The Relationship Between Volume Overload in End-Stage Renal Disease and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is common, underdiagnosed, and undertreated among patients with end-stage renal disease (ESRD). As in all cases, pathogenesis of OSA is related to repeated upper airway (UA) occlusion or narrowing, but in ESRD, additional contributory factors likely include uremic destabilization of central respiratory control and anatomic changes in the UA related to fluid status. Pulmonary congestion is common in acute and chronic kidney failure and is a consequence of cardiomyopathy and fluid overload, two potentially reversible risk factors. Emerging evidence suggests that volume overload also reduces the UA caliber. The diminution in UA area as well as destabilization of ventilatory control in ESRD have been postulated as causes of increased OSA prevalence and severity in these patients, and creates a vicious cycle wherein OSA exacerbates fluid overload disorders such as in congestive heart failure (CHF) and ESRD, which then further worsen OSA. Dialysis modalities may differ in their effects on volume status, the accumulation of uremic toxins, and acid-base status, and as a consequence, on the emergence and severity of OSA. Given the contribution of excess fluid to both the severity of nocturnal hypoxia and UA narrowing, establishing and maintaining dry weight is of particular importance when managing OSA in ESRD. Clinical trials to determine the extent to which more aggressive fluid removal in ESRD patients may alleviate OSA are needed.