Comparison of effects of three anaesthetic techniques on patients with severe pulmonary obstructive disease

Abstract

Tim PURPOSE OF this study was to compare the effects of three anaesthetic techniques when used for major abdominal surgery in a group of patients with well defined and measurable degrees of pulmonary disability. The techniques compared were (1) nitrous oxide anaesthesia with d-tubocurarine, (2) lumber epidural block supplemented with nitrous oxide, (3) nitrous oxide and diethyl ether. Arterial blood gases, pulmonary function studies and the clinical course were analyzed to define the postoperative respiratory status. METHODSAll patients were men admitted for major abdominal procedures. A singlebreath expirogram using the Vitalor~ apparatus 1,2 was taken by a trained technician. The one criterion for inclusion in this study was a maximum expiratory flow rate (MEFR) of less than 75 liters per minute which was considered indicative of a severe degree of obstructive pulmonary disease. 3,4 The test was repeated several times over a period of days to ensure uniformity of results. When MEFR was less than 75 L/rain, arterial blood sampling for PaO~, PaCO2, and pH, chest x-rays, and Ecc were done. If pulmonary infection was present, the operation was delayed and the patient was given appropriate antibiotic therapy following which the MEFR was remeasured. One of the three anaesthetic techniques was seleeted at random on the day before the operation.On the morning of the operation, patients in the curare group were premedieated with morphine and scopolamine (average doses 5.5 mg and 0.95 mg respectively) and patients in the epidural and ether groups received pentobarbital (Nembutal| and scopolamine (average doses 75.4 mg and 0.39. mg respectively). The braehial or radial arteries were cannulated using a modified Seldinger technique. ~ Anaesthesia was administered by anaesthesia residents under close supervision by one of the authors.Anaesthetic techniques: Nitrous oxide -d-tubocurarine anaesthesia 6 was induced with thiopental and d-tubocurarine and maintained with nitrous oxideoxygen( 7:3 L/rain), and repeated increments of curare. Reversal of curarization was accomplished with atropine and neostigmine and evaluated with a nerve-muscle stimulator.Epidural block to the level of the fifth thoracic dermatome was established