BACKGROUND

Exercise-induced O desaturation contributes to dyspnea and exercise intolerance in various respiratory diseases. This study assessed whether automated O titration was superior to fixed-flow O to improve exertional dyspnea and walking exercise endurance. We also aimed at evaluating possible additive effects of high-flow nasal cannula coupled with automated O titration on these outcomes.

METHODS

Subjects with chronic respiratory diseases and exercise-induced desaturation performed a 3-min constant-speed shuttle test (CSST) and an endurance shuttle walking test (ESWT) with either (1) fixed-flow O, (2) automated O titration targeting an S of 94% (± 2%), and (3) automated O titration + high-flow nasal cannula according to a randomized sequence. The main outcome was Borg dyspnea score at the end of the 3-min CSST. Secondary outcomes included endurance time and dyspnea during ESWT and oxygenation status during exercise.

RESULTS

Ten subjects with COPD, 10 with interstitial lung disease, 5 with pulmonary hypertension, and 3 with cystic fibrosis completed the study. Compared to fixed-flow O, automated O titration did not reduce dyspnea at the end of the 3-min CSST. Endurance time during the ESWT was prolonged with automated O titration (mean difference 298 [95% CI 205-391] s, < .001), and dyspnea at isotime was reduced. No further improvement was noted when high-flow nasal cannula was added to automated O titration. Compared to fixed-flow O, O flows were higher with automated O titration, resulting in better oxygenation.

CONCLUSIONS

Automated O titration was superior to fixed-flow O to alleviate dyspnea and improve exercise endurance during the ESWT in subjects with a variety of chronic respiratory diseases. Adding high-flow nasal cannula to automated O titration provided no further benefits.