Phenotyping OSAH patients during wakefulness.

Area of Science:

• Sleep Medicine
• Respiratory Physiology
• Cardiovascular Research

Background:

• Obstructive sleep apnea-hypopnea (OSAH) diagnosis relies on complex pathophysiological trait measurements.
• Current methods are difficult to implement in routine clinical practice.
• A simpler, daytime phenotyping approach is needed for OSAH patients.

Purpose of the Study:

• To investigate a simpler daytime protocol for phenotyping OSAH patients.
• To assess if daytime measurements can yield similar pathophysiological profiles as established methods.
• To establish a more accessible method for understanding OSAH mechanisms.

Main Methods:

• A pilot study compared a reference method (dial-down CPAP during polysomnography) with a novel daytime protocol.
• The reference method assessed upper airway collapsibility, loop gain (LG), arousal threshold (AT), and upper airway muscle gain (UAG).
• The daytime protocol used negative expiratory pressure (NEP) for collapsibility/UAG, maximal voluntary apnea for LG, and clinical predictors for AT.

Main Results:

• 13 out of 15 OSAH patients completed both procedures.
• Strong and significant correlations (r² > 0.75, p < 0.001) were found for all phenotypic traits between the reference and daytime methods.
• The daytime protocol successfully replicated measurements of upper airway collapsibility, LG, AT, and UAG.

Conclusions:

• OSAH patients can be phenotyped using a simpler daytime approach.
• This awake-based method provides meaningful pathophysiological insights similar to traditional techniques.
• The findings suggest a practical, accessible tool for OSAH phenotyping in clinical settings.