Showing papers by "Gernot Marx published in 2006"

Attenuation of capillary leakage by hydroxyethyl starch (130/0.42) in a porcine model of septic shock.

Abstract: Objectives: Capillary leakage, a frequent complication in septic shock, is characterized by loss of intravasal fluid resulting in generalized edema and hemodynamic instability despite massive fluid therapy. We have shown that administration of an established colloid 200/0.5 hydroxyethyl starch (HES) stabilized plasma volume in a porcine septic shock model. Recently, a new HES with a low molecular weight (130 kD) and lower molar substitution (0.42) has been developed. In this study, we compared effects of HES 130/0.42 and HES 200/0.5 on capillary leakage in porcine septic shock. Design: Prospective randomized, controlled animal study. Setting: University department of anesthesiology. Subjects: Fourteen pigs (22.9 ± 2.8 kg). Interventions: Anesthetized and mechanically ventilated pigs were observed over 6 hrs. Measurement and Main Results: Septic shock was induced with fecal peritonitis (0.75 g·kg -1 of body weight autologous feces). Animals were allocated to volume-replacement therapy with either HES 130/0.42 (n = 5) or HES 200/0.5 (n = 5) and compared with nonseptic controls receiving HES 130/0.42 (n = 4). Infusion rate was titrated to maintain a central venous pressure of 12 mm Hg. Albumin escape rate was calculated using iodine 125-labeled albumin. Plasma volume was determined using chromium-51-tagged erythrocytes. Albumin escape rate increased significantly in both groups in comparison to controls (HES 200/0.5, 45% ± 3; HES 130/0.42, 38% ± 5), but this increase was significantly smaller with HES 130/0.42. Both HES 200/0.5 (-14%, not significant) and HES 130/0.42 (-1%, not significant) stabilized plasma volume compared with controls. Systemic oxygenation was not significantly altered in either group. Conclusions: In this porcine septic shock model, HES 130/0.42 attenuated capillary leakage significantly more effectively than HES 200/0.5.

Haemodynamic, acid–base and blood volume changes during prolonged low pressure pneumoperitoneum in rabbits

Abstract: Background The anaesthetic management of small infants during advanced laparoscopic surgery can be complicated by the major pathophysiological effects of increased intra-abdominal pressure. In this study haemodynamic, acid–base and blood volume changes were investigated during pneumoperitoneum in a small animal model. Methods Ten fasted, anaesthetized, mechanically ventilated and multi-catheterized New Zealand rabbits were randomized to carbon dioxide pneumoperitoneum (PP, duration 210 min, pressure 8 mm Hg) or control group. Cardiac index was determined using trans-cardiopulmonary thermodilution and total blood volume was measured by thermal-dye dilution with indocyanine green using a fibreoptic monitor system. Results In PP cardiac index (CI), central venous oxygen saturation ( S cv O 2 ), total blood volume (TBV) and base excess (BE) decreased significantly during the study whereas all variables remained constant in the control group. After release of PP the measured variables did not return to baseline within 30 min [PP, baseline vs study end: CI 108 (22) vs 85 (14) ml kg −1 min −1 , S cv O 2 81.4 (8.9) vs 56.7 (9.8)%, TBV 318 (69) vs 181 (54) ml, BE −1.9 (2.7) vs −8.7 (1.8) mmol litre −1 ; P Conclusion Our animal model suggests that a decrease in CI, metabolic acidosis and hypovolaemia could occur after prolonged low pressure pneumoperitoneum in small infants, which is possibly not detectable by the standard monitor setting. Therefore, the routine use of an extended monitoring including measurement of central venous oxygen saturation and acid–base parameters should be considered during and soon after operation, when pneumoperitoneum will last longer than 2 h.

Reliability of continuous cardiac output determination by pulse-contour analysis in porcine septic shock.

