Desflurane improves neurologic outcome after low flow cardiopulmonary bypass in newborn pigs

Background.: Despite improvements in neonatal heart surgery, neurologic complications continue to occur from low-flow cardiopulmonary bypass (LF-CPB) and deep hypothermic circulatory arrest (DHCA). Desflurane confers neuroprotection against ischemia at normothermia and for DHCA. This study compared neurologic outcome of a desflurane-based with a fentanyl-based anesthetic for LF-CPB. Methods: Thirty piglets aged 1 week received either fentanyl-droperidol (F/D), desflurane 4.5% (Des4.5), or desflurane 9% (Des9) during surgical preparation and CPB. Arterial blood gases, glucose, heart rate, arterial pressure, brain temperature, and cerebral blood flow (laser Doppler flowmetry) were recorded. After CPB cooling (22 C brain) using pH-stat strategy, LF-CPB was performed for 150 min followed by CPB rewarming, separation from CPB, and extubation. On postoperative day 2, functional and histologic outcomes were assessed. Results: Cardiovascular variables were physiologically similar between groups before, during, and after LF-CPB. Cerebral blood flow during LF-CPB (13% of pre-CPB value) did not differ significantly between the groups. Functional disability was worse in F/D than in Des9 (P = 0.04) but not Des4.5 (P = 0.1). In neocortex, histopathologic damage was greater in F/D than in Des4.5 (P = 0.03) and Des9 (P = 0.009). In hippocampus, damage was worse in F/D than in Des9 (P = 0.01) but not Des4.5 (P = 0.08). The incidences of ventricular fibrillation during LF-CPB were 90, 60, and 10% for F/D, Des4.5 (P = 0.06), and Des9 (P = 0.0002), respectively. Conclusions: Desflurane improved neurologic outcome following LF-CPB compared with F/D in piglets, indicated by less functional disability and less histologic damage, especially with Des9. Desflurane may have produced cardiac protection, suggested by a lower incidence of ventricular fibrillation.