Cardiac effects of atropine and gallamine in patients receiving suxamethonium

Bradycardia and cardiac asystole following a single injection of suxamethonium

Twenty cases of severe bradycardia, including 12 cases of cardiac asystole, following administration of a single dose of suxamethonium to 17 adult patients are presented. Treatment consisted of i.v. atropine in 16 cases, and in four cases external cardiac massage or a precordial thump was also given. Remission was complete in all cases. The mechanism is not known, but it is suggested that i.v. administration of fentanyl at induction may enhance the tendency to bradycardia following suxamethonium. Absence of preoperative atropine may also be of importance.

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.

The heart rate response to succinylcholine in children: a comparison of atropine and glycopyrrolate

To determine whether intravenous atropine and glycopyrrolate are equally effective in preventing succinylcholine-induced heart rate changes, we studied the heart rate during the first 78 seconds of anaesthesia in 40 children anaesthetized with either thiopentone, atropine (0.02 mg X kg-1) and succinylcholine (2 mg X kg-1), or thiopentone, glycopyrrolate (0.01 mg X kg-1) and succinylcholine (2 mg X kg-1). Each treatment group was divided into four subgroups which differed only in the interval (6, 10, 15, 20 seconds) between injection of atropine or glycopyrrolate and succinylcholine. During the 54 seconds after succinylcholine, the mean heart rate of each subgroup decreased transiently and then returned to the pre-induction heart rate or higher. There was no difference in either the magnitude or the duration of the decrease in heart rate or the subsequent increase in heart rate between respective subgroups. Bradycardia occurred in only two patients, both of whom received glycopyrrolate. We conclude that atropine (0.02 mg X kg-1) and glycopyrrolate (0.01 mg X kg-1) are equally effective in attenuating succinylcholine-induced changes in heart rate in children.

Cardiac effects of self-taming of succinylcholine and repeated succinylcholine administration

Pretreatment with small (10 mg) doses of succinylcholine ("self-taming") decreases the incidence of muscle fasciculations following succinylcholine administration and may decrease the incidence of other unwanted effects. This study was designed to assess the cardiac effects of such self-taming and to assess the degree of protection afforded against bradydysrhythmias following subsequent succinylcholine administration. Sixty patients were studied and allocated randomly to three groups of twenty. Each group was assigned a different form of pretreatment. Patients in group I received 10 mg of succinylcholine immediately after induction. Patients in group II were treated with d-tubocurarine 0.04k mg . kg-1 three minutes before induction. Patients in group III received no pretreatment. All patients were induced with thiopentone 4 mg . kg-1 followed by succinylcholine 1 mg . kg-1 45 seconds later. A second dose of succinylcholine 1 mg . kg-1 was administered to the patients in the two pretreatment groups between four and five minutes after the first dose of succinylcholine. Following both the first and second doses of succinylcholine patients in the self-taming group showed a significantly greater incidence of bradydysrhythmias when compared to the other two groups. It is concluded that the use of a self-taming technique is potentially hazardous, and that it does not confer protection against repeated succinylcholine administration.

Effect of atropine on bradydysrhythmias induced by succinylcholine following pretreatment with D-tubocurarine

This study was designed to compare the effectiveness of pretreatment with the combination of d-tubocurarine and atropine with d-tubocurarine alone in preventing changes in cardiac rate and rhythm following repeated administration of succinylcholine. Sixty subjects were randomly divided into three groups of twenty. Group one received d-tubocurarine 0.04 mg.kg-1 and atropine 0.01 mg.kg-1, and group two d-tubocurarine 0.04 mg.kg-1 only, given three minutes before induction of anaesthesia. Group three received no pretreatment. Immediately following thiopentone induction succinylcholine 1 mg.kg-1 was given to all patients. A further dose of succinylcholine 1 mg.kg-1 was given to patients in the pretreatment groups following recovery of neuro-muscular function. Both pretreatment groups showed a small statistically significant fall in mean heart rate after the second dose of succinylcholine. One patient in each pretreatment group showed a fall in heart rate to less than 50 beats min-1; two patients in the group who received both d-tubocurarine and atropine, and three patients in the d-tubocurarine only group, showed a fall in heart rate of 25 per cent or more. It is concluded that the addition of atropine may be unnecessary for prevention of succinylcholine-induced bradydysrhythmias when d-tubocurarine pretreatment is given.