Cardiovascular effects of nondepolarizing relaxants employed for pretreatment prior to succinylcholine.

A pregnant woman with severe pre-eclampsia experienced a hypertensive crisis following a pretreatment dose (20 mg) of gallamine. That episode initiated a study to determine the cardiovascular effects of non-depolarizing muscle relaxants in 58 nonobese, ASA physical status I and II adults. Subjects were assigned randomly to one of five treatment groups as follows: gallamine (0.29 mg X kg-1), d-tubocurarine (0.04 mg X kg-1), metocurine (0.014 mg X kg-1), pancuronium (0.007 mg X kg-1), or normal saline (control). Baseline measurements of systolic, diastolic, mean arterial pressure, heart rate (HR) and rate pressure product (calculated RPP) were recorded at one-minute intervals while electrocardiogram, lead II, was recorded continuously. Statistically significant increases occurred in HR at minutes 2, 3 and 4; RPP at minutes 3 and 4; and per cent change in HR at minutes 2, 3 and 4 following gallamine pretreatment. The rise in RPP was predominantly due to the elevation in HR. These results suggest that even modest doses of gallamine should be avoided in clinical situations where lability of cardiovascular dynamics can be anticipated.