Obstructive sleep apnea (OSA) may play an important role in the progression of nonalcoholic fatty liver disease (NAFLD).The effect of continuous positive airway pressure (CPAP) treatment, the first-line therapy for OSA, on liver disease in OSA patients is still debated. We provide this review of previous studies to summarize the effects of CPAP treatment on liver disease in OSA patients in aspects of liver function, liver steatosis, fibrosis, and incidence of liver disease. CPAP treatment may be beneficial to liver disease in subjects with OSA independent of metabolic risk factors, but a sufficiently long therapeutic duration (perhaps greater than 3 months) may be needed to achieve these positive effects. Though the mechanism of impact of CPAP treatment on liver in OSA patients is unclear, the influence of CPAP treatment on the factors of the "Two-hit" hypothesis (insulin resistance, fatty acids dysregulation, oxidative stress, and inflammation) may be a reasonable explanation.
Keywords: Continuous positive airway pressure; Intermittent hypoxia; Nonalcoholic fatty liver disease; Obstructive sleep apnea.