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Increased variability of forced oscillation technique seen in asthmatic children
School-aged children with asthma had increased day-to-day variability of forced oscillation technique, relating to disease severity and symptom control, compared with healthy children in a recent study.
Researchers in Australia studied 22 children (mean age, 10.5 years; 17 males) who were attending a 5-day camp for children with asthma. Day-to-day variability in forced oscillation technique (FOT) respiratory system resistance (Rrs) and respiratory system reactance (Xrs) was compared with peak expiratory flow. On each test, FOT was performed at 6 Hz in triplicate. The researchers reviewed daily FOT variability (within-subject standard deviation [SDW]) relationships with asthma control and severity based on Global Initiative for Asthma recommendations.
A separate cohort of 38 healthy children (mean age, 9.5 years; 18 males; controls) had normal baseline FOT values and variability measured on two occasions.
Persistent asthma (n=16) had greater day-to-day Rrs variability vs. intermittent (n=6) asthma (mean SDW=0.69 cm H2O/L/second vs. 0.39 cm H2O/L/second; P≤.01).
“Day-to-day Rrs variability was increased in uncontrolled (n=13) vs. partly controlled asthma (n=9; mean SDW=0.75 cm H2O/L/second vs. 0.42 cm H2O/L/second; P≤.05),” the researchers wrote. “PEF variability did not differentiate the groups.”
Children with asthma had a day-to-day variability of Rrs and Xrs but not baseline values compared with controls (Rrs mean SDW=0.61 cm H2O/L/second vs. 0.33 cm H2O/L/second [P≤.05]; Xrs mean SDW=0.24 cm H2O/L/second vs. 0.15 cm H2O/L/second; [P≤.05]).
“Day-to-day variability of Rrs in school-aged children with asthma is related to both disease severity and symptom control and is greater than that observed in healthy children,” the researchers concluded. “These findings, combined with low variability of Rrs in healthy, school-aged children, suggest potential utility of daily FOT measurement in pediatric asthma management. Future studies are needed to confirm these relationships in the home setting.”
Disclosure: See the study for a full list of relevant financial disclosures.