A newer and simpler technique for monitoring children with asthma: Study

Asthma is the most frequent diagnosis for recurrent and chronic cough in children and pulmonary function testing is required for making a diagnosis of asthma. As there is limitation of conventional spirometry in children, researchers from Sir Gangaram hospital, New Delhi found Forced Oscillation Technique(FOT) as a simple and rapid tool for assessment of airway function among asthmatic children.

Spirometry is the gold standard technique for demonstration of airway reversibility, but requirements of technical expertise, patient cooperation, and forceful respiratory efforts are some of the limitations, especially in children and the elderly. FOT is a simple and rapid method, for evaluation of airway resistance and reactance. FOT is based on ultrasonic signal transduction over spontaneous normal tidal breath with requirement of minimal cooperation from the patient hence making it feasible in pediatric population .

There is limited literature available for FOT use especially in children. Dr.Neeraj and his collegues included 345 children aged 2-18 years with history suggestive of asthma in the study and using FOT baseline and postbronchodilator pulmonary functions were assessed. Airway resistance, reactance and resonant frequency(Fres) were monitored and recorded. 400mcg of inhaled corticosteroid was used for bronchodilation in the study.

Upon analysis, it was found that the baseline mean (±SD)values of resistance at wider and narrower airways were 5.23±1.93 and 1.6±1.16cmH2O/L/s respectively. As the enrolled population was dominated by younger children, the baseline peripheral airway resistance contributed significantly (23.3%) to the total airway resistance (R5) and higher mean Fres than the adult values.

Researchers found a median change of 19.9% in total airway resistance after inhaled salbutamol which signifies reversible airflow obstruction. Also central airways showed more reversibility as compared to peripheral airways. Among the parameters reflecting peripheral airway status, median change in reactance was found to be maximum making it more sensitive indicator.

Also respiratory parameters were variable as per height, age and BMI. With increasing height and age a significant reduction was noticed in all respiratory variables. Resonant frequency was more in younger children and showed a reducing trend with advancing age. In the study best negative correlation was observed between all measured variables (resistance,reactance and resonance)with height followed by BMI. There was no gender difference in any of the study parameters.

Authors conclude-"FOT/IOS is a potentially useful and feasible tool for assessment of airway reversibility in children who are unable to perform spirometry"

Source: Gupta N, Sachdev A, Gupta D, Gupta S. Assessment of airway reversibility in asthmatic children using forced oscillation technique - A single-center experience from North India. Lung India. 2021 May-Jun;38(3):229-235. doi: 10.4103/lungindia.lungindia_354_20.