Titrating Oxygen Requirements During Exercise: Evaluation of a Standardized Single Walk Test Protocol

Abstract

Oxygen supplementation for exercise-induced hypoxemia is a common clinical practice that improves exercise tolerance. However, we know of no standardized exercise oxygen titration protocol using a single walk test. We report our experience with a protocol developed in our laboratory. Our protocol is based on the 6-min walk test (6MWT). Pulse oximetry readings (oxygen saturation [Spo2]) are monitored, and supplemental oxygen is added in 2 L/min increments to keep Spo2 > 88%. This continues for at least 6min of walking with the Spo2 remaining > 88%for at least 3 min. The records of consecutive patients over 4months undergoing this procedure were reviewed for test performance, oxygen titration results, and adverse events. Two hundred twenty-two patients were tested; only two prematurely terminated the protocol because of intractable dyspnea. One hundred fifty-six patients (38%) required oxygen supplementation, with the first titration most commonly occurring between 1 and 2 min of walking. Nine of the patients had the first titration after 5min of walking. The average test duration was 7min (maximum, 15 min). The average number of titrations was 2.2 (maximum six). Sixteen patients could not maintain Spo2 > 88%for 3min despite administration of 15 L/min of supplemental oxygen (maximal dose). Our protocol was easily performed as a modification of a standard 6MWT with no serious adverse events. Because it is based on a widely accepted measurement of functional capabilities, and because it determined a stable final oxygen dose for≥ 3min of walking in most patients, we believe this protocol can be easily adapted for clinical use.