Anaesthesia depth study confirms safety

A 10-year, international study into anaesthetic depth has found there is no difference in mortality or complications between deep and light anaesthesia in older patients having major surgery.

The Balanced Anaesthesia Study, published in The Lancet, is positive news for anaesthetists and patients, as it gives them more confidence to target anaesthetic depth to individual patient need during surgery.

Anaesthetic depth and complications after major surgery: An international, randomised controlled trial, led by the Australian and New Zealand College of Anaesthetists (ANZCA) and involving Monash University researchers, studied patients from 73 centres in seven countries.

Monash University lead Professor Kate Leslie AO FAHMS said there had been observational studies that suggested deep anaesthesia was associated with worse outcomes than light anaesthesia, but evidence from a large randomised controlled trial was lacking.

This study randomised 6,640 patients who were aged 60 years and over, with significant co-morbidity, to deep (bispectral index = 35) or light (bispectral index = 50) general anaesthesia.

There were no significant differences in one-year mortality (7.2 per cent in the deep group versus 6.5 per cent in the light group) or any of the secondary outcomes, and there was only one case of awareness (in the light group).

“These results are great news, because we have defined a broad range of anaesthetic depth over which anaesthetists can safely titrate anaesthesia to meet the individual needs of each patient,” Professor Leslie said.