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Canadian Journal of Anesthesia, Vol 32, 435-448, Copyright © 1985 by Canadian Anesthesiologists' Society

Anaesthetic Implications of Calcium Channel Blockers

LEONARD C. JENKINS BA MD CM FRCPC1 and PETER J. SCOATES BSC MD FRCPC1

1 Department of Anaesthesia, Faculty of Medicine, University of British Columbia, Vancouver General Hospital and Royal Columbian Hospital, Vancouver, British Columbia

Address correspondence to: Dr. Leonard C. Jenkins, Department of Anaesthesia, University of British Columbia, Room 3200, 910 West 10th Avenue, Vancouver, British Columbia V5Z 4E3

Clinical uses of calcium channel blockers are expanding. In addition to the established uses in patients with arrhythmias, angina pectoris or hypertension, newer and to some extent investigational uses indicate widespread application. For instance, their use has been reported in hypertrophic cardiomyopathy and cold cardioplegia, as well as in pulmonary hypertension, antiplatelet therapy, asthma, achalasia and oesophageal spasm, increased intraocular pressure and in cerebral vasospasm. Their use in obstetrical practice has been proposed.

Thus, the presentation of a patient who is treated with calcium channel blockers and who requires anaesthesia will become more common.

Calcium channel blockers may, under certain cirumstances, potentiate haemodynamic and MAC depressive effects of inhalation agents. There is also evidence that the effects of neuromuscular blocking agents may be potentiated. The anaesthetist should be aware that the potential for interactions exists with digoxin, propranolol, quinidine, theophylline or dantrolene.

Of interest and some significance are the anaesthetic implications of pathophysiological alterations that can be induced by calcium channel blockers, by affecting lower oesophageal tone, intracranial hypertension, bronchomotor tone (asthma), muscular dystrophy, neuromuscular function, hypoxic pulmonary vasoconstriction, malignant hyperthermia, inhibition of platelet aggregation and hyperkalemia.

Despite these significant potential anaesthetic implications and because, at this time, in some instances withdrawal has clearly demonstrated increase in the signs of myocardial ischaemia, it would not seem necessary to recommend preoperative discontinuation of calcium channel blocker medication in patients presenting for anaesthesia. It is, however, appropriate that there is a high index of awareness of potential problems, unless there is some modification in inhalation anaesthetic concentrations and neuromuscular blocker dosage. Monitoring of cardiovascular and neuromuscular functions is essential.

Calcium channel blockers would appear to be currently the drugs of choice for angina pectoris, arrhythmias or hypertension in patients with associated chronic obstructive pulmonary disease.






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Copyright © 1985 by the Canadian Anesthesiologists' Society.