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Biomedical subjects

B Leskosek

Publications and source records attributed to B Leskosek.

At least 19 recordsLinked to original sources
PubMed1997

Biventricular assist using a portable driver in combination with implanted devices: preliminary experience.

Left ventricular assist systems with portable drive units are increasingly used in the clinical setting. However, such systems usually are not suitable for right ventricular support, and therefore, in the case of biventricular heart failure, they must be combined with other support devices that require additional drive consoles. As a result, most of the benefits of the wearable drive units (early mobilization and outpatient care) are lost. This present study was performed to evaluate biventricular support with implanted assist devices and a portable DC/battery-powered driver (Thoratec TLC-II). Electronic control by nonvolatile RAM accessible via RS232 interface, internal backup emergency battery, and optional manual activation are additional features of this 6 kg biventricular drive unit. In 3 bovine experiments (body weight 70 +/- 5 kg) partial cardiopulmonary bypass (CPB) was established, and two ventricular assist devices were implanted into a preperitoneal pocket on each side after connection to the right atrium and the pulmonary artery and to the left atrium and aorta, respectively. After weaning the patient from CPB, activated coagulation time (ACT) was kept at greater than 180 s, and biventricular support with the portable driver was activated. After 10 min, mean device flow stabilized at 3.5 +/- 0 L/min and remained at that level throughout the ensuing 6 h (3.5 +/- 0.3 L/min; NS). The heart rate moved from 130 +/- 13 beats per minute (bpm) at the end of CPB to 116 +/- 13 bpm after 10 min of assist (p < 0.05). Right atrial pressure moved from 11 +/- 2 mm Hg at the end of CPB to 13 +/- 3 mm Hg after 10 min of assist (not significant [NS]). Mean pulmonary artery pressure was 18 +/- mm Hg at the end of CPB and 17 +/- 5 mm Hg after 10 min of assist (NS). Left atrial pressure was 10 +/- 1 mm Hg at the end of CPB and 13 +/- 3 mm Hg after 10 min of assist (NS). Mean aortic pressure was 73 +/- 11 mm Hg at the end of CPB and 77 +/- 3 mm Hg after 10 min of assist (NS). Mixed venous oxygen saturation increased from 49 +/- 9% at the end of CPB to 58 +/- 10% after 10 min of assist (p < 0.05). The portable drive unit that was tested provides adequate power to maintain significant biventricular support with implanted right and left assist devices. The configuration of batteries tested driving two ventricles provides independence for 60 min.

Animals↗
PubMed1996

Effect of intermittent warm blood cardioplegia on functional recovery after prolonged cardiac arrest.

BACKGROUND: There is some evidence that continuous warm blood cardioplegia offers good myocardial protection; however, the effects of interrupting cardioplegia remain controversial. To study this, we compared the effects of continuous and intermittent antegrade warm (37 degrees C) blood cardioplegia on functional recovery after prolonged cardiac arrest (180 minutes). METHODS: Twenty-four juvenile pigs were randomly assigned into four groups. Group 1 received continuous cardioplegia, group 2 underwent several periods of 15 minutes of cardioplegia interrupted by 5 minutes of normothermic ischemia, and group 3 underwent several periods of 10 minutes of cardioplegia interrupted by episodes of 10 minutes. The hearts of group 4 received no cardioplegia. Left ventricular systolic function was assessed from fractional left ventricular shortening and percentage left ventricular wall thickening, and left ventricular diastolic function was determined from the time constant of relaxation and the constant of myocardial stiffness. RESULTS: Systolic and diastolic functions were slightly depressed 1 and 2 hours after cross-clamp removal in all four groups, without significant differences among the groups. CONCLUSIONS: These data suggest that antegrade warm blood cardioplegia can be interrupted for up to 10 minutes without obvious negative effects on left ventricular function in the normal myocardium, provided that the intermittent doses of cardioplegia are sufficient to restore the metabolic demands of the arrested myocardium.

Animals↗
PubMed1996

[Thrombosis-resistant heparin-coated diffusion membrane oxygenators: an experimental study].

