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Imbesi, S. G. y C. W. Kerber. "Pressure Measurements across Vascular Stenoses". Interventional Neuroradiology 5, n.º 2 (junio de 1999): 139–44. http://dx.doi.org/10.1177/159101999900500205.
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We describe and analyze pressure measurements across vascular stenoses in an atherosclerotic human carotid bulb replica using catheters of different diameters. Replicas of an atherosclerotic human carotid bulb were created using the lost wax technique, and were placed in a circuit of pulsating non-newtonian fluid. Flows were adjusted to replicate human physiologic flow profiles. Common carotid artery total flow volume of 600 milli-liters/minute was studied. A pressure recording device was calibrated; data were received from catheters placed longitudinally in the common carotid artery and internal carotid artery. The internal carotid artery pressures were obtained both through the stenosis as is usually performed in the angiography suite and through the vessel side-wall beyond the stenosis as a control. Internal carotid artery flow volumes were also measured with and without the catheter through the stenosis. Multiple pressure recordings and volume measurements were obtained in the replica using 7 French, 5 French, and 2.5 French catheters. Measurements of the replica showed a 58% diameter stenosis and an 89% area stenosis of the carotid bulb. All longitudinal pressure measurements in the common carotid artery agreed with control values regardless of the diameter of the catheter used. Pressure measurements were also in agreement with control values in the internal carotid artery using the 2.5 French catheter. However, when larger diameter catheters were employed, pressures measured with the catheter through the stenosis fell when compared to control values. Additionally, internal carotid artery flow volumes were also decreased when the larger diameter catheters were placed across the stenosis. Large diameter catheters when placed across vascular stenoses may cause an occlusive or near-occlusive state and artifactually increase the measured transstenotic vascular pressure gradient as well as decrease forward vascular flow.
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Antony, Kathleen, Diana Racusin, Michael Belfort y Gary Dildy. "Under Pressure: Intraluminal Filling Pressures of Postpartum Hemorrhage Tamponade Balloons". American Journal of Perinatology Reports 07, n.º 02 (abril de 2017): e86-e92. http://dx.doi.org/10.1055/s-0037-1602657.
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Objective Uterine tamponade by fluid-filled balloons is now an accepted method of controlling postpartum hemorrhage. Available tamponade balloons vary in design and material, which affects the filling attributes and volume at which they rupture. We aimed to characterize the filling capacity and pressure-volume relationship of various tamponade balloons. Study Design Balloons were filled with water ex vivo. Intraluminal pressure was measured incrementally (every 10 mL for the Foley balloons and every 50 mL for all other balloons). Balloons were filled until they ruptured or until 5,000 mL was reached. Results The Foley balloons had higher intraluminal pressures than the larger-volume balloons. The intraluminal pressure of the Sengstaken-Blakemore tube (gastric balloon) was initially high, but it decreased until shortly before rupture occurred. The Bakri intraluminal pressure steadily increased until rupture occurred at 2,850 mL. The condom catheter, BT-Cath, and ebb all had low intraluminal pressures. Both the BT-Cath and the ebb remained unruptured at 5,000 mL. Conclusion In the setting of acute hemorrhage, expeditious management is critical. Balloons that have a low intraluminal pressure-volume ratio may fill more rapidly, more easily, and to greater volumes. We found that the BT-Cath, the ebb, and the condom catheter all had low intraluminal pressures throughout filling.
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Brown, I. G., P. A. McClean, P. M. Webster, V. Hoffstein y N. Zamel. "Lung volume dependence of esophageal pressure in the neck". Journal of Applied Physiology 59, n.º 6 (1 de diciembre de 1985): 1849–54. http://dx.doi.org/10.1152/jappl.1985.59.6.1849.
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There is conflicting evidence in the literature regarding tissue pressure in the neck. We studied esophageal pressure along cervical and intrathoracic esophageal segments in six healthy men to determine extramural pressure for the cervical and intrathoracic airways. A balloon catheter system with a 1.5-cm-long balloon was used to measure intraesophageal pressures. It was positioned at 2-cm intervals, starting 10 cm above the cardiac sphincter and ending at the cricopharyngeal sphincter. We found that esophageal pressures became more negative as the balloon catheter moved from intrathoracic to cervical segments, until the level of the cricopharyngeal sphincter was reached. At total lung capacity, esophageal pressures were -10.5 +/- 2.9 (SE) cmH2O in the lower esophagus, -18.9 +/- 3.0 just within the thorax, and -21.3 +/- 2.73 within 2 cm of the cricopharyngeal sphincter. The variation in mouth minus esophageal pressure with lung volume was similar in cervical and thoracic segments. We conclude that the subatmospheric tissue pressure applied to the posterior membrane of the cervical trachea results in part from transmission of apical pleural pressure into the neck. Transmural pressure for cervical and thoracic tracheal segments is therefore similar.
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Mukerji, Nitin, Julian Cahill, Desiderio Rodrigues, Savithru Prakash y Roger Strachan. "Flow dynamics in lumboperitoneal shunts and their implications in vivo". Journal of Neurosurgery 111, n.º 3 (septiembre de 2009): 632–37. http://dx.doi.org/10.3171/2009.2.jns08912.
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Object Lumboperitoneal shunting is the standard treatment for pseudotumour cerebri or idiopathic intracranial hypertension. Complications are common, particularly the problem of overdrainage leading to low pressure symptoms. The authors designed a simple experiment using catheters of different lengths that drained at different pressure heads and with different vertical drops to study the flow characteristics in these shunts and determine the optimal catheter placement and length that would reduce the occurrence of low pressure headaches. Methods The flow rates through catheters of 3 different lengths (60, 83, and 100 cm) with the same internal radius, at 3 different pressure heads (15, 25, and 35 cm H2O to simulate 3 different placements in the lumbar theca), and 3 different vertical drops (10, 20, and 30 cm to simulate the possible effect of siphoning) were measured and the results analyzed. Results Application of Poiseuille's law and Bernoulli's principle to the experimental design shows that the volume of flow is directly proportional to the sum of the pressure head and the vertical drop and inversely proportional to the length of the catheter. The flow rate through the standard catheter lengths over the course of 24 hours can be abnormally high. An attempt to predict the optimal catheter length was made. Conclusions Although the catheter position in the theca and abdomen cannot be altered significantly and the internal radius of the tube cannot be reduced further without increasing the risk of blockage, the length of the tube can be increased to combat overdrainage. The authors suggest that currently available catheters are too short.
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Brand, Paul H., Nianning Qi, Patricia J. Metting y Steven L. Britton. "A self-powered constant infusion device for use in unrestrained rats". American Journal of Physiology-Heart and Circulatory Physiology 278, n.º 6 (1 de junio de 2000): H2157—H2162. http://dx.doi.org/10.1152/ajpheart.2000.278.6.h2157.
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We developed a device that delivers fluid through a catheter at a constant rate and can be used in conscious animals to solve a variety of problems. For example, this device can be used for delivering drugs and maintaining intravascular catheter patency. The device provides infusions at low flows (1.0–1.5 ml/day), so that experimental agents may be administered with minimal volume loading of the rat. Arterial and venous catheter patency is maintained by infusion of heparinized saline through indwelling catheters attached to the device. The catheters exit from the rat in the intrascapular area and are routed through a protective spring to the device, which is suspended above the cage. The catheters may be attached to pressure transducers, blood may be sampled, and injections or infusions may be made without disturbing the rat. Because the device is self-contained, it can be suspended by a fluid-free swivel that rotates through 360°, providing minimal restraint. The device has been used successfully to measure arterial and central venous blood pressures in two studies using rats.
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Ito, H., M. Takaki, H. Yamaguchi, H. Tachibana y H. Suga. "Left ventricular volumetric conductance catheter for rats". American Journal of Physiology-Heart and Circulatory Physiology 270, n.º 4 (1 de abril de 1996): H1509—H1514. http://dx.doi.org/10.1152/ajpheart.1996.270.4.h1509.
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Left ventricular (LV) volume (V) is an essential parameter for assessment of the cardiac pump function. Measurement of LVV in situ by a conductance catheter method has been widely used in dogs and humans but not yet in small experimental animals such as rats. We instituted a miniaturized six-electrode conductance catheter (3-F) for rat LVV measurement and its signal processing apparatus. We compared stroke volumes (SVs) simultaneously measured with this conductance catheter introduced into the LV through the apex and an electromagnetic flow probe placed on the ascending aorta during gradual decreases in LVV by an inferior vena caval occlusion. A high and linear correlation (r = 0.982) was obtained between these differently measured by SVs pooled from six rats. In another group of three rats, LV pressure was simultaneously measured with a 3-F catheter-tip micromanometer introduced into the LV through the apex. We obtained the slope of the end-systolic pressure-volume (P-V) relationship (Emax) by a gradual ascending aortic occlusion. After administration of propranolol, Emax obviously decreased with no change in volume intercept of the P-V relationship. The conductance volumetry proved to be useful in rats.
