Pulse oximetry and peak expiratory flow rate correlations in acute asthma exacerbation in children

Background: The relationship between oxygen saturation (SpO2) and peak expiratory flow rate (PEFR) in patients with acute asthma is variable. Aim: This study aims to assess the predictive value and correlation of this relationship in identifying children with mild symptoms of asthma exacerbation and defining their role in guiding early intervention decision-making. Patients and Methods: This was a retrospective review of the register of children with asthma seen at the respiratory clinic of a tertiary center in Nigeria from April 2014 to February 2020. Information on their biodata, medical history, clinical status, baseline SPO2, and %predicted PEFR was retrieved and analyzed. Results: The mean values for participants with no symptoms and those with mild symptoms of asthma exacerbation were respectively: SpO2 was 97 ± 1.6% and 96 ± 2.6% (MD: 1.2; 95% CI; 0.7–1.7, P < 0.001); %predicted PEFR: 77.8 ± 17.8 and 64.1 ± 23 (MD; 13.68; 95% CI; 7.3 to 20.0, P < 0.001). Among those with uncontrolled asthma who were having mild symptom exacerbation of their asthma, the correlation between SpO2 and %predicted PEFR was significantly moderate (r = 0.44, P = 0.04). Children with SpO2 between the range of 92%–95% were significantly more likely to have mild symptoms of asthma exacerbation (OR: 2.52,95% CI: 1.22, 5.2, P = 0.01) compared to those with SpO2 >95%. Conclusion: Children with SpO2 of <95% are more likely to have an acute asthma exacerbation. While SpO2 and PEFR have more role in identifying children without acute asthma exacerbation and a limited role in identifying children with mild symptoms of asthma due to their exacerbation due to their moderate to poor correlation.