In the present study the thromboresistance of heparin-coated diffusion membrane oxygenators (Jostra, M 30) combined with heparin-coated venous reservoirs, tubing sets and arterial filters was investigated in six bovine experiments (70 +/- 5 kg). The perfusion with reduced systemic heparin dose (100 IE/kg) body weight) was performed with activated clotting time over 180 seconds. The perfusion began with a blood flow of 31/min and was maintained during six hours. Clotting studies including blood platelet count, activated clotting time, fibrinogen (factor I), antithrombin III and fibrinopeptid A were performed before the operation and ten minutes, two hours and five and six hours after beginning of bypass. The venous and arterial saturation remained stable during the whole investigation. After ten minutes activated clotting time dropped from 619 +/- 114s to 203 +/- 15s after six hours (p < 0.05). The antithrombin III level changed significantly from 109 +/- 11% to 95 +/- 16%. Factor 1 and fibrinopeptid A changes were not significant: from 1.6 +/- 0.3 g/1 to 1.5 +/- 0.3 g/1, and 3.0 +/- 1.4 ng/mL to 3.5 +/- 1.2 ng/mL, accordingly. There were no mechanical defects and especially no plasma leakage. Slight sediments were found only in areas of stagnant blood flow. The investigated bypass circuit with reduced systemic heparinization seems therefore particularly appropriate for long-term perfusions.

Animals↗
PubMed1995

Influence of hemodynamics on the performances of intravascular gas exchangers.

BACKGROUND: The intravascular gas exchanger is a lung assist device for augmentation of gas exchange in critically ill patients with severe acute respiratory failure. These patients often require inotropic support therapy due to the cardiovascular instability that almost inevitably accompanies severe respiratory failure. METHODS: We investigated the interaction of vasoactive medication (dopamine, nitroglycerin, and noradrenaline) with the gas exchange performances of the intravascular gas exchanger in a bovine experimental model. RESULTS: Dopamine administration highly increased cardiac output, caval flow rates, and diameter of vena cava inferior. These effects resulted in a significant increase in oxygen transfer (baseline, 35 +/- 6 mL/min versus 153 +/- 27 mL/min at 20 micrograms.kg-1.min-1 of dopamine, p < 0.001) and carbon dioxide elimination (baseline, 35 +/- 2 mL/min versus 47 +/- 4 mL/min at 20 micrograms.kg-1.min-1 of dopamine, p < 0.001). Administration of nitroglycerin did not cause significant changes of the hemodynamic parameters nor did it affect the oxygen transfer or carbon dioxide elimination. Noradrenaline caused a moderate increase in cardiac output and caval flow, but no changes of caval diameter. hemodynamic changes were accompanied by an increase in oxygen transfer from 38 +/- 5 mL/min to 68 +/- 7 mL/min (p < 0.01) and carbon dioxide elimination from 33 +/- 1 mL/min to 40 +/- 1 mL/min (p = 0.03). The multiple regression analysis showed significant influence of changes in cardiac output on oxygen transfer (p < 0.001) and carbon dioxide elimination (p = 0.004). The administration of vasoactive drugs induced slight changes in caval diameter that did not significantly affect the gas transfer. CONCLUSIONS: The results from our study reveal the major influence of cardiac output on efficiency of gas transfer of the intravascular oxygenator.

Animals↗
PubMed1995

Continuous versus bolus thermodilution cardiac output measurements--a comparative study.

OBJECTIVE: To compare the methods for continuous and bolus thermodilution cardiac output measurements. DESIGN: In vivo and in vitro experimental studies. SETTING: Surgical research division in a university hospital. SUBJECTS: Eight calves and flow bench model. INTERVENTIONS: Data were collected in vivo from eight calves instrumented with pulmonary artery catheters, which allowed both continuous and bolus thermodilution measurements. The pulmonary artery catheter was placed through the external jugular vein. All in vitro measurements were performed using a flow bench model. MEASUREMENTS AND MAIN RESULTS: A total of 232 bolus and continuous thermodilution measurements were analysed in vivo to determine the degree of agreement between the two methods. The absolute measurement bias was 0.14 L/min with 95% confidence limits ranging from -0.83 to 1.15 L/min. In vitro analysis of 576 measurements at six different temperature points (range 31 degrees to 41 degrees C), using clinically relevant flows (2 to 9 L/min), showed overestimation of flow values using continuous and bolus thermodilution methods. However, the continuous method showed better accuracy by a lower degree of overestimation. Systematic error was 9.7 +/- 8.4 (SD) % for continuous and 11.1 +/- 6.3% for the bolus method (p < .001). This effect was especially evident at lower flow rates. The influence of various temperatures on the accuracy and reproducibility of both methods of measurement was statistically significant but not clinically relevant. The infusion of lactated Ringer's lactate solution (infusion rates 100 to 1000 mL/hr) affects both methods at a low flow rate of 2 L/min, without causing a significant effect on continuous measurement at a higher flow rate (4 L/min). Shunting of 50% of circulating volume to the distal part of the thermal filament of the pulmonary catheter impaired the accuracy of continuous measurement without affecting results from bolus measurements (systematic error -26.8 +/- 8.2% for continuous and -5.2 +/- 4.1% for bolus thermodilution). CONCLUSIONS: Continuous thermodilution cardiac output measurement provided higher accuracy and greater resistance to thermal noise than standard bolus measurements. The correct placement of the catheter is essential for precise measurements.

