Modest doses of nitroglycerin do not interfere with beef lung heparin anticoagulation in patients taking nitrates
The results of a prior clinical report suggested that nitroglycerin may interfere with the anticoagulant effect of heparin. Therefore, 30 adult patients undergoing cardiac surgery were studied in a controlled, prospective fashion. Thirteen patients on chronic nitrate therapy received an intraoperative nitroglycerin infusion at 1 micrograms/kg/min intravenously. Seventeen patients received no preoperative or intraoperative nitrates (control group). Heparin, 300 units/kg, was administered to all patients in three consecutive doses: 40 units/kg, 80 units/kg, and 180 units/kg. The activated coagulation time and activated partial thromboplastin time were measured prior to heparin, and 5 minutes after each heparin dose. There were no differences in automated activated coagulation times or in activated partial thromboplastin times between the groups at any measurement period. The study is limited in that only patients on chronic nitrates were included in the treatment group and that only a modest dose of nitroglycerin was used. However, it is concluded that a modest dose of intravenous nitroglycerin does not interfere with the anticoagulant effect of boluses of beef lung heparin in patients undergoing cardiac surgery.
Desmopressin acetate is a mild vasodilator that does not reduce blood loss in uncomplicated cardiac surgical procedures
Desmopressin acetate (DA) is a synthetic analog of vasopressin that may improve perioperative coagulation in cardiac surgical patients. Twenty-seven adult patients with good left ventricular function and normal preoperative coagulation profiles scheduled to undergo elective cardiac surgery participated in the double-blinded, placebo-controlled study. The 14 patients in the DA group received the drug over 10 minutes (starting 15 minutes after protamine administration). The 13 patients in the placebo group received an equal volume of saline. Preoperative template bleeding time was longer in the placebo group (P = 0.04). Otherwise, there were no statistically significant differences between the groups in demographics, coagulation variables, renal concentrating function, blood loss, or transfusion requirements at any study interval. The only significant hemodynamic differences detected were an increase in cardiac output in the DA group and a corresponding decrease in systemic vascular resistance. Five of 13 patients who received DA required treatment for hypotension, whereas none of 12 patients who received placebo required treatment during the infusion (P = 0.008). The authors conclude that DA causes mild vasodilation, but does not reduce blood loss or transfusion requirements in patients undergoing primary uncomplicated cardiac surgical procedures.