EFFECTS OF RAPID INCREASES OF DESFLURANE AND SEVOFLURANE TO CONCENTRATIONS OF 1.5-MAC ON SYSTEMIC VASCULAR-RESISTANCE AND CATECHOLAMINE RESPONSE DURING CARDIOPULMONARY BYPASS

Background: Airway irritation was hypothesized to trigger the transien t cardiovascular stimulation associated with desflurane. The authors a dministered desflurane during cardiopulmonary bypass (CPB), thus avoid ing airway contact, and compared the effects of rapid increases of des flurane to 1.5 MAC on systemic vascular resistance index (SVRI) and ca techolamine response to those of 1.5 MAC sevoflurane. Methods: Forty-e ight patients, undergoing elective coronary bypass surgery, were rando mly allocated to receive either desflurane or sevoflurane during hypot hermic (32-33 degrees C) nonpulsatile CPB at exhaust gas concentration s of 1.5 MAC for 15 min. SVRI was calculated at baseline, 1, 2, 3, 4, 5, 7, 9, 12, and 15 min after starting volatile anesthetics' delivery. Plasma catecholamine concentrations were determined in 12 desflurane- treated patients and 12 sevoflurane-treated patients at baseline, 5, a nd 15 min. Results: The time-course of Delta SVRI, (changes in SVRI fr om baseline), from baseline to 5 min was significantly different betwe en desflurane-and sevoflurane-treated patients, whereas there was no d ifference from 7 to 15 min. In the desflurane group, SVRI from 1 to 7 min remained unchanged to baseline level, thereafter declining to sign ificantly lower values at 9, 12, and 15 min compared with values from 0 to 5 min, whereas sevoflurane produced an immediate and significant reduction in SVRI. With desflurane, catecholamine concentrations remai ned unchanged to baseline level at 5 and 15 min; with sevoflurane, the y decreased with time. Conclusions The authors' results indicate that desflurane is associated with a different hemodynamic and catecholamin e response compared with sevoflurane when administered into the oxygen ator's gas supply line during CPB.