Exercise-induced desaturation (EID) is a frequent but often underrecognized problem among patients recovering from acute exacerbations of COPD, according to a recent multicenter retrospective study published in the Journal of the COPD Foundation.1 The findings suggest that routine exercise oximetry may play an important role in identifying patients who require closer monitoring and more individualized rehabilitation strategies during the early postexacerbation period.
Researchers evaluated 262 patients admitted to inpatient pulmonary rehabilitation (PR) within 15 days of an acute COPD exacerbation. EID was defined as a drop in oxygen saturation of at least 4 percentage points from baseline, with a nadir below 90% during a 6-minute walk distance test.
The authors noted that while EID has been described in stable COPD populations, relatively little information has been available regarding its prevalence in the immediate postexacerbation period, when patients are beginning rehabilitation and recovering from severe physiologic stress.
“In everyday clinical practice within an inpatient pulmonary rehabilitation setting, it is very common to observe patients who develop exercise-induced desaturation during the 6-minute walk test or other exercise assessments after an acute exacerbation of COPD,” said coauthor Michele Vitacca, MD, Director of the Respiratory Rehabilitation Unit at the Scientific Institute of Pavia Maugeri IRCCS in Lumezzane, Italy. “What our study adds is objective evidence that quantifies this phenomenon in a large real-world population.”
The authors said the main contribution of the study is the demonstration that desaturation is not an isolated occurrence but a common feature of recovery following exacerbation, occurring in almost six out of 10 patients with chronic respiratory failure and more than three out of 10 patients with COPD without chronic respiratory, said coauthor Mara Paneroni, PhD, Coordinator of Cardiorespiratory Physiotherapy Service in the Respiratory Rehabilitation Unit at the Scientific Institute of Pavia Maugeri IRCCS.
Overall, 50.4% of patients experienced EID. The prevalence was substantially higher among patients receiving supplemental oxygen at rest, occurring in 61.5% of that group compared with 33.9% of patients breathing room air.
Compared with patients not receiving oxygen, those receiving oxygen had greater airflow limitation, reduced exercise capacity, higher symptom burden, and more dyspnea-related disability. Their 6-minute walk distances were significantly shorter, regardless of whether EID occurred during testing.
The subgroup analyses further reinforced that patients using oxygen represented a more clinically compromised population. However, even oxygen supplementation did not prevent desaturation in many individuals, suggesting that resting oxygen prescriptions may not adequately reflect physiologic needs during exertion.
One of the study’s findings was the poor relationship between oxygen desaturation and subjective symptom measures.
The authors said that patients who experienced EID did not consistently report greater dyspnea or fatigue during exercise than those who maintained oxygen saturation. Although patients receiving oxygen who developed EID exhibited a greater heart rate response during exercise, symptom scores alone frequently failed to detect desaturation events.
That disconnect reflects the complex nature of breathlessness in COPD, Dr. Vitacca said.
“Dyspnea is an extremely complex and multifactorial symptom. Oxygen desaturation is only one of many physiological mechanisms contributing to breathlessness during exercise,” he said.
The investigators added that patients often have a poor perception of declining oxygen saturation and that numerous factors—including dynamic hyperinflation, respiratory muscle loading, cardiovascular responses, deconditioning, and psychological influences—can affect subjective breathlessness independently of oxygen levels.
“This highlights why subjective symptom assessment cannot replace objective physiological monitoring during exercise,” Dr. Paneroni said. “Our findings suggest that clinicians should approach oxygen titration with greater awareness of the frequency of exercise-induced desaturation and should base their decisions on objective exercise testing rather than resting measurements alone.”
At the same time, the investigators cautioned against interpreting the results as evidence that every patient who desaturates should automatically receive supplemental oxygen. Literature remains inconclusive regarding whether ambulatory oxygen consistently improves rehabilitation outcomes.
Instead, they said oxygen use should be individualized based on oxygen saturation, symptoms, exercise tolerance, perceived exertion, and overall functional response.
The study also highlighted the importance of routine pulse oximetry during PR programs.
“Routine exercise oximetry should be considered a fundamental component of inpatient pulmonary rehabilitation, particularly during the early postexacerbation period,” Dr. Vitacca said. “Beyond identifying desaturation, exercise oximetry can help clinicians tailor exercise intensity, evaluate responses to supplemental oxygen, and safely advance rehabilitation programs based on objective physiologic data.”
References
1. Paneroni M, Spinello L, Salvi B, et al. Prevalence of exercise-induced desaturation among COPD patients enrolled in early inpatient pulmonary rehabilitation. Chronic Obstr Pulm Dis. 2026;13(2):136-146. doi:10.15326/jcopdf.2025.0724
