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Featured researches published by B. Leskosek.


Journal of Heart and Lung Transplantation | 2008

Ex vivo reconditioning of marginal donor lungs injured by acid aspiration

Ilhan Inci; Luca Ampollini; Stephan Arni; Wolfgang Jungraithmayr; Demet Inci; Sven Hillinger; B. Leskosek; Peter Vogt; Walter Weder

BACKGROUND Injured lungs due to gastric acid aspiration may be rejected for transplantation because of the possibility of early graft dysfunction. We hypothesized that diluted surfactant administration during ex vivo perfusion would recondition the lungs injured by acid aspiration and permit their use as suitable grafts for transplantation. METHODS Using a pig model, lung injury was induced with 5-ml/kg administration of a betaine-HCl/pepsin mixture via a flexible bronchoscope. After injury, animals were randomly assigned to three study groups (n = 6/group): saline lavage during ex vivo perfusion (control); surfactant lavage ex vivo (SL-Exvivo); and surfactant lavage before harvest (SL-Pre); and a normal group (n = 4), with no lung injury. Cold storage time was 3 hours. A volume of 10 ml/kg (4 mg/ml, 40 mg/kg) surfactant (Curosurf) was used for lavage. Bronchoalveolar lavage (BAL) was performed before and after injury and at the end of the experiment. Protein and neutrophil percentage in BAL were assessed. Hemodynamic and aerodynamic parameters were measured every 30 minutes during a 2-hour observation period. RESULTS An approximately 50% decrease in Pao(2) was observed in all animals after injury. Ex vivo surfactant lavage resulted in lower pulmonary vascular resistance, lower oxygenation index and higher Pao(2)/Fio(2) ratio compared with the control group (p = 0.001, p = 0.0001 and p = 0.0001, respectively, according to analysis of variance for repeated measures). Wet-to-dry weight ratio was lower in the SL-Exvivo group compared with the control group (p = 0.015). BAL neutrophil percent at the end of the experiment differed significantly between control and all other groups (p < 0.05). CONCLUSION Diluted surfactant lavage during ex vivo perfusion improves graft function of lungs injured by gastric acid aspiration.


Critical Care Medicine | 1995

Continuous versus bolus thermodilution cardiac output measurements : a comparative study

Tomislav Mihaljevic; Ludwig K. von Segesser; Martin Tönz; B. Leskosek; Burkhardt Seifert; Rolf Jenni; Marko Turina

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 Ringers 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.


European Journal of Cardio-Thoracic Surgery | 1990

Superior hemodynamics in left heart bypass without systemic heparinization

L. K. Von Segesser; Branko M. Weiss; A. Gallino; B. Leskosek; F. Redha; A. Von Felten; Turina M

Open-chest left heart bypass was performed in 10 canine experiments (30 +/- 9 kg) by a servo controlled roller pump for 6 h at a pump flow of 50 ml/min per kg bodyweight. The surfaces of the tubing sets were either standard (with systemic heparinization) or with end-point attached heparin (no systemic heparin). Besides continuous monitoring of hemodynamics, a standard battery of blood samples was taken before bypass, after 10 min and every hour thereafter. There is no evidence of increased fibrin production in the group with end-point attached heparin surfaces perfused without systemic heparinization. Superior hemodynamics in left heart bypass performed without systemic heparinization appear to be due to improved hemostasis, reduced blood loss and therefore reduced transfusion requirements. Left heart bypass with heparin-coated equipment has been successfully used for resection of a thoracoabdominal aneurysm in six patients.


European Journal of Cardio-Thoracic Surgery | 2001

Optimization of venous return tubing diameter for cardiopulmonary bypass

Yiming Ni; B. Leskosek; Liping Shi; Yinglian Chen; Linfeng Qian; Renyuan Li; Zhengliang Tu; Ludwig K. von Segesser

OBJECTIVE To determine the optimal venous tubing diameter for adult cardiopulmonary bypass (CPB) to improve gravity drainage and to reduce priming volume. METHODS (A) Maximum bovine blood flow rates by gravity drainage were assessed in vitro for four different tubing diameters (1/2, 3/8, 5/16,1/4 inch) with three different lengths and various pre- and afterloads. Based on the results of (A) and multiple regression analyses, we developed equations to predict tubing sizes as a function of target flows


