Purpose: Postoperative delirium constitutes a range of neuropsychological disturbances with incidence of up to 57% of cardiac surgery patients. Lack of natural daylight exposure in the intensive-care setting induces a circadian rhythm disturbance, which may result in delirium. We evaluated the effect of lack of daylight exposure on the prevalence, intensity, and duration of postoperative delirium.
Methods: Altogether, 942 patients were enrolled and constituted 2 groups: (i) Group D (Dark) of 485 patients, operated from October 10, 2010, to October 30, 2011, while the cardiac surgery department resided in the hospital’s underground floor, with no daylight exposure; (ii) Group L (Light) of 457 patients, operated from November 1, 2011, to October 1, 2012, while the department resided on the hospital’s 6th floor, with normal daylight exposure. The prevalence, intensity, and duration of delirium were retrospectively assessed by means of (i) haloperidol prescribed [yes/no]; (ii) its amount [mg]; and (iii) administration length [days], respectively.
Results: During both periods, 190 patients developed delirium, of whom 88 (19.2%) were from group L and 102 (21%) patients from group D (P=NS). The average haloperidol dose was larger in group D both in males (19.1±19.1 vs. 13.6±3.5; P=0.021) and females (19.0±14.4 vs. 10.5±3.9, P=0.004). The average postoperative length of stay was longer in group D (15.4±11.9 vs. 13.6±6.9 days; P=0.003). Among females, delirium in group D lasted longer (3.7±4.2 vs. 2.4±3.9 days; P=0.028).
Conclusions: Without daylight exposure: (i) females and males experienced more intense delirium; (ii) females and males were hospitalized for a longer duration; and (iii) females also suffered of longer delirium. These findings emphasize the importance of daylight exposure for maintaining circadian rhythm and thus reducing the risk of developing postoperative delirium among cardiac patients.
