Changes in free and total catecholamine concentrations in plasma in patients undergoing coronary artery bypass...

We measured free and total catecholamine in ten patients undergoing coronary artery-bypass grafting under high-dose fentanyl (93.9 +/- 2.2 microg.kg(-1), mean +/- SE) anesthesia. Arterial blood samples were obtained: 1) before induction of anesthesia (control), 2) 1 min after intubation, 3) 1 min after skin incision, 4) 1 min after median sternotomy and, 5) just before termination of cardiopulmonary bypass (CPB). The concentrations of free and total catecholamine were measured by HPLC using fully automated analyzer, 8030-TOHSO. Free and total catecholamine concentrations did not change significantly before CPB. At the termination of CPB, however, the levels in free dopamine, norepinephrine and epinephrine all increased several fold as compared with control. Similarly, total norepinephrine and epinephrine also increased at the end of PCB, while total dopamine did not change. Present results indicated that 1) the measurement of free CAs is more significant than the measurement of total CAs for the assessment of sympathoadrenal responses to surgical stimuli, and that 2) high-doses of fentanyl produce hemodynamic stability by suppressing sympathoadrenal responses elicited by the usual surgical procedures. However, stress triggered by CPB could not be suppressed totally by fentanyl even with high dose.