Analysis of Variance↗
PubMed1994

Quantitative gas transfer of an intravascular oxygenator.

The intravascular oxygenator is a newly developed device for intracaval gas exchange in critically ill patients with respiratory failure. In an experimental ex vivo model, performance characteristics of the intravascular oxygenator/carbon dioxide removal device were studied. With a mean hemoglobin concentration of 6.2 +/- 1.9 g/dL (mean +/- standard deviation), total O2 transfer was 21.8 +/- 4.8 mL/min at a blood flow of 1 L/min, 37.0 +/- 12.6 mL/min at 2 L/min, at 2 L/min, and 47.5 +/- 16.7 mL/min at 3 L/min. Total CO2 transfer was 27.3 +/- 6.6 mL/min at a blood flow of 1 L/min, 38.6 +/- 8.9 mL/min at 2 L/min, and 40.4 +/- 9.3 mL/min at 3 L/min. In contrast to total gas transfer, O2/CO2 transfer rates (mL/L) diminished significantly with increasing blood flow. In addition, there was a negative correlation between O2 transfer rate and venous O2 partial pressure (r = -0.73; p < 0.0001), a positive correlation between CO2 transfer rate and venous CO2 partial pressure (r = 0.65; p < 0.0001), and a positive correlation between O2 and CO2 transfer rates and blood hemoglobin level (r = 0.57 [p < 0.01] and r = 0.70 [p < 0.01], respectively). These results demonstrate that the behavior of the intravascular hollow-fiber oxygenator is similar to that of the classic membrane oxygenator used for cardiopulmonary bypass: total gas transfer correlates directly with blood flow and venous CO2 partial pressure and indirectly with venous O2 partial pressure. The O2 and CO2 transfer rates increase significantly with increasing hemoglobin content of the blood.

Animals↗
PubMed1994

Treatment of acute pulmonary hypertension with inhaled nitric oxide.

We examined the effectiveness of inhaled nitric oxide (NO) as a selective pulmonary vasodilator in acute pulmonary hypertension in an in vivo canine model with fixed cardiac output. In 5 dogs, total right heart bypass was instituted, and pulmonary hypertension was induced by infusion of the thromboxane analogue U-46619. During U-46619 infusion, NO was administered at 10 and 40 ppm for 5 minutes followed by breathing of the oxygen mixture without NO. Pump flow was held constant during the experiment. Infusion of the thromboxane analogue resulted in an increase in pulmonary vascular resistance and systemic vascular resistance from 147 +/- 83 to 740 +/- 126 dyne.s.cm-5 and from 1,720 +/- 113 to 2,407 +/- 232 dyne.s.cm-5, respectively. During inhalation of 10 ppm NO, pulmonary vascular resistance significantly decreased to 613 +/- 55 dyne.s.cm-5 (p < 0.05) and further decreased to 527 +/- 163 dyne.s.cm-5 with 40 ppm NO inhalation (p < 0.05). Systemic vascular resistance did not change during NO treatment (2,300 +/- 70 dyne.s.cm-5 during 40 ppm NO). There was no increase in intrapulmonary shunting or methemoglobin levels during NO inhalation. In this setting, with a constant cardiac output throughout the experiment, NO acted as a selective pulmonary vasodilator without altering systemic vascular resistance. However, induced pulmonary vasoconstriction was only partially reversed by NO inhalation.

Acute Disease↗
PubMed1994

Continuous thermodilution measurement of cardiac output: in-vitro and in-vivo evaluation.