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Szwarc, Richard S. y Howard A. Ball. "Simultaneous LV and RV volumes by conductance catheter: effects of lung insufflation on parallel conductance". American Journal of Physiology-Heart and Circulatory Physiology 275, n.º 2 (1 de agosto de 1998): H653—H661. http://dx.doi.org/10.1152/ajpheart.1998.275.2.h653.
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One aspect in the measurement of ventricular volume using the conductance catheter technique is the assessment of parallel electrical conductivity of structures extrinsic to the ventricular blood pool. Because it is sometimes necessary to make volume measurements during ventilation or spontaneous respiration, the extent to which parallel conductance may vary with lung insufflation was investigated. Anesthetized pigs (11–15 kg) were ventilated and instrumented with both left (LV) and right ventricular (RV) conductance and pressure-tip catheters and end-hole catheters for injection of hypertonic saline into the inferior vena cava and pulmonary artery. Data were recorded during ventilation with tidal volumes of 10 and 20 ml/kg, and the associated fluctuations to LV and RV end-diastolic (EDV) and stroke (SV) volumes were measured. With the use of a saline dilution technique, parallel conductance (Vc) was determined for each ventricle with the ventilator off and lungs insufflated to 0, 10, and 20 ml/kg. Whereas ventilation caused marked oscillations in LV and RV EDV and SV, these variations could not be attributed to Vc, which remained statistically unchanged from their baseline values of 34.1 ± 3.1 in the LV and 31.1 ± 4.4 in the RV. These results indicate that the fluctuations that occur in conductance catheter-derived LV and RV volume signals with ventilation are not caused by any significant changes to parallel conductance.
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Szwarc, R. S., D. Laurent, P. R. Allegrini y H. A. Ball. "Conductance catheter measurement of left ventricular volume: evidence for nonlinearity within cardiac cycle". American Journal of Physiology-Heart and Circulatory Physiology 268, n.º 4 (1 de abril de 1995): H1490—H1498. http://dx.doi.org/10.1152/ajpheart.1995.268.4.h1490.
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The conductance catheter gain factor, alpha, is usually determined by an independent measure of stroke volume and, as such, is assumed to be constant. However, nonlinearity of the conductance-volume relation has been proposed on theoretical grounds. The present study was designed to establish the extent of nonlinearity, or variability of alpha, within the cardiac cycle using magnetic resonance imaging (MRI) as the reference method. Pentobarbital-anesthetized minipigs (n = 10, 10–13 kg) were instrumented with left ventricular (LV) conductance and Millar catheters. Conductance catheter signals were recorded, and volumes were corrected for parallel conductance using a saline-dilution technique. Animals were then placed in a 4.7-T magnet, and first time derivative of LV pressure-gated transverse MRI images (5-mm slices) acquired during isovolumic contraction (end diastole) and relaxation (end systole). LV cavity volumes were then determined using a third-order polynomial model. The gain alpha was computed three ways: by dividing conductance stroke volume by MRI stroke volume (alpha SV), by dividing conductance end-diastolic volume by MRI end-diastolic volume (alpha ED), and by dividing conductance end-systolic volume by MRI end-systolic volume (alpha ES). alpha SV was 0.62 +/- 0.15, with alpha ED (0.71 +/- 0.17) significantly lower than alpha ES (0.81 +/- 0.21; P < 0.001). Using alpha SV to adjust conductance gain (i.e., assuming constant gain) resulted in a significantly larger end-diastolic volume (25.8 +/- 4.6 ml) and smaller ejection fraction (46.8 +/- 7.2%) than those obtained with MRI (23.0 +/- 4.1 ml and 53.1 +/- 7.3%, respectively; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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Biais, Matthieu, Karine Nouette-Gaulain, Alice Quinart, Stéphanie Roullet, Philippe Revel y François Sztark. "Uncalibrated Stroke Volume Variations Are Able to Predict the Hemodynamic Effects of Positive End-Expiratory Pressure in Patients with Acute Lung Injury or Acute Respiratory Distress Syndrome after Liver Transplantation". Anesthesiology 111, n.º 4 (1 de octubre de 2009): 855–62. http://dx.doi.org/10.1097/aln.0b013e3181b27fb2.
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Background Positive end-expiratory pressure (PEEP) may reduce cardiac output and total hepatic blood flow after liver transplantation. Pulse pressure variation is useful in predicting the PEEP-induced decrease in cardiac output. The aim of the study was to examine the relationships between stroke volume variations (SVV) obtained with the Vigileo monitor (Edwards Lifesciences, Irvine, CA), and the hemodynamic effects of PEEP. Methods Over 2 yr, patients presenting an acute lung injury or an acute respiratory distress syndrome in the 72 h after liver transplantation were prospectively enrolled. Patients were monitored with a pulmonary artery catheter (stroke volume) and with the Vigileo system (stroke volume and SVV). Measurements were performed in duplicate, first during zero end-expiratory pressure and then 10 min after the addition of 10 cm H2O PEEP. Results Twenty-six patients were included. Six patients were excluded from analysis. On PEEP, SVV and pulse pressure variation increased significantly and stroke volume decreased significantly. PEEP-induced changes in stroke volume measured by pulmonary artery catheter were significantly correlated with SVV (r = 0.69; P < 0.001) and pulse pressure variation on zero end-expiratory pressure (r = 0.66, P < 0.001). PEEP-induced decrease in stroke volume measured by pulmonary artery catheter > or = 15% was predicted by an SVV > 7% (sensitivity = 100%, specificity = 80%) and by a pulse pressure variation > 8% (sensitivity = 80%, specificity = 100%). PEEP-induced changes in stroke volume measured by pulmonary artery catheter and Vigileo device were correlated (r = 0.51, P < 0.005). Conclusions SVV obtained with Vigileo monitor is useful to predict decrease in stroke volume induced by PEEP. Moreover, this device is able to track changes in stroke volume induced by PEEP.
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Yaksh, T. L., P. A. Durant y C. R. Brent. "Micturition in rats: a chronic model for study of bladder function and effect of anesthetics". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, n.º 6 (1 de diciembre de 1986): R1177—R1185. http://dx.doi.org/10.1152/ajpregu.1986.251.6.r1177.
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The volume-evoked micturition reflex (VEMR) and the effects of anesthetics on the VEMR were studied in a chronic unanesthetized rat model. The bladder catheter was implanted chronically through a laparotomy and externalized percutaneously. An intrathecal (IT) catheter was implanted chronically in animals scheduled for an IT injection. By 2 days after implantation, infusion of saline (200 microliter/min) in the bladder reliably resulted in a low base-line pressure (BP) followed by a transient increase in bladder pressure, an opening of the sphincter (bladder opening pressure, BOP) corresponding to expression of urine (volume of urination, V), then a further rise in pressure (peak pressure, PP) and a subsequent return to base line. Seven days after implantation, values (means +/- SE) for BP, BOP, PP, and V were 10 +/- 0.3, 30 +/- 2, 67 +/- 6 cmH2O, and 1.0 +/- 0.1 ml, respectively. Residual volumes were reliably less than 2-4% of the expressed volume. The VEMR was reliably evoked up to 28 days after implantation. V values in unimplanted and implanted animals were not different. In implanted animals, VEMR parameters were not different during infusion or during spontaneous urination after oral fluid load. Administration of pentobarbital sodium (50 mg/kg ip), alpha-chloralose (130 mg/kg ip), ketamine (100 mg/kg im), halothane (in air 2%), and local anesthetics (2-chloroprocaine 3% or bupivacaine 0.75%, 10 microliter IT) produced a complete blockade of the VEMR and overflow incontinence at pressures significantly higher than BOP values. To compare overflow pressures and passive compliance of the bladder, unanesthetized animals were decapitated.(ABSTRACT TRUNCATED AT 250 WORDS)
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Cingolani, Oscar H. y David A. Kass. "Pressure-volume relation analysis of mouse ventricular function". American Journal of Physiology-Heart and Circulatory Physiology 301, n.º 6 (diciembre de 2011): H2198—H2206. http://dx.doi.org/10.1152/ajpheart.00781.2011.
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Nearly 40 years ago, the Sagawa laboratory spawned a renaissance in the use of instantaneous ventricular pressure-volume (P-V) relations to assess cardiac function. Since then, this analysis has taken hold as the most comprehensive way to quantify ventricular chamber function and energetics and cardiovascular interactions. First studied in large mammalian hearts and later in humans employing a catheter-based method, P-V analysis was translated to small rodents in the late 1990s by the Kass laboratory. Over the past decade, this approach has become a gold standard for comprehensive examination of in vivo cardiac function in mice, facilitating a new era of molecular cardiac physiology. The catheter-based method remains the most widely used approach in mice. In this brief review, we discuss this instrumentation, the theory behind its use, and how volume signals are calibrated and discuss elements of P-V analysis. The goal is to provide a convenient summary of earlier investigations and insights for users whose primary interests lie in genetic/molecular studies rather than in biomedical engineering.
