Decrease Obstructive Sleep Apnea (OSA) Sympathetic Tone : Impact of APAP vs CPAP

Background: Sleep apnea syndrome (SAS) currently affects 10% of general population. It is characterized by the occurrence during the sleep of the upper airways closure which cause repeated asphyxia. It is a public health problem due to its cardiometabolic complications. Indeed, the absence of SAS treatment increases cardiovascular mortality by 12% at 10 years.

The main physiopathological mechanism is the activation of cardiovascular sympathetic control (the short-term regulation of blood pressure which bring in the sympathetic nervous system) An exposure to intermittent chronic hypoxia (caused by SAS) bring an increased of muscle sympathetic nerve activity (MSNA) contributing to elevated blood pressure Continuous Positive Airway Pressure (CPAP) can partly reduce this risk by decreasing elevation of blood pressure caused by the SAS. It has recently been demonstrated that all CPAP devices are not equivalent. Indeed, the auto-adjusted CPAP treatment induces a reduction in blood pressure lower than the reference treatment fixed CPAP.

To this extent it is interesting to conduct a new randomized trial comparing these two treatments with vascular sympathetic tone. This will be assessed by peroneal microneurography recording.

Objective: Compare Muscle Sympathetic Neural Activity (MSNA) by microneurography after one month of fixed versus auto-adjusted CPAP treatment in OSA patients naive from pressure therapy Methods: Prospective study, single-site, randomized, double-blind, parallel, one month controlled trial. After the diagnosis of sleep apnea, patients will be randomized for one month treatment with fixed ou auto-adjusting CPAP. Measurements of MSNA, heart rate variability and catecholamines will be held before and after treatment.

An interim analysis will be performed after the inclusion of 24 patients based on group sequential design.

Assuming an α error of 5%, a statistical power of 80%, and a unilateral situation : 34 patients per arm will be needed to be enrolled in the study. The enrollment target for the study will be reviewed and may be refined following the study interim analysis and taking account 20% of study drop-out.

Inclusion criteria

• patient with OSA (AHI ≥20 / h)
• patient with daytime sleepiness
• naive of any pressure treatment of OSA
• patient able to provide written informed consent
• not a vulnerable person or legally protected adult.

Exclusion criteria

• pregnancy
• Person deprived of liberty or subject to a legal protection measure.
• Patient with serious heart failure (According to investigator judgment)
• patient with central sleep apnea index above 20% of AHI
• Patient with a significant intercurrent pathology that can influence the results. (According to investigator judgment).