A comparative analysis of the effects of moderate vs mild hypothermia on serum neuron-specific enolase, S100β, and near-infrared spectroscopy during cardiopulmonary bypass-assisted open-heart surgery: a single-centre study.

PURPOSE: Neurological injury remains a critical concern in cardiac surgery despite advancements in surgical and anaesthetic techniques. Hypothermia is commonly utilised for neuroprotection during cardiopulmonary bypass (CPB); however, the optimal temperature range remains undetermined. This study evaluates the neuroprotective effectiveness of mild versus moderate hypothermia by assessing neuron-specific enolase (NSE) and S100β levels, near-infrared spectroscopy (NIRS) cerebral oxygenation, and cognitive function in patients undergoing CPB-assisted open-heart surgery.

METHODS: Forty elective coronary artery bypass grafting (CABG) patients were randomised to mild (32-34°C, n = 20) or moderate (28-32°C, n = 20) hypothermia groups. Serum NSE and S100β levels were measured preoperatively and at 0, 12, 24, and 48 hours postoperatively. Cerebral oxygenation via NIRS and Mini-Mental State Examination (MMSE) scores were evaluated preoperatively and at 24 and 48 hours postoperatively. This is a single-centre study. The primary outcome was the between-group difference in S100β levels at 24 and 48 hours; all other variables were predefined secondary outcomes.

RESULTS: Postoperative NSE levels increased in both groups, with no significant intergroup differences (p > 0.05). However, S100β levels were significantly lower in the moderate hypothermia group at 24 and 48 hours (p = 0.012, p = 0.004). NIRS values and MMSE scores remained comparable between groups (p > 0.05).

CONCLUSION: Our findings suggest that moderate hypothermia may offer improved neuroprotection by attenuating S100β release without adversely affecting cerebral oxygenation or cognitive outcomes. Although these results are encouraging, further validation through larger, multicentre studies is warranted before definitive conclusions can be drawn.