No abstract

The results of this study demonstrate that 60 mg of lidocaine sprayed down the tracheal tube before extubation and 40 mg sprayed down the tracheal tube before extubation and 40 mg sprayed down during tracheal tube removal prevents increases in blood pressure and pulse rate during and after extubation. The data suggest that this manoeuvre should be of advantage to patients with coronary artery disease who may not be able to tolerate the increased cardiac dynamics which usually accompany extubation.

FENTANYL ill doses of 0.05-2.0 mg/kg and oxygen has recently been evaluated in dogs and suggested as an alternative anaesthetic technique to large doses of morphine and oxygen in critically ill patients. 1 However, the renal effects of these doses of fentanyl are unknown. This study was conducted to determine the effects of 1 mg/kg of fentanyl with 50 per cent nitrous oxide in oxygen on renal function in the dog. METHODSFourteen unpremedicated male mongrel dogs weighing 15-23 kg, were used in the experiment. All were given 9.-3 mg/kg of sodium thiopentone and 2 mg/kg of succinylcholine intravenously. The trachea was intubated and the lungs were then ventilated with 100 per cent oxygen. Respirations were controlled with a volume limited respirator to keep Pacoe between 30-35 torr as measured in aortic blood every 15-30 minutes. Basal anaesthesia was maintained with intermittent doses of sodium thiopentone 25-50 nag every 15-20 minutes throughout the experiment. Catheters were placed into the femoral artery (threaded into the thoracic aorta), into a vein in the forelimb and the urinary bladder. The aortic catheter was attached through an arterial pressure transducer to a central digital computer substation in the operating room. After dye dilution calibration the method of Warner, Gardner and Toronto'-" for analyzing the central aortic pulse-pressure curve was used for arterial blood pressure and cardiac output determinations during the control period and throughout the experiment.Following catheter placement an infusion of 0.45 per cent sodium chloride was begun at a rate of 15-20 ml/min in order to establish a urine flow rate exceeding 5 ml/min. When this had been achieved, loading doses of inulin and paraaminohippurate (PAH) were given through the intravenous catheter. Constant inulin and PAH plasma concentrations of 9.5 and 2.5 nag per cent respectively were maintained with an 8 to 12 ml/min drip of 0.22 per cent inulin and 0.15 per cent PAH in 0.45 per cent sodium chloride. The latter was administered at a rate which maintained the desired urine output above 5 ml/min. After it had remained at this level for 30 minutes, the bladder was emptied and the first of two 15-minute control measurements was begun. At the end of each 15-minute collection period complete bladder emptying was ensured by supra-pubic pressure and instillation of 30 ml of air into the bladder followed by its aspiration. During each collecting period urine

FENTANYL, l" (2-phenethyl)-4-(n-propionylanelino)-piperidine, in doses of 0.02 mg/kg, has little effect on left ventricular dynamics in the neurally intact, bloodperfused dog heart. 1,2 Large doses of the drug (0.05-2.0 mg/kg) administered together with oxygen have been shown to maintain normal arterial blood pressure and cardiac output in the dog and to produce adequate anaesthesia for thoracotomy, a Preliminary data indicate that 0.01-0.5 mg/kg of fentanyl with oxygen produces no significant change in cardiovascular dynamics in patients with mitral stenosis undergoing mitral valve replacementA However, the amnesic qualities of these doses of fentanyl appear to be inferior to equi-anaesthetic doses of morphine. 4 This suggests that an amnesic supplement will be required with fentanyl for complete anaesthesia. While the addition of droperidol or nitrous oxide is known to significantly decrease myocardial contractility and cardiovascular dynamics after large doses of fentanyl, 1,5 the effects of diazepam, another popular amnesic, on myocardial mechanics and cardiovascular dynamics after fentanyl are unknown. This study was undertaken to investigate the cardiovascular effects of diazepam and of diazepam and pancuronium after 0.5 mg/kg of fentanyl in dogs. METHODSThirteen fasted, mongrel dogs of 16 kg average weight (range 12--20 kg) served as the experimental animals. Each was premedicated with atropine (0.3-0.5 rag) intramuscularly one hour before induction of anaesthesia and had an intravenous infusion of lactated Ringer's solution (10 ml/kg/hour) started in a foreleg immediately before anaesthesia. Following this anaesthesia was induced with 2 to 3 mg/kg of sodium thiopentone and each animal was then given succinylcholine 2 mg/kg intravenously. The ta'achea was intubated and the lungs were ventilated with 100 per cent oxygen at a tidal volume of 5 to 12 ml/kg with a volume limited respirator. The minute volume was adjusted as necessary to maintain Paco._, between 30 torr and 35 torr as measured in aortic blood every 15 to 30 minutes. Basal anaesthesia was maintained with thiopentone 1 to 3 mg/kg administered every 15 to 20 minutes throughout the experiment.