Effect of motor subtypes of delirium in the intensive care unit on fast-track failure after cardiac surgery

Abstract

Objective: The purpose of the study was to evaluated the association between motor subtypes of postoperative delirium in the intensive care unit (ICU) and fast-track failure (a composite outcome of prolonged stay in ICU more than 48 hours, ICU readmission and 30-day mortality) after cardiac surgery. Methods: This was a secondary analysis of a prospective cohort study of 600 consecutive adults undergoing cardiac surgery at a university hospital in Hong Kong (July 2013 - July 2015). The motor subtypes of delirium were classified using the Richmond Agitation Sedation Score and Confusion Assessment Method-ICU assessments performed by trained bedside nurses. A generalized estimating equation was used to estimate a common relative risk (RR) of fast-track failure (FTF) associated with motor subtypes. Results: The incidence of hypoactive, hyperactive and mixed motor subtypes were 4.3% (n = 26), 4.0% (n = 24) and 5.5% (n = 33), respectively. Fast-track failure occurred in 88 (14.7%) patients. There was an association between delirium (all subtypes) and FTF (P = .048); hyperactive delirium (RR 1.95; 95% CI, 0.96 - 3.94), hypoactive delirium (RR 2.79; 95% CI, 1.34 - 5.84) and mixed delirium (RR 2.55; 95% CI, 1.11 - 5.88). Among the individual components of FTF, hypoactive and mixed subtypes were associated with prolonged stay in ICU (both P = .001). Conclusions: Patients with pure hypoactive delirium had a similar risk of developing FTF as other motor subtypes. Differentiation of motor subtypes is unlikely to be clinically important for prognostication of FTF but treatment strategies should address individual subtypes.