Endocrine responses during CPAP withdrawal in obstructive sleep apnoea: data from two randomised controlled trials

Area of Science:

• Cardiology
• Neurology
• Endocrinology
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) is a prevalent condition associated with significant cardiovascular and metabolic comorbidities.
• Continuous positive airway pressure (CPAP) is the primary treatment for OSA, but adherence can be challenging, leading to treatment withdrawal.
• The impact of CPAP withdrawal on key physiological systems, including neurometabolic and cardiometabolic markers, requires further elucidation.

Purpose of the Study:

• To investigate the effects of CPAP withdrawal on neurometabolic and cardiometabolic markers in patients with OSA.
• To assess the changes in sympathetic activation, hypothalamic-pituitary-adrenal (HPA) axis, and renin-angiotensin-aldosterone system (RAAS) following CPAP cessation.

Main Methods:

• Two parallel, randomized controlled trials were conducted involving 70 patients (mean age 61±10 years, 82% men) previously treated with CPAP.
• Patients underwent a 2-week period of CPAP withdrawal.
• Neurometabolic markers (e.g., 3,4-dihydroxyphenylglycol, norepinephrine) and cardiometabolic markers (e.g., cortisol, RAAS determinants) were evaluated.

Main Results:

• CPAP withdrawal led to a significant increase in 3,4-dihydroxyphenylglycol and norepinephrine, indicating heightened sympathetic activation.
• Elevated cortisol levels were observed, suggesting transient HPA axis activation.
• No statistically significant changes were documented in the determinants of the renin-angiotensin-aldosterone system (RAAS).

Conclusions:

• Short-term CPAP withdrawal in OSA patients is primarily associated with increased sympathetic nervous system activation.
• The findings suggest that the immediate physiological consequences of CPAP cessation may involve heightened stress responses rather than substantial RAAS or HPA axis dysregulation.
• Further research is warranted to understand the long-term implications of CPAP withdrawal on cardiometabolic health.