Journal of Heart and Lung Transplantation | 2010

Prevention of primary graft dysfunction in lung transplantation by N-acetylcysteine after prolonged cold ischemia

Ilhan Inci; Barbara V. Erne; Stephan Arni; Wolfgang Jungraithmayr; Demet Inci; Sven Hillinger; Peter Vogt; B. Leskosek; Walter Weder

BACKGROUND N-Acetylcysteine (NAC), a thiol-containing compound that has been used as an anti-oxidant, may also lead to an increased glutathione synthesis. This study assessed the protective effect of NAC on primary graft dysfunction after lung transplantation. METHODS Porcine single left-lung transplantation was performed in 2 experimental groups after 24 hours of cold storage. Donor and recipient animals were treated with intravenous injection of 150 mg/kg NAC 60 minutes before harvest and reperfusion, followed by 12.5 mg/kg/hour continuous perfusion during the 8-hour observation period (NAC). Control animals did not receive any treatment. Hemodynamic and respiratory parameters were recorded throughout the observation period. Bronchoalveolar lavage (BAL) nitrite, neutrophil elastase (NE), protein accumulation, interleukin (IL)-8, nuclear factor-κB (p50 sub-unit), and reduced glutathione (GSH) in lung tissue and red blood were measured. RESULTS During the observation period, the mean pulmonary artery pressure, oxygenation, airway pressure, and static lung compliance were significantly better in NAC animals compared with controls (p < 0.05). Extravascular lung water index was higher at points during the reperfusion in the control group. BAL protein, nitrite, NE, and IL-8 cytokine levels at the end of the experiment were significantly higher in the controls than in the NAC group (p < 0.05). Lung tissue reduced GSH levels were significantly higher in the NAC group than in the control group. Red blood cell GSH levels were always higher in the NAC group during the reperfusion period. Reverse transcription polymerase chain reaction for IL-8 messenger RNA was significantly higher in controls during the reperfusion period than in the NAC group (p = 0.001). The amount of lung tissue nuclear NF-κB (p50 sub-unit) was significantly higher in controls than in NAC pigs (p = 0.03). CONCLUSION In this model, donor and recipient treatment with NAC effectively protected the lung from primary graft dysfunction after prolonged cold ischemia.


Asaio Journal | 1993

Coagulation patterns in bovine left heart bypass with phospholipid versus heparin surface coating.

L. K. Von Segesser; A. Olah; B. Leskosek; Turina M

The current study was designed to evaluate tubing sets with either polymeric phospholipids or ionically bound heparin in six bovine experiments (body weight, 70 ± 5 kg). No heparin was given systemically. Left heart bypass was started with 300 ml of clear priming solution and maintained over 6 hours (50 ml/kg/min). Coagulation studies included platelet counts, activated coagulation time (ACT), thrombin time (TT), fibrinogen (Factor I), antithrombin III (AT III), and fibrinopeptide A (FPA). Normalized platelet levels dropped from 100 ± 12% before to 86 ± 13% after 6 hours of left heart bypass for heparin, compared with 100 ± 46% to 90 ± 44% for phospholipid coating (NS). The ACT increased from 146 ± 7 sec at 10 min to 159 ± 16 sec after 6 hours for heparin, compared with 122 ± 4 to 126 ± 5 sec for phospholipid (p<0.05). Thrombin time changed from 18 ± 0 sec before to 19 ± 1 sec after 6 hours for heparin, as compared with 16 ± 1 sec to 18 ± 1 sec for phospholipid (NS). Factor I levels decreased from 1.5 ± 0.3 g/L to 1.3 ± 0.1 g/L for heparin, compared with 1.5 ± 0.2 g/L to 1.4 ± 0.3 g/L for phospholipid. Antithrombin III levels changed from 102 ± 26% to 91 ± 7% for heparin, compared with 123 ± 12% to 118 ± 12% for phospholipid. Fibrinopeptide A levels changed from 100 ± 60% to 130 ± 13% for heparin, compared with 100 ± 11% to 99 ± 6% for phospholipid (P<0.05). No macroscopic red clots were found in either group. Surfaces with polymeric phospholipids appear to be as thromboresistant as those with bonded heparin.


