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Supplemental oxygen therapy is frequently required for patients presenting with acute respiratory distress and COPD exacerbation. Over-oxygenation can derail compensatory physiologic responses to hypoxia,1 resulting in worsening VQ mismatch and, to a lesser degree, decreases in minute ventilation, that cause worsened respiratory failure.
The 2012 DECAF (Dyspnea, Eosinopenia, Consolidation, Acidaemia, and Atrial Fibrillation) score was found to predict risk of in-hospital mortality in patients admitted with acute COPD exacerbation.2,3 Data from the DECAF study’s derivation and external validation cohorts were examined specifically to look at outcome associated with varying levels of oxygen saturation.
- 1027 patients from 6 UK hospitals receiving supplemental oxygen at admission
- Lowest in-hospital mortality seen in the 88-92% cohort
- Adj OR for in-hospital mortality in ≥97% vs 88-92% group: 2.97 (95% CI 1.58-5.58, p=0.001)
- Adj OR for in-hospital mortality in 93-96% vs 88-92% group: 1.98 (95% CI 1.09-3.60, p=0.025)
- Surprisingly, mortality risk seen more in normocapnic than hypercapnic patients
- Association between admission SpO2 and mortality persisted after adjusting for baseline risk and disease severity using the DECAF and NEWS 2 score
Bottom Line
In patients presenting to the ED with acute COPD exacerbation requiring oxygen supplementation, a target oxygen saturation of 88-92% is associated with the lowest in-hospital mortality, and higher oxygen saturations should be avoided independent of patients' PCO2 levels.
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