A High Risk of Sleep Apnea Is Associated With Less Postoperative Cognitive Dysfunction After Intravenous Anesthesia

Results of an Observational Pilot Study

Soeren Wagner; Joerg Quente; Sven Staedtler; Katharina Koch; Tanja Richter-Schmidinger; Johannes Kornhuber; Harald Ihmsen; Juergen Schuettler

Disclosures

BMC Anesthesiol. 2018;18(139) 

In This Article

Background

The Obstructive Sleep Apnea Syndrome (OSAS) is the most common type of sleep apnea disorder. It is caused by an obstruction of the upper airway and causes dramatic arterial oxygen desaturation during sleep. The disease is characterized by repetitive episodes of hypopnea or apnea with intermittent arousals and considerable disruption of normal sleep architecture.[1] Epidemiological findings suggest that merely 2% of middle-aged (30–60 years of age) women and 4% of middle-aged (30–60 years of age) men are affected, however almost 75% of OSAS patients still remain undiagnosed.[2] OSAS patients are seriously affected by daytime sleepiness, fatigue and neuropsychological impairment compromising several areas of cognitive function including attention, vigilance, memory and executive function. Harmful hypoxemic intervals are also frequently observed in the immediate phase after general anesthesia procedures. The incidence of hypoxic episodes in the post anesthesia unit has been reported to be between 7.6%[3] and 13.5%.[4] These repeated episodes of desaturation often occur unrecognized and prolonged.[5] On the other hand, there is clinical evidence that exposure to intermittent hypoxia has beneficial effects such as increasing ischemia resistance and preserving cardiovascular and brain function, also described as ischemic preconditioning.[6]

Ischemic preconditioning potentially affects postoperative function via numerous pathways, including the regulation of neurotrophin expression, strengthening the neurovascular network decreasing inflammation and apoptosis.[7] However, most studies were based on rodents and the translation to humans remains to be evaluated. On the other hand, the expression of brain derived neurotrophic factor (BDNF) is correlated positively with cognitive function in older adults.[8] Furthermore, intermittent hypoxia stimulates the expression of BDNF in the adult hippocampus[9] and enhances the process of learning.[10] Hence, intermittent hypoxia might result in an improvement in cognitive function. One may therefore hypothesize that the hypoxemic intervals associated with OSAS may have a beneficial effect on the postoperative cognitive function in terms of an ischemic preconditioning. We investigated this question in a pilot study in patients with a high risk of OSAS and in control patients undergoing non-cardiac surgery with total intravenous anesthesia.

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