Halothane anaesthesia and suxamethonium I: the significance of preoperative atropine administration. A double-blind study

Succinylcholine, cholinoceptors and catecholamines: proposed mechanism of early adverse haemodynamic reactions

An hypothesis is proposed to account for the occurrence of adverse haemodynamic reactions to succinylcholine. Interaction of succinylcholine with cholinergic receptors is postulated to result in release of endogenous catecholamines (predominantly norepinephrine). The occurrence and the clinical manifestations of the adverse reactions would be dependent on the extent of the release. Based on literature reports of findings in experimental animals with nicotinic and muscarinic agents, a mechanism for the release of norepinephrine is outlined. Interaction of succinylcholine with muscarinic and nicotinic receptors is proposed to result in an initial activation which is followed by a phase of chemical insensitivity. Activation of the presynaptic nicotinic receptors on the postganglionic sympathetic terminals leads to a short-lasting release of norepinephrine. Activation of the presynaptic muscarinic receptors produces attenuation of the norepinephrine release. In the majority of patients these opposing actions are balanced and the net result is small, variable, and of little clinical importance. An unbalanced response leading to clinical manifestations can be expected if the two types of the presynaptic cholinoceptors are differentially activated.

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.

Routine induction of anaesthesia with thiopental and suxamethonium: apnoea without ventilation?

Changes in Paco2 and Paco2 during the induction of anaesthesia with thiopental suxamethonium, and intubation were investigated in 20 patients who received preoxygenation for 2 min, but no ventilation before intubation. Both in fit patients below the age of 60 years (Group I) and in patients above the age-several suffering from cardiopulmonary disease - (group II), Pao2 increased to about 40 kPa during preoxygenation and remained at the level during apnoea. Mean Paco2 increased to 6.3 and 5.7 kPa in Groups I and II, respectively. No complications were seen, and it is concluded that the apnoea involved in the "crash induction" technique is sage. Pulmonary aspiration of acid gastric fluid may also occur in fasting patients, and it is suggested that even in elective cases ventilation might advantageously be replaced by preoxygenation when anaesthesia is induced with thiopental and suxamethonium.

Atropine and hyoscine

The drugs atropine and hyoscine are reviewed in the context of their use by anaesthetists. The results of recent studies are stressed and guidelines given for use of these drugs in modern anaesthetic practice.

Arrhythmias during halothane anesthesia IV. The influence of a single dose of suxamethonium

The effect of a single dose of suxamethonium on cardiac rate and rhythm during halothane anesthesia with babiturate induction was studied in a prospective, triple-blind trial with 28 patients. No atropine was given and patients were not intubated. A slight but significant preponderance of sinus-bradycardia without hemodynamic consequences was found in the group given suxamethonium. Suxamethonium did not provoke ventricular ectopies or conduction disturbances. It is concluded that in anesthesia with barbiturate induction, but without atropine or intubation, the use of a single dose of suxamethonium is a safe procedure with regard to cardiac rate and rhythm.

Halothane anaesthesia ans suxamethonium II. The significance of preoperative gallamine administration

Preoperative administration of gallamine was evaluated during inhalation anaesthesia with nitrous-oxide and halothane with two administrations of suxamethonium 1 mg/kg body weight, 5 min apart. Sixty healthy patients were randomly divided into three groups and preanaesthetic gallamine, 0.3, 0.4 or 0.5 mg/kg body weight, respectively was administered intravenously 3 min before induction, according to the allocation. Just before induction of anaesthesia the patients were examined for signs and symptoms of partial curarization. After induction of anaesthesia by nitrous-oxide-oxygen-halothane, suxamethonium 1 mg/kg was given intravenously. Exactly 5 min later the same dose was repeated. ECG was monitored continuously and serum potassium, Pao2 and Paco2 were measured at appropriate intervals. It was found that none of the examined doses of gallamine gave any reliable protection against serious bradyarrhythmias after repeated doses of suxamethonium. Furthermore the higher doses of gallamine caused an unacceptably high frequency of patients with tachycardia and signs and symptoms of partial curarization.