The current study was designed to evaluate a method for continuous measurement of cardiac output. The system consists of a modified pulmonary artery catheter that uses the thermodilution principle for determination of cardiac output. The evaluation was performed in vitro and in vivo. In-vitro evaluation was performed using a simple flow bench model (flow 2-9 L/min). Both continuous and bolus thermodilution methods were compared. Both methods showed good correlation with the pump flow calibrated using a volumetric tank and timer (correlation coefficient (r) for bolus thermodilution = 0.92, r for continuous thermodilution = 0.90). In-vivo evaluation was performed in six bovine experiments. Data from a total of 87 pairs of bolus versus continuous measurements were obtained. The cardiac output ranged from 1.9 to 8.9 L/min. The absolute measurement bias was not significant (mean: -0.07 L/min; 95% confidence limits: -0.87 and 0.73 L/min). The squared correlation coefficient from linear regression was 0.92. The results from this study suggest that the new continuous thermodilution measurement system for cardiac output provides accurate data in vitro and in vivo. Continuous monitoring of cardiac output adds a new dimension for evaluation of the patient's hemodynamic profile. Furthermore, significant volume load due to bolus thermodilution measurements can be avoided.

Animals↗
PubMed1994

Heparin surface coated hard shell venous reservoirs: experimental evaluation ex vivo.

The present study was designed for ex vivo evaluation of a heparin coated hard shell venous reservoir in comparison to uncoated control reservoirs. An open chest bovine right heart bypass model (n = 9, bodyweight 72 +/- 6 kg) with passive blood drainage from the right atrium into the venous reservoir and active retransfusion into the pulmonary artery (roller pump) was selected for this purpose. Clear priming was used for the open perfusion circuit. No heparin was given before or during the evaluation period which was scheduled for 6 hours. Reservoir blood flow was at the beginning 3.5 +/- 0.6 l/min for coated versus 3.4 +/- 0.3 l/min for uncoated (NS). After 6 hours, blood flow was 3.3 +/- 0.1 l/min for coated versus 2.7 +/- 0.4 l/min for uncoated (p < 0.05). Hematocrit moved from a baseline level of 30 +/- 2% for coated versus 28 +/- 3% for uncoated (NS) to 28 +/- 3% for coated versus 27 +/- 5% for uncoated (NS) after 6 hours. Prebypass platelet levels of 100% in both groups moved to 84 +/- 3% for coated versus 78 +/- 23% for uncoated (NS) after 6 hours. Activated coagulation time (ACT) before bypass was 148 +/- 12 s for coated and 153 +/- 6 s for uncoated (NS). After 6 hours, ACT was 160 +/- 9 s for coated versus 152 +/- 5 s for uncoated (NS). Thrombin time before bypass was 15 +/- 2 s for coated versus 16 +/- 2 s for uncoated (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Hemodynamic properties of the hemopump].

The hemopump HP 31 is an improved version of a catheter-mounted, transvalvular, left ventricular assist device, which can be placed into the left ventricle through the ascending aorta. The purpose of this study was to examine the influence of hematocrit and afterload on the pump flow. The hemopump was tested using a flow bench model filled with heparinized bovine blood. The measurements were performed at four various hematocrit values: 16%, 24%, 32%, and 40%. The pump flow was measured at each hematocrit value under increasing afterload pressures (40-120 mm Hg), by all pump speed levels (n = 7). The average pump flow at highest pump speed and lowest afterload was 5.1 +/- 0.3 l/min (mean +/- standard deviation). The influence of afterload on the pump flow was statistically significant (p < 0.001). The highest afterload pressure of 120 mm Hg caused a reduction in pump flow of 24 +/- 5%. The alterations of hematocrit values caused no statistically significant influence on the pump flow (p = 0.72). The results of our study enabled the construction of the nomogram for the in vivo determination of the pump flow. The in vivo performances of the hemopump can be improved through the afterload reduction, especially in the weaning phase of treatment. The oxygen delivery can be improved through the increase in hematocrit values without significant impairment of the pump flow.

Animals↗
PubMed1994

Evaluation of phospholipidic surface coatings ex-vivo.

