No paradoxical bronchodilator response with forced oscillation technique in children with cystic fibrosis.
OBJECTIVE
The aim of the present study was to evaluate the forced oscillation technique (FOT) in cystic fibrosis (CF) children and to participate in the discussion about the usefulness of beta2-antagonists in CF.


METHODS
Pulmonary function was measured with spirometry, body plethysmography, and FOT before and after inhalation of 200 microg of albuterol (salbutamol). The following were collected: vital capacity (VC), FEV1, FEV1/VC, airway resistance (Raw), thoracic gas volume, respiratory system resistance (Rrs) and respiratory system reactance (Xrs) at 6 Hz (Rrs6 and Xrs6), and resonance frequency.


METHODS
The study was set up at a university hospital with a CF population of 125 children and adolescents.


METHODS
Data were collected on 20 patients in stable condition able to perform the three lung function tests.


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 FEV1. The relationship between FEV1 and Raw or Rrs6 was poor. Xrs6 and FEV1/VC correlated weakly (r=0.56; p < 0.05). After bronchodilator administration, 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 was never found; in two patients, an increase of Raw of < 10% was found. In 13 patients, the decrease of Rrs6 was > 12%.


CONCLUSIONS
The results suggest that FOT measurements cannot replace baseline spirometric measurements in CF, but that the evaluation of the effect of beta2-agonists on the airway diameter in CF should include an FOT measurement.
Hellinckx
J
J
Department of Pediatrics, University Hospital Gasthuisberg, Leuven, Belgium.
De Boeck
K
K
Demedts
M
M
D000280:Administration, Inhalation; D000293:Adolescent; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000403:Airway Resistance / Q000187:drug effects; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D002648:Child; D003550:Cystic Fibrosis / Q000188:drug therapy / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D010993:Plethysmography, Whole Body; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests / Q000379:methods*; D013147:Spirometry / Q000379:methods; D014797:Vital Capacity / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D000420:Albuterol