Continuous oxygen monitoring—a better way to prescribe long-term oxygen therapy

Summary

Study objective

The purpose of this study was to determine if an oxygen prescription based on continuous oximetry monitoring, would result in an increased percentage of time spent within an SpO₂ level between 88% and 92%.

Methods

We conducted a prospective, cohort study in an outpatient, pulmonary setting in a tertiary care referral center, on 17 patients with stable chronic obstructive pulmonary disease (COPD) who had previously been prescribed long-term oxygen therapy. The patients were monitored for ∼24 h with a portable oximeter that recorded SpO₂ and EKG readings. During the initial 24 h of monitoring, the patients were on their previous oxygen prescription. Their oxygen prescription was then altered based on a predetermined protocol described below. The patients were then monitored for an additional 24 h.

Results

Sixteen patients completed the study. Based on the initial continuous oximetry, the median oxygen prescription was reduced from 2.5 to 1.2 L/min ($P<0.001$). The oxygen prescription during exercise, rest, and sleep decreased from 3.0±0.9 to 1.8±1.3 L/min ($P<0.001$), 2.2±0.4 to 0.8±0.7 L/min ($P<0.001$), and 2.2±0.4 to 0.9±0.8 L/min ($P<0.001$) respectively. After the oxygen prescription was adjusted, the percentage of the time that the SpO₂ was between 88 and 92% increased from 24.8±21.7% to 52.8±25.0% ($P=0.001$), but the percentage of time that the SpO₂ was below 88% did not change significantly (2.8±6.1% to 4.3±8.1%).

Conclusions

This study demonstrates that an oxygen prescription based on continuous oximetry monitoring results in (1) a significant increase in the percentage of time that the SpO₂ is between 88% and 92%, (2) a significant decrease in the amount of oxygen prescribed, (3) a slight increase in the amount of time that the SpO₂ is below 88% that was not statistically significant.