Impact of Real-Time Assessment of Pulse Oximetry on the 6-Min Walk Distance in Patients With Chronic Respiratory...

Continuous monitoring of pulse oximetry (S_pO2 ) is recommended during the 6-min walk test (6MWT) to ensure that the lowest S_pO2 is recorded. In this case, severe exercise-induced desaturation (EID; S_pO2 < 80%) triggers walking interruption by the examiner. Our main objective was to assess the impact of this approach on 6MWT distance in patients with chronic respiratory diseases and, second, to evaluate the safety of the test without interruption due to severe EID.

6MWTs with continuous monitoring of S_pO2 were prospectively performed in subjects with chronic respiratory disease. The participants were randomly allocated to walk with or without S_pO2 real-time assessment. S_pO2 visualization during the test execution was available only in the first group, and walking interruption was requested by the examiner if S_pO2 < 80%.

One hundred forty-five participants were included in each group (68.6% females, 62 [52-69] y old) without differences in demographic and resting lung function parameters between them. The main respiratory conditions were COPD (n = 101), asthma (n = 73), pulmonary hypertension (n = 47), and interstitial lung disease (n = 39). The walked distance was similar comparing groups (349.5 ± 117.5 m vs 351.2 ± 105.4 m). Twenty-five subjects presented with severe EID in the group with real-time S_pO2 assessment, and 20 subjects had severe EID in the group without real-time assessment respectively (overall prevalence of 15.5%). The 23 participants who had their test interrupted by the examiner due to severe EID in the first group (2 subjects stopped by themselves due to excessive symptoms) walked a shorter distance compared to the 11 subjects with severe EID without test interruption in the second group (9 subjects stopped by themselves due to excessive symptoms): 240.6 ± 100.2 m versus 345.9 ± 73.4 m. No exercise-related serious adverse events were observed.

Interruption driven by severe EID reduced the walked distance during the 6MWT. No serious adverse event, in turn, was observed in subjects with severe desaturation without real-time S_pO2 assessment.