Study of platelet-activating factor acetylhydrolase in the perioperative period of patients undergoing cardiac surgery.

After operations with cardiopulmonary bypass, patients often show early symptoms of the systemic inflammatory response syndrome (SIRS). Potential mediators of SIRS include the platelet-activating factor (PAF), which has been linked to septic shock and multiple organ dysfunction. We studied the effect of cardiac surgery on PAF acetylhydrolase, the PAF-degrading plasma enzyme, as well as the relationship between the enzyme and the postoperative state of the patients. PAF acetylhydrolase activity decreased by 38+/-8% after instituting cardiopulmonary bypass because of plasma dilution and returned to near-preoperative levels within 6 h postsurgery. After that, enzyme levels decreased again, resulting in a 24+/-12% reduction until at least 3 days postsurgery. Patients in poor postoperative condition (Acute Physiology Score >9) had a lower preoperative PAF acetylhydrolase activity than did normal patients (12+/-4 vs. 17+/-4 nmol min(-1) mL(-1); p < .05). Likewise, patients who developed postoperative SIRS had a lower preoperative PAF acetylhydrolase activity than did patients without SIRS (12+/-3 vs. 17+/-4 nmol min(-1) mL(-1); p < .05). The data suggest that PAF acetylhydrolase deficiency is among the factors associated with postoperative distress after cardiac surgery.