased PEEPi. Both mechanisms increase mean alveolar and transpulmonary pressures, and may thereby improve lung recruitment and gas exchange. However, when compared with conventional mechanical ventilation using an increased external PEEP to reach the same magnitude of total PEEP as that produced intrinsically by IRV, IRV has no advantage. Airway pressure release ventilation (APRV) provides a PCV-like squared pressure pattern by time-cycled switches between two continuous positive airway pressure levels, while allowing unrestricted spontaneous breathing in any ventilatory phase. Maintaining spontaneous breathing with APRV is associated with recruitment and improved ventilation of dependent lung areas, improved ventilation-perfusion matching, cardiac output, oxygenation, and oxygen delivery, whereas need for sedation, vasopressors, and inotropic agents and duration of ventilator support decreases.
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DeCampos, Kleber N. Lung preservation for transplantation: The role of reperfusion flow rate and alveolar recruitment on post-ischemic pulmonary function in rats. 1996.
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Ware, Lorraine B. Pathophysiology of acute respiratory distress syndrome. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0108.
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The acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure characterized by the acute onset of non-cardiogenic pulmonary oedema due to increased lung endothelial and alveolar epithelial permeability. Common predisposing clinical conditions include sepsis, pneumonia, severe traumatic injury, and aspiration of gastric contents. Environmental factors, such as alcohol abuse and cigarette smoke exposure may increase the risk of developing ARDS in those at risk. Pathologically, ARDS is characterized by diffuse alveolar damage with neutrophilic alveolitis, haemorrhage, hyaline membrane formation, and pulmonary oedema. A variety of cellular and molecular mechanisms contribute to the pathophysiology of ARDS, including exuberant inflammation, neutrophil recruitment and activation, oxidant injury, endothelial activation and injury, lung epithelial injury and/or necrosis, and activation of coagulation in the airspace. Mechanical ventilation can exacerbate lung inflammation and injury, particularly if delivered with high tidal volumes and/or pressures. Resolution of ARDS is complex and requires coordinated activation of multiple resolution pathways that include alveolar epithelial repair, clearance of pulmonary oedema through active ion transport, apoptosis, and clearance of intra-alveolar neutrophils, resolution of inflammation and fibrinolysis of fibrin-rich hyaline membranes. In some patients, activation of profibrotic pathways leads to significant lung fibrosis with resultant prolonged respiratory failure and failure of resolution.
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Lucangelo, Umberto, and Massimo Ferluga. Pulmonary mechanical dysfunction in the critically ill. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0084.
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In intensive care units practitioners are confronted every day with mechanically-ventilated patients and should be able to sort out from all the data available from modern ventilators to tailored patient ventilatory strategy. Real-time visualization of pressure, flow and tidal volume provide valuable information on the respiratory system, to optimize ventilatory support and avoiding complications associated with mechanical ventilation. Early determination of patient–ventilator asynchrony, air-trapping, and variation in respiratory parameters is important during mechanical ventilation. A correct evaluation of data becomes mandatory to avoid a prolonged need for ventilatory support. During dynamic hyperinflation the lungs do not have time to reach the functional residual capacity at the end of expiration, increasing the work of breathing and promoting patient-ventilator asynchrony. Expiratory capnogram provides qualitative information on the waveform patterns associated with mechanical ventilation and quantitative estimation of expired CO2. The concept of dead space accounts for those lung areas that are ventilated but not perfused. Calculations derived from volumetric capnography are useful indicators of pulmonary embolism. Moreover, alveolar dead space is increased in acute lung injury and its value decreased in case of positive end-expiratory pressure (PEEP)-induced recruitment, whereas PEEP-induced overdistension tends to increment alveolar dead space.
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Cuartero, Mireia, and Niall D. Ferguson. High-frequency ventilation and oscillation. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0098.
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High-frequency oscillatory ventilation (HFOV) is a key member of the family of modes called high-frequency ventilation and achieves adequate alveolar ventilation despite using very low tidal volumes, often below the dead space volume, at frequencies significantly above normal physiological values. It has been proposed as a potential protective ventilatory strategy, delivering minimal alveolar tidal stretch, while also providing continuous lung recruitment. HFOV has been successfully used in neonatal and paediatric intensive care units over the last 25 years. Since the late 1990s adults with acute respiratory distress syndrome have been treated using HFOV. In adults, several observational studies have shown improved oxygenation in patients with refractory hypoxaemia when HFOV was used as rescue therapy. Several small older trials had also suggested a mortality benefit with HFOV, but two recent randomized control trials in adults with ARDS have shed new light on this area. These trials not show benefit, and in one of them a suggestion of harm was seen with increased mortality for HFOV compared with protective conventional mechanical ventilation strategies (tidal volume target 6 mL/kg with higher positive end-expiratory pressure). While these findings do not necessarily apply to patients with severe hypoxaemia failing conventional ventilation, they increase uncertainty about the role of HFOV even in these patients.
