Is intensified diuretic therapy an effective new treatment strategy in obstructive sleep apnoea patients with uncontrolled hypertension?

Abstract

There is evidence of an important mutual interaction between sleep disorders and cardiovascular problems. Patients with cardiovascular diseases often complain of several sleep disturbances such as sleep fragmentation, insomnia and breathing disorders during sleep. On the contrary, patients with sleep disorders are more frequently affected by cardiovascular problems. Such a reciprocal interaction makes it often difficult to determine which is the cause and which is the effect between these conditions. Sleep-related breathing disorders, particularly obstructive sleep apnoea syndrome (OSAS), formerly named Pickwickian syndrome, are highly prevalent in the general population, OSAS affecting at least 4% of middle-aged men and 2% of middle-aged women in the developed world, with its prevalence increasing in parallel with the growing prevalence of obesity. Individuals with OSAS are also characterized by a worsened quality of life and by excessive daytime somnolence, and are at an increased risk of road traffic and workplace accidents when compared with nonapnoeic individuals [1–3]. From a public health viewpoint, also the reported increased risk of cardiovascular morbidity and mortality associated with a diagnosis of obstructive sleep apnoea (OSA) is of particular importance [4,5]. OSA is associated with a higher prevalence of hypertension, in particular resistant hypertension, myocardial infarction, cardiac arrhythmias, congestive heart failure and stroke. Indeed, untreated severe OSA confers a three-fold increased risk of death from cardiovascular causes [1,2,6]. Prevalence of hypertension in OSA patients ranges from 35 to 80% and appears to be influenced by OSA severity. In fact, more than 60% of individuals with respiratory disturbance index greater than 30 were found to be hypertensive. Conversely, approximately 40% of hypertensive patients are diagnosed with OSA. Finally, when focussing on patients with resistant hypertension, OSA prevalence is significantly higher, reaching 83% [7]. Given this background, and the relevant interaction between OSA and cardiovascular disorders, it is evident that strategies for OSA treatment also play a key role in cardiovascular diseases prevention.