Volume 187 - Issue 4
The effects of oxygen therapy in patients presenting to an emergency department with exacerbation of chronic obstructive pulmonary disease
Authors: Simon A Joosten, David Smallwood, Mariko S Koh, Louis B Irving and Xiaoning Bu
Med J Aust 2007; 187 (4): 253-254. || doi: 10.5694/j.1326-5377.2007.tb01225.x
Published online: 20 August 2007
Published online: 20 August 2007
In reply: We performed a retrospective audit as part of a quality improvement program following a number of serious adverse events in various areas of our hospital. Our article showed that carbon dioxide retention in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is common (41 of 65 patients admitted with chronic obstructive pulmonary disease [COPD] over 4 months), and that guidelines on blood gas measurement and oxygen use were not being followed.
Dent and colleagues state that more patients in our study who received more than 4 litres of oxygen per minute were in a triage category that indicated a more serious condition. However, the multivariate analysis showed that triage category did not predict length of stay. In contrast, partial pressure of arterial oxygen (Pao2) did, and patients with a Pao2 of less than 74.5 mmHg (range, 36.7–74.0 mmHg) had a shorter length of stay than those with a Pao2 of 74.5 mmHg or higher (range, 74.5–452.0 mmHg). Many patients had a Pao2 much higher than neccessary to achieve a haemoglobin saturation of about 90%.
Dent and colleagues state that our data did not support the claim that oxygen therapy is often uncontrolled in the emergency setting. In fact, only 68% of the patients receiving more than 4 litres of oxygen per minute had arterial blood gas measurements performed.
We agree with Dent et al that the management of AECOPD may not be as simple as following guidelines. However, we hope to raise awareness of the fact that hypercapnia in COPD is common, requires careful assessment, and that oxygen therapy should be titrated to physiological endpoints.