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M Zimpfer

Publications and source records attributed to M Zimpfer.

At least 73 records · Page 4Linked to original sources
PubMed1996

Application of SHFJV for surgical procedures.

Using SHFJV in combination with the jet laryngoscope it is possible to ventilate patients for laryngeal surgery with out the necessity for any kind of endotracheal tube or catheters. This technique can also safely be applied in patients with underlying pulmonary or cardiac disease or in obese patients. Patients with laryngeal stenosis can be ventilated from above the stenosis eliminating the danger of barotrauma. The laser can be used at any time the surgeon desires without any additional protective measures. The SHFJV can be used for tracheobronchial stent insertion. Only in cases were the glottis can not be visualized through the jet laryngoscope sufficient ventilation is not ensured and therefore transtracheal high frequency ventilation is the technique of choice.

Adolescent↗
PubMed1996

High frequency ventilation techniques in ARDS.

High frequency ventilation techniques are not applied as routine measures but are still regarded as lastditch efforts in treating patients with severe ARDS or with extensive bronchoplural fistula when conventional mechanical ventilation is not capable in providing sufficient gas exchange. High frequency ventilation techniques can be used in patients with septicemia or recent cerebral bleeding, which is a contraindication for ECMO, or in patients with increased ICP. We believe that high frequency ventilation techniques provide an important therapeutic tool in the treatment of pulmonary insufficiency since the hardware requirement is minimal and, after a brief explanation, the application is easy.

Adult↗
PubMed1995

Platelet disorders in uraemia before and after haemodialysis under the influence of low dose aspirin.

Thrombocyte dysfunction and increased bleeding time (BT) are well documented in uraemic patients. However, these patients are frequently medicated with low dose aspirin (ASA) in order to maintain shunt patency and prevent cardiovascular events. Recently, life- threatening gastrointestinal haemorrhage in an uraemic subject taking low dose aspirin has been reported. In this work ASA related bleeding risk in uraemic patients and the effect of haemodialysis on their bleeding tendency was studied by measuring in vitro bleeding time (BT) using the Thrombostat 4000 in 34 uraemic patients on chronic haemodialysis compared to 50 healthy subjects. Our results indicate that low dose aspirin does not influence uraemic thrombopathia 8 to 10h after ingestion but seems to increase bleeding risk shortly after ingestion. Moreover, haemodialysis alters uraemic in vitro BT with regard to the time after ingestion of ASA.

Adult↗
PubMed1995

Hemodynamic and analgesic effects of clonidine added repetitively to continuous epidural and spinal blocks.

Clonidine in spinal and epidural blocks prolongs anesthesia, but can cause hypotension and bradycardia. The aim of our study was to compare hemodynamic and analgesic effects of spinal versus epidural clonidine alone and after repetitive dosing. In a prospective, randomized, double-blind study, we evaluated 40 patients scheduled for lower extremity orthopedic surgery under continuous spinal or epidural anesthesia with bupivacaine 0.5% (initial dose 5 mg and 50 mg, respectively). In either spinal or epidural technique one-half of patients received clonidine (150 micrograms) in addition to bupivacaine. Repeat doses of the same anesthetic mixture were allowed in cases of subsequent pain. Mean arterial pressure (MAP) and heart rate were recorded for 6 h after each injection. Duration of clinically useful anesthesia was defined as the time from drug administration to first sensation of pain. Intrathecal, but not epidural, clonidine decreased MAP significantly compared with bupivacaine alone. MAP after intrathecal clonidine with bupivacaine was lower than epidural clonidine with bupivacaine 5 and 6 h after injection. Repetitive administration caused no further decrease in MAP. Onset time required to surgical anesthesia (sensory block of T11) did not differ among the four groups. Duration of spinal and epidural anesthesia was increased more than two fold by clonidine. In summary, the addition of clonidine prolongs analgesia by either route. These results may be explained by clonidine's sites of action in hemodynamic control and the density of bupivacaine-induced block.

Aged↗
PubMed1995

Forced-air warming maintains normothermia during orthotopic liver transplantation.

