Abstract & Commentary
Let There be Light — In the ICU!
By Linda L. Chlan, RN, PhD, School of Nursing, University of Minnesota, is Associate Editor for Critical Care Alert.
Dr. Chlan reports that she receives grant/research support from the National Institutes of Health.
Synopsis: While national guidelines direct new critical care units to ensure natural lighting, the results of this study did not find any association with greater ambient light levels and better patient outcomes, suggesting further work is needed in this area.
Source: Verceles AC, et al. Ambient light levels and critical care outcomes. J Crit Care 2012; Jul 2. [Epub ahead of print.]
The purpose of this study was to measure light levels in patient rooms, and also to determine if there were any relationships between greater light levels and mortality, length of stay, ventilator-free days, and amount of medication. A retrospective, observational design was used to evaluate 3799 consecutive first- and single-patient admissions to the medical intensive care unit (MICU) at the University of Maryland Medical Center from April 2006 to June 2009. The MICU is a 29-bed, closed unit with 24/7 intensivist staffing. Of note, the MICU did not have any protocols in place for environmental regulation (noise, light, interactions with patients) or designated quiet-time hours during the conduct of the study. Each patient room contained a window with retractable shades to allow entry of ambient light. Light measurements were obtained using the Actitrac actigraph/luxmeter (IM Systems, Baltimore, MD) for 10-minute periods between 1100 and 1330 to coincide with solar noon. Patient rooms were categorized based on their orientation: north, south, east, west. Patient data were abstracted from the hospital's electronic medical record and administrative record systems. The primary study outcome was MICU length of stay. Secondary outcomes were in-hospital and MICU mortality, 28-day ICU-free days, 28-day ventilator-free days, and medications received (percent of patients receiving sedative and opioid medications and dose received). Patient variables were also assessed, including Charlson co-morbidity index, Case Mix Index, age, gender, and race; none of these were significantly different based on light levels or room orientation.
South-facing rooms were found to receive the highest level of light and also had the widest range of light exposure. There were no significant differences reported between room orientation and any of the patient outcomes. The only difference in medications received was in the south-facing rooms where patients received a 25 mcg higher median daily dose of fentanyl. The results of this study did not support the researchers' hypothesis that room orientations with higher-intensity light levels would be associated with better patient outcomes.
Commentary
For several years, design requirements have been in existence that stipulate ICU patient rooms need to have direct, ambient light. However, there is no agreement as to what constitutes "healthy" light levels for ICU patients. The findings from Verceles and colleagues further add to this conundrum, as the results from this study do not add any strong evidence in support of these design recommendations: Higher levels of light did not lead to any positive patient outcomes. Clearly, additional research is needed in this area using accurate measurements of light levels and salient patient outcomes. Levels of ambient light are only one aspect of the environmental milieu requiring careful attention for ICU patient healing and beneficial, salient outcomes.
While this was not part of the design or aims of the study conducted by Verceles et al, it is not known how alert patients were, if patients were even awake, or if patients were aware of light levels in their room during the study light measurement periods. Likewise, we do not know what the night-time environment was like in the MICU over the lengthy study period, and how that may have contributed to the reported outcomes. As articulated by the researchers, activity and noise levels were not reported or accounted for in this study nor were there any environmental enhancements in place in the form of protocols during the study period. Activity regulation and noise reduction strategies may be equally important when designing studies on environmental manipulation for promoting positive outcomes for ICU patients. Natural, ambient light may be important, but probably is not the only essential component for promoting a healing milieu in the ICU.
The purpose of this study was to measure light levels in patient rooms, and also to determine if there were any relationships between greater light levels and mortality, length of stay, ventilator-free days, and amount of medication.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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