Need for sedation and analgesia in patients with a history of substance misuse admitted to an intensive care unit

Background: Patients with a history of substance misuse may develop tolerance to analgesics and psychotropic drugs which alter the need for sedation and analgesia after ICU admittance. Aims: The objective was to qualify and quantify the needs for sedation and analgesia in critically ill patients with and without a history of substance misuse admitted to an intensive care unit (ICU). Design: A 2-year prospective, observational study. Methods: Patients admitted to an ICU who required sedation and analgesia for ≥72 h were included and were classified as substance misusers and non-substance misusers. We analysed demographic data and the consumption of alcohol and other substances. Comparisons between groups were made using the non-parametric Mann-Whitney test for quantitative variables and Fisher's exact test for qualitative variables. The analysis was made using SPSS version 17.0 (SPSS Inc., Chicago, IL, USA) for Windows. Statistical significance was established as p < 0·05. Results: We included 44 patients, of whom 31 (70·3%) were users of ≥1 substance. The median age was 47 years, 8 (18·2%) patients were female. The most-consumed substances were tobacco (56·8%), alcohol (54·5%), cannabis (13·6%), amphetamines (11·4%) and cocaine (9·1%). Toxicological samples were positive for alcohol (65·2%, mean blood alcohol level 1·38 ± 1·05 g/L). There were no significant differences in the need for sedation between substance misusers and non-substance misusers (p > 0·05). Conclusions: The prevalence of substance misuse in this population was high. We found no greater need for sedation in patients with a history of substance misuse although these patients often require three or more drugs to achieve optimal sedation. Relevance to clinical practice: Physicians and nurses should be aware of substance misuse in order to provide adequate care by optimizing drug administration and dosages in the ICU.