Sleep apnea and mortality in the ICU

In the past, sleep apnea has been linked with increased rates of mortality. This makes sense, as untreated sleep apnea puts a lot of stress on the body from repeated oxygen deprivation and sleep fragmentation. The current study sought to replicate these findings, to confirm that sleep apnea does indeed increase the risk for mortality.

A team of researchers attempted this replication with the use of patients in an intensive care unit (ICU). As you may know, the ICU is usually reserved for those who have had a very severe accident or those with intense or life-threatening illnesses. The research team used this population to see whether those with sleep apnea were more likely to pass away during their stay.

Research participants in this study included all patients who had entered the ICU within a 2-year timeframe. Using existing diagnoses databases, those with sleep apnea were found, and their severity was recorded. The following variables were also extracted from the ICU database: comorbidities, ICU admission category (low-risk monitor, high-risk monitor, and active), reason of ICU admission, first ICU day Acute Physiology Score (APS), and mortality rates. Differing ICU factors were taken into account when calculating whether those with sleep apnea had worse outcomes than those without sleep apnea.

Results showed that a very high rate of all of the patients that entered the ICU had sleep apnea, either diagnosed outside of the research hospital or diagnosed in the hospital. More specifically, about 8% were diagnosed by physicians outside of the hospital, and 71% were diagnosed with sleep apnea (i.e., had more than 5 apneas per hour) by those in the hospital. Very unexpectedly, those with sleep apnea had lower mortality rates and a shorter hospital stay than those without sleep apnea.

So do these results go against everything that we know about sleep apnea? Although these results are surprising, it does not mean we have always been wrong – it simply means that we have a lot more to find out about sleep apnea. The authors of this article suggest that what may have been protective to this population was, of all things, obesity! There is a surprising “paradox” where those with excess weight tend to have increased survival rates in certain situations. It may be that nutrient stores help the body heal after injury or disease. Since we know that those with sleep apnea are more likely to be overweight, it could be that our apnea population is more overweight and therefore had “enhanced” recovery abilities. This is good news, but it certainly does not negate what we know about the negative consequences of sleep apnea, and it is still important to get treated and stay treated!

Bolona, E., Hahn, P. Y., & Afessa, B. (2015). Intensive care unit and hospital mortality in patients with obstructive sleep apnea. Journal of critical care, 30(1), 178-180.


Janna Mantua

Author

Janna is a PhD Student / Graduate Research Assistant at University of Massachusetts Amherst with a background in clinical sleep research and psychology. Janna Mantua is a PhD student in the Behavioral Neuroscience department at the University of Massachusetts. Her research focuses on sleep and aging, with specific projects on cognitive health, inflammation, memory formation, and neuroimaging. Prior to her PhD work, Janna was involved in research on sleep apnea and cognitive decline at the NYU Sleep Disorders Center.



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