Five different non-depolarizing muscle relaxants and a control solution of saline were studied as precurarization agents. Two hundred and twenty-two surgical patients (ASA I-II) were allocated in a double-blind fashion to one of the following groups: d-tubocurarine 0.05 mg/kg, alcuronium 0.03 mg/kg, pancuronium 0.01 mg/kg, gallamine 0.25 mg/kg, ORG NC-45 (vecuronium) 0.01 mg/kg and saline solution 0.005 ml/kg. Pretreatment was performed 4 min before administering a 1.5 mg/kg bolus of succinylcholine (SCh). Fasciculations, intubation conditions, duration of neuromuscular blockade after SCh, serum potassium changes and postoperative myalgias (in 60 patients) were recorded. All the drugs studied prevented fasciculations significantly (P less than 0.05) more than in the control group. d-Tubocurarine and alcuronium were superior to the others in this respect. Intubation conditions were best in the control and pancuronium groups, but there was no significant difference between the pancuronium and d-tubocurarine or between the d-tubocurarine and alcuronium groups. Pancuronium pretreatment prolonged the SCh block significantly, whereas other agents shortened the duration of the SCh block. The antagonism of the SCh block apparently also affected intubation conditions, although intubation remained satisfactory. A statistically significant rise in serum potassium level was measured only in the control and pancuronium groups. In the control and pancuronium groups, four patients out of 10 had postoperative myalgias, whereas in the other groups only one or none out of 10 had them (0/10 vs. 4/10; 0.10 greater than P greater than 0.05). In conclusion, d-tubocurarine and alcuronium seem to have advantages over pancuronium, ORG NC-45 and gallamine for precurarization.

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Cardiac arrhythmias occur frequently during and after intubation. Since the report of REID and BRACE (1940)', articles on such arrhythmias have been published widely in the literature, and the causes and significance of these changes have been considered. BURSTEIN et al. (1950)* reported electrocardiographic changes during endotracheal intubation in 68% of their cases. Also KING et al. (1951y and WYCOFF (1960p described circulatory changes during intubation. The influence of vagal stimulation and hypoxia was studied by JACOBY et al. (1955)4.The effects of thiopental induction on the electrocardiogram have been studied by ROSNER et al. (1953)8 and many others, whereas propanidid has been studied much less in this respect. RADNEY (1965)" described tachycardia in 90% after propanidid induction. Also topical cocainization of the larynx has been shown to increase cardiac disorders (ARCURI et al. (1953))'.The purpose of this study was to compare the effect of thiopental and propanidid induction on the electrocardiogram. MATERIAL A N D METHODSThe series consisted of 277 patients scheduled for different kinds of operations, 83 males and 194 females (table 1). Six patients were under 20 years of age, and 55 over 60. Routine pre-operative examinations, including chest radiography and electrocardiography, were performed in all cases.The premedication consisted of 10 mg morphine and 0.3-0.4 mg scopolamine. Some patients were given 50-75 mg pethidine.Induction was accomplished with injection of thiopental or propanidid. The dose of thiopental was 3-8 mg/kg; that of propanidid varied between 300 and 500 mg. The rate of injection was 0.2-1.4 mg/kg/sec. for thiopental,