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Biomedical subjects

K Steinbereithner

Publications and source records attributed to K Steinbereithner.

At least 19 recordsLinked to original sources
PubMed1992

Porcine model for studying the passage of non-depolarizing neuromuscular blockers through the blood-brain barrier.

A method has been developed for blood-brain barrier disruption to provide reproducible access to the cerebrospinal fluid of the cerebello-medullary cistern. The technique was used successfully to investigate transfer of pancuronium to the cerebral CSF compartment in pigs. After osmotic disruption of the blood-brain barrier, pancuronium concentrations increased significantly in the cerebrospinal fluid.

Animals↗
PubMed1992

Anaesthetic uptake and washout characteristics of patient circuit tubing with special regard to current decontamination techniques.

The amounts of halothane and isoflurane trapped after exposure for up to 3 h at 2 MAC in commonly used anaesthesia circuit tubing were quantitated by gas chromatography. The decontaminating effects of procedures such as flushing with oxygen, thermal disinfection and/or routine storage were assessed in a similar way. After halothane exposure, anaesthetic content was highest in silicone (398 +/- 55 mg 100 g-1). Lower quantities were found in all other tubings investigated (electrically conductive latex: 64 +/- 4, conductive rubber: 62 +/- 4, polyethylene-vinyl-acetate (PEVA): 293 +/- 10 and 149 +/- 17 for non-conductive corrugated and spiral tubes, respectively, polysulfone (Hytrel): 155 +/- 10 mg 100 g-1). The isoflurane contents were substantially lower (silicone: 278 +/- 23; others: 55 +/- 7, 61 +/- 6, 163 +/- 9 and 86 +/- 8, 74 +/- 4 mg 100 g-1). The tubings' content did not correlate with the material's partition coefficient as full saturation was not achieved during exposure. Decontamination procedures reduced the content of volatile anaesthetics to a variable extent. Conductive latex and rubber showed the highest residual content, even after thermal disinfection and subsequent storage. Twenty-minute flushing with oxygen (8 l min-1) decreased effluent gas concentrations below 5 p.p.m. in all tubings. With silicone, after 1 h flushing, halothane concentrations still exceeded 10 p.p.m. (isoflurane: 8 p.p.m.). It is concluded that urgent decontamination by a 20-min flush warrants the safe re-use of previously 'contaminated' conductive rubber and latex as well as polysulfone tubings in critical situations, e.g. in malignant hyperthermia patients if disposable tubing is not immediately available.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

Effects of nimodipine administration during cardiopulmonary resuscitation in pigs.

The haemodynamic effects of nimodipine during cardiopulmonary resuscitation (CPR) were investigated in 25 anaesthetized pigs. After 5 min of ventricular fibrillation (VF) and 5 min of closed-chest CPR, adrenaline (50 micrograms kg-1), either nimodipine (10 micrograms kg-1 as a bolus followed by 1 microgram kg-1 min-1 continuously) or the equivalent volume of placebo (solvent for nimodipine) were administered followed by the first countershock. If this failed to restore spontaneous circulation, adrenaline and countershocks were repeated for a maximum of 30 min. CPR was successful in nine out of 10 nimodipine-treated animals, but only in six out of 15 placebo-treated animals (P less than 0.02). In resuscitated pigs there were no significant differences in the number of countershocks, the number of seconds required for restoration of spontaneous circulation and the total doses of adrenaline required for both nimodipine and placebo pigs. After restoration of spontaneous circulation haemodynamic responses to nimodipine were characterized by decreases in systemic vascular resistance and mean arterial pressure with consequent increases in heart rate and cardiac output, but they were not significantly different from those of the placebo-treated animals. We therefore conclude that high doses of nimodipine are well tolerated during and after CPR; nimodipine administration may even result in higher initial CPR success rates. The underlying mechanisms need further investigation.

Animals↗
PubMed1991

Muscle biopsy for diagnosis of malignant hyperthermia susceptibility in two patients with severe exercise-induced myolysis.

Muscle biopsy and in vitro contracture tests for diagnosis of susceptibility to malignant hyperthermia (MH) were performed in two patients who had developed fever and severe myolysis during exercise. MH susceptibility was confirmed in one patient, but in the other, exercise-induced heat stroke proved to be the correct diagnosis. Clinical presentation and epidemiology of exercise-induced MH and its relation to the heat stroke syndrome are discussed.

Adult↗
PubMed1991

Isoflurane impairs the function of ischemic myocardium in acutely but not in chronically instrumented dogs.

