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The incidence of sub-optimal sedation in the ICU: a systematic review

Daniel L Jackson1*, Clare W Proudfoot2, Kimberley F Cann2 and Tim S Walsh3

Author Affiliations

1 GE Healthcare, Pollards Wood, Nightingales Lane, Chalfont St. Giles, Bucks, HP8 4SP, UK

2 Heron Evidence Development Ltd, Building 210A, Butterfield Technology and Business Park, Luton, LU2 8DL, UK

3 Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 2SA, UK

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Critical Care 2009, 13:R204  doi:10.1186/cc8212

Published: 16 December 2009



Patients in intensive care units (ICUs) are generally sedated for prolonged periods. Over-sedation and under-sedation both have negative effects on patient safety and resource use. We conducted a systematic review of the literature in order to establish the incidence of sub-optimal sedation (both over- and under-sedation) in ICUs.


We searched Medline, Embase and CINAHL (Cumulative Index to Nursing and Allied Health Literature) online literature databases from 1988 to 15 May 2008 and hand-searched conferences. English-language studies set in the ICU, in sedated adult humans on mechanical ventilation, which reported the incidence of sub-optimal sedation, were included. All abstracts were reviewed twice by two independent reviewers, with all conflicts resolved by a third reviewer, to check that they met the review inclusion criteria. Full papers of all included studies were retrieved and were again reviewed twice against inclusion criteria. Data were doubly extracted. Study aims, design, population, comparisons made, and data on the incidence of sub-optimal, optimal, over-sedation or under-sedation were extracted.


There was considerable variation between included studies in the definition of optimal sedation and in the scale or method used to assess sedation. Across all included studies, a substantial incidence of sub-optimal sedation was reported, with a greater tendency toward over-sedation.


Our review suggests that improvements in the consistent definition and measurement of sedation may improve the quality of care of patients within the ICU.