Effect of therapeutic hypothermia in neonates with hypoxic-ischemic encephalopathy on platelet function.

Objective: Platelet dysfunction has been described in adults during hypothermia. We sought to determine whether it also occurs in neonates. Methods: We measured bleeding times and PFA-100 (platelet function analyzer) times in 10 neonates with hypoxic-ischemic encephalopathy during and after head cooling. Results: The 10 neonates were born at 38.2 +/- 1.6 weeks' gestation (mean +/- SD), with birth weights of 3,222 +/- 746 g, pH 6.79 +/- 0.17, base excess -25 +/- 8, and 10-min Apgar 4 +/- 2. Cooling was instituted 111 min (range: 66-180) after birth and continued 72 h. Bleeding times before cooling averaged 170 s (95% CI: 100-240). These lengthened during hypothermia, averaging 410 s (p = 0.000) and shortened after rewarming (p = 0.000). PFA-100 times were similar: prolongation during cooling and normalization after rewarming. Six neonates had clinical bleeding problems in the first 24 h of cooling, but were managed successfully, and no intracranial hemorrhages were identified. Conclusion: Defective platelet plug formation occurs during therapeutic hypothermia of neonates in a manner similar to that described in adults. Platelet impairment can be severe, but rapidly improves after rewarming. Copyright (C) 2011 S. Karger AG, Basel