Canadian journal of anaesthesia = Journal canadien d'anesthésie
-
The hypothesis that histamine H2 receptor blockade adversely affects neuromuscular function was tested, in vivo, in rats anaesthetised with urethane during mechanical pulmonary ventilation. Succinylcholine was administered as a bolus and constant-rate infusion to maintain 49.2% (+/- 1.5 SEM) twitch suppression in 19 rats. Cimetidine iv, 3.2, 7.5, 10, 17.8, 23.7, 31.6, or 56.2 mg.kg-1 was then administered in groups of two to three rats. ⋯ There was a good relationship between peak potentiation and serum cimetidine concentration with 50% potentiation occurring at 46.5 (+/- 4.6) micrograms.ml-1. Potentiation at steady-state was not correlated to serum cimetidine concentration but there was a weak relationship between reversal and serum cimetidine concentration. These results support reports from patients of an interaction between cimetidine and succinylcholine.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of hyperbaric solutions of bupivacaine and tetracaine during continuous spinal anaesthesia.
The aim of this study was to compare two equipotent solutions of hyperbaric bupivacaine and tetracaine in 30 elderly patients undergoing elective hip surgery under continuous spinal anaesthesia. With the patient in the supine position, 2 ml (8 mg) of either hyperbaric solution (density 1.030) were administered in a double-blind and randomized fashion. The median maximum sensory and temperature discrimination levels (T5 and T4) were similar with both solutions. ⋯ The haemodynamic changes and vasopressor requirements were comparable. The plasma catecholamine levels measured at four different times remained unchanged and were not different between the two groups at any time. The authors conclude that, during continuous spinal anaesthesia, equipotent hyperbaric solutions of bupivacaine and tetracaine have similar anaesthetic and haemodynamic effects.
-
The effects of dobutamine on diaphragmatic contractility were studied in 24 dogs anaesthetized with secobarbital and receiving mechanical lung ventilation. The phrenic nerves were stimulated supramaximally for two seconds with electrodes placed around the fifth and sixth cervical roots when the airway was closed at the level of FRC. The stimulating frequency ranged from 10 to 100 Hz. ⋯ The Edi was not altered by dobutamine infusion. This enhancement of Pdi by dobutamine was abolished by simultaneous infusion of nicardipine, a Ca-channel blocker, but was not affected by prostaglandin E1. These results suggest that dobutamine has a stimulating effect on canine diaphragmatic contraction, and this action may be related to the increased inward movement of extracellular calcium.