Histamine antagonists and d-tubocurarine-induced hypotension in cardiac surgical patients

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Abstract
Hemodynamic effects and histamine release by bolus injection of 0.35 mg/kg of d-tubocurarine were studied in 24 patients. H1- and H2-histamine antagonists or placebo were given before during with d-tubocurarine in a randomzied double-blind fashion to four groups: group 1.sbd.placebo; group 2.sbd.cimetidine, 4 mg/kg, plus placebo; group 3.sbd.chlorpheniramine, 0.1 mg/kg, plus placebo; and group 4.sbd.cimetidine plus chlorpheniramine. Histamine release occurred in most patients, the highest level 2 minutes after d-tubocurarine dosing. Group 1 had a moderate negative correlation between plasma histamine change and systemic vascular resistance (r = 0.58; P < 0.05) not present in group 4. Prior dosing with antagonists partially prevented the fall in systemic vascular resistance. These data demonstrate that the hemodynamic changes associated with d-tubocurarine dosing are only partially explained by histamine release. Thus prior dosing with H1- and H2-antagonists provides only partial protection.