The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

CONTINUOUS OXYGEN MONITORING DEMONSTRATES MANY COPD PATIENTS HAVE OXYGEN OVERPRESCRIBED.

Randal Barnette BS RRT, Kevin M Fussell MD, Rita Gupta BS RRT, R Michael Rodriguez MD, Angelo Canonico MD, and Richard W Light MD. Department of Pulmonary Medicine, Saint Thomas Hospital, Nashville, Tennessee and Department of Allergy, Pulmonary and Critical Care Medicine, Vanderbilt University, Nashville, Tennessee.

Background: Long-term oxygen therapy (LTOT) for hypoxic patients with chronic obstructive pulmonary disease (COPD) has been shown to significantly decrease mortality. It has also been shown that the mortality benefit is directly proportional to the amount of time the oxygen is used. The purpose of this study was to determine if the use of continuous oximetry monitoring for ~24 hours would result in an oxygen prescription with an increased percentage of time spent with the Sp02 level betweenlevel between 88% and 92%. We hypothesized that with ambulatory oximetry monitoring we could increase the percentage of time with the SpO2 in this range.

Methods: We conducted a prospective, cohort study in an outpatient pulmonary setting in a tertiary care referral center, with 13 stable COPD patients who had previously been prescribed LTOT. The mean age of our patients was 63. Patients were monitored for the initial 24 hours on their prescribed oxygen prescription, and then their oxygen prescription was altered based on a predetermined protocol. Then the patients were monitored for an additional 24 hours.

RESULTS: The mean FVC was 2.71 ± 1.11, the mean FEV1 was 1.80 ± 1.07, and the mean FEV1/FVC was 48% ±. 9.34. One of the patients was found to be within the 88% to 92% range over 75% of the initial 24-hour period, and was not studied further. The remaining 12 patients were initially on a median oxygen flow of 2.5 L/min overall, 3.5 L/min on exercise, 2 L/min at rest, and 2 L/min while sleeping. Based on the initial continuous oximetry, the median oxygen prescription was reduced significantly (p <0.001) from 2.5 to 1.5 L/min..  The patients were then decreased an average 1.0 l/min. flow on their oxygen, and restudied for an additional 24 hours. The patients exhibited a median change in oxygen liter flow requirements of 1.5Ll/min overall, a change of exercise liter flow from 3.5 L/min down to 2 L/min (p = 0.004), a change in resting liter flow from 2 L/min to 1 L/min (p = <0.001), and a decrease in sleeping liter flow from 2 L/min down to 1 L/min (p = <0.001). There was a significant (p = 0.014) increase in the amount of time the patients were in the 88 - 92% range, from 21.8% to 48%, and there was a significant (p = 0.020) decrease in the amount of time patients were above 92% Spo2, from 74.8% to 47%. There was not a significant (p = 0.465) increase in the percentage of time below 88% Sp02, with a change of 3.4% to 5%, /despite the fact the oxygen prescription was reduced by almost 50%.

CONCLUSION: The study revealed that continuous oximetry monitoring demonstrated that the oxygen prescription of many COPD patients was higher than necessary. The prescription of oxygen based on the use of the continuous oxygen monitoring resulted in (1) a significant decrease in the amount of oxygen prescribed, (2) a significant increase in the percentage of time that the SpO2 was between 88 and 92%, and no significant change in the amount of time that the SpO 2 was below 88%.

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