NO PARADOXICAL BRONCHODILATOR RESPONSE WITH FORCED OSCILLATION TECHNIQUE IN CHILDREN WITH CYSTIC-FIBROSIS

Study objectives: The aim of the present study was to evaluate the for ced oscillation technique (FOT) in cystic fibrosis (CF) children and t o participate in the discussion about the usefulness of beta(2)-antago nists in CF. Design: Pulmonary function was measured with spirometry, body plethysmography, and FOT before and after inhalation of 200 mu g of albuterol (salbutamol). The following were collected: vital capacit y (VC), FEV1, FEV1/VC, airway resistance (Raw), thoracic gas volume, r espiratory system resistance (Rrs) and respiratory system reactance (X rs) at 6 Hz (Rrs6 and Xrs6), and resonance frequency.Setting: The stud y was set up at a university hospital with a CF population of 125 chil dren and adolescents. Patients: Data were collected on 20 patients in stable condition able to perform the three lung function tests. Measur ements and results: Mean baseline values (+/-SD) were 0.36+/-0.15 kPa/ L/s for Raw, 0.5+/-0.15 kPa/L/s for Rrs6, and 61+/-22% predicted for F EV1. The relationship between FEV1 and Raw or Rrs6 was poor, Xrs6 and FEV1/VC correlated weakly (r=0.56; p<0.05). After bronchodilator admin istration, the mean changes +/-SD in percent of baseline were +3+/-11% for FEV1, -16+/-22% for Raw, and -16+/-9% for Rrs6, In six patients, a paradoxical decrease in FEV1 was measured but an increase in Rrs6 wa s never found; in two patients, an increase of Raw of <10% was found. In 13 patients, the decrease of Rrs6 was >12%. Conclusions: The result s suggest that FOT measurements cannot replace baseline spirometric me asurements in CF, but that the evaluation of the effect of beta 2-agon ists on the airway diameter in CF should include an FOT measurement.