We evaluated the efficacy of forced-air warming to maintain normothermia during liver transplantation. In a prospective, clinical trial 20 patients were randomly assigned to routine thermal management (circulating-water mattress set at 42 degrees C, intravenous fluid warming to 37 degrees C and passive insulation) or routine management with additional forced-air warming of head, chest, and arms. Core temperature was measured in the pulmonary artery. Morphometric and demographic characteristics were similar in each group, as was total administered fluid volume replacement. Core temperatures in each group decreased by about 0.6 degrees C during the first 70 min of anaesthesia and then by 0.9 degree C within 90 to 120 min in the patients given routine thermal management, but only by 0.4 degree C in those warmed with forced-air. Subsequently, core temperatures in the control group increased to only 35.7, SD 0.25 degree C whereas those in the patients given forced-air warming increased to 36.5, SD 0.2 degree C. Despite the relatively high ambient temperature, patients warmed only with a circulating-water mattress and passive insulation became hypothermic during surgery. In contrast, when forced-air warming was added to this routine thermal management, patients were normothermic at the end of surgery. Forced-air warming prevented intra-operative hypothermia during liver transplantation.

Body Temperature↗
PubMed1995

[Changes in hemostasis during orthotopic liver transplantation and massive transfusion: a case report].

UNLABELLED: Changes in hemostasis during orthotopic liver transplantation (OLT) and an intraoperative bleeding complication requiring massive transfusion are discussed. DESIGN: The monitoring of hemostasis included bed-sided thromboelastography, measurement of in vitro platelet function with the thrombostat and routine coagulation tests as well as retrospective analysis of coagulation factors. RESULTS: Changes in hemostasis during OLT were documented as reported previously until reperfusion of the donor organ. Due to an incongruence between the caval veins and massive surgical bleeding, the liver had to be clamped again for reconstruction and perfused with University-of-Wisconsin solution. The second reperfusion was technically uncomplicated. However, the coagulation profile deteriorated dramatically: especially a decrease in platelet function and hyperfibrinolysis led to massive oozing. Successful therapeutical intervention included substitution of packed red blood cells. fresh frozen plasma, platelets. concentrates of hemostatic factors, and aprotinin. The patient was discharged from hospital after 5 weeks with a good liver function and a normal coagulation profile. CONCLUSION: During OLT, clinically relevant changes in hemostasis can occur suddenly. Therefore. a close perioperative monitoring of primary and secondary coagulation is mandatory.

Blood Coagulation Tests↗
PubMed1994

Influence of positive end-expiratory pressure on right and left ventricular performance assessed by Doppler two-dimensional echocardiography.

The advent of modern Doppler two-dimensional ultrasound technology has overcome the need of invasive measurements of several important cardiac parameters. It allows estimation of preload, contractility, and afterload. Positive end-expiratory pressure (PEEP) is associated with a reduction in cardiac output. The responsible mechanisms are controversial. To evaluate the cardiovascular responses to PEEP, we employed different Doppler hemodynamic indices for the first time, combined with conventional two-dimensional echocardiography. Twenty-one healthy, young, and unsedated volunteers were admitted to the study. Under spontaneous respiration, PEEP level was increased stepwise (0, 5, 7.5, 10, 12.5 cm H2O). At each PEEP level, the following right and left ventricular parameters were assessed with Doppler two-dimensional echocardiography: two-dimensional variables: end-diastolic volume indices (EDVI), ejection fraction (EF), and left ventricular afterload-LaPlace relation (combined with cuff systolic pressure); Doppler variables: cardiac index (CI) (combined with two-dimensional measure of valve area), maximum velocity (Vmax), time velocity integral (TVI), acceleration time (AT), deceleration time (DT), deceleration rate (DR), ratio of early to atrial peak (E/A), ratio of isovolumic contraction time to ejection time (IVCT/ET), and maximum blood acceleration (dv/dt) in aorta and main pulmonary artery. Increasing PEEP resulted in a proportional decrease in biventricular EDVI. Moreover, PEEP application is also causing a drop of CI, which is determined from a decrease in Vmax and TVI, while EF, IVCT/ET, dv/dt, Doppler trans-atrioventricular parameters, and afterload stay in normal ranges. Employing Doppler hemodynamic indices for the first time in this study setting clearly supports data that the drop in EDVI and CI during PEEP is caused by reduction in ventricular filling due to decreased venous return. Using the Doppler parameters IVCT/ET and dv/dt, changes in myocardial contractility, as well as changes in afterload (LaPlace relation) can be ruled out.

Adult↗
PubMed1994

Anticoagulation with prostacyclin and heparin during continuous venovenous hemofiltration.

