AB099. SOH24AB_123. Spectral entropy in the operating theatre

Background: National Institute for Health and Care Excellence (NICE) and Association of Anaesthetists of Great Britain and Ireland (AAGBI) considers depth of anaesthesia monitoring likely cost effective and of clinical benefit in patients receiving total intravenous anaesthesia (TIVA) and in patients considered at higher risk of unintended awareness or of excessively deep levels of anaesthesia.

Methods: Audit of all surgical cases performed during the week, including within a subset of older patients (age >80 years); inclusion criteria mandated the use of neuromuscular blockade (NMB) or TIVA. Each case examined for the use of entropy, the response entropy (RE) and state entropy (SE) achieved, and the average time per case RE/SE remained either above 60 or below 40.

Results: A total of 82 participants met inclusion criteria. Entropy compliance was 100% with TIVA. Entropy was used on 45% of total patients requiring NMB. The median RE/SE achieved were 39 and 37. The average percentage of time RE/SE hovered above 60 was 7.6/6.5% with a fall below 40 at 46/51%. In older patients, entropy was used on 57% of patients requiring NMB, and the average percentage of time RE/SE fell below 40 was 54/63%.

Conclusions: Our study found excellent use of entropy with TIVA. The use of entropy in older patients with concomitant NMB was appropriately higher than the general population.

Keywords: Entropy; electroencephalography; total intravenous anaesthesia (TIVA); neuromuscular blockade (NMB); general anaesthesia