To evaluate the thromboresistant properties of phospholipidic surface coatings mimicking the lipid surface of blood cells, we studied four different types of phospholipids bound onto PVC tubings in comparison to uncoated as well as heparin bonded controls. The samples analyzed included diacetylenic phospholipid coated as a monomeric treatment (A), diacetylenic phospholipid polymerised prior to being coated (B), and two types of polymeric phospholipids made using methacrylate containing monomers (C and D). A bovine (bodyweight 67 +/- 3 kg) left heart bypass model (pump flow 3.2 +/- 0.1 l/min) was selected and the surfaces were exposed to the blood stream up to 360 min without systemic heparinization. Thereafter another set of samples was exposed to stagnant blood over 20 min. Besides hemodynamic, hematologic and biochemical analyses, the macroscopic appearance of 119 blood exposed surface samples was graded semiquantitatively on a scale of 0 to 10: no macroscopic deposits = grade 0, 1 spot (1 mm diameter) = grade 1, 2 spots = grade 2, 5 or more spots = grade 5, up to 10% of the surface covered with clots = grade 6, 100% covered = grade 10 (P < 0.05 = *): mean grade of deposits was 0.0 +/- 0.0 for segments perfused and 0.0 +/- 0.0 for segments exposed to stagnant blood with surfaces exposing to the blood either heparin, phospholipid A, or phospholipid B (NS). Phospholipids C and D were graded 0.0 +/- 0.0 if perfused and 0.7 +/- 1.2 if exposed to stagnant blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Hemodynamic effects of the implantation of an intracaval oxygenator].

Treatment of severe respiratory failure by extracorporeal membrane oxygenation (ECMO) is complex. However, there is now an intravascular gas exchanger (IVOX) available that provides extrapulmonary gas transfer without requiring an extracorporeal blood path. The present study was performed to determine the hemodynamic effects resulting from the intracaval placement of the intravascular device. A bovine model (n = 6; body-weight = 72 +/- 5 kg) was selected for temporary lung support with the intravascular device. The latter was placed in the caval axis under fluoroscopic control after full instrumentation of the animal for hemodynamic measurements including a pulmonary artery catheter for determination of cardiac output by thermodilution and continuous readout of mixed venous oxygen saturation. All measurements were taken after a stabilization period of 15 min. The heart rate moved from 65 +/- 8 before to 72 +/- 10 after implantation and 68 +/- 9 after onset of intravascular gas exchange (NS). Right atrial pressure was 13 +/- 3 mm Hg before, 12 +/- 3 mm Hg after implantation and 10 +/- 3 mm Hg after onset (NS) whereas femoral venous pressure moved from 14 +/- 3 mm Hg to 17 +/- 4 mm Hg (p < 0.05) and remained at 17 +/- 4 mm Hg after onset. Cardiac output was 5.3 +/- 0.7 l/min before, 5.4 +/- 0.7 l/min after implantation and 5.3 +/- 1.1 l/min after onset (NS) while mixed venous oxygen saturation dropped from 60 +/- 7% to 54 +/- 11% and moved to 57 +/- 11 after onset of the device (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Coronary artery resistance and oxygen uptake during reperfusion: is there any difference between warm and cold cardioplegia?

To evaluate the effects of warm continuous versus cold intermittent blood cardioplegia on coronary blood flow patterns after prolonged cardioplegic arrest, nine pigs underwent cardiopulmonary bypass with 210 minutes of aortic cross-clamping. Antegrade blood cardioplegia was administered either cold intermittent (n = 4) or warm continuous (n = 5). During the first 30 minutes of reperfusion, there was decreased coronary blood flow with higher coronary vascular resistance in the cold group (mean +/- standard error; warm vs. cold: 30 min: flow: left anterior descending artery (LAD): 66 +/- 6 vs 36 +/- 4 ml/min, right coronary artery (RCA): 88 +/- 2 vs 61 +/- 4, p < 0.05, resistance: LAD: 33 +/- 3 vs 69 +/- 5 dyn.s.cm-5 x 10(3), RCA: 41 +/- 3 vs 58 +/- 8, p < 0.05). After one hour of reperfusion there were no differences between groups. Arterio-venous oxygen difference was higher in the cold group after 15 min (3.1 +/- 0.5 vs 4.8 +/- 0.3 ml O2/100 ml, p < 0.05) and 30 min (4.2 +/- 0.5 vs 6.2 +/- 0.7, p < 0.05) with equal values after 1 hour. During reperfusion there is reduced myocardial blood flow after cold intermittent blood cardioplegia. This may reflect superior myocardial protection with warm continuous cardioplegia.

Animals↗
PubMed1993

Regional diastolic dysfunction in postischaemic myocardium in calf: effect of nisoldipine.