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Morris, Kevin P., Warwick W. Butt y Tom R. Karl. "Effect of peritoneal dialysis on intra-abdominal pressure and cardio-respiratory function in infants following cardiac surgery". Cardiology in the Young 14, n.º 3 (junio de 2004): 293–98. http://dx.doi.org/10.1017/s1047951104003075.
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Objective:To investigate the relationship between dialysate volume, intra-abdominal pressure, and cardio-respiratory function in infants following cardiac surgery.Design:Prospective pilot study.Setting:Paediatric intensive care unit.Patients:Six infants undergoing peritoneal dialysis within 24 h of cardiopulmonary bypass.Interventions:Manipulation of the volume of dialysate at levels of 0, 10, 20, and 30 ml/kg in variable order.Measurements and main results:Intra-abdominal pressure was measured at each volume of dialysate via a pressure transducer connected to the dialysis catheter. Haemodynamic data was collected, including cardiac output, which was measured by thermodilution via a 3.5-French gauge catheter placed in the pulmonary arterial pathway. Respiratory data included PaO2, PaCO2, and dynamic compliance. Intra-abdominal pressure increased with increasing volume of dialysate (p < 0.001), though there was considerable variation between patients in the magnitude of increase. Intra-abdominal pressure remained low even with 30 ml/kg in the abdomen. In three infants, intra-abdominal pressure was re-measured in the absence of muscle relaxants, and was found to be higher in each case. No negative effects on cardiac output, markers of delivery of oxygen, or respiratory function were seen even at volumes of 30 ml/kg. Cardiac index was significantly higher with 10 ml/kg than when the abdomen was empty or contained a larger volume (p < 0.05).Conclusions:In this small group of infants, intra-abdominal pressure increased with increasing volumes of dialysate but remained low, even with 30 ml/kg in the abdomen, and was not associated with any deleterious effects on cardio-respiratory performance.
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Hu, Yin C. y Michael F. Stiefel. "Force and aspiration analysis of the ADAPT technique in acute ischemic stroke treatment". Journal of NeuroInterventional Surgery 8, n.º 3 (24 de enero de 2015): 244–46. http://dx.doi.org/10.1136/neurintsurg-2014-011563.
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IntroductionThe development of new revascularization devices has significantly improved recanalization rates and time to reperfusion. A direct aspiration first-pass (ADAPT) technique for stroke thrombectomy was recently shown to be an effective and rapid way to achieve revascularization. The technique focuses on engaging and removing a clot without the use of a separator or retriever by relying on the force and aspiration generated by the catheter. We sought to compare the physical and fluid dynamic properties (force and aspiration) of commercially available catheters to determine the most effective catheter for the ADAPT technique.MethodsBenchtop models were employed to compare aspiration for each catheter by submersing the catheter into a graduated cylinder and aspirating water. The volume of fluid aspirated and flow rates were calculated. Force of aspiration at the tip of each catheter was measured using a vacuum pressure gauge while the catheter was attached to a standard aspiration pump. Force was then calculated.ResultsThe Penumbra 5MAX ACE catheter had the greatest aspiration rate of all the catheters at 245 mL/min. The Penumbra 5 MAX catheter aspirated 212 mL/min, followed by the Navien 058 and DAC 057 with 198 mL/min and 197 mL/min, respectively. The Penumbra 5MAX ACE generated the greatest tip force (18.25 g) and the 5MAX had the least amount of force (14.77 g).ConclusionsThe physical and fluid dynamic properties of currently available catheters suggest that the 5MAX ACE is the optimal catheter to use in direct aspiration for stroke therapy.
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Washko, George R., Carl R. O'Donnell y Stephen H. Loring. "Volume-related and volume-independent effects of posture on esophageal and transpulmonary pressures in healthy subjects". Journal of Applied Physiology 100, n.º 3 (marzo de 2006): 753–58. http://dx.doi.org/10.1152/japplphysiol.00697.2005.
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Ventilator management decisions in acute lung injury could be better informed with knowledge of the patient's transpulmonary pressure, which can be estimated using measurements of esophageal pressure. Esophageal manometry is seldom used for this, however, in part because of a presumed postural artifact in the supine position. Here, we characterize the magnitude and variability of postural effects on esophageal pressure in healthy subjects to better assess its significance in patients with acute lung injury. We measured the posture-related changes in relaxation volume and total lung capacity in 10 healthy subjects in four postures: upright, supine, prone, and left lateral decubitus. Then, in the same subjects, we measured static pressure-volume characteristics of the lung over a wide range of lung volumes in each posture by using an esophageal balloon catheter. Transpulmonary pressure during relaxation (Plrel) averaged 3.7 (SD 2.0) cmH2O upright and −3.3 (SD 3.2) cmH2O supine. Approximately 58% of the decrease in Plrel between the upright and supine postures was due to a corresponding decrease in relaxation volume. The remaining 2.9-cmH2O difference is consistent with reported values of a presumed postural artifact. Relaxation volumes and pressures in prone and lateral postures were intermediate. To correct estimated transpulmonary pressure for the effect of lying supine, we suggest adding 3 cmH2O (95% confidence interval: −1 to +7 cmH2O). We conclude that postural differences in estimated transpulmonary pressure at a given lung volume are small compared with the substantial range of Plrel in patients with acute lung injury.
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Berthoud, H. R., W. B. Laughton y T. L. Powley. "A method for large volume blood sampling and transfusion in rats". American Journal of Physiology-Endocrinology and Metabolism 250, n.º 3 (1 de marzo de 1986): E331—E337. http://dx.doi.org/10.1152/ajpendo.1986.250.3.e331.
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A new protocol that makes it feasible to withdraw large volumes of whole blood from an individual rat within 1 h or less is described. This method involves the use of indwelling catheters for withdrawal of blood from the inferior vena cava with concurrent isovolemic replacement of whole blood into the superior vena cava. Simultaneity of the transfusion and withdrawal, strict equality of volumes, and a smooth exchange of blood are assured by the use of separate channels of the same multiple-channel peristaltic pump for withdrawal and replacement. Validation experiments using both anesthetized and unanesthetized rats indicate that several responses remain essentially undisturbed during large volume blood sampling; these parameters include blood pressure, heart rate, hematocrit, plasma hormones including insulin and glucagon, plasma glucose levels, and feeding behavior. Considerations of technical and physiological limitations of the protocol, including choice of catheters and catheter placement, pump, sampling parameters, and obtaining donor blood, are discussed.
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Gufler, Hubert, Sabine Wagner, Sabine Niefeldt, Christian Klopsch, Richard Brill, Walter Alexander Wohlgemuth y Can Yerebakan. "Levels of agreement between cardiac magnetic resonance and conductance catheter measurements of right ventricular volumes after pulmonary artery banding". Acta Radiologica 61, n.º 7 (21 de noviembre de 2019): 894–902. http://dx.doi.org/10.1177/0284185119886318.
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Background Pressure-volume analysis is the gold standard for quantifying pump function of the right ventricle (RV); however, volume measurements based on a conductive catheter may be imprecise. The reference method for volume assessment is cardiac magnetic resonance (CMR). Purpose To determine the levels of agreement between RV volume measurements obtained by cine CMR, phase-contrast CMR (PC CMR), and a conductance catheter in an animal model. Material and Methods CMR was performed in 20 sheep three months after pulmonary artery banding. Ejection fraction (EF), end-diastolic (EDV), end-systolic (ESV), and stroke volumes (SV) were obtained by cine CMR and conductance catheter. Results Statistically significant differences between cine CMR and conductance catheter derived volume measurements were found for EDV ( P < 0.001), ESV ( P < 0.05), and SV ( P < 0.05). Bland–Altman analysis showed very poor agreement between the two methods: EDV, bias 36.27 mL, agreement of limits 1.96–70.57 mL; ESV, bias 15.33 mL, agreement of limits –6.89–37.55 mL; and SV, bias 20.69 mL, agreement of limits 8.01–49.10 mL. Good agreement was found for SV between cine CMR and PC CMR (bias –7.0 mL, agreement of limits –24.01–9.98 mL), while SV derived from PC CMR measurements showed poor agreement with conductance catheter (bias 27.76 mL, agreement of limits –3.84–59.26 mL). Conclusion Poor agreement between the conductance catheter and CMR RV volume measurements was found. PC CMR and cine CMR measurements of SV agreed well.
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Applegate, R. J., W. E. Johnston, J. Vinten-Johansen, H. S. Klopfenstein y W. C. Little. "Restraining effect of intact pericardium during acute volume loading". American Journal of Physiology-Heart and Circulatory Physiology 262, n.º 6 (1 de junio de 1992): H1725—H1733. http://dx.doi.org/10.1152/ajpheart.1992.262.6.h1725.
