P008 Sleep in the ICU: comparing PSG & structured observation

Introduction Patients in Intensive Care Units (ICU) frequently suffer from disturbed sleep and are often prescribed sleep-promoting medications. Assessing the effectiveness of these medications in the ICU by polysomnography (PSG) is difficult due to atypical sleep EEG patterns and is intrusive for the patients. A more commonly used set of tools are structured assessments and questionnaires. The present study compared total sleep time (TST) measured by structured nurse assessment & PSG in subset of ICU patients enrolled in a larger RCT. Methods This was a prospective, single-centre, blinded, placebo-controlled, parallel-group, randomised clinical trial. A single weight and age-adjusted dose of temazepam (10-30 mg) or matching placebo was administered enterally at 21:00 hours. The primary outcome was TST between 21:00-07:00 hours by structured nurse assessment. PSG was also performed on a subgroup and the comparative results are presented here. Results Of the 56 patients randomised to temazepam (n = 28) or placebo (n = 28), five successful PSGs (3 temazepam, 2 placebo) were available for paired t-test comparison of TST determined by PSG and structured nurse assessment. The mean TST (standard deviation (SD)) was overestimated by structured nurse assessment when compared to PSG, (384 (117) vs 234.3 (33.3) minutes, t(4)2.78, p<.05). Discussion Whilst the barriers and limitations of measuring sleep in the ICU are well known, this study provides clear evidence for the value of performing these difficult EEG-based studies (PSG) on at least a subset of patients when attempting to assess sleep in the ICU, as structured assessments can over-estimate TST.