Supine fluid redistribution: should we consider this as an important risk factor for obstructive sleep apnea?

Obstructive sleep apnea (OSA) is a common medical disorder affecting at least 2 % of women and 4 % of men living in Western societies. Obesity, older age, male gender, alcohol and sedative use, smoking, craniofacial parameters, and volume overload are some of the risk factors for this disorder. OSA is a known risk factor complicating the course of arterial hypertension, heart failure, and chronic kidney disease. It is important to note that all of the aforementioned comorbid disorders are associated with volume overload. This explains why patients with OSA and comorbid disorders associated with fluid overload can benefit from treatment with diuretics and drugs modulating the renin-angiotensin-aldosterone system. Additionally, patients with heart failure and high sodium intake are at increased risk for OSA, further supporting the complex interrelationship. Hemodialysis and renal transplantation can markedly improve the severity of OSA in patients with concomitant kidney disease. Finally, there is a potential of a vicious cycle between OSA and fluid overload disorders, whereby OSA can contribute to the pathogenesis of arterial hypertension, heart failure, and chronic kidney disease, which in turn will significantly contribute to the course OSA.