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To determine the effect of the intact pericardium on ventricular end-diastolic pressures (EDP) during acute volume loading, we measured left ventricular (LV) and right ventricular (RV) micromanometer pressure and LV volume using a conductance catheter in eight open-chest, anesthetized dogs. A range of LV pressure and volume was obtained by intravascular volume expansion with the pericardium intact and then over a similar range after removal of the pericardium. Pericardial pressure (Pper) was calculated using static equilibrium analysis as the difference between LVEDP with the pericardium present and absent at a constant LV volume. At the beginning of the fluid infusion (LVEDP 7.3 +/- 1.7 mmHg and RVEDP 4.4 +/- 2.6 mmHg, mean +/- SD), Pper was not different from zero (-1.0 +/- 2.3 mmHg, P not significant). The onset of pericardial restraint (Pper greater than or equal to 0 mmHg) occurred when LVEDP was 9.1 +/- 2.9 mmHg and RVEDP was 4.1 +/- 2.9 mmHg. At low cardiac volumes before fluid infusion, RV transmural pressure was positive and significantly greater than the near zero Pper. After the onset of pericardial restraint, however, RVEDP and Pper increased similarly and were related according to Pper = 1.1 (+/- 0.34) RVEDP - 4.2 (+/- 2.6) mmHg, standard deviation 0.6 +/- 0.8 mmHg, r = 0.98 +/- 0.10. These data indicate that the intact pericardium behaves in two functionally distinct ways. At low cardiac volumes, Pper is zero and the pericardium does not affect LV filling. RV transmural pressure is positive and greater than Pper.(ABSTRACT TRUNCATED AT 250 WORDS)
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MERTLICH, GARY B., SUSAN J. QUAAL, PAUL R. BORGMEIER y K. LAWRENCE DEVRIES. "Effect of increased intra-aortic balloon pressure on catheter volume". Critical Care Medicine 20, n.º 2 (febrero de 1992): 297–303. http://dx.doi.org/10.1097/00003246-199202000-00018.
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STEENDIJK, P. "Pressure?volume measurements by conductance catheter during cardiac resynchronization therapy". European Heart Journal Supplements 6 (agosto de 2004): D35—D42. http://dx.doi.org/10.1016/j.ehjsup.2004.05.012.
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Clark, James E. y Michael S. Marber. "Advancements in pressure-volume catheter technology - stress remodelling after infarction". Experimental Physiology 98, n.º 3 (16 de noviembre de 2012): 614–21. http://dx.doi.org/10.1113/expphysiol.2012.064733.
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Ferguson, James J., Michael J. Miller, Peter Sahagian, Ba, Julian M. Aroesty y Raymond G. Mckay. "Assessment of aortic pressure-volume relationships with an impedance catheter". Catheterization and Cardiovascular Diagnosis 15, n.º 1 (1988): 27–36. http://dx.doi.org/10.1002/ccd.1810150107.
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Asanoi, H., S. Ishizaka, T. Kameyama, T. Nozawa, K. Miyagi y S. Sasayama. "Serial reproducibility of conductance catheter volumetry of left ventricle in conscious dogs". American Journal of Physiology-Heart and Circulatory Physiology 262, n.º 3 (1 de marzo de 1992): H911—H915. http://dx.doi.org/10.1152/ajpheart.1992.262.3.h911.
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Although the conductance catheter technique has been currently applied to in situ measurement of left ventricular volume, reproducibility of this method has not been examined within the same subject on separate days. Accordingly, serial catheter volumetries (mean 5 days apart) were performed in 10 normal conscious dogs, which were chronically instrumented with the conductance catheter, a micromanometer, and caval cuff occluders. Left ventricular end-systolic pressure-volume relationship was also determined during transient caval occlusion. All hemodynamic variables were compared at the same heart rate. There were no significant changes in blood resistivity (10 +/- 7 omega cm, 8%) and the parallel conductance of the surrounding tissues (7 +/- 6 ml, 10%). The mean difference was 3 +/- 2 ml (7%) for end-diastolic volume and 3 +/- 2 ml (11%) for end-systolic volume. Stroke volume and ejection fraction were also reproducible with mean difference of 2 +/- 1 ml (9%) and 3 +/- 2% (8%) respectively. The end-systolic pressure-volume relationships were nearly superimposable with the slope being 6.05 +/- 1.82 mmHg/ml on day 1 and 6.13 +/- 2.22 mmHg/ml on day 2. The difference averaged 0.63 +/- 0.42 mmHg/ml (11%). These results suggest that highly reproducible volume estimates by conductance catheter offer its feasibility of serial assessment of ventricular performance in vivo.
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Carlson, D. E., M. J. Brunner y D. S. Gann. "Carotid baroreceptor control of right atrial mechanics in dogs". American Journal of Physiology-Heart and Circulatory Physiology 261, n.º 6 (1 de diciembre de 1991): H1903—H1912. http://dx.doi.org/10.1152/ajpheart.1991.261.6.h1903.
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To investigate the influence of the carotid arterial baroreceptors on right atrial mechanics, the carotid sinus region was isolated surgically in eight dogs prepared acutely under pentobarbital. Right atrial pressure and conductance volume were measured with a strain-gauge tip catheter and a conductance catheter, respectively. Reduction of carotid sinus pressure from 225 to 50 mmHg elicited significant increases in the a wave in right atrial pressure, in atrial stroke volume, in atrial stroke work (2.5-fold), and in atrial stroke power (4-fold). Mean central venous pressure and atrial volume at the onset of each beat did not change. These responses were unchanged after bilateral cervical vagotomy. Head-up tilt was applied at carotid sinus pressures less than or equal to 150 mmHg in four dogs to oppose any contribution of decreased systemic venous capacity to the responses through increased atrial filling. Tilt did not change atrial stroke work or atrial filling during late ventricular systole before vagotomy but inhibited these variables significantly after vagotomy. The slope of the relationship between right atrial stroke work and atrial volume at the onset of contraction increased significantly with reduction of carotid sinus pressure. This response was unaffected by either vagotomy or tilt. Carotid arterial hypotension appears to augment right atrial stroke work and stroke volume through an increase in atrial contractility. A decrease in venous capacity may contribute to this response especially after vagotomy.
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Fried, T. A., M. A. Ayon, G. McDonald, A. Lau, T. Inagami y J. H. Stein. "Atrial natriuretic peptide, right atrial pressure, and sodium excretion rate in the rat". American Journal of Physiology-Renal Physiology 253, n.º 5 (1 de noviembre de 1987): F969—F975. http://dx.doi.org/10.1152/ajprenal.1987.253.5.f969.
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This study examined the relationship between right atrial pressure (RAP), urine flow rate, sodium excretion rate, and plasma atrial natriuretic peptide (ANP) levels after an acute Ringer expansion. Two groups of rats had their RAP monitored and balloon catheters placed in their thoracic inferior venae cavae. In one group the balloon remained deflated, and in the second group the balloon was inflated during the volume expansion in an attempt to prevent the rise in RAP. The peak RAP was 7.3 +/- 0.8 mmHg when the balloon remained deflated and 3.5 +/- 0.6 mmHg in the group with the balloon catheter inflated (P less than 0.005). The corresponding peak ANP levels were 682 +/- 140 and 223 +/- 40 pg/ml. There was a significant correlation between the peak RAP and ANP levels (r = 0.754; P less than 0.05). The inflation of the balloon catheter significantly decreased the urine flow rate and the urine sodium excretion rate. A final group of animals had 200 microliters of rabbit serum containing antibody to ANP infused before the volume expansion. The antibody-treated animals had significantly lower urine flow and sodium excretion rates than nonantibody-treated control rats. We conclude that ANP is one of the factors which allows the rat to excrete an acute Ringer expansion.
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Nielsen, Jan Møller, Steen B. Kristiansen, Steffen Ringgaard, Torsten Toftegaard Nielsen, Allan Flyvbjerg, Andrew N. Redington y Hans Erik Bøtker. "Left ventricular volume measurement in mice by conductance catheter: evaluation and optimization of calibration". American Journal of Physiology-Heart and Circulatory Physiology 293, n.º 1 (julio de 2007): H534—H540. http://dx.doi.org/10.1152/ajpheart.01268.2006.
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The conductance catheter (CC) allows thorough evaluation of cardiac function because it simultaneously provides measurements of pressure and volume. Calibration of the volume signal remains challenging. With different calibration techniques, in vivo left ventricular volumes (VCC) were measured in mice ( n = 52) with a Millar CC (SPR-839) and compared with MRI-derived volumes (VMRI). Significant correlations between VCC and VMRI [end-diastolic volume (EDV): R2 = 0.85, P < 0.01; end-systolic volume (ESV): R2 = 0.88, P < 0.01] were found when injection of hypertonic saline in the pulmonary artery was used to calibrate for parallel conductance and volume conversion was done by individual cylinder calibration. However, a significant underestimation was observed [EDV = −17.3 μl (−22.7 to −11.9 μl); ESV = −8.8 μl (−12.5 to −5.1 μl)]. Intravenous injection of the hypertonic saline bolus was inferior to injection into the pulmonary artery as a calibration method. Calibration with an independent measurement of stroke volume decreased the agreement with VMRI. Correction for an increase in blood conductivity during the in vivo experiments improved estimation of EDV. The dual-frequency method for estimation of parallel conductance failed to produce VCC that correlated with VMRI. We conclude that selection of the calibration procedure for the CC has significant implications for the accuracy and precision of volume estimation and pressure-volume loop-derived variables like myocardial contractility. Although VCC may be underestimated compared with MRI, optimized calibration techniques enable reliable volume estimation with the CC in mice.