The Annals of Thoracic Surgery | 1994

TREATMENT OF ACUTE PULMONARY HYPERTENSION WITH INHALED NITRIC OXIDE

Martin Tönz; Ludwig K. von Segesser; Julian Schilling; Thomas F. Lüscher; Georg Noll; B. Leskosek; Marko Turina

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.


Perfusion | 1990

Cardiopulmonary bypass with low systemic heparinization: an experimental study.

L. K. Von Segesser; Mario Lachat; B. Leskosek; Turina M; A. Von Felten; P. Pei

At present, state-of-the-art cardiopulmonary bypass still requires high-dose systemic heparinization with all its well-known drawbacks during and especially after perfusion. Most manufacturers still recommend maintenance of the activated clotting time (ACT) above 480 seconds throughout perfusion. This is mainly due to the continuing poor biocompatibility of standard cardiopulmonary bypass equipment. Actual approaches to improve the biocompatibility of blood-exposed surfaces include endothelial cell seeding, heparin-like biomaterials and heparin surface coating. As heparin surface coating can be applied to existing devices, this procedure appears to be the most promising for improved biocompatibility of devices with shortand medium-term applications. We have previously reported our experience with heparin surface-coated equipment in canine experiments without any systemic heparinization during open-chest cardiopulmonary bypass, as well as during left-heart bypass with a servocontrolled roller pump.2 Our group has also studied left-heart bypass by means of heparin-coated centrifugal pumps in bovine experiments,3 and other groups have evaluated heparin surface coating during prolonged extracorporeal membrane oxygenation (ECMO) in animal4 and clinical5 studies. Clinical trials with slightly reduced systemic heparin doses (225 IU/kg bodyweight, ACT>300) have also been performed with promising results.6 6


Journal of Heart and Lung Transplantation | 2008

Impact of topical cooling solution and prediction of pulmonary graft viability from non-heart-beating donors.

Ilhan Inci; Stephan Arni; Demet Inci; Wei Zhai; Sven Hillinger; B. Leskosek; Peter Vogt; Walter Weder

BACKGROUND Functional assessment of the potentially damaged graft from a non-heart-beating donor (NHBD) is mandatory for successful outcome after transplantation. We investigated the impact of the topical cooling solution on graft preservation and whether inflammatory markers in bronchoalveolar lavage (BAL) can predict pulmonary graft viability in a pig ex vivo lung perfusion model. METHODS Pigs were euthanized and left untouched for 1 (SAL-1, PER-1) or 3 (SAL-3, PER-3) hours. Topical cooling was done with saline or low-potassium dextran solution (Perfadex) for 1 or 3 hours. In the heart-beating donor control group, the lungs were flushed, explanted and stored for 4 hours. BAL samples were taken from right lungs after explantation and assessed for nitrite, interleukin-8 (IL-8) and protein levels. Left lungs were prepared for ex vivo evaluation. Hemodynamic and oxygenation parameters were measured. RESULTS Pulmonary vascular resistance (PVR), oxygenation index and Pao(2)/Fio(2) ratio differed significantly between the SAL-3 (42.2 +/- 6.0, 15.9 +/- 3.2 and 148 +/- 14.6 Wood units, respectively) and PER-3 (23.9 +/- 2.7, 6.4 +/- 0.8 and 221.7 +/- 15.06 Wood units, respectively) groups (p < 0.05). BAL IL-8 levels were higher in the SAL-3 group compared with the PER-3 group. BAL nitrite and protein levels were statistically higher in the SAL-3 group (0.98 +/- 0.17 micromol/liter, 728.3 +/- 75.7 microg/ml) than in the PER-3 (0.22 +/- 0.09 micromol/liter, 393.3 +/- 51.1 microg/ml) group (p < 0.05) and correlated with an increase in PVR (r = 0.623, p = 0.001; r = 0.530, p = 0.006, respectively). CONCLUSIONS After 3 hours of warm ischemia topical cooling with Perfadex resulted in better graft function. Nitrite and protein levels in BAL correlated well with PVR and may therefore be used as a non-invasive marker to predict graft function for NHBDs.


The Annals of Thoracic Surgery | 1994

Quantitative gas transfer of an intravascular oxygenator

Martin Tönz; Ludwig K. von Segesser; B. Leskosek; Marko Turina

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.

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Turina M

University of Zurich

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