Authors of a new paper raise concerns about using polysomnography in the ICU and call for more research into how to interpret sleep study results.

Researchers from Denmark recently reviewed observational studies and case series of sleep quality and circadian rhythm disruption in patients in the intensive care unit (ICU), including how sleep quality correlates with the severity of critical illness. The study, published in the journal Nature and Science Sleep, concludes that polysomnography (PSG) is challenging in the ICU and that there are no validated methods of sleep scoring for this patient population. Furthermore, the authors note that more research needs to be done to find better testing methods and develop interventions to provide patients with better sleep quality in the ICU.

“Sleep disturbance in critically ill patients is a significant problem,” says Yuliya Boyko, MD, PhD, a student at Odense University Hospital and an author of the study. “Sleep disturbances in the ICU have recently been getting more attention among intensivists due to potential association between disturbed sleep and delirium.” But, Boyko says, knowledge is scarce due to the challenges of sleep monitoring and analysis in critically ill patients.

The study’s main takeaways are that there are currently no validated methods of scoring sleep for the ICU patient population, which keeps sleep clinicians from being able to intervene with sleep-promoting strategies, and that the use of PSG has proven to be a challenge in the ICU. This is in part because most critically ill patients have abnormal hypograms (high arousal index, abnormal sleep stage shifts, etc) that do not fall into the American Academy of Sleep Medicine’s standard scoring patterns. This, according to Boyko, calls for more research into the best ways to assess this patient population. “There is a need of validating sleep scoring methods for scoring polysomnographic sleep studies in this patient population,” she says. “Further research in the pathophysiology of sleep disturbances in ICU with subsequent assessment of therapeutic strategies in large controlled studies is required.”

The authors also provide other vital criteria that play a role in the patient’s quality of sleep. According to their review, sleep-disturbing environmental factors like sound, light, and interruptions disrupt the patient’s sleep. Another issue they cite is mechanical ventilation; the authors state this is “mainly due to patient–ventilator asynchrony and hyper-assistance resulting in central apneas.”

Sedative agents, such as propofol, opioids, and benzodiazepines were also found to negatively impact the ICU patient’s quality of sleep; propofol and benzodiazepines were found to reduce REM sleep. The process of melatonin secretion can also make or break a patient’s sleep patterns, according to the study.

As far as clinical implications are concerned, it seems that with more proper assessment tools of sleep quality in this patient population would come more effective means of intervention that eventually would lead to more efficient therapeutic options. “Further research in this field would give a better understanding of the pathophysiological mechanisms of disturbed sleep and, consequently, lead to some therapeutic solutions,” says Boyko. “As sleep disruption might be associated with unfavorable outcome in critically ill patients, evaluation of sleep patterns could have some prognostic value.”

Dillon Stickle is associate editor for Sleep Review.