The interrupter technique: feasibility in children in acute asthma.

BACKGROUND: Asthma exacerbation's severity is difficult to evaluate, as it is mainly assessed by clinical parameters. Evaluation of lung function during the acute asthma might provide an objective assessment on the severity of respiratory function impairment.
OBJECTIVE: To determine feasibility of interrupter technique in evaluating respiratory resistance (Rocc) on children with acute asthma
Methods: The study included 30 children aged 3 to 14 years, diagnosed with asthma, during an exacerbation; severity of acute asthma has been assessed according to the GINA classification 2007, evaluating individual parameters like intercostals retractions, wheezing, air entry intensity, as well as their association in a clinical score. For every patient spirometry, peakflowmetry and the interrupter technique was applied for assessing respiratory function. The feasibility rate for each method was calculated and compared with the clinical parameters.
RESULTS: Out of the 30 children examined, the feasibility rate during the attack was 90% for the interrupter technique, 47% for peakflowmetry and only 27% for spirometry. Fifty-three percent of the exacerbations were classified as mild, 30% of moderate intensity and the remaining 37% being classified as severe exacerbations. The baseline Rocc has been correlated with clinical parameters and the clinical severity score. Best correlations were recorded between baseline Rocc and respiratory rate (r=0.73, p<0.0001), Rocc and heart rate (r=0.5, p=0.0076) and Rocc and the clinical score (r= 0.78, p<0.0001).
CONCLUSION: The study shows good feasibility of interrupter technique during asthma exacerbations, as well as strong correlation with clinical parameters assessing severity.