OBJECTIVE: The aim was to assess the effect of nisoldipine on left ventricular systolic and diastolic function during prolonged myocardial ischaemia. METHODS: The left circumflex coronary artery was ligated for 2 h and reperfused for 4 h in 12 calves. The animals were randomised to a control group (n = 6) or to treatment with 1.25 mg.h-1 intravenous nisoldipine (n = 6) during 2 h of ischaemia. Circulatory support by a ventricular assist device was performed throughout the experiment except for the time of haemodynamic measurements. Regional wall thickening of a normal and an ischaemic left ventricular region was determined using pairs of ultrasonic crystals. Left ventricular pressure was measured by micromanometry. Left ventricular wall thickness and regional wall stiffness at a common preload of 10 mm Hg were calculated using an elastic model with shifting asymptote. RESULTS: Ten animals survived after 6 h. No difference was observed in systolic function between controls and nisoldipine treated animals. Systolic thickening of the ischaemic wall remained depressed 4 h after reperfusion and showed some recovery after dopamine infusion. Ischaemic wall stiffness at a common preload was lower after nisoldipine during ischaemia and reperfusion than in controls. Control wall stiffness remained unchanged during the whole experiment with and without nisoldipine. Diastolic thinning of the ischaemic wall was prevented by nisoldipine during ischaemia and after reperfusion. CONCLUSIONS: Prolonged myocardial ischaemia is associated with increased myocardial stiffness of the ischaemic wall. Mechanical unloading can help to bridge the acute phase but cannot prevent postischaemic diastolic dysfunction of the ischaemic wall. Nisoldipine has a beneficial effect on regional diastolic function during ischaemia and reperfusion by decreasing regional wall stiffness and preventing diastolic thinning of the ischaemic wall.

Animals↗
PubMed1993

[Are the advantages of percutaneous catheterization technique gained by increased blood trauma?].

UNLABELLED: The development of thin-walled cannulas which can be introduced by percutaneous technique into femoral artery and vein has revived interest in emergency cardiopulmonary support (CPS). To assess possible blood damaging effect due to the small-bore cannulas, 8 in vitro perfusions were performed with two parallel pump circuits: one circuit with a 17 F arterial and a 21 F venous cannula, one circuit without cannulas (control). The circuits were filled with 61 of bovine blood and run for 6 hours at a temperature of 37 degrees C and a flow of 4 l/min. Serial blood samples were taken before and during the experiment. There was a significantly higher level of free plasma haemoglobin (pl Hb) and a decreased number of leukocytes (Lc) after 6 hours of perfusion in the group with percutaneous cannulas as compared with control (pl Hb: 63.2 +/- 0.3 vs. 26.3 +/- 4.1 mumol/l, p < 0.05, Lc: 2.4 +/- 0.6 vs. 4.6 +/- 0.8 x 10(9)/l, p < 0.05, mean +/- se). CONCLUSION: percutaneous cannulas are associated with an increased blood trauma. If extended cardiopulmonary support is considered (more than several hours), percutaneous cannulas should be replaced by large-bore cannulas.

Animals↗
PubMed1993

[Hemodynamic effects of implantation of an intracaval gas exchanger].

Treatment of severe respiratory failure by extracorporeal membrane oxygenation (ECMO) is complex. However, there is now an intravascular gas exchanger (IVOX) available that provides extrapulmonary gas transfer without requiring an extracorporeal blood path. The present study was performed to determine the hemodynamic effects resulting from the intracaval placement of the intravascular device. A bovine model (n = 6; bodyweight = 72 +/- 5 kg) was selected for temporary lung support with the intravascular device. The latter was placed in the caval axis under fluoroscopic control after full instrumentation of the animal for hemodynamic measurements including a pulmonary artery catheter for determination of cardiac output by thermodilution and continuous read out of mixed venous oxygen saturation. All measurements were taken after a stabilization period of 15 min. The heart rate moved from 65 +/- 8 before to 72 +/- 10 after implantation and 68 +/- 9 after onset of intravascular gas exchange (NS). Right atrial pressure was 13 +/- 3 mm Hg before, 12 +/- 3 mm Hg after implantation and 10 +/- 3 mm Hg after onset (NS) whereas femoral venous pressure moved from 14 +/- 3 mm Hg to 17 +/- 4 mm Hg (p < 0.05) and remained at 17 +/- 4 mm Hg after onset. Cardiac output was 5.3 +/- 0.7 l/min before, 5.4 +/- 0.7 l/min after implantation and 5.3 +/- 1.1 l/min after onset (NS) and mixed venous oxygen saturation dropped from 60 +/- 7% to 54 +/- 11% and moved to 57 +/- 11 after onset of the device (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