Does pressure affect performance? Continuous positive airway pressure for sleep-disordered breathing in heart failure

摘要

Sleep-disordered breathing is very common in patients with congestive heart failure. Either obstructive sleep apnoea (OSA) or central sleep apnoea (CSA) have been reported to occur in > 50% of this population, often with both coexisting in the same patient. In OSA, there is repetitive respiratory effort against an obstructed airway, whereas in CSA there is waxing and waning ventilatory drive leading to periods of apnoea alternating with hyperpnoea. The type of respiratory event has important haemodynamic implications in heart failure. OSA leads to exaggerated negative intrathoracic pressure swings, which increase left ventricular (LV) trans-mural pressure and therefore LV afterload. This has been shown to reduce stroke volume and cardiac output in awake and, more importantly, sleeping heart failure patients. Furthermore, severe OSA has been associated with an increased risk of developing heart failure and portends a poor long-term prognosis in those with both conditions. With this in mind, it is not surprising that continuous positive airway pressure (CPAP) treatment for OSA in heart failure prevents these advefse haemodynamic effects and has been shown to improve LV function in two randomized controlled trials. Although these trials were not large or long enough to address mortality, observational studies have suggested improved survival in those heart failure patients with CPAP-treated OSA compared with untreated OSA.