Having both COPD and obstructive sleep apnea can have a profound effect on patients’ muscle strength, ultimately impacting their quality of life.
That’s according to a study, “Impact of Obstructive Sleep Apnea on Functional Performance and Muscle Quality of Patients With COPD,” published in Scientific Reports.
“Although it’s generally associated only with lung function, COPD is systemic, with multiple impacts,” said study author Audrey Borghi Silva, PhD, coordinator of the Cardiopulmonary Physiotherapy Laboratory at the Federal University of Sao Carlos in Sao Paulo, Brazil, in a news release. “When combined with obstructive sleep apnea syndrome (OSAS), muscle damage worsens, leading to a loss of strength and more serious medical outcomes, such as hospitalizations and increased risk of death compared to patients with COPD alone.”
The researchers evaluated 44 adults aged 50 years or older, of both sexes, with a confirmed clinical and spirometric diagnosis of COPD. The patients were equally divided between those with COPD and obstructive sleep apnea, and those with just COPD alone. The results showed statistically significant differences in functional performances between the two groups.
Researchers conducted a number of tests, including pulmonary and cardiac function, home sleep assessment, handgrip strength and six-minute walk tests.
Grip strength, recognized as an indicator of muscle strength, was significantly lower in the group with both diseases — 26-kilogram force (kgf) compared to 30 kgf in the group with COPD alone.
In the six-minute walk test, which is used to assess functional capacity, patients with both conditions walked an average of 984 feet, while those with COPD alone walked an average of 1,194 feet. Distances of less than 1,148 feet in this test are associated with a higher risk of hospitalization and mortality.
The severity of sleep apnea is typically assessed using the Apnea-Hypopnea Index (AHI), which tracks the number of breathing pauses per hour of sleep. However, the researchers found that muscle quality loss was most strongly associated with the Oxygen Desaturation Index (ODI), which measures the frequency of drops in blood oxygen levels during sleep.
“More than poor performance on the tests, the study results indicate that the magnitude of nocturnal oxygen desaturation during sleep is more strongly associated with muscle quality and functional performance than the frequency of respiratory events itself,” said principal investigator Patricia Faria Camargo, of the Cardiopulmonary Physiotherapy Laboratory at the Federal University of Sao Carlos in Sao Paulo, Brazil. “This suggests that intermittent nocturnal hypoxia, by compromising tissue oxygenation, may be a central pathophysiological mechanism in the loss of muscle mass and function in patients with COPD and sleep apnea.”
She said these conditions can aggravate damage to mitochondria, compromising muscle contraction and regeneration, and result in progressive weakening and functional limitation.
The study’s researchers point to the need to monitor people with both conditions. “The results reinforce the need to screen for sleep-disordered breathing in the COPD population. The finding directly impacts public health policies, clinical protocols and rehabilitation programs, highlighting the fundamental role of sleep in quality of life,” Dr. Camargo said.