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Miki, K., M. R. Klocke, S. K. Hong y J. A. Krasney. "Interstitial and intravascular pressures in conscious dogs during head-out water immersion". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 257, n.º 2 (1 de agosto de 1989): R358—R364. http://dx.doi.org/10.1152/ajpregu.1989.257.2.r358.
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Water immersion (WI) causes an increase in plasma volume in humans and dogs. To determine the mechanism for this fluid movement, the transmission of external water hydrostatic pressure to the interstitial and vascular compartments was studied in six conscious dogs. Systemic arterial, central venous, peripheral arterial (ulnar artery) and venous (cephalic vein), pleural, intra-abdominal, and interstitial fluid hydrostatic (by Guyton's capsule and wick catheter method) pressures and external reference water pressure were measured at three different levels of WI: 1) extremities only, 2) midchest, and 3) midcervical levels at 37 degrees C. There was a significant linear relationship between interstitial fluid hydrostatic pressure (X) and external water pressure (Y): (Y = 0.86X + 1.4, r = 0.93 by Guyton's capsule; Y = 0.85X + 2.4, r = 0.93 by wick catheter. However, vascular pressures did not change when dogs were immersed at the level of the extremities. These pressures increased only during WI at the midchest and midcervical levels. Therefore the pressure gradient that develops between the interstitial and intravascular compartments is probably the major reason for the transcapillary fluid shift during WI.
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Jung, Fang, Shang-Shing P. Chou, Shih-Hsing Yang, Jau-Chen Lin y Guey-Mei Jow. "Closed Endotracheal Suctioning Impact on Ventilator-Related Parameters in Obstructive and Restrictive Respiratory Systems: A Bench Study". Applied Sciences 11, n.º 11 (6 de junio de 2021): 5266. http://dx.doi.org/10.3390/app11115266.
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A closed suctioning system (CSS) in patients with coronavirus disease 2019 (COVID-19) prevents spraying respiratory secretions into the environment during suction. However, it is not clear whether ventilation is maintained during the suction procedure, especially in patients with compromised pulmonary mechanics. This paper determines the effects of endotracheal tube (ETT) size, suction catheter size, and two lung mechanics (resistance and compliance) on ventilator-related parameters measured during suction. Suction was performed on an adult training lung, ventilated with either volume-controlled (VC-CMV) or pressure-controlled mandatory ventilation (PC-CMV), using ETT sizes of 6.5–8.0 mm paired with suction catheter sizes of 8–14 French (Fr). Peak inspiratory pressure (PIP) increased by 50% when the ETT’s ventilation area was less than 25 mm2 in size, especially in patients with high airway resistance ventilated with VC-CMV. Positive end-expiratory pressure (PEEP) levels significantly decreased when using 14 Fr SC during VC-CMV and fewer effects during PC-CMV. Change of expiratory minute volume increased with higher outer diameter of suction catheters and decreased with severe lung compliance during PC-CMV. The change in ventilator-related parameters were intently monitored in the patient whose pulmonary mechanic was compromised through the CSS endotracheal tube suctioning procedures in clinical airway management.
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Herbertson, M. J., H. A. Werner y K. R. Walley. "Nitric oxide synthase inhibition partially prevents decreased LV contractility during endotoxemia". American Journal of Physiology-Heart and Circulatory Physiology 270, n.º 6 (1 de junio de 1996): H1979—H1984. http://dx.doi.org/10.1152/ajpheart.1996.270.6.h1979.
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Decreased contractility of myocytes after cytokine exposure can be prevented by nitric oxide synthase inhibition. Whether this is true in an intact animal model of sepsis is unknown. Anesthetized pigs were pretreated with saline or a nitric oxide synthase inhibitor, N omega-nitro-L-arginine, and then treated with saline or endotoxin. We measured hemodynamics and left ventricular pressures (Millar catheter) and volumes (conductance catheter). Left ventricular contractility was assessed using the slope (E(max)) of the end-systolic pressure-volume relationship. Four hours after endotoxin infusion, E(max) had decreased by 44 +/- 5% (P < 0.05) and mean arterial pressure had decreased by 30 +/- 10% (P < 0.05). Pretreatment with N omega-nitro-L-arginine significantly reduced the decrease in E(max) to 28 +/- 3% (P < 0.05) and prevented the decrease in mean arterial pressure. However, it also raised pulmonary arterial pressure. We conclude that nitric oxide contributes to the early decrease in left ventricular contractility after endotoxin in the intact animal. However, the vascular effects of nitric oxide synthase inhibition increase right and left ventricular afterloads, which were detrimental to cardiac function.
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Gärtner, Theresa, Efthymios Beropoulis, Regina Wendl, Jasmin S. Hanke, Günes Dogan, Anamika Chatterjee, Axel Haverich et al. "In vitro study for the evaluation of transluminal aspiration as a novel treatment option for thrombosis in the HeartWare HVAD". International Journal of Artificial Organs 41, n.º 11 (18 de julio de 2018): 764–71. http://dx.doi.org/10.1177/0391398818785557.
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Introduction: Pump thrombosis of left ventricular assist devices remains a devastating complication with high morbidity and mortality. Despite the improvements made, the matter affects many patients and the treatment options are limited to thrombolysis and surgical replacement. An alternative approach using the aspiration Indigo catheter was tested. Methods: An Indigo thrombectomy catheter was used within an in vitro model to assess the direct aspiration of prefabricated clots from three different positions within the HeartWare HVAD (inlet, outlet, and housing). The experiments were conducted with a straight and an angled catheter. The aspiration pressure was constant. The flow, power consumption, and pressure head of the left ventricular assist devices were measured at pre-defined measuring points. Results: The device was more effective (success rate 71%) at inlet and outlet of the left ventricular assist device. In addition, the duration of aspiration and the aspiration volume were shorter in comparison to the aspiration in the housing (inlet M = 19.75 s, outlet M = 60.50 s, and housing M = 38.75 s). Moreover, the aspiration volume was associated with the aspiration duration and the weight of thrombi but not with their volume. Noteworthy, the angled catheter showed an improved performance compared to the straight one (67%–33%). The recorded parameters showed no major changes during the use of the catheter. After application of the Indigo catheter, flow and pressure head of the pump could be restored. Conclusions: The aspiration system showed promising results under specific conditions for the treatment of pump thrombosis in an in vitro model. However, further examination, including in vivo experiments, will justify its effectiveness.
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Baert, Edward Jozef, Jelle Vandersteene, Frank Dewaele, Anna Vantilborgh, Dirk Van Roost y Filip De Somer. "A new dynamic model for in vitro evaluation of intravascular devices". International Journal of Artificial Organs 42, n.º 1 (4 de noviembre de 2018): 42–48. http://dx.doi.org/10.1177/0391398818806158.
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Introduction: A dynamic model to evaluate thrombus formation on intravascular catheters in vitro is presented. The model enables fluid infusion, variation in the catheter orientation, and variable flow conditions. It was applied on a catheter used to shunt cerebrospinal fluid to a vein, a dural venous sinus, for the treatment of hydrocephalus. Methods: Fresh human blood-filled circuits were circulated in a non-occlusive roller pump. A catheter infused either with cerebrospinal fluid, Ringer’s lactate, or no fluid (control) was inserted through each circuit’s wall. Sixteen circuits (six cerebrospinal fluid, six Ringer’s lactate, four control) ran for 60 min. Qualitative assessment was performed by measuring viscoelastic properties of blood at the start and end of the experiment; quantitative evaluation of clot formation by scanning electron microscope. Results: Average blood velocity was 79 mm/s, with a pressure wave between 5 and 15 mm Hg. At the experiment’s end, the infused fluid represented 5.88% of the blood/infusion volume in the circuit. The control circuits showed no statistical difference between the start and end for viscoelastic testing, whereas both Ringer’s lactate and cerebrospinal fluid enhanced coagulation, most pronounced for the latter. Most thrombus material was observed on catheters in the cerebrospinal fluid group. Clot formation was less pronounced on the surface of the catheter facing the blood flow. Discussion: A dynamic model for intravascular catheter testing mimics better clinical conditions when evaluating blood–material interaction. Catheter position, blood flow around the catheter, and infusion fluid all have a potential impact on the hemocompatibility of a given catheter.
