Detection and early treatment of exacerbations in children with cystic fibrosis (CfEx) is essential to avoid lung damage. Respiratory rate (RR) is an important early marker of respiratory deterioration, but is often inaccurately recorded. We have validated a technique to derive RR from a pulse oximeter plethysmogram (pleth) trace recorded in the home1. CLIMB-CF was a multicentre study examining feasibility of home monitoring of biomarkers using a mobile app2. At one site we asked patients to record daily 2-minute pleth traces, and we analysed these to derive RR during clinical stability and during a CfEx.
12 children collected pleth data over 6 months. During clinical stability in month 1, pleth traces were recorded on median (range) 89 (36-96)% of days, RR was mean (SD) 26 (3), with mean (SD) intra-subject CV 12(5)%. Over months 2 to 6, 7 children required a course of oral antibiotics: in 5 there was no change in RR relative to baseline variability, while in 2 there was a rise in RR (to 34/min and 35/min respectively) prior to starting antibiotic. 4 children required intravenous antibiotics (IVAb). In two children these were elective IVAb, not associated with increased symptoms, and no increase in RR was observed. Two children had unplanned IVAb associated with increased symptoms: in both cases there was a rise in RR (to 35/min and 36/min respectively) prior to starting IVAb.
These initial observations suggest that home monitoring of RR using this technique is feasible, and may help in early detection of CfEx. Further work with a larger sample is needed to assess whether it adds value to standard clinical assessment
1. Seddon P et al Arch Dis Child 2018;103:603-5
2. Edmondson C et al J Cyst Fibros 2022;21:70-7