Canadian journal of anaesthesia = Journal canadien d'anesthésie
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The alkalinization of certain local anaesthetics with sodium bicarbonate hastens the onset of epidural analgesia. Increases in both the pH and PCO2 of the local anaesthetic are necessary to hasten onset. However, carbon dioxide can diffuse from local anaesthetic solutions following alkalinization with sodium bicarbonate and change both the pH and PCO2 of the mixture. ⋯ The pH and PCO2 of each solution were measured at time 0 and at 5, 10, 15, 20, 30, 40, 50 and 60 min intervals. The solutions were placed in containers as follows: 30 ml in 40 ml containers, 10 ml in 40 ml containers, 10 ml in 13 ml containers, and 10 ml in polypropylene syringes. The pH and PCO2 increased following alkalinization but gradually decreased in all containers except in polypropylene syringes.
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Randomized Controlled Trial Clinical Trial
[Peridural anesthesia for surgery of the ankle and foot: effect of the sitting position].
The effects of the sitting position on the quality of both sensory and motor blockade of segments L5 and S1 and the haemodynamic consequences during epidural anaesthesia were studied on 39 patients undergoing ankle or foot surgery. After insertion of an epidural catheter with the patient in the lateral position, 19 patients were kept sitting for 15 min following the injection of the local anaesthetic and 20 remained supine for the duration of anaesthesia (control group). All patients received a dose of 20 ml of 1.73% carbonated lidocaine with epinephrine 1:200,000. ⋯ Fourteen patients of the sitting group achieved motor blockade of more than three of five myotomes compared with five patients in the supine group (P less than 0.001). The maximum decrease in mean arterial pressure occurred sooner in the sitting group (14 +/- 9 min) than in the control group (21 +/- 10 min; P less than 0.01) and was more severe (-24 +/- 10% vs -16 +/- 10% respectively; P less than 0.05). Our results indicate that placing the patient in the sitting position for 15 min after inducing epidural anaesthesia does not influence caudal sensory blockade but does increase the depth of motor blockade.
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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.