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Georgakopoulos, Dimitrios, Wayne A. Mitzner, Chen-Huan Chen, Barry J. Byrne, Huntly D. Millar, Joshua M. Hare y David A. Kass. "In vivo murine left ventricular pressure-volume relations by miniaturized conductance micromanometry". American Journal of Physiology-Heart and Circulatory Physiology 274, n.º 4 (1 de abril de 1998): H1416—H1422. http://dx.doi.org/10.1152/ajpheart.1998.274.4.h1416.
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The mouse is the species of choice for creating genetically engineered models of human disease. To study detailed systolic and diastolic left ventricular (LV) chamber mechanics in mice in vivo, we developed a miniaturized conductance-manometer system. α-Chloralose-urethan-anesthetized animals were instrumented with a two-electrode pressure-volume catheter advanced via the LV apex to the aortic root. Custom electronics provided time-varying conductances related to cavity volume. Baseline hemodynamics were similar to values in conscious animals: 634 ± 14 beats/min, 112 ± 4 mmHg, 5.3 ± 0.8 mmHg, and 11,777 ± 732 mmHg/s for heart rate, end-systolic and end-diastolic pressures, and maximum first derivative of ventricular pressure with respect to time (dP/d t max), respectively. Catheter stroke volume during preload reduction by inferior vena caval occlusion correlated with that by ultrasound aortic flow probe ( r 2 = 0.98). This maneuver yielded end-systolic elastances of 79 ± 21 mmHg/μl, preload-recruitable stroke work of 82 ± 5.6 mmHg, and slope of dP/d t max-end-diastolic volume relation of 699 ± 100 mmHg ⋅ s−1 ⋅ μl−1, and these relations varied predictably with acute inotropic interventions. The control normalized time-varying elastance curve was similar to human data, further supporting comparable chamber mechanics between species. This novel approach should greatly help assess cardiovascular function in the blood-perfused murine heart.
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Maruyama, T. "Determination of end-systolic pressure-volume relationship using IABP balloon catheter." Japanese Journal of Cardiovascular Surgery 19, n.º 3 (1989): 581–83. http://dx.doi.org/10.4326/jjcvs.19.581.
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Yagi, K., S. Ikeda y J. F. Schweiss. "DYNAMIC VOLUME AND PRESSURE CHANGES DURING PULMONARY ARTERY CATHETER BALLOON INFLATION". Anesthesiology 71, Supplement (septiembre de 1989): A422. http://dx.doi.org/10.1097/00000542-198909001-00422.
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Szwarc, Richard S., Reena Sandhu, Lee N. Benson, John G. Coles y Gregory J. Wilson. "Computer-aided analysis of impedance catheter derived ventricular pressure-volume data". Journal of Molecular and Cellular Cardiology 22 (mayo de 1990): S110. http://dx.doi.org/10.1016/0022-2828(90)91853-y.
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Agah, Shahram, Sahar Tavakoli, Hajar Nikbakht, Mehrdokht Najafi y Abdolreza Al-agha. "Central venous pressure catheter for large-volume paracentesis in refractory ascites". Indian Journal of Gastroenterology 33, n.º 4 (24 de abril de 2014): 310–15. http://dx.doi.org/10.1007/s12664-014-0448-0.
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Konecny, Filip. "The Left Ventricular End-Systolic Pressure Correlation with Aortic Valve Timing; a Novel Inotropic Index Description Using a Dual Pressure Catheter". Journal of Cardiology and Clinical Management 1, n.º 1 (5 de marzo de 2022): 1–16. http://dx.doi.org/10.56391/jccm.2022.1012.
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Myocardial contraction is generated by ventricular pressure in early systole by the isometric force against closed valves, as ventricle is contracting without changing volume. This initial contractile phase of cardiac cycle (early systole) is followed by rapid shortening, isotonic contraction, allowing ejection of the blood against changing LV afterload. LV is coupled to the systemic arterial pressure; hence LV ejection is closely linked to the properties of the aortic valve, aorta, and its distributing arteries. Isometric relationship in the LV was characterized using the load-dependent example (naïve vs. post-dobutamine), observed mostly in case of rate of rise of LVP, LV ESP and decrease of pulse wave velocity, characteristics of LV baroinometry. Furthermore, by performing load-independent maneuver, afterload (LV ESP) was adjusting at every cardiac cycle, while an assessment of LV ESP and aortic valve timing was able to be established. By plotting decaying LV ESP against aortic valve timing, highly linear correlation of load-independent isotonic, but also an isometric contractility was captured. Steeper linear slope and time-axis intercept (IC) were identified in case of post-inotropic challenge, recapitulating changes otherwise measured during pressure-volume exam. This relationship, measured by dual-pressure catheter, could serve as novel inotropic index of functional cardiac contractility. Keywords: Left Ventricle (LV); Contractility; Inotropy; Load-Dependent and Independent; Stressed Volume; Dual Pressure Catheter. 1. Assessment of cardiac contractility using dual pressure catheter. 2. IVCO inferior vena cava occlusion, ECC excitation-contraction coupling, EF ejection fraction, TTE transthoracic echocardiography, Ea end arterial elastance, PRSW preload recruitable stroke work, IC intercept, PWV pulse wave velocity.
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Hug, M. I., V. Buettiker, A. Cornelius y M. Weiss. "Variability in Infusion Pressure and Continuous Flow Rate Delivered from Pressurized Bag Pump Flush Systems". Anaesthesia and Intensive Care 30, n.º 3 (junio de 2002): 341–47. http://dx.doi.org/10.1177/0310057x0203000313.
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Using 10 different infusion bag pressure pumps, indicated manometer pressures were compared with measured infusion pressures proximal to the flow-regulating device in an in vitro experiment. Flow rates delivered through the flow-regulating device were gravimetrically measured at different monitored pressure levels. Significant differences were found between manometer and measured infusion pressures among the tested pressure bag pumps (e.g. 500 ml bag volume pressurized to 300mmHg manometer pressure: 219.6±7.8 to 407.2±2.7 mmHg). The infusion pressures were additionally affected by the vertical level of the infusion bag pump and by the volume of the infusion bag. Flow rates delivered through the flow-regulating device were directly correlated to the measured infusion pressure (r 2 =0.9926). Differences in flow rates can have a considerable impact on maintaining catheter patency and avoidance of fluid overload and retrograde flushing into the central arterial circulation in neonates and small children. A simple manoeuvre using the invasive pressure transducer allows monitoring and adjustment of the infusion pressure in the clinical setting.
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Feher, A., R. Castile, J. Kisling, C. Angelicchio, D. Filbrun, R. Flucke y R. Tepper. "Flow limitation in normal infants: a new method for forced expiratory maneuvers from raised lung volumes". Journal of Applied Physiology 80, n.º 6 (1 de junio de 1996): 2019–25. http://dx.doi.org/10.1152/jappl.1996.80.6.2019.
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Forced expiratory maneuvers generated by rapid thoracic compression have been used to assess airway function in infants. It remains unclear whether flow limitation can be achieved in healthy infants because low pressure transmission across the chest wall and inspiratory effort may limit the maximum transpulmonary pressure developed during the maneuver. We have found that several rapid inflations to a lung volume set at an airway pressure of 30 cmH2O (V80) briefly inhibit respiratory effort and allow forced expiration to proceed from V80 to residual volume. We used a water-filled esophageal catheter to measure isovolume pressure-flow curves in seven healthy infants (3-88 mo). Forced vital capacity (FVC) was defined as the volume between V80 and residual volume. Pressure transmission between the compression jacket and the esophagus decreased with decreasing lung volume and averaged 60 and 37% at 50 and 75% of expired FVC, respectively. Subjects demonstrated plateaus in their isovolume pressure-flow curves at 50% of expired FVC and lower lung volumes. We conclude that this new methodology enables forced expiratory maneuvers to achieve flow limitation in healthy infants over at least the lower portion of their lung volume.
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Tontodonati, Marcello, Debbie Ridley, René Remie y Peter Clements. "Improved method for the catheterization of the right ventricle in a rat model of pulmonary artery hypertension". Interactive CardioVascular and Thoracic Surgery 30, n.º 4 (21 de enero de 2020): 535–37. http://dx.doi.org/10.1093/icvts/ivz314.
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Abstract Ventricle catheterization in the rat is widely practiced in cardiopulmonary research. The catheters deployed are either fluid filled or solid tip pressure or pressure–volume catheters. The access to the right ventricle is through the right jugular vein, most commonly without direct visualization such as fluoroscopy. Advancement of the catheter tip is aided by visualizing the pressure signals of the monitoring/recording systems used. This approach may present challenges due to various reasons, including the stiffness of new catheters, their dimensions or anatomical changes associated with the animal disease model. In this article, we present a novel approach, which has been optimized, successfully validated surgically and adopted in current projects. It has been shown to improve both the overall quality of the signals recorded and the time to access the right ventricle, thus reducing the overall time of surgery. The method presented in this article is safe, easy to reproduce and does not require additional skills compared to a more ‘standard’ approach.
