Plasma propranolol before, during, and after cardiopulmonary bypass

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Abstract
Changes in propranolol plasma levels before, during and after cardiopulmonary bypass (CPB) were evaluated. Patients [2 groups] were studied, all of whom had been on long-term propranolol and had received their last oral dose 10-15 h before surgery. Approximately 100 min before CPB began, group I patients (n = 7) received 0.1 mg/kg propranolol i.v. while group II patients (n = 7) received a placebo. Before CPB the plasma propranolol levels fell in accordance with published descriptions for nonsurgical patients receiving oral and i.v. propranolol. Thereafter, the changes in the plasma levels were similar in both groups. With the onset of CPB the plasma levels decreased by .apprx. 50%. There was an insignificant fall in plasma levels during CPB. In each patient the plasma levels obtained 5, 60, 120 and 240 min after CPB were higher than the last level during CPB. Mean plasma levels did not decline in either group during the 4-h period. The sustained rise in the propranolol levels after CPB may be due to the redistribution of propranolol from the lungs to the plasma coupled with reduction in hepatic elimination.