Acta anaesthesiologica Scandinavica
-
Acta Anaesthesiol Scand · Jul 1987
In vitro diagnosis of susceptibility to malignant hyperthermia: evaluation of tests with halothane-caffeine, potassium chloride, suxamethonium and caffeine-suxamethonium.
Susceptibility to MH was determined in 77 patients according to the protocol of the European MH Group. Additional muscle bundles were used for diagnostic in vitro tests with caffeine in the presence of 1% halothane, potassium chloride, suxamethonium, and caffeine-suxamethonium. Significant differences between MH-susceptible (MHS) and MH-negative (MHN) patients were obtained with the halothane-caffeine test and the potassium chloride test, whereas no differences were found with the suxamethonium test. ⋯ In all tests there was an overlap in results between MHS and MHN groups, and the predictive values of the tests ranged between 63 and 95%. Prior small doses of caffeine followed by a 4 mmol/l dose of caffeine elicited significantly smaller contractures than 4 mmol/l given as the first dose of caffeine. This underlines the necessity of a common protocol for performance and interpretation of diagnostic tests for MH.
-
Acta Anaesthesiol Scand · Jul 1987
Gas exchange in low-compression HFPPV is maintained at low distending pressures in the pig.
The fact that collateral ventilation normally occurs in the human lung has led to the suggestion that it might contribute to the successful clinical effects of low-compression high-frequency positive-pressure ventilation (HFPPV). As the pig has poor collateral ventilation, pulmonary vasoconstriction has to be part of the regulatory mechanisms matching ventilation-perfusion. A study was made on nine pigs anesthetized with ketamine hydrochloride intravenously to elucidate the maintenance of ventilation-perfusion balance during mechanical ventilation. ⋯ The tidal volume required for normoventilation differed significantly between the three ventilatory patterns, but there were no differences in circulatory and oxygen-transport variables. By measurements of airway pressure and intrapleural liquid surface pressure, it was demonstrated that the distending pressure (at end-inspiration) was significantly lower with a low-compression system (H-20 versus SV-20), especially at a high ventilatory frequency (H-60 versus H-20). Consequently, although the mean airway pressure was set at the same level for the three different ventilatory modalities, the distending pressures required for the same alveolar ventilation and arterial oxygenation differed significantly.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Acta Anaesthesiol Scand · Jul 1987
Effect of chronic bupivacaine infusion on seizure threshold to bupivacaine.
Thirty rats were pretreated with a continuous infusion of bupivacaine or placebo. On the fourth day the acute seizure threshold to bupivacaine was determined for both groups. The seizure dose, blood and brain concentration of bupivacaine showed no difference between the groups. The tachyphylaxis seen clinically when bupivacaine is used for a regional nerve blockade does not seem to evolve for the CNS-effects.
-
Acta Anaesthesiol Scand · May 1987
Comparative StudyPostoperative water and electrolyte changes in skeletal muscle: a clinical study with three different intravenous infusions.
Twenty-seven patients admitted for cholecystectomy were matched for age and sex in three groups for different perioperative fluid therapies over a period of 3 days. Group I was given an acetated half-isotone "balanced" saline solution with the addition of 2.5% glucose, Group II an acetated Ringer solution and Group III an isotonic glucose solution. Percutaneous muscle biopsies were performed before and on the third day after surgery for the determination of water content and the concentration of sodium, potassium, magnesium and chloride in skeletal muscle. ⋯ The concentration of sodium and chloride in skeletal muscle increased significantly in Groups II and III, whereas the concentration of potassium decreased in all groups. The cumulative sodium balance was positive in Groups I and II; the potassium balance was negative in all groups. In conclusion, the patients given the balanced saline solution showed the least change in water content and electrolyte concentrations in skeletal muscle.
-
Acta Anaesthesiol Scand · May 1987
Randomized Controlled Trial Clinical TrialEffect of clonidine on haemodynamic responses to endotracheal intubation and on gastric acidity.
Sixty-three patients (ASA 1-2), scheduled for elective surgery under general anaesthesia, were randomly given either oral clonidine (225-375 micrograms) + diazepam (5 15 mg), cimetidine (300 mg the night before and 300 mg in the morning) + diazepam or only diazepam for premedication. Anaesthesia was induced with thiopentone and maintained with N2O + O2 (70:30), enflurane and fentanyl. Vecuronium bromide was used as a muscle relaxant. ⋯ On the electrocardiogram (ECG) during the endotracheal intubation, the incidence of bigeminy was higher in the diazepam patients (5/20) than in the cimetidine patients (2/20) and the clonidine patients (0/23). There were significantly more gastric content samples with a pH above 2.5 in the cimetidine group than in the other groups, and clonidine patients did not differ from diazepam patients in this respect. The high incidence of bradycardia with the concomitant hypotension may limit use of this drug to highly selected patients.