Normothermic systemic perfusion (35-37 °C) during cardiopulmonary bypass has been shown to lead to reduced inflammatory response in adults undergoing cardiac surgery (Birdi et al. 1999). Paediatric cardiac surgery is routinely performed under hypothermic conditions (18-28 °C). We studied the effects of cardiopulmonary bypass perfusion temperature on inflammatory (interleukins 6 and 8) and anti-inflammatory (interleukin 10) cytokine response in paediatric cardiac surgery. This cytokine release has previously been documented (Brix-Christensen, 2001) and is known to jeopardise postoperative outcome (Seghaye et al. 1993) but the link with perfusion temperature remains unclear.

Having obtained ethical approval and informed consent, 30 patients, matched for age and with similar underlying pathology, were assigned to normothermic or hypothermic (28 °C) cardiopulmonary bypass. Anaesthesia was induced with maidazolam (200 to 500 µg kg^-1) or sevoflourane and pancuronium (200 µg kg^-1) and then maintained using a fentanyl infusion of 15 µg kg^-1 h^-1. Cytokine release was assessed by measuring interleukins 6, 8 and 10 pre-, intraoperatively and up to 24 h post-operatively using an ELISA assay (Amersham Biosciences).

Cardiopulmonary bypass times were similar in the two groups as were preoperative values of all interleukins for both groups. There was a time-dependent release of IL-6 that was similar in both groups except at 24 h where the level (mean ± S.E.M.) was significantly higher in the hypothermic group (16.16 ± 5.90 vs. 5.34 ± 1.94 pg ml^-1, P = 0.049, Mann-Whitney U test). The release of interleukin 8 was higher overall in the hypothermic group, especially at 6 h after bypass where it tended towards statistical significance (22.79 ± 4.44 vs. 13.16 ± 2.65 pg ml^-1, P = 0.057). The release of interleukin 10 was no different for the two groups. Maintaining normothermia leads to less inflammatory cytokine release both intra- and post-operatively. This is likely to lead to better functional recovery post-paediatric cardiac surgery.

This work was supported by British Heart Foundation and BUPA Foundation.