Reproducibility of 6 Minute Walk Tests for Oxygen Desaturation

Over 16 million adults in the United States are afflicted with chronic obstructive pulmonary disease (COPD) and is the fourth leading cause of death.(McCrory et al. 1190-209). COPD accounts for direct health-care costs of $18 billion.(McCrory et al. 1190-209). Oxygen therapy has been shown to decrease mortality in COPD patients with severe hypoxemia at rest. Oxygen therapy now accounts for the number one expenditure for durable medical equipment. Current requirements for oxygen therapy for COPD patients include a resting or exercise paO2 or spO2 of 55 mmHg or 88% respectively. We have shown that a resting spO2 of < 95% is predictive of those at risk of exercise induced hypoxemia in COPD patients(Knower et al. 732-36) based on continuous spO2 monitoring during a 6 minute walk. Although, the reproducibility of a 6 minute walk has been addressed in terms of a hospital test, simulated home test and actual home test (Guyatt), its inter-variability is not well studied.

We propose to investigate the reliability and inter-variability of the 6 minute walk for oxygen prescription. Currently, two programs are providing pulmonary rehabilitation for COPD patients in the community. Patients perform 6 minute walks under supervision and are monitored by pulse oximetry on a routine basis as part of these programs. We plan to capture the oximetry data in order to determine the reliability of oxygen prescriptions using the 6 minute walk. Patients who are performing a 6 minute walk will be eligible for enrollment. Protocols for the 6 minute walk are already in place and approved by their respective authority in both of the Pulmonary Rehabilitation Programs. These patients will have repeat 6 minute walks on separate in close proximity to determine the reliability of spO2 on any given day. Statistical analysis will be done by the kappa statistic for inter-test agreement in a 3 dimensional matrix.

We ask to waive consent for this study as there is no change to the daily routine of the 6 minute walks already being done as part of Pulmonary Rehabilitation. We plan only to capture the data from these walks.