Abstract: Department of Anaesthesia, Hannover Medical School, Hannover, GermanyBackground: Pulse-contour analysis represents a technique forcardiac output (CO)-measurement and allows continuouslymonitoring trends in CO. We evaluated reliability of pulse-con-tour CO (COpc) in septic shock.Methods: Seventeen anaesthetized and mechanically ventilatedpigs were investigated. After baseline measurements, 14 animalsreceived 0.75 g/kg body weight faeces into the abdominal cavityto induce sepsis and were observed over 9 h, three animalsserved as controls. A central venous catheter was inserted intothe jugular vein and an arterial catheter for thermodilution wasinserted into the femoral artery. Two bedside computers wereused for COpc. After induction of sepsis, COpc-computer No. 1(COpcCAL) was recalibrated hourly. No further calibrations wereperformed in computer No. 2 (COpcNoCAL). We directly com-pared COpcCAL hourly before recalibration with COpcNoCAL.One hundred and seventy parallel triplicatedeterminations ofCOwere analysed using the method of Bland—Altman.Results: Three hours after sepsis induction, correlation betweenrecalibrated and non-recalibrated CO was r ¼ 0.74, P < 0.01, at5hr ¼ 0.59, P < 0.05 and 9 h r ¼ 0.02, NS. Three hours aftersepsis induction, bias SD (limits of agreement) between bothgroups was 1.6 15.5 ( 29.4—32.6) ml/kg/min, at 5 h 15.0 24.3 ( 63.6—33.7) ml/kg/min and at 9 h 87.0 90.8( 268.5—94.6) ml/kg/min.Conclusion: Continuous CO determination using pulse-contouranalysis is a reliable method of assessing CO up to 5 h withoutrecalibration in porcine septic shock. Thus, COpc may be auseful tool for assessment of unpredictable haemodynamicchanges in sepsis.

Correlation of oxygen delivery with central venous oxygen saturation, mean arterial pressure and heart rate in piglets

Abstract: Summary Background: Accurate assessment and monitoring of the cardiocirculatory function is essential during major pediatric and pediatric cardiac surgery. Invasive monitoring of cardiac output and oxygen delivery (DO2) is expensive and sometimes associated with adverse events. Measurement of central venous oxygen saturation (ScvO2) is less invasive and may reflect the DO2. Therefore, we investigated the correlation of ScvO2 with cardiac index (CI) and DO2 and in comparison the more common monitored parameters heart rate (HR) and mean arterial pressure (MAP) with DO2 in an animal experimental setting. Methods: In five fasted, anesthetized and mechanically ventilated piglets CI (transpulmonary thermodilution), venous and arterial blood gases, HR and MAP was measured during normal conditions, volume loading, inotropic support, and exsanguination. Results: In the five piglets 168 measurements could be performed. In a wide hemodynamic range (CI 22–335 ml·kg−1min−1) we found significant correlations of ScvO2 with DO2 (r2 = 0.91, P < 0.0001) and CI (r2 = 0.88, P < 0.0001) and also between DO2 and MAP (r = 0.86, P < 0.0001) and HR (r = 0.19, P < 0.05). Conclusions: ScvO2 is a better parameter for indirect estimation of DO2 than MAP and heart rate. Measurement of ScvO2 is simple and does not necessitate additional invasive techniques. In the clinical setting ScvO2 should be used in combination with other standard vital parameters, i.e. MAP, central venous pressure, lactate, base excess, and urine output.

Hemodynamic changes during acute elevation of intra‐abdominal pressure in rabbits

