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Hypothermia during craniotomy not associated with CV events
24 August 2010
MedWire News: Peri-operative hypothermia does not increase the risk for cardiovascular (CV) events in patients undergoing surgery for cerebral aneurysm, study results show.
There has been concern that by increasing the activity of the sympathetic nervous system, peri-operative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage.
To address this concern, Bradley Hindman (University of Iowa, USA) and team undertook a prespecified safety analysis of the Intraoperative Hypothermia for Aneurysm Surgery trial. This was a randomized controlled trial in which 1000 patients undergoing cerebral aneurysm surgery were operated on under mild systemic hypothermia (33.3°C) or normothermia (36.7°C).
Patients in the hypothermia group were ‘rewarmed’ before endotracheal extubation, even if this required ventilation in the post-anesthesia recovery area for 2 hours, note Hindman et al in the journal Anesthesiology.
The primary safety endpoint was the rate of CV events (26 events were defined, including hypotension, arrhythmias, vasopressin use, and myocardial infarction) at 3 months.
There was no difference between the normothermia and hypothermia groups in the rate of any single CV event or in the composite endpoint. Furthermore, mortality was identical (6%) in both groups.
Most secondary endpoints were also similar between the groups, including post-operative versus pre-operative left-ventricular regional wall motion and ejection fraction.
However, normothermic patients showed a small post-operative increase in cardiac troponin-I levels whereas this parameter was unchanged in hypothermic patients (median change 0.01 vs 0.00 µg/l). This difference was statistically significant.
“We suggest that the evidence on which peri-operative temperature management standards are based should be reconsidered with regard to the risks of cardiovascular complications with mild peri-operative hypothermia,” Hindman and team conclude.
“Maintenance of peri-operative hypothermia to decrease cardiovascular complications in patients with CAD may be reasonable,” they add.
“However, in patients with low risk of CAD, our findings indicate that peri-operative hypothermia does not increase the occurrence of cardiovascular events.”
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