• Yahya Shehabi, Rinaldo Bellomo, Suhaini Kadiman, Ti Lian Kah LK Yong Loo Lin School of Medicine, National University of Singapore, National University Hospital, Singapore., Belinda Howe, Michael C Reade, Tien Meng Khoo, Anita Alias, Yu-Lin Wong, Amartya Mukhopadhyay, Colin McArthur, Ian Seppelt, Steven A Webb, Maja Green, Michael J Bailey, and Sedation Practice in Intensive Care Evaluation (SPICE) Study Investigators and the Australian and New Zealand Intensive Care Society Clinical Trials Group.
• Critical Care and Perioperative Services, Monash University and Monash Health, Melbourne, VIC, Australia.
• Crit. Care Med. 2018 Jun 1; 46 (6): 850-859.

ObjectivesIn the absence of a universal definition of light or deep sedation, the level of sedation that conveys favorable outcomes is unknown. We quantified the relationship between escalating intensity of sedation in the first 48 hours of mechanical ventilation and 180-day survival, time to extubation, and delirium.DesignHarmonized data from prospective multicenter international longitudinal cohort studies SETTING:: Diverse mix of ICUs.PatientsCritically ill patients expected to be ventilated for longer than 24 hours.InterventionsRichmond Agitation Sedation Scale and pain were assessed every 4 hours. Delirium and mobilization were assessed daily using the Confusion Assessment Method of ICU and a standardized mobility assessment, respectively.Measurements And Main ResultsSedation intensity was assessed using a Sedation Index, calculated as the sum of negative Richmond Agitation Sedation Scale measurements divided by the total number of assessments. We used multivariable Cox proportional hazard models to adjust for relevant covariates. We performed subgroup and sensitivity analysis accounting for immortal time bias using the same variables within 120 and 168 hours. The main outcome was 180-day survival. We assessed 703 patients in 42 ICUs with a mean (SD) Acute Physiology and Chronic Health Evaluation II score of 22.2 (8.5) with 180-day mortality of 32.3% (227). The median (interquartile range) ventilation time was 4.54 days (2.47-8.43 d). Delirium occurred in 273 (38.8%) of patients. Sedation intensity, in an escalating dose-dependent relationship, independently predicted increased risk of death (hazard ratio [95% CI], 1.29 [1.15-1.46]; p < 0.001, delirium hazard ratio [95% CI], 1.25 [1.10-1.43]), p value equals to 0.001 and reduced chance of early extubation hazard ratio (95% CI) 0.80 (0.73-0.87), p value of less than 0.001. Agitation level independently predicted subsequent delirium hazard ratio [95% CI], of 1.25 (1.04-1.49), p value equals to 0.02. Delirium or mobilization episodes within 168 hours, adjusted for sedation intensity, were not associated with survival.ConclusionsSedation intensity independently, in an ascending relationship, predicted increased risk of death, delirium, and delayed time to extubation. These observations suggest that keeping sedation level equivalent to a Richmond Agitation Sedation Scale 0 is a clinically desirable goal.

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