Bupivacaine for intercostal nerve blockade in patients on long-term beta-receptor blocking therapy.
Possible cardiovascular side effects of a local anaesthetic in patients on long-term beta-receptor blocking therapy were studied in 26 patients given postoperative intercostal nerve blockades (ICB) with 18-28 ml of plain bupivacaine 0.5% (1.30-1.82 mg kg-1). The patients had a history of hypertension and/or ischaemic heart disease and were scheduled for gall bladder surgery. Thirteen patients were randomized to a gradual preoperative withdrawal of the beta-receptor blockers and the other 13 continued the beta-receptor blockade until surgery. Cardiovascular changes were measured noninvasively and 11 patients were also monitored with pulmonary artery catheters. Blood pressure and heart rate (HR) were stable in all patients although those in whom the beta-receptor blockade was withdrawn had the highest HR and most frequent arrhythmias both before and after ICB. The ICB was associated with a decrease in the overall postoperative arrhythmia incidence, but seemed most efficient (P less than 0.02) concerning the ventricular arrhythmias in the beta-receptor-blocked patients (even including idionodal rhythm). The bupivacaine blood levels did not modify other cardiovascular changes except in one beta-receptor-blocked patient with cardiac failure in whom signs of a slight transient cardiodepression were observed. It is concluded that bupivacaine does not negatively affect cardiovascular stability in long-term beta-receptor-blocked patients. In the presence of cardiac failure, however, an additive cardiodepression may be elicited.