Abstract · Target oxygen saturation intervals · Nebulizers · Patients who deteriorate. These studies and previous studies confirmed that uncontrolled administration of oxygen to patients with acute exacerbation of very severe COPD can induce hypercapnia and that the level of hypoxemia is a predictor of the development of hypercapnia. Therefore, it is important to review the mechanisms of oxygen-induced hypercapnia in patients with COPD, in particular the role of oxygen-induced hypoventilation. Adopting target saturations of 88 to 92% for all patients hospitalized with COPD would simplify clinical pathways and should improve outcomes.
For most patients with COPD, the target saturation range should be set at 88— 92% until blood gases are available. With hypoxemia, the heart and respiratory rate may increase. A small device called a pulse oximeter measures the amount of oxygen in the blood. Normal levels are between 95% and 100%.
A reading of 88% or less indicates hypoxemia. The Night Oxygen Therapy Trial (NOTT) and the MRC Working Group Trial (MRC), of 1980 and 1981 respectively, are the only trials that show a survival benefit for LTOT in COPD. Therefore, a target range of 88 to 92% is recommended and this has been extrapolated from COPD to include other groups at risk for T2RF. Treatment of all COPD patients with target saturations of 88 to 92% will simplify prescribing and should improve outcomes.
In particular, this case highlights the challenge of proper oxygen administration in the context of an exacerbation of COPD. Many of the serious problems that COPD causes occur because the lungs and bloodstream receive too little oxygen. The latter study focused on patients who received acute NIV; COPD was the most common indication, and oxygen toxicity contributed to approximately a quarter of all episodes of acute hypercapnic respiratory failure. Based on these studies and others, the UK Emergency Oxygen Guideline will recommend a target oxygen saturation range of 88% to 92% for most patients with exacerbated COPD.
This increase in oxygen tension probably led to progressive hypercapnia (increased CO2 level) during the night (see below for a more detailed explanation of the risks of excess oxygen in patients with severe COPD). The main objective of this study was to examine in-hospital mortality in COPD, first in the groups with oxygen saturation at admission of (87% or less, (88— 92%), (93— 96%) or (97— 100%) in (a) those who received oxygen and (b) those who did not receive oxygen at the time of admission, and second in the subgroup of patients with hypercapnia and normocapnia. Results In COPD patients who received supplemental oxygen, oxygen saturations greater than 92% were associated with increased mortality and an adverse dose response. In most cases, this is an unwise decision, which puts at risk the safety of patients with acute exacerbation of COPD.