OBJECTIVES: To investigate anticoagulation with prostacyclin (prostaglandin I2 [PGI2]) and/or heparin during continuous venovenous hemofiltration, and the role of in vitro tests of primary hemostasis in controlling anticoagulation. DESIGN: Prospective, randomized, controlled trial. SETTING: Intensive care unit. PATIENTS: Forty-six consecutive, critically ill, mechanically ventilated patients with postoperative acute renal failure. INTERVENTIONS: Anticoagulation of the patient's blood was accomplished using heparin (6.0 +/- 0.3 IU/kg/hr for group 1), PGI2 (7.7 +/- 0.7 ng/kg/min for group 2), or both PGI2 and heparin (6.4 +/- 0.3 ng/kg/min, 5.0 +/- 0.4 IU/kg/hr, respectively, for group 3), administered into the extracorporeal line before the hemofilter during continuous venovenous hemofiltration. MEASUREMENTS AND MAIN RESULTS: After Ethics Committee approval and informed consent were obtained, tests of primary and secondary hemostasis, plasma concentrations of 6-ketoprostaglandin F1 alpha (by radioimmunoassay), and hemodynamic measurements were performed before hemofiltration and 24 hrs after hemofiltration. In groups 1 and 3, hemodynamic parameters remained stable, whereas in group 2 (the PGI2 group), there were significant reductions in systemic and pulmonary vascular resistances and mean arterial pressure. Platelet function was unchanged in group 1, and was inhibited in groups 2 and 3. Corresponding with the prolongation of in vitro bleeding time, the 6-ketoprostaglandin F1 alpha concentration was increased, indicating an effective inhibition of platelet aggregation within the hemofilter. Platelet counts remained stable in all patients. Plasma coagulation tests were stable in groups 2 and 3, and were prolonged in group 1. In all patients, no major bleeding complications were observed and there was no clinically important bleeding. Mean hemofilter duration lasted longest in group 3. Blood urea nitrogen and circulating creatinine concentrations decreased significantly in groups 2 and 3 within the study period. CONCLUSIONS: Patients receiving both PGI2 and heparin showed better hemodynamic profiles and enhanced hemofilter duration compared with the other groups and no bleeding complications were observed. Therefore, we recommend anticoagulation with PGI2 and heparin during continuous venovenous hemofiltration with close monitoring of platelet function, coagulation profile, and overall hemodynamics.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Oxygen kinetics during liver transplantation: the relationship between delivery and consumption.

In anesthetized humans, oxygen consumption is independent of oxygen delivery above a critical threshold. Below this critical level, lactic acid is a marker of anaerobic metabolism and tissue oxygen debt, and heralds a supply dependency of oxygen consumption. The goal of this study was to determine whether a threshold value for oxygen delivery below which oxygen consumption becomes supply dependent can be identified in patients with normal, impaired, or absent liver function. Measurements were made in 34 surviving patients (group 1) and in 16 nonsurvivors with sepsis and postoperative liver graft failure (group 2). Hemodynamic measurements and blood samples were taken 10 minutes after introduction of anesthesia, 10 minutes after cross-clamping, and 10 minutes after reperfusion of the new liver. At these time points, we measured blood lactate, cardiac output, and arterial and mixed venous oxygen contents in order to calculate oxygen consumption and oxygen delivery. In both groups, cardiac output, oxygen delivery, and oxygen consumption decreased during the anhepatic phase and increased after unclamping of the inferior vena cava. Lactate increased in both groups during surgery, but was significantly higher in nonsurvivors (6.6 +/- 0.4 mmol/L) than in survivors (4.6 +/- 0.1 mmol/L) (P < .05). With similar changes for oxygen delivery and oxygen consumption during increased lactate levels we could not identify a clear supply dependency of oxygen consumption in survivors and nonsurvivors during liver transplantation. We conclude that the interpretation of blood lactate levels during circulatory shock can be biased due to a reduced lactate clearance in patients with impaired liver function, unrelated to the status of the relationship between oxygen delivery and consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Oxygen uptake-oxygen delivery alterations in the isolated liver after hydrogen peroxide challenge.

