Abstract
Perhaps including a larger number of patients, a sicker group of patients (ie, those with an American Society of Anesthesiologists physical status of 4), or more accurate bispectral index (BIS) targeting could produce a different result, but it is probable that this difference would shrink towards clinical irrelevance. [...]we have planned a secondary analysis of our data to investigate further relationships between anaesthetic depth, anaesthetic agent sensitivity, and blood pressure (ie, the triple low state), and the effect of these factors on mortality. The targets chosen were close to the first and third quartiles for mean BIS recorded in an audit of a large tertiary hospital's anaesthetic database.2 We appreciate Philip E Vlisides and colleagues' suggestions; however, we did not age-adjust our volatile anaesthetic doses because such an adjustment is made by use of pooled population data derived from a small number of individuals, has wide CIs, and could confound any statistical treatment.