Presentation of the intraoperative hypothermia for intracranial aneurysm surgery ( IHAST 2) results
Nigel Robertson
Department of Anaesthesia, Auckland City Hospital
Introduction
There are innumerable animal studies demonstrating the value of hypothermia in reducing the severity of many different neurologic insults. A major area of interest with hypothermia is neurosurgery where it has been used since 1955 and is used by ~50% of centres. However no outcome assessments have been made. This presentation will report on the results of the IHAST 2 trial
Method
The study was an international multi-centre randomised single blind study. Intra-operative hypothermia of 33°C was compared to normothermia of 36.5°C study in 1000 patients presenting with WFNS grade I - III ruptured intracranial aneurysms. The primary outcome variable was the Glasgow Outcome Score at 90 days, assessed by a blinded examiner. The hypothesis was that hypothermia would result in a 10% improvement in the incidence of GOS=1.
Result
1001 patients were randomised and outcome follow-up was completed in 1000 patients. Average age was 52 years, 65% were female. Preoperative WFNS grades were 66% grade 1, 28% grade 2 and 6% grade 3. Temperature at the time of clip application was 33.3±0.8°C in the hypothermic group and 36.7±0.5°C in the normothermic group. Good outcomes ( GOS = 1 ) were achieved in 65.9% in the hypothermic group and 62.7% in the normothermic group (difference 3.2%, non-significant) There were 29 deaths in the hypothermic group and 32 in the normothermic group. There were no differences in the incidence of peri-operative events except for a 5% vs 2.5% incidence of post-operative bacteraemia in the hypothermic group.
Conclusion
There were no indications that intra-operative cooling to a target temperature of 33°C results in any alteration in outcome compared with normothermia, using the Glasgow Outcome Score as the primary end-point.
Acknowledgements
This study was sponsored by the National Institutes of Health (USA)
Time of Presentation
Saturday 7 May 2005 - 1030-1200
References
1. Todd, Michael J et al. Mild Hypothermia During Surgery for Intracranial Aneurysm. N Engl J Med, Volume 352(2). January 13, 2005.135-145
