Pre-operative forced-air warming as a method of anxiolysis

We tested the hypothesis that pre-operative forced-air warming is as effective for anxiolysis as intravenous midazolam, using a blinded, placebo controlled factorial design. One hundred and twenty patients were randomly assigned to cotton blanket and saline injection (n = 30), forced-air warmer and saline injection (n = 30), midazolam 30 microg x kg(-1) and cotton blanket (n = 30), and forced-air warmer and midazolam 30 microg x kg(-1) (n = 30). Patients completed visual analogue scales for anxiety and thermal comfort, and the State-Trait Anxiety Inventory, at baseline and after 20 min. The estimated effect of midazolam on visual analogue scores for anxiety was -10 (95% CI -3 to -18; p = 0.007) and on state anxiety was -5 (95% CI -7 to -4; p = 0.03). Warming had no influence on visual analogue scores for anxiety (p = 0.50) or state anxiety (p = 0.33), but its estimated effect on thermal comfort was +23 (95% CI 19-27; p < 0.0001). There was no interaction between midazolam and warming. Pre-operative warming was not equivalent to midazolam for anxiolysis and cannot be recommended solely for this purpose.