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Hedenstierna, Göran, and Hans Ulrich Rothen. Physiology of positive-pressure ventilation. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0088.
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During positive pressure ventilation the lung volume is reduced because of loss of respiratory muscle tone. This promotes airway closure that occurs in dependent lung regions. Gas absorption behind the closed airway results sooner or later in atelectasis depending on the inspired oxygen concentration. The elevated airway and alveolar pressures squeeze blood flow down the lung so that a ventilation/perfusion mismatch ensues with more ventilation going to the upper lung regions and more perfusion going to the lower, dependent lung. Positive pressure ventilation may impede the return of venous blood to the thorax and right heart. This raises venous pressure, causing an increase in systemic capillary pressure with increased capillary leakage and possible oedema formation in peripheral organs. Steps that can be taken to counter the negative effects of mechanical ventilation include an increase in lung volume by recruitment of collapsed lung and an appropriate positive end-expiratory pressure, to keep aerated lung open and to prevent cyclic airway closure. Maintaining normo- or hypervolaemia to make the pulmonary circulation less vulnerable to increased airway and alveolar pressures, and preserving or mimicking spontaneous breaths, in addition to the mechanical breaths, since they may improve matching of ventilation and blood flow, may increase venous return and decrease systemic organ oedema formation (however, risk of respiratory muscle fatigue, and even overexpansion of lung if uncontrolled).
Book chapters on the topic "Alveolar recruitment"
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Bigatello, L. M., and P. Caironi. "Alveolar Recruitment." In Anaesthesia, Pain, Intensive Care and Emergency Medicine — A.P.I.C.E., 215–24. Milano: Springer Milan, 2002. http://dx.doi.org/10.1007/978-88-470-2099-3_18.
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Mergoni, M., A. Volpi, and A. Rossi. "Inflection Point and Alveolar Recruitment in ARDS." In Yearbook of Intensive Care and Emergency Medicine, 556–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-13450-4_46.
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Kuraszkiewicz, Bozenna. "Modelling of Alveolar Recruitment Phenomena in Human Lungs." In Advances in Soft Computing, 231–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-04462-5_23.
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Sydow, M., and H. Burchardi. "Influence of Time on Alveolar Recruitment in Acute Lung Injury." In Yearbook of Intensive Care and Emergency Medicine, 127–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79154-3_11.
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Lovas, A., and Z. Molnár. "Alveolar Recruitment in Patients with Assisted Ventilation: Open Up the Lung in Spontaneous Breathing." In Annual Update in Intensive Care and Emergency Medicine 2018, 205–15. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-73670-9_17.
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Scott, J. Aaron, and Vivek Moitra. "Positive End-Expiratory Pressure Setting in Adults with ALI and ARDS." In 50 Studies Every Intensivist Should Know, edited by Edward A. Bittner and Michael E. Hochman, 147–51. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190467654.003.0024.
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The ExPress Trial examined the role of a positive end-expiratory pressure (PEEP) strategy targeting increased alveolar recruitment versus minimal alveolar distension in the treatment of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Although lung protective ventilation in ALI and ARDS showed significant mortality benefit, the optimal PEEP strategy was unclear. The primary outcome of the study was 28 day mortality. Secondary outcomes included ventilator-free days, organ failure–free days, and barotrauma-related adverse events. Even though there was no significant difference in mortality between the two arms of the study, a significant difference was identified in ventilator-free days and organ failure–free days, which supported an increased recruitment PEEP strategy in the ALI/ARDS population and encouraged further examination.
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Shah, Chirag V. "What Is the Role of Alveolar Recruitment Maneuvers in the Management of ARDS?" In Evidence-Based Practice of Critical Care, 118–24. Elsevier, 2010. http://dx.doi.org/10.1016/b978-1-4160-5476-4.00019-5.
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Cheung, Cindy, and Christopher W. Tam. "Robotic Mitral Valve Surgery and Unilateral Pulmonary Edema." In Cardiothoracic Critical Care, 171–78. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780190082482.003.0017.
