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Ambulatory oximetry fails to predict survival in chronic obstructive pulmonary disease with mild-to-moderate hypoxaemia

Authors


Correspondence: James M. Trauer, Department of Respiratory and Sleep Disorders Medicine, First Floor, Main Building, Western Hospital, Gordon Street, Footscray, Vic. 3011 Australia. Email: james@msdc.com.au

Abstract

Background and objective

Although long-term oxygen therapy is one of few treatments known to improve survival in COPD, no patient subgroup likely to derive benefit has been identified in over 30 years. We assessed the prognostic value of point measurement of PaO2 and proportion of ambulatory oximetry with saturations below 90% in this context.

Methods

Subjects were community-living patients with COPD and PaO2 56–70 mm Hg when stable. Baseline assessments included clinical, physiological and laboratory assessments, as well as 24-h ambulatory oximetry. Patients were followed to death from any cause, first exacerbation and first admission.

Results

Despite poor survival overall, there was no significant difference in prognosis between mildly hypoxaemic and moderately hypoxaemic patients. There were also no significant differences for secondary end–points (exacerbation and hospital admission). On multivariate analysis, trends were observed towards improved survival, with higher PaO2 and greater proportion of ambulatory oximetry below 90%.

Conclusions

Neither resting PaO2 nor proportion of ambulatory oximetry below 90% saturation effectively predicted survival in COPD.

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