Effect of site of venous protamine administration, previously alleged risk factors, and preoperative use of aspirin on acute protamine-induced pulmonary vasoconstriction.

OBJECTIVE: To determine whether the incidence of protamine-induced pulmonary vasoconstriction (PIPV) is influenced by central venous versus peripheral venous infusion of protamine and whether aspirin ingestion within a week of surgery would decrease the incidence of PIPV. DESIGN: Single-institution, prospective, observational, randomized trial. SETTING: University teaching hospital. PARTICIPANTS: One thousand four hundred ninety-seven consecutive patients undergoing cardiopulmonary bypass procedures. INTERVENTION: Protamine neutralization of heparin by infusion pump via either central venous or peripheral venous route. MEASUREMENTS AND MAIN RESULTS: Five previously suspected risk factors (valve surgery, prior protamine exposure, history of pulmonary hypertension, fish allergy, and vasectomy), aspirin ingestion within 7 days of surgery, and demographic information were recorded. PIPV was defined as an abrupt increase in mean PA pressure of 7 mmHg or more with associated right ventricular dysfunction as assessed by observation of the right ventricle in the field and regional wall motion abnormality by transesophageal echocardiogram and hypotension (systolic blood pressure < or = 90 mmHg). Data were collected via continuous strip chart recording. A total of 10 patients (0.6%) developed PIPV during protamine infusion. The incidents were similar with respect to the site of venous administration. Prior exposure to protamine was associated with a greater incidence of PIPV (odds ratio 6.9; p < 0.01). Other previously suspected risk factors did not achieve statistical significance. None of the 766 patients who ingested aspirin experienced PIPV as opposed to 10 of the 731 patients who did not ingest aspirin (odds ratio 0.08; p < 0.001). CONCLUSIONS: Although the site of venous protamine administration does not influence incidence of PIPV, aspirin ingestion within 1 week of surgery may decrease it. These data also confirmed other studies suggesting that previous protamine administration predisposes to this protamine reaction.

Comparison of thermodilution bolus cardiac output and Doppler cardiac output in the early post-cardiopulmonary bypass period.

OBJECTIVE: To evaluate the accuracy of measuring cardiac output (CO) in the early post-cardiopulmonary bypass (CPB) period by comparing thermodilution with Doppler methods. DESIGN: Prospective and blinded human trial. SETTING: Academic medical center. PARTICIPANTS: Thirty adult patients undergoing elective coronary artery bypass graft surgery. MEASUREMENTS AND MAIN RESULTS: Thermodilution CO (TCO) was obtained in triplicate. Doppler CO (DCO) in triplicate was obtained at the left ventricular outflow tract (LVOT), aortic valve (AV), and right ventricular outflow tract (RVOT). CO measurements were made (1). before CPB (baseline), (2). immediately after CPB, (3).15 minutes after CPB, and (4). 30 minutes after CPB. Before CPB, the DCO at LVOT, RVOT, and AV showed good correlations (r = 0.87, r = 0.88, and r = 0.84, respectively) with TCO. Bias analysis showed no significant difference among TCO and 3 DCOs (p > 0.05 each). Correlation between DCO and TCO decreased but remained significant after CPB (r between 0.57 and 0.85, p < 0.001). The bias among TCO and each of the DCOs at the LVOT, RVOT, and AV increased immediately after CPB (p < 0.01, p < 0.01, and p < 0.05, respectively) and remained significant at 15 minutes and 30 minutes post-CPB except for DCO at the AV. TCO exceeded DCO by 0.44 to 0.72 L/min immediately after CPB. The CO measured by both thermodilution and Doppler methods gradually decreased over time post-CPB. The decrease in CO was significant at 30 minutes post-CPB (p < 0.01). CONCLUSION: This study adds further support that DCO is a clinically acceptable method to accurately assess the CO in patients even during periods of uneven regional body temperatures as may occur in the early post-CPB period.