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McCabe, Colm, Paul A. White, Stephen P. Hoole, Richard G. Axell, Andrew N. Priest, Deepa Gopalan, Dolores Taboada et al. "Right ventricular dysfunction in chronic thromboembolic obstruction of the pulmonary artery: a pressure-volume study using the conductance catheter". Journal of Applied Physiology 116, n.º 4 (15 de febrero de 2014): 355–63. http://dx.doi.org/10.1152/japplphysiol.01123.2013.
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Pressure-volume loops describe dynamic ventricular performance, relevant to patients with and at risk of pulmonary hypertension. We used conductance catheter-derived pressure-volume loops to measure right ventricular (RV) mechanics in patients with chronic thromboembolic pulmonary arterial obstruction at different stages of pathological adaptation. Resting conductance catheterization was performed in 24 patients: 10 with chronic thromboembolic pulmonary hypertension (CTEPH), 7 with chronic thromboembolic disease without pulmonary hypertension (CTED), and 7 controls. To assess the validity of conductance measurements, RV volumes were compared in a subset of 8 patients with contemporaneous cardiac magnetic resonance (CMR). Control, CTED, and CTEPH groups showed different pressure-volume loop morphology, most notable during systolic ejection. Prolonged diastolic relaxation was seen in patients with CTED and CTEPH [tau = 56.2 ± 6.7 (controls) vs. 69.7 ± 10.0 (CTED) vs. 67.9 ± 6.2 ms (CTEPH), P = 0.02]. Control and CTED groups had lower afterload (Ea) and contractility (Ees) compared with the CTEPH group (Ea = 0.30 ± 0.10 vs. 0.52 ± 0.24 vs. 1.92 ± 0.70 mmHg/ml, respectively, P < 0.001) (Ees = 0.44 ± 0.20 vs. 0.59 ± 0.15 vs. 1.13 ± 0.43 mmHg/ml, P < 0.01) with more efficient ventriculoarterial coupling (Ees/Ea = 1.46 ± 0.30 vs. 1.27 ± 0.36 vs. 0.60 ± 0.18, respectively, P < 0.001). Stroke volume assessed by CMR and conductance showed closest agreement (mean bias +9 ml, 95% CI −1 to +19 ml) compared with end-diastolic volume (+48 ml, −16 to 111 ml) and end-systolic volume (+37 ml, −21 to 94 ml). RV conductance catheterization detects novel alteration in pressure-volume loop morphology and delayed RV relaxation in CTED, which distinguish this group from controls. The observed agreement in stroke volume assessed by CMR and conductance suggests RV mechanics are usefully measured by conductance catheter in chronic thromboembolic obstruction.
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Oakley, RE, B. Olivier, GE Eyster y JG Hauptman. "Experimental evaluation of central venous pressure monitoring in the dog". Journal of the American Animal Hospital Association 33, n.º 1 (1 de enero de 1997): 77–82. http://dx.doi.org/10.5326/15473317-33-1-77.
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The measurement of central venous pressure (CVP) will provide objective information about intravascular blood volume. Limitations exist with direct and indirect methods of measuring CVP; however, the purpose of this study was to determine if such factors as catheter size, patient position, or measurements taken with either a water manometer or a strain-gauge transducer would affect the accuracy of CVP measurements. The study population consisted of six adult, mixed-breed dogs. Catheter sizes evaluated were 16- and 19-gauge. Patient positions evaluated were right and left lateral recumbencies. Right atrial pressures (RAPs) were used as the reference standards for CVP measurements. Measurements of RAP and CVP were obtained with a water manometer and a strain-gauge transducer. No significant differences were observed in measured CVPs for the effects of catheter size and right versus left lateral recumbency. A 2.7-mmHg difference in water manometry was demonstrated when compared to strain-gauge transducer measurements. Also, strain-gauge transducer measurements had less precision compared to water manometer measurements.
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Jansen-Winkeln, Boris, Stefan Niebisch, Uwe Scheuermann, Ines Gockel y Matthias Mehdorn. "Biomechanical Effects of Incisional Negative Wound Pressure Dressing: An Ex Vivo Model Using Human and Porcine Abdominal Walls". BioMed Research International 2018 (30 de diciembre de 2018): 1–7. http://dx.doi.org/10.1155/2018/7058461.
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Introduction. Incisional negative pressure wound therapy (iNPWT) has been of recent interest in different surgical fields as beneficial outcomes on high-risk wounds have been reported. Nevertheless, its mechanisms of function are not widely studied to date. Methods. We established two ex vivo setups of iNPWT in porcine and human abdominal wall for measuring pressures within the wound which result from iNPWT application. For pressure measurements, a high-resolution manometry catheter and a balloon catheter probe were used in a wound sealed with either a commercially available PREVENA VAC kit or a self-made iNPWT kit. Furthermore, we evaluated seroma evacuation by iNPWT. Results. Both setups showed similar characteristics of pressure curves within the wound when applying increasing negative pressures. Application of high pressures did not result in a similar increase in wound pressure. Only subtotal evacuation of seroma by iNPWT application (about 75% of volume) could be detected. Conclusion. Our ex vivo model of iNPWT in porcine and human abdominal wall could show reproducible measurements of pressures within the wounds in both types of tissue. As intrawound pressures did not increase in the same way as the applied negative pressure, we suggest that our results do not advocate the idea of using iNPWT for wound care especially as seroma evacuation remains insufficient.
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Hull, Garret J., Nancy L. Moureau y Shramik Sengupta. "Quantitative assessment of reflux in commercially available needle-free IV connectors". Journal of Vascular Access 19, n.º 1 (enero de 2018): 12–22. http://dx.doi.org/10.5301/jva.5000781.
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Introduction: Blood reflux is caused by changes in pressure within intravascular catheters upon connection or disconnection of a syringe or intravenous tubing from a needle-free connector (NFC). Changes in pressure, differing with each brand of NFC, may result in fluid movement and blood reflux that can contribute to intraluminal catheter occlusions and increase the potential for central-line associated bloodstream infections (CLABSI). Methods: In this study, 14 NFC brands representing each of the four market-categories of NFCs were selected for evaluation of fluid movement occurring during connection and disconnection of a syringe. Study objectives were to 1) theoretically estimate amount of blood reflux volume in microliters (μL) permitted by each NFC based on exact component measurements, and 2) experimentally measure NFC volume of fluid movement for disconnection reflux of negative, neutral and anti-reflux NFC and fluid movement for connection reflux of positive displacement NFC. Results: The results demonstrated fluid movement/reflux volumes of 9.73 μL to 50.34 μL for negative displacement, 3.60 μL to 10.80 μL for neutral displacement, and 0.02 μL to 1.73 μL for pressure-activated anti-reflux NFC. Separate experiment was performed measuring connection reflux of 18.23 μL to 38.83 μL for positive displacement NFC connectors. Conclusions: This study revealed significant differences in reflux volumes for fluid displacement based on NFC design. While more research is needed on effects of blood reflux in catheters and NFCs, results highlight the need to consider NFCs based on performance of individual connector designs, rather than manufacturer designation of positive, negative and neutral marketing categories for NFCs without anti-reflux mechanisms.
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Kass, D. A., T. Yamazaki, D. Burkhoff, W. L. Maughan y K. Sagawa. "Determination of left ventricular end-systolic pressure-volume relationships by the conductance (volume) catheter technique." Circulation 73, n.º 3 (marzo de 1986): 586–95. http://dx.doi.org/10.1161/01.cir.73.3.586.
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Elrakhawy, Hany M., Mohamed A. Alassal, Ayman M. Shaalan, Ahmed A. Awad, Sameh Sayed y Mohammad M. Saffan. "Impact of Major Pulmonary Resections on Right Ventricular Function: Early Postoperative Changes". Heart Surgery Forum 21, n.º 1 (15 de enero de 2018): 009. http://dx.doi.org/10.1532/hsf.1864.
