Oxygen saturation as a marker for admission or relapse with acute bronchospasm

Oxygen saturation (SaO2) as measured by pulse oximetry was evaluated as a means of complementing or supplementing peak expiratory flow rate (PEFR) for early identification of the adult patient needing prolonged therapy for acute bronchospasm. SaO2 was recorded at baseline and at the time of peak drop after initial bronchodilator therapy for 28 patient visits. PEFR was recorded at baseline and at 15 minutes after initial bronchodilator therapy. Potential admission criteria based on these parameters were compared to patients actually admitted or returned within 72 hours (prematurely discharged). Mean patient age was 36 +/- 16.8 years. Mean baseline SaO2 was 95.4 +/- 2.3% (92 to 100%) and SaO2 at the peak drop after the first bronchodilator therapy was 91.9 +/- 3.0% (86 to 97%). Of the criteria evaluated, the following had a significant correlation with admission or premature discharge: baseline PEFR less than or equal to 100 L/min (P = .017); PEFR after first bronchodilator therapy less than or equal to 160 L/min (P less than .0004); the combination of a baseline PEFR less than or equal to 100 L/min with an improvement in PEFR less than or equal to 100 L/min (P less than .0003); and the combination of baseline SaO2 less than or equal to 95% with an improvement in PEFR less than or equal to 100 L/min (P = .0017). As isolated variables, SaO2 at baseline and SaO2 at peak drop following bronchodilator therapy were not useful predictors of outcome, although patients severely hypoxemic at presentation were not evaluated.