The rewarming index formula for pediatric cardiopulmonary perfusion.

Careful rewarming of perfusion blood following cardiopulmonary bypass surgery is critical to a successful outcome, but the optimal rewarming strategy is not clear. The purpose of this study was to derive a formula for a rewarming index (defined as [rewarming time x perfusion flow]/[body weight x body surface area]) that would enable the calculation of the ideal rewarming conditions for pediatric cardiopulmonary perfusion. We retrospectively investigated 220 pediatric cardiopulmonary bypass operations conducted from July 2005 to June 2008 in Okayama University Hospital, Japan. We determined the formula as Phi = (T x Q)/(R x S) = |0.9127P - 0.0152|, where Phi = rewarming index, T = rewarming time (min), Q = perfusion volume (L), R = body weight (kg), S = body surface area (m(2)), and P = temperature gap (right angle). The formula will help those who perform pediatric cardiopulmonary bypass surgery to establish ideal perfusion flow conditions and to control physiological temperature during rewarming.