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Background: Right ventricular (RV) dysfunction after pulmonary resection in the early postoperative period is documented by reduced RV ejection fraction and increased RV end-diastolic volume index. Supraventricular arrhythmia, particularly atrial fibrillation, is common after pulmonary resection. RV assessment can be done by non-invasive methods and/or invasive approaches such as right cardiac catheterization. Incorporation of a rapid response thermistor to pulmonary artery catheter permits continuous measurements of cardiac output, right ventricular ejection fraction, and right ventricular end-diastolic volume. It can also be used for right atrial and right ventricular pacing, and for measuring right-sided pressures, including pulmonary capillary wedge pressure.Methods: This study included 178 patients who underwent major pulmonary resections, 36 who underwent pneumonectomy assigned as group (I) and 142 who underwent lobectomy assigned as group (II). The study was conducted at the cardiothoracic surgery department of Benha University hospital in Egypt; patients enrolled were operated on from February 2012 to February 2016. A rapid response thermistor pulmonary artery catheter was inserted via the right internal jugular vein. Preoperatively the following was recorded: central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, right ventricular ejection fraction and volumes. The same parameters were collected in fixed time intervals after 3 hours, 6 hours, 12 hours, 24 hours, and 48 hours postoperatively.Results: For group (I): There were no statistically significant changes between the preoperative and postoperative records in the central venous pressure and mean arterial pressure; there were no statistically significant changes in the preoperative and 12, 24, and 48 hour postoperative records for cardiac index; 3 and 6 hours postoperative showed significant changes. There were statistically significant changes between the preoperative and postoperative records for heart rate, mean pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, right ventricular ejection fraction and right ventricular end diastolic volume index, in all postoperative records. For group (II): There were no statistically significant changes between the preoperative and all postoperative records for the central venous pressure, mean arterial pressure and cardiac index. There were statistically significant changes between the preoperative and postoperative records for heart rate, mean pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, right ventricular ejection fraction and right ventricular end diastolic volume index in all postoperative records. There were statistically significant changes between the two groups in all postoperative records for heart rate, mean pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, right ventricular ejection fraction and right ventricular end diastolic volume index.Conclusion: There is right ventricular dysfunction early after major pulmonary resection caused by increased right ventricular afterload. This dysfunction is more present in pneumonectomy than in lobectomy. Heart rate, mean pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, right ventricular ejection fraction, and right ventricular end diastolic volume index are significantly affected by pulmonary resection.
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Sato, Takayuki, Toshiaki Shishido, Toru Kawada, Hiroshi Miyano, Hiroshi Miyashita, Masashi Inagaki, Masaru Sugimachi y Kenji Sunagawa. "ESPVR of in situ rat left ventricle shows contractility-dependent curvilinearity". American Journal of Physiology-Heart and Circulatory Physiology 274, n.º 5 (1 de mayo de 1998): H1429—H1434. http://dx.doi.org/10.1152/ajpheart.1998.274.5.h1429.
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We developed a miniaturized conductance catheter for in situ rat left ventricular (LV) volumetry. After the validation study of the conductance volumetry in 11 rats, we characterized the end-systolic pressure-volume relationship (ESPVR) in 24 sinoaortic-denervated, vagotomized and urethan-anesthetized rats. Stroke volume (SV) measured with the conductance catheter correlated closely with that measured by electromagnetic flowmetry ( r > 0.95). No significant difference was found between the in situ LV end-diastolic volumes measured by conductance volumetry and postmortem morphometry; a linear regression analysis indicated that the correlation coefficient was 0.934, that the slope was not significantly different from 1, and that the intercept was not significantly different from 0. During cardiac sympathotonic conditions, the ESPVR was curvilinear. The estimated slope of ESPVR (end-systolic elastance, E es) by quadratic curve fitting at end-systolic pressure of 100 mmHg was 2,647 ± 846 mmHg/ml. Bilateral cervical and stellate ganglionectomy depressed contractility and made the ESPVR linear; a quadratic equation did not improve the fit. E es was 946 ± 55 mmHg/ml with the volume-axis ( V 0) intercept of 0.076 ± 0.007 ml. Administration of propranolol (1 mg/kg) further reduced E es (573 ± 61 mmHg/ml, P < 0.001) and increased V 0 slightly (0.091 ± 0.011 ml). We conclude that the conductance catheter method is useful for the assessment of the ESPVR of the in situ rat left ventricle and that the ESPVR displays contractility-dependent curvilinearity.
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Allen, S., J. Gabel y R. Drake. "Left atrial hypertension causes pleural effusion formation in unanesthetized sheep". American Journal of Physiology-Heart and Circulatory Physiology 257, n.º 2 (1 de agosto de 1989): H690—H692. http://dx.doi.org/10.1152/ajpheart.1989.257.2.h690.
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We studied the effect of left atrial pressure (LAP) elevation on the formation of pleural effusion in unanesthetized sheep. We prepared the animals by placing catheters in the left atrium, pulmonary artery, femoral artery, and vein. We also placed a balloon catheter in the left atrium. After a recovery period of at least 1 wk, we measured LAP, pulmonary artery pressure (PAP), systemic arterial pressure, systemic venous pressure, cardiac output, plasma protein concentration, and plasma colloid osmotic pressure (pi c). We calculated capillary pressure (Pc) as 0.5(PAP - LAP). We then elevated LAP such that Pc-pi c was between -10 and 19.5 mmHg for 6-24 h. At the end of the experiment, we killed the sheep and measured the volume and protein concentration of the right pleural effusion. We also determined the extravascular fluid to blood free dry weight of the right lung. We found that pleural effusions and pulmonary edema formed when Pc-pi c greater than 5 mmHg. We also found that the pleural effusion volume correlated with the amount of pulmonary edema. Our data show that elevated LAP may cause pleural effusions, but only after pulmonary edema has developed.
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Kjekshus, Harald, Cecilie Risoe, Tim Scholz y Otto A. Smiseth. "Methods for assessing hepatic distending pressure and changes in hepatic capacitance in pigs". American Journal of Physiology-Heart and Circulatory Physiology 279, n.º 4 (1 de octubre de 2000): H1796—H1803. http://dx.doi.org/10.1152/ajpheart.2000.279.4.h1796.
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The equilibrium pressure obtained during simultaneous occlusion of hepatic vascular inflow and outflow was taken as the reference estimate of hepatic vascular distending pressure (Phd). Phdat baseline was 1.1 ± 0.2 (mean ± SE) mmHg higher than hepatic vein pressure (Phv) and 0.7 ± 0.3 mmHg lower than portal vein pressure (Ppv). Norepinephrine (NE) infusion increased Phdby 1.5 ± 0.5 mmHg and Ppvby 3.7 ± 0.6 mmHg but did not significantly increase Phv. Hepatic lobar vein pressure (Phlv) measured by a micromanometer tipped 2-Fr catheter closely resembled Phdboth at baseline and during NE-infusion. Dynamic pressure-volume (PV) curves were constructed from continuous measurements of Phvand hepatic blood volume increases (estimated by sonomicrometry) during brief occlusions of hepatic vascular outflow and compared with static PV curves constructed from Phddeterminations at five different hepatic volumes. Estimates of hepatic vascular compliance and changes in unstressed blood volume from the two methods were in close agreement with hepatic compliance averaging 32 ± 2 ml · mmHg−1· kg liver−1. NE infusion reduced unstressed blood volume by 110 ± 38 ml/kg liver but did not alter compliance. In conclusion, Phlvreflects hepatic distending pressure, and the construction of dynamic PV curves is a fast and valid method for assessing hepatic compliance and changes in unstressed blood volume.
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Bell, A. M., J. H. Pemberton, R. B. Hanson y A. R. Zinsmeister. "Variations in muscle tone of the human rectum: recordings with an electromechanical barostat". American Journal of Physiology-Gastrointestinal and Liver Physiology 260, n.º 1 (1 de enero de 1991): G17—G25. http://dx.doi.org/10.1152/ajpgi.1991.260.1.g17.
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Rectal wall tone (the contractile state of the rectal tunica muscularis) should mediate accommodation and influence rectal emptying. Such changes in tone however can be only inferred from changes in baseline pressure recorded with conventional manometry. We used an isobaric volumetric device, the rectal electromechanical barostat, to quantify variations in tone of the rectal wall in response to feeding and to perturbations in response to the pharmacological agents neostigmine and glucagon. The barostat quantitates muscular wall tone indirectly by measuring its reciprocal, e.g., the volume of air within a flaccid intraluminal bag that is maintained at a constant and preselected pressure, by an electronic feedback mechanism. The barostat as well as a three-channel perfused manometric catheter were positioned in the rectum of 14 healthy volunteers. Three patterns of changes were observed: 1) respiratory fluctuations, 2) rapid volume waves, and 3) slow volume changes. Rectal tone varied little during fasting; rapid or slow changes in intrabag volume were infrequent. Ingestion of a standard meal was followed by a significant decrease in barostat bag volume (85 +/- 6 ml fasting vs. 50 +/- 8 ml fed, P less than 0.05). Pharmacological agents also induced predictable responses; neostigmine decreased bag volume and induced phasic pressure activity, whereas glucagon abolished phasic pressure activity and increased barostat bag volume. Perfused manometric catheters showed no concomitant changes in baseline pressure. We concluded that a rectal barostat measured variations in human rectal tone, which were not recorded by conventional manometric techniques. These changes in rectal tone might have important functional significance.
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Ikeda, Shigemasa, Keiichi Yagi, John F. Schweiss y Sharon M. Homan. "In vitro reappraisal of the pulmonary artery catheter balloon volume-pressure relationship: comparison of four different catheters". Canadian Journal of Anaesthesia 38, n.º 5 (julio de 1991): 648–53. http://dx.doi.org/10.1007/bf03008203.
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