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This chapter describes robotic or minimally invasive mitral valve surgery, which was pioneered in 1998 to be the less invasive approach to sternotomy-based mitral valve operations. Patients undergoing robotic valve surgery carry a similar risk of complications that may occur with traditional median sternotomy surgery, but minimally invasive valve surgery has its own inherent complications associated with cardiac access, perfusion, and ventilation methods used in robotic surgeries. Unilateral pulmonary edema (UPE) is an uncommon but potentially life-threatening complication of robotic mitral valve surgery. The incidence of unilateral lung injury, which commonly manifests as UPE, has been reported to be quite variable. The variation in incidence could be related to the difference in patient populations, diagnostic criteria, as well as management. Moreover, the pathophysiology of UPE associated with robotic mitral valve repair remains unclear. The current literature suggests that UPE can be prevented by shorter cardiopulmonary bypass times, avoiding barotrauma, limiting blood product transfusion, and minimizing lung isolation times. Lung preventive ventilation, such as low-level positive pressure and frequent alveolar recruitment, while on cardiopulmonary bypass may be beneficial. Meanwhile, treatment for UPE is dependent on the severity of symptoms.
Conference papers on the topic "Alveolar recruitment"
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Dianti, J. M., M. S. Venuti, E. Gogniat, M. Ducrey, M. Madorno, M. Las Heras, S. Giannasi, E. San Roman, and G. Tusman. "Stress Index Predicts Alveolar Recruitment After a Lung Recruitment Maneuver." In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a1657.
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Cereda, Maurizio, Kiarash Emami, Stephen Kadlecek, Yi Xin, Puttisarn Mongkolwisetwara, Harilla Profka, Amy Barulic, et al. "Quantitative Imaging Of Alveolar Recruitment With Hyperpolarized Gas MRI." In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a2632.
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Degryse, Amber L., Xiaochuan C. Xu, Harikrishna Tanjore, Vasiliy V. Polosukhin, Brittany Jones, Frank B. Mc Mahon, Camilla Ortiz, Timothy S. Blackwell, and William E. Lawson. "TGFBeta Signalling In Epithelium Regulates Bleomycin Induced Alveolar Injury And Fibroblast Recruitment." In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a6144.
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Silva, Pedro L., Lilian Moraes, Raquel Santos, Cynthia S. Samary, Felipe Saddy, Humberto C. Junior, Tatiana Maron-Gutierrez, et al. "Effects Of Different Recruitment Maneuvers On Lung Morpho-function And Alveolar Stress." In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a1688.
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Stewart, Glenn, Caitlin Fermoyle, Courtney Wheatley, Briana Ziegler, and Bruce Johnson. "Influence of ultra-endurance exercise on alveolar-capillary recruitment and lung diffusion." In ERS International Congress 2018 abstracts. European Respiratory Society, 2018. http://dx.doi.org/10.1183/13993003.congress-2018.pa2441.
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Jose, Ann Mary. "Alveolar recruitment improving oxygenation in Acute Respiratory Distress Syndrome: A prospective observational study." In ERS International Congress 2018 abstracts. European Respiratory Society, 2018. http://dx.doi.org/10.1183/13993003.congress-2018.pa2338.
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Risquez, Cristobal F., Avignat Patel, Juan C. Osorio, Isis E. Fernandez, Andrew Goodwin, Ying Shi, Xiaomeng Tang, Danielle Morse, Ivan O. Rosas, and Yuanyuan Shi. "Syndecan-2 And CCL2 Interactions Promote Alveolar Macrophage Recruitment During Acute Lung Injury." In American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a3700.
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Amin, Samir, Henrique T. Moriya, Béla Suki, and Adriano M. Alencar. "Airway Tree Model Of Lung Recruitment: Effect Of Alveolar Compliance On Pressure Volume Fluctuations." In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a3656.
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Wall, Wolfgang A., Andrew Comerford, Lena Wiechert, and Sophie Rausch. "Coupled and Multi-Scale Building Blocks for a Comprehensive Computational Lung Model." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206407.
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Mechanical ventilation is a vital supportive therapy for critical care patients suffering from Acute Respiratory Distress syndrome (ARDS) or Acute Lung Injury (ALI) in view of oxygen supply. However, a number of associated complications often occur, which are collectively termed ventilator induced lung injuries (VILI) [1]. Biologically, these diseases manifest themselves at the alveolar level and are characterized by inflammation of the lung parenchyma following local overdistension or high shear stresses induced by frequent alveolar recruitment and derecruitment. Despite the more recent adoption of protective ventilation strategies based on the application of lower tidal volumes and a positive end-expiratory pressure (PEEP), patient mortality rates are with approximately 40% still very high. Understanding the reason why the lungs still become damaged or inflamed during mechanical ventilation is a key question sought by the medical community. In this contribution, an overview on recently developed building blocks of a comprehensive lung model will be given, with a main focus on lower airways.
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Vadasz, I., Y. Buchaeckert, R. Ruehl, W. Seeger, and RE Morty. "Recruitment Maneuvers Impair Alveolar Epithelial Function by Inhibiting Na,K-ATPase Function in Rabbit Lungs." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a4945.
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