Background: Peak expiratory flow rate (PEFR) is used in asthma diagnosis, management and monitoring. Asthma triggers, including hormonal changes during pregnancy can be detected. Electronic PEFR (ePEFR) devices may offer advantages over manual PEFR, including feedback on technique, alerting systems and facilitating remote monitoring. 

Method: We evaluated all patients commenced on ePEFR monitoring at our tertiary centre during 2022. Daily maximum ePEFR values per patient were analysed; evaluating asthma diagnosis, adherence to monitoring, ePEFR technique and patterns during pregnancy. 

Results: N=51 patients were enrolled. N=4 (8.9%) never used the device; 1 (25%) smart device was incompatible, 3 (75%) were non-adherent. Of remaining n=45, n=9 (20%) were pregnant, n=35 (80%) non-pregnant. In n=42 (93%) asthma diagnosis was confirmed with >20% ePEFR variability. Non-pregnant patient mean (std dev) adherence 62.4% (26.3%) compared with pregnant patient mean (std dev) adherence 41.5% (19.6%), p<0.05. Flow volume loops facilitated feedback on ePEFR technique with n=44 (97.8%) achieving adequate technique. N=4 (44%) of pregnant patients developed respiratory symptoms during the third trimester. ePEFR ruled out asthma as a driver in n=4 (100%). 

Conclusions: Our study confirms that ePEFR monitoring is a highly valuable tool in asthma managment, even when adherence is sub-optimal. In pregnant patients it aided differentiation between asthma and pregnancy-related respiratory symptoms, avoiding unnecessary escalation of asthma therapies. In only three individuals ePEFR did not demonstrate significant variability, confirming rare diagnostic limitations to ePEFR.