Submaximal exercise in patients with severe obstructive sleep apnea.

Area of Science:

• Cardiopulmonary exercise testing
• Sleep medicine
• Clinical exercise physiology

Background:

• Obstructive sleep apnea (OSA) is a common sleep disorder.
• Cardiopulmonary exercise testing is used to assess OSA patients.
• The 6-minute walk test (6MWT) has not been previously investigated in OSA patients.

Purpose of the Study:

• To evaluate the feasibility and utility of the 6-minute walk test (6MWT) in patients with obstructive sleep apnea (OSA).
• To compare 6MWT performance between OSA patients and matched healthy controls (obese and lean).
• To explore correlations between 6MWT results and OSA severity or polysomnographic variables.

Main Methods:

• Consecutive, newly diagnosed OSA patients and matched healthy controls (obese and lean) were recruited.
• All participants underwent a sleep study and a single 6MWT within one week.
• Obese controls were matched for age, gender, height, and weight; lean controls were matched for age, gender, and height.

Main Results:

• No significant difference in 6-minute walk distance (6MWD) was found between OSA patients and obese controls.
• 6MWD did not correlate with age, apnea-hypopnea index, or other polysomnographic parameters in the OSA group.
• OSA patients showed significantly increased heart rate, blood pressure, and dyspnea perception post-6MWT compared to healthy subjects.

Conclusions:

• The 6MWT is a feasible and well-tolerated test for patients with OSA.
• 6MWD is not related to OSA severity or polysomnographic findings.
• Patients with OSA demonstrate altered hemodynamic responses to submaximal exercise, as indicated by the 6MWT.