INCREASED PLASMA-CONCENTRATIONS OF SERUM AMYLOID-A - AN INDICATOR OF THE ACUTE-PHASE RESPONSE AFTER CARDIOPULMONARY BYPASS

Objectives: To assess the expression of mixed and hepatic venous serum amyloid A (SAA) concentrations and its relationship to plasma concent rations of C-reactive protein, interleukin-6 (IL-6), and endotoxin dur ing and after cardiopulmonary bypass (CPB). Design: Prospective, conse cutive sample with repeated measurements. Setting: Surgical intensive care unit (ICU) in a university hospital. Patients: Twenty patients wh o underwent elective coronary bypass grafting. Interventions: A radial artery catheter, pulmonary artery catheter, and right hepatic vein ca theter were inserted. Blood samples were collected to determine the di fferent mediators, lactate concentrations, and oxygen saturations. Mea surements and Main Results: After induction of anesthesia, baseline va lues were obtained and the following parameters were determined 20 min s after onset of CPB, 20 mins after termination of CPB, at admission t o the ICU, and 6, 8, 12, and 24 hrs later: hemodynamics, body core tem perature, hepatic venous oxygen saturation, and mixed and hepatic Veno us lactate, endotoxin, interleukin (IL)-6, C-reactive protein (CRP), a nd SAA concentrations. Endotoxin and IL 6 plasma concentrations increa sed during CPB, peaked 6 hrs after admission to the ICU (endotoxin: 23 .1 +/- 6.2 pg/mL; IL-6: 646 +/- 104 pg/mL), and decreased thereafter; SAA and CRP concentrations began to increase after 6 and 8 hrs, respec tively, with the highest concentrations reached 24 hrs postoperatively (CRP: 14 +/- 3.6 mg/L; SAA: 668 +/- 114 mu g/mL). Lactate concentrati ons began to increase 20 mins after CPB, and continued to increase unt il 12 hrs postoperatively. There were no significant differences betwe en mixed and hepatic venous values of endotoxin, IL-6, CRP, SAA, and l actate (p <.05). Body core temperature, which was <37.5 degrees C befo re surgery for all patients, increased 6 hrs after admission to the IC U and peaked 12 hrs postoperatively (38.3 +/- 1.1 degrees C). Hepatic venous oxygen saturation did not change. Correlations were obtained be tween IL-6 values and heart rate (r(2) =.20; p <.005), and endotoxin c oncentrations and systemic vascular resistance (r(2) =.18; p<.001). Bo dy core temperature correlated significantly closer with SAA (r(2) =.5 2; p <.0001) values than with IL-6 (r(2) =.27; p <.0001) or CRP (r(2) =.16; p <.001) values (p <.05). Conclusions: SAA is an additional and sensitive marker of the acute-phase response following CPB; the increa se in SAA concentrations parallels the temporary increase in body core temperature and is preceded by endotoxemia and IL-6 secretion.