Ranitidine or dobutamine alone or combined has no effect on gastric intramucosal-arterial PCO(2) difference after cardiac surgery.

Abstract

To test the hypothesis that ranitidine, either alone or in combination with dobutamine, modifies the gastric intramucosal-arterial PCO(2) difference. Full factorial design (double-blinded for ranitidine). Intensive Care Unit of a university hospital. Sixty-four haemodynamically stable coronary artery bypass surgery patients. Ranitidine (150 mg preoperatively per os and 50 mg intravenously postoperatively) and dobutamine (4 micro g. kg(-1). min(-1) for 3 h postoperatively) were administered in four randomised groups of patients: preoperative and postoperative ranitidine, either alone (n = 15) or in combination with dobutamine (n = 17), dobutamine alone (n = 15) or neither ranitidine nor dobutamine (n = 17). Gastric intramucosal-arterial PCO(2) difference was measured during the first 5 postoperative hours. No differences in the postoperative pattern of gastric intramucosal-arterial PCO(2) difference were found among the groups. Ranitidine and dobutamine have no effect on the gastric tonometry results on intramucosal-arterial PCO(2) difference after uncomplicated cardiac surgery. Hence, the routine use of H(2)-antagonists for gastrointestinal tonometry is not warranted. Our results must be limited to results obtained by tonometry; they do not allow any conclusions on the effects of these drugs on splanchnic blood flow or its distribution.