METHODS: We conducted a multicentre prospective longitudinal cohort study in 11 Malaysian hospitals including medical/surgical patients (n = 259) who were sedated and ventilated ≥24 h. Patients were followed from ICU admission up to 28 days in ICU with 4-hourly sedation and daily delirium assessments and 180-day mortality. Deep sedation was defined as Richmond Agitation Sedation Score (RASS) ≤-3.
RESULTS: The cohort had a mean (SD) age of 53.1 (15.9) years and APACHE II score of 21.3 (8.2) with hospital and 180-day mortality of 82 (31.7%) and 110/237 (46.4%). Patients were followed for 2,657 ICU days and underwent 13,836 RASS assessments. Midazolam prescription was predominant compared to propofol, given to 241 (93%) versus 72 (28%) patients (P < 0.0001) for 966 (39.6%) versus 183 (7.5%) study days respectively. Deep sedation occurred in (182/257) 71% patients at first assessment and in 159 (61%) patients and 1,658 (59%) of all RASS assessments at 48 h. Multivariable Cox proportional hazard regression analysis adjusting for a priori assigned covariates including sedative agents, diagnosis, age, APACHE II score, operative, elective, vasopressors and dialysis showed that early deep sedation was independently associated with longer time to extubation [hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.89-0.97, P = 0.003], hospital death (HR 1.11, 95% CI 1.05-1.18, P < 0.001) and 180-day mortality (HR 1.09, 95% CI 1.04-1.15, P = 0.002), but not time to delirium (HR 0.98, P = 0.23). Delirium occurred in 114 (44%) of patients.
CONCLUSION: Irrespective of sedative choice, early deep sedation was independently associated with delayed extubation and higher mortality, and thus was a potentially modifiable risk in interventional trials.
DESIGN: Harmonized data from prospective multicenter international longitudinal cohort studies SETTING:: Diverse mix of ICUs.
PATIENTS: Critically ill patients expected to be ventilated for longer than 24 hours.
INTERVENTIONS: Richmond 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 RESULTS: Sedation 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.
CONCLUSIONS: Sedation 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.