Alteration in obstructive apnea pattern induced by changes in oxygen- and carbon-dioxide-inspired concentrations

Area of Science:

• Respiratory Physiology
• Sleep Medicine
• Neuromuscular Control

Background:

• Obstructive sleep apnea (OSA) is characterized by upper airway collapse during sleep.
• The role of ventilatory control and pharyngeal muscle activity in OSA pathophysiology is not fully understood.

Purpose of the Study:

• To investigate the effects of hypercapnia (elevated CO2) and hyperoxia (elevated O2) on upper airway muscle activity and apnea events in patients with OSA.
• To determine if manipulating respiratory drive can alter the pattern of upper airway collapse during sleep.

Main Methods:

• Seven patients with symptomatic OSA were studied.
• Inhalation of 3-6% CO2 and 50% O2 during sleep.
• Measurement of pharyngeal and chest wall inspiratory muscle electrical activity.
• Quantification of apnea time and periodic breathing.

Main Results:

• CO2 inhalation preferentially stimulated upper airway inspiratory muscles, decreased apnea time from 60% to 12% of sleep time, and diminished periodic breathing.
• O2 inhalation decreased inspiratory muscle activity and increased apnea time to 75% of sleep time.
• Significant changes in upper airway inspiratory collapse patterns were observed with CO2 and O2 manipulation.

Conclusions:

• Manipulation of respiratory drive via CO2 and O2 significantly alters upper airway muscle activity and breathing patterns during sleep in OSA patients.
• Physiologic variables controlling upper airway inspiratory muscles are crucial in OSA pathophysiology.
• Targeting respiratory control mechanisms may offer therapeutic potential for OSA.