To compare the effects of isoflurane on ischemic myocardium in acutely and chronically instrumented animals, 12 mongrel dogs were monitored with electromagnetic or Doppler ultrasonic flow transducers and hydraulic occluders around the left circumflex coronary artery, pressure transducers in the left ventricle, and heparin-filled catheters in the descending aorta. Regional function of normal and ischemic myocardium was assessed by sonomicrometry. The hemodynamic effects of isoflurane (2% inspired concentration) were more pronounced in the acutely than in the chronically instrumented dogs. Decreases in mean arterial pressure (-47% +/- 5% in the acute and -22% +/- 4% in the chronic preparation, P less than 0.01), left ventricular contractility (-51% +/- 6% and -33% +/- 4%, P less than 0.01), and coronary perfusion pressure (-59% +/- 6% and -12% +/- 9%, P less than 0.01) were more distinct in the acutely instrumented animals. Although the reduction of regional function during isoflurane anesthesia was similar in normal myocardium in both preparations (-33% +/- 4% acute and -34% +/- 6% chronic preparation, not a significant difference), an exaggerated dysfunction was observed in the ischemic myocardium of the acutely instrumented dogs (-66% +/- 2% and -30% +/- 4%, P less than 0.01). It is concluded that acutely instrumented dogs respond to the hemodynamic effects of isoflurane, resulting in ischemic myocardial dysfunction, significantly more than do chronically instrumented dogs.

Animals↗
PubMed1991

[Anesthetic gas contamination in the operating room--an unsolved problem? Results of our own studies].

Ambient air concentrations of nitrous oxide (N2O) and volatile anesthetics were assessed under routine conditions in a total of 41 surgical suites located at seven Vienna hospitals. Continuous measurements were performed by means of infrared trace gas analyzers throughout a period of approximately 450 h. Additional analyses of ventilation facilities (if installed) revealed no essential deficiencies; however, anesthetic gas scavenging (AGS) systems yielded insufficient flow rates in 32% (less than 25 l/min). In surgical suites without mechanical ventilation or scavenging systems (2 out of 41), maximum occupational threshold limits (i.e., 100 ppm N2O; 5 ppm halothane) were exceeded continuously and to considerable degrees throughout the duration of anesthesia. During measurements conducted in operating rooms (ORs) in otolaryngology departments, extreme peaks (greater than 2600 ppm N2O, greater than 150 ppm halothane) of several minutes duration were documented when open-circuit anesthesia was performed. In the general surgical ORs equipped with modern ventilation facilities ambient air contamination was lowest, time-weighted average (TWA) values ranging from 8 to 15 ppm (mean 11 +/- 3 ppm) for N2O and 0.1 to 0.6 ppm (mean 0.3 +/- 0.2 ppm) for the halogenated anesthetic. Despite good ventilation and scavenging in the gynecological ORs, distinctly higher concentrations (mean 83 +/- 49, range 24-211 ppm N2O; mean 0.75 +/- 0.3, range 0.3 to 1.3 ppm volatile agent) were measured in cases where anesthesia was delivered by mask. TWA values exceeding currently established maximum workplace concentrations were found in an unscavenged but ventilated urological OR. At present, short-term concentration peaks seem to be inevitable even under optimal OR ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution, Indoor↗
PubMed1991

[A case of serum cholinesterase anenzymia].

A report is given on a 66-year-old man suffering from serum cholinesterase anenzymia. The following tests were performed to characterize the genetic pseudo-cholinesterase variants: plasma cholinesterase activity using benzoyldicholine as substrate (according to Kalow) and dibucaine and sodium fluoride as inhibiting substances. In addition, polyacrylamide density gradient gel electrophoresis followed by esterase staining technique (Mascall) was used for the electrophoretic separation of cholinesterase isoenzymes. Similarly, the only daughter's and the granddaughter's sera were analyzed. Determination of activity and inhibitor numbers indicated that the propositus had the homozygote "silent gene" genotype (A = 2, DN = 0, FN = 0). The granddaughter showed an isoenzyme constellation within normal ranges (A = 128, DN = 80, FN = 58); for the daughter apparently normal values were also found for activity and inhibitor numbers (A = 73, DN = 82, FN = 58). Figure 1 shows the results of electrophoretic separation from the sera tested and Fig. 2 results obtained by densitometric assessment. Electrophoretic separation and the zymogram obtained from the propositus' serum show only sample peak and albumin fractions. In contrast, the granddaughter's serum turned out to be absolutely normal. In the daughter's sample, however, three cholinesterase components normally found in serum were missing, as also shown by densitometry. Despite apparently normal activity and rather insignificant inhibitor numbers, gradient gel electrophoresis clearly revealed her to be a heterozygote carrier of the silent gene Es variant. As our data are in accordance with results obtained by other investigators, this observation cannot be regarded as exceptional.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Prediction of malignant hyperthermia susceptibility: statistical evaluation of clinical signs.