Abstract: Summary Background: The intra-abdominal pressure (IAP) may be increased during pneumoperitoneum for minimally invasive surgery, after high tension repairs of congenital abdominal wall defects, major abdominal surgery, liver transplantation, abdominal trauma, peritonitis or ileus. The aim of this study was to investigate hemodynamic changes during elevation of IAP using an experimental setting, which mirrors anatomical and physiological conditions of neonates and small infants as closely as possible. Methods: In five fasted, anesthetized, mechanically ventilated and multicatheterized New Zealand rabbits, the IAP was gradually increased by intra-abdominal infusion of normal saline (total volume 1000 ml). At baseline and after each infusion of 100 ml normal saline cardiac output (CO, transcardiopulmonary thermodilution), pressure in the superior (SVCP) and inferior vena cava (IVCP), mean arterial pressure (MAP), peak airway pressure (PAP) and IAP was recorded. Results: During the study, IAP, SVCP and IVCP increased significantly. IVCP was significantly higher than SVCP from timepoint 200 ml to study end. After abdominal decompression IAP, SVCP and IVCP decreased to baseline levels. Changes in MAP were not significant. CO increased significantly from baseline to timepoint 200 ml (peak value), remained nearly constant until timepoint 800 ml and decreased thereafter until the abdominal infusion ceased. After abdominal decompression CO returned to baseline level. SVCP, IVCP and PAP correlated significantly with IAP (SVCP, r = 0.73; IVCP, r = 0.97; PAP, r = 0.94; P < 0.0001). Conclusions: The hemodynamic changes caused by increased IAP cannot be recognized by routine monitoring of arterial blood pressure and transcutaneous oxygen saturation. The increase in central venous pressure may be misinterpreted as an elevation of cardiac preload. One major effect of a prolonged increase in IAP is a decreased CO.

Chronic pain after surviving sepsis

Abstract: In Germany about 90,000 patients survive sepsis per year. Few data are available indicating quality of life and chronic pain states of sepsis long-term survivors [1].

Blood volume measurements using an integrated fiberoptic monitoring system in a porcine septic shock model.

Abstract: Objectives:To compare the accuracy of an integrated fiberoptic monitoring system using transpulmonary thermo-dye dilution technique to measure blood volume (BV) with standard method using chromium-51-tagged erythrocytes in septic shock.Design:Prospective blinded animal laboratory study.Setting:Unive

Pulse-contour-derived cardiac output is unreliable in septic shock. Authors' reply

Abstract: Sir, We read with interest the comment of P.G. Berthelsen. Our experimental model is well established (1–3). To compare measures such as cardiac output (CO) between individuals, the correct method of presentation is as an index related to the body surface area (BSA) in humans. The underlying reason is that the cardiac index (CI) provides a more individual-specific measure of cardiac performance. Therefore, we disagree completely with Dr Berthelsen’s comment that we have chosen an ‘odd’ way of presenting our results. We divided CO by the weight of the animal to yield the CI in order to eliminate weight-related differences. This is the scientifically correct and generally accepted way of presenting CO data in the chosen experimental design (1, 4, 5). Furthermore, Dr Berthelsen’s extrapolation of animal data to an average human man is inappropriate and incorrect. We have already established that arterial transpulmonary thermodilution (ATD) is a reliable technique for the measurement of CO. Previously, our group compared ATD and pulmonary artery thermodilution (PATD) with the physiological standard, indirect calorimetry, using our model (6). The correlation between the indirect calorimetry-derived CO estimation and transpulmonary CO was high (r 1⁄4 0.91, r 1⁄4 0.83, P < 0.001). The bias was 0.75 ml/min/kg (95% CI, –3.8 to 5.3 ml/min/kg) with limits of agreement of –39.7 to 41.2 ml/min/kg. The data analysis in the present study was performed in accordance with Altman and Bland. Furthermore, pulse-contour-derived CO has been demonstrated to be reliable in comparison with pulmonary arteryderived CO (7) and in hemodynamically unstable cardiac surgery patients (8). In conclusion, even during hemodynamic instability in septic shock, the correlation of ATDand PATD-derived CO with indirect calorimetry is good. In the present study, we demonstrated that pulse-contour-derived CO is a reliable way of measuring CO continuously up to 5 h. As CO obtained by arterial thermodilution is less invasive than that obtained by PATD, it may offer practical advantages.

Impact of high-molecular hydroxyethyl starch solutions on plasma volume and haemodynamics in porcine faecal peritonitis

Abstract: Early fluid resuscitation is suggested to be beneficial sepsis therapy. Using a faecal peritonitis model we tested effects of two new synthetic high-molecular hydroxyethyl starches, 6%HES 700/0.42/2.5:1 (HES700/2.5:1) and 6%HES 700/0.42/6:1 (HES700/6:1), compared with 6%HES 130/0.42 (HES130) and ringer's solution (RS) on plasma volume (PV), heart rate (HR), mean arterial pressure (MAP) and mixed venous oxygen saturation (SvO2).