Purpose: It is a challenge to control oxygen saturation (SpO2) in patients with exacerbations of COPD during admission. We tested a newly developed closed-loop system, O2matic®, and its ability to keep SpO2 within a specified interval compared with manual control by nursing staff.
Patients and methods: We conducted a crossover trial with patients admitted with an exacerbation of COPD and hypoxemia (SpO2 ≤88% on room air). Patients were monitored with continuous measurement of SpO2. In random order, they had 4 hours with manually controlled oxygen and 4 hours with oxygen delivery controlled by O2matic. Primary outcome was time within a prespecified SpO2 target interval. Secondary outcomes were time with SpO2 <85%, time with SpO2 below target but not <85%, and time with SpO2 above target.
Results: Twenty patients were randomized and 19 completed the study. Mean age was 72.4 years and mean FEV1 was 0.72 L (33% of predicted). Patients with O2matic-controlled treatment were within the SpO2 target interval in 85.1% of the time vs 46.6% with manually controlled treatment (P<0.001). Time with SpO2 <85% was 1.3% with O2matic and 17.9% with manual control (P=0.01). Time with SpO2 below target but not <85% was 9.0% with O2matic and 25.0% with manual control (P=0.002). Time with SpO2 above target was not significantly different between treatments (4.6% vs 10.5%, P=0.2). Patients expressed high confidence and a sense of safety with automatic oxygen delivery.
Conclusion: O2matic was able to effectively control SpO2 for patients admitted with an exacerbation of COPD. O2matic was significantly better than manual control to maintain SpO2 within target interval and to reduce time with unintended hypoxemia.
Keywords: closed-loop; hyperoxia; hypoxia; oxygen saturation; oxygen therapy.