The anaesthetic records of 61 patients who had experienced adverse reactions thought to be malignant hyperthermia (MH) were reviewed retrospectively to evaluate the diagnostic importance of clinical symptoms. Using the in vitro contracture test, 38 (62%) patients were identified as MH susceptible (MHS), the remainder showing normal test results (MHN). Generalized rigidity, ventricular arrhythmias, cyanosis and postoperative myoglobinuria were observed significantly more often in MHS patients. Median values of body temperature and creatine kinase serum concentrations were significantly greater in the MHS group. Masseter spasm and sinus tachycardia were as common in MHS as in MHN individuals. Statistical models using generalized rigidity, ventricular arrhythmias, cyanosis and fever exceeding 38 degrees C for prediction of MH showed a maximum sensitivity and specificity of 78% and thus are not acceptable for clinical use. For definitive diagnosis of MH, the well established in vitro contracture test remains essential.

Adolescent↗
PubMed1990

Anaesthesia in malignant hyperthermia-susceptible patients without dantrolene prophylaxis: a report of 30 cases.

The intra- and postoperative course of 30 anaesthetics in 24 MH-carriers verified by in vitro contracture tests is reported. None of the patients received dantrolene prophylactically and only agents known to be nontriggers were used for anaesthesia. Neither MH-related changes in perioperative heart rates, body temperatures, and CK levels nor any other symptoms of MH were observed. We conclude that the prophylactic use of dantrolene is not necessary in patients suspected to be prone to MH if triggering agents are avoided and the patients are closely monitored.

Adolescent↗
PubMed1990

Echocardiographic assessment of mitral valve function during mechanical cardiopulmonary resuscitation in pigs.

Using two-dimensional and M-mode echocardiography, mitral valve function was assessed during mechanical cardiopulmonary resuscitation (CPR). In 10 anesthetized pigs CPR began 1 min after induction of ventricular fibrillation; in all pigs three different compressive forces (200, 350, and 500 Newton [N]) were applied in randomized sequence for 3 min each, thus resulting in a reduction of anterior-posterior chest diameter by 15%, 20%, and 25%, respectively. Echocardiographic recordings of adequate technical quality were obtained from seven animals. During ventricular fibrillation, mitral valve leaflets showed fibrillatory movements without closure. During CPR systole with a compressive force of 200 N, the mitral valve closed in 114 of 700 CPR cycles (16%). This rate increased significantly (P less than 0.001) to 399 of 584 cycles (68%) with 350 N, and further to 470 of 494 cycles (95%) with 500 N. The higher mitral valve closure incidence was linked to statistically significant increases in systolic cerebral (+125%) and diastolic myocardial perfusion pressures (+136%) and cardiac output. We thus conclude that with low compressive force blood flow during mechanical CPR is due mainly to the chest pump mechanism, whereas the cardiac pump mechanism is effective with high compressive forces.

Animals↗
PubMed1990

Anesthesia in malignant hyperthermia susceptible patients.

The intra- and postoperative course of 30 general and 3 regional anesthetics in 27 MH-carriers verified by in vitro contracture tests is reported. None of the patients received dantrolene prophylactically. Disposable tubings were used for ventilation, vaporizers and soda lime were removed. ECG, esophageal temperature, blood pressure, oxygen saturation, and end tidal pCO2 were monitored. Minor tranquilizers were offered for premedication. Fentanyl, thiopentone, nitrous oxide, non depolarizing relaxants, neuromuscular antagonists and naloxone were used. In three patients, surgery was performed during epidural or spinal anesthesia with the use of amide local anesthetics. Neither MH-related changes in perioperative heart rates, body temperatures, and CK levels nor any other symptoms of MH were observed in any patient. The anesthetic techniques used seem to be safe and reliable; the anesthetic management of known MHS patients is discussed in detail.

Adult↗
PubMed1989

Effect of large volume replacement with balanced electrolyte solutions on extravascular lung water in surgical patients with sepsis syndrome.

