Respiratory event type and duration modulate PPG waveforms in OSA

Area of Science:

• Cardiology
• Sleep Medicine
• Biomedical Engineering

Background:

• Obstructive sleep apnea (OSA) elevates cardiovascular disease (CVD) risk.
• Photoplethysmography (PPG) signals reflect vascular health but are understudied in OSA.
• Investigating PPG waveform changes during respiratory events can reveal insights into OSA's physiological impact.

Purpose of the Study:

• To analyze the immediate effects of respiratory event characteristics on PPG waveforms in OSA patients.
• To identify potential PPG patterns associated with cardiovascular health in the context of OSA.

Main Methods:

• Retrospective analysis of 520 polysomnographies from suspected OSA patients.
• Focused on PPG segments before, during, and after respiratory events (n=14442 each).
• Quantified PPG waveform parameters (FWHM, Δt, Δtrel, ΔA, ΔArel) and assessed effects of event type and duration.

Main Results:

• Longer respiratory events significantly increased ΔArel and FWHM, and decreased ΔA and Δtrel before and during events (p<0.001).
• These effects were more pronounced during apneas than hypopneas.
• PPG parameters fluctuated post-event, influenced by event type, duration, pre-event values, and heart rate (p<0.001).

Conclusions:

• PPG waveform analysis offers a method to evaluate physiological stress from respiratory events in OSA.
• This approach can potentially enhance CVD risk assessment tools for OSA patients.