Acute, diffuse lung injury is frequently complicated by systemic organ injury and alterations in the relationship between oxygen uptake (VO2) and oxygen delivery (QO2). In this regard, systemic organ neutrophil accumulation and morphologic alterations consistent with systemic organ injury often occur in nonpulmonary organs in these settings. However, whether VO2-QO2 matching is also altered in these injured systemic organs remains unproven. Thus, the present study was designed to test the hypothesis that hydrogen peroxide (H2O2), a product of neutrophil oxidative metabolism, will cause systemic organ structural abnormalities and alter VO2-QO2 matching. To test this hypothesis, VO2-QO2 relationships, morphologic changes, and organ water content were evaluated in both uninjured, isolated perfused rabbit livers and in isolated perfused rabbit livers after injury with 5 mmol/L H2O2. Following H2O2 injury, peak VO2 fell from 1.36 +/- 0.35 mL/min/100 g to 0.79 +/- 0.16 mL/min/100 g (P < .05) and peak O2 extraction fell from 0.83 +/- 0.09 to 0.66 +/- 0.04 (P < .05). In addition, VO2 was lower for any given level of QO2 in the H2O2-injured livers compared with the control livers (P < .01). Finally, liver extravascular water content was increased in H2O2-injured livers compared with the control livers (0.79 +/- 0.02 v 0.71 +/- 0.05; P < .05). These observations indicate that H2O2, a product of neutrophil oxidative metabolism, is capable of producing both morphologic changes as well as gas exchange alterations in the isolated, perfused liver.

Animals↗
PubMed1993

Effects of propofol on the function of normal, collateral-dependent, and ischemic myocardium.

To examine the effects of propofol on the function of normal, collateral-dependent, and acutely ischemic myocardium, nine mongrel dogs were chronically instrumented with hydraulic occluders and ameroid constrictors were inserted around the left coronary artery, pressure transducers in the left ventricle, and heparin-filled catheters in the descending aorta and the left atrium. Regional function of normal, collateral-dependent, and acutely ischemic myocardium was assessed by sonomicrometry. Propofol (5 mg/kg intravenously) reduced function in normal myocardium (-15% +/- 5%, 1 min and -14% +/- 5%, 3 min after injection) and in collateral-dependent myocardium (-14% +/- 5% and -13% +/- 5%) to similar degrees, whereas ischemic myocardial function deteriorated significantly more (-25% +/- 10% and -23% +/- 10%, P < 0.01). Although left ventricular end-diastolic pressure remained unchanged and left ventricular contractility was reduced (-16% +/- 4%, 1 min and -15% +/- 3%, 3 min after propofol, P < 0.01), significant increases in heart rate (35% +/- 7% and 26% +/- 7%, P < 0.01) and decreases in coronary perfusion pressure (-14% +/- 5%, P < 0.05 and -19% +/- 6%, P < 0.01) occurred, likely affecting the function of ischemic myocardium. Thus, whereas collateral-dependent myocardium tolerated these adverse hemodynamic effects, ischemic myocardium responded with impairment of regional function that was significantly more pronounced than the impairment which occurred in normal or collateral-dependent areas after a 5 mg/kg intravenous bolus of propofol.

Animals↗
PubMed1993

Perioperative liver graft function: the role of oxygen transport and utilization.

To assess the evolution of satisfactory neohepatic graft function or failure, hemodynamic variables, along with data for oxygen delivery and utilization, were analyzed retrospectively in 99 patients undergoing orthotopic liver transplantation. Caval cross-clamping without venovenous bypass initiated a series of hemodynamic events, characterized by decreases in pulmonary artery pressures, cardiac output, and arterial pressures and increases in systemic vascular resistance, with reciprocal changes after unclamping. Concerning oxygen transport, the increased oxygen delivery after caval unclamping led to increases of mixed venous oxygen tension, decreases of oxygen extraction, and the arteriovenous oxygen content difference. The most striking result, however, was that with similar values for oxygen delivery, the patients with primary nonfunction (n = 9) had both lower anhepatic oxygen consumption, much smaller increases in oxygen consumption, and lower ratios of oxygen extraction during reperfusion of the liver than the patients with normal initial graft function (n = 90). Thus, distinct increases in total body oxygen consumption were found to be indicative of the onset of hepatocellular function and satisfactory neohepatic graft function. The authors conclude that perioperative measurements of whole-body oxygen consumption are important in reflecting early allograft viability during orthotopic liver transplantation without anhepatic venovenous bypass.

Adult↗