We investigated the effect of large volume replacement with balanced electrolyte solutions on extravascular lung water (EVLW) in 16 adult surgical patients with sepsis syndrome. Patients entered the study within the 24 h period following surgical interventions for acute necrotizing pancreatitis, intra-abdominal abscesses, and/or peritonitis. Sequential measurements (n = 108) were made at intervals of 6-12 h over a 48 h period. There were no significant differences between initial and final values of thermal-dye EVLW (5.0 +/- 1.1 vs. 5.7 +/- 1.1 ml/kg), plasma colloid osmotic pressure (COP, 13.3 +/- 2.5 vs. 13.2 +/- 2.9 mmHg), pulmonary artery wedge pressure (PAWP, 9.2 +/- 3.0 vs. 10.8 +/- 3.0 mmHg), and COP-PAWP gradient (4.0 +/- 3.5 vs. 2.4 +/- 3.9 mmHg). All results expressed as (mean +/- SD). The EVLW did not correlate with plasma COP, PAWP, or COP-PAWP gradient. We conclude that large volume replacement with balanced electrolyte solutions with the secondary decrease in plasma COP and COP-PAWP gradient do not necessarily contribute to a substantial increase in EVLW. This study fails to show any causal relationship between decrease in plasma COP or COP-PAWP gradient and oedema formation in the lung.

Adult↗
PubMed1989

[The action of ketamine on muscle contractile behavior. In vitro studies on the musculature of subjects susceptible to malignant hyperthermia].

Since ketamine has been incriminated as triggering malignant hyperthermia (MH) [3, 9, 13, 14, 18], but has still been used uneventfully in MH susceptible patients, we performed an in vitro study to examine the safety of ketamine for use in human MH. METHODS. Muscle specimens of 20 patients who had muscle biopsies to diagnose MH were investigated. In every patient diagnostic contracture tests (2 halothane (Hal) and 2 caffeine (Caf) were done according to the protocol established by the European MH group (EMHG). In addition, one test unit for investigating the effect of stepwise increased bath-concentrations of ketamine (5, 10, 20, 60, 120, 240 and 960 mumol/l) and a further one serving as control (no drugs added to the bath) were used. Combined Hal (2 vol%) and Ket (960 mumol/l) tests were performed in 9 patients (4 MHS, 4 MHN, 1 MHEh). Changes in baseline contractures and mechanical twitch tension were evaluated. RESULTS. The diagnostic test showed MHS in 8, MHN in 8 and MHEh in 4 patients. Ketamine did not induce baseline contractures in any of the tests performed. Contractures induced by 2 vol% of halothane in 4 MHS muscles did not change significantly when ketamine was added to the bath (concentration 960 mumol/l). A significant, dose-related decrease in mechanical twitch tension occurred, when ketamine was added to the test. At the highest concentration (960 mumol) twitch tension was reduced by 55%. Twitch tension remained stable in untreated muscles. No significant differences were found between the specimens from MHS, MHN and MHE patients. This reduction in twitch tension was more pronounced in specimens exposed to both halothane (2 vol%) and ketamine (960 mumol/l), resulting in an average decrease of 71%. CONCLUSION. In accordance with Fletcher et al., our results indicate that ketamine - at least in vitro - does not trigger MH. In MHS muscles, ketamine does not augment halothane-induced baseline contractures. The ketamine-induced reduction of mechanical twitch tension in directly stimulated human muscles has not been described before. Analogous findings in frog sartorius muscles can be found in the literature. Whereas the effect of ketamine on indirectly stimulated muscle has been investigated by several authors, the underlying mechanism of ketamine-induced twitch suppression in directly stimulated muscles is not known. Inhibition of calcium release from or accelerated uptake into the sarcoplasmatic reticulum have been reported.

Caffeine↗
PubMed1988

Malignant hyperthermia susceptibility confirmed in both parents of probands. A report of three Austrian families.

From 1976 to 1986, 79 cases of suspected malignant hyperthermia (MH) were reported to the authors' institution. A total of 233 muscle biopsies was done in 66 families. The mother and father of the proband were investigated in 44 families; in three of these, both parents of probands gave positive test results. These three families, all from Vorarlberg, a secluded mountain area, represent 4.5% of all our MH-positive families (n = 61) and 7.3% of all MH-positive families where both parents had been tested (n = 41). This observation might be explained by: 1) a much higher incidence of MH in this part of Austria, and 2) a different test policy, as at the authors' institution, if possible, both parents are investigated, even if there is a positive test result in one of them. It is concluded that family investigations of MH susceptibility should always include both parents of a proband.

Adult↗