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No paradoxical bronchodilator response with forced oscillation technique in children with cystic fibrosis
J Hellinckx1, K De Boeck, M Demedts
1Department of Pediatrics, University Hospital Gasthuisberg, Leuven, Belgium.
Insights
The forced oscillation technique (FOT) shows potential for evaluating bronchodilator response in cystic fibrosis (CF) patients, but cannot replace spirometry. FOT can help assess airway diameter changes in CF.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Medical Technology Assessment
Background:
- Cystic Fibrosis (CF) is a genetic disorder affecting lung function.
- Assessing airway obstruction and bronchodilator response in children with CF is crucial.
- The forced oscillation technique (FOT) offers an alternative method for lung function assessment.
Purpose of the Study:
- To evaluate the utility of the forced oscillation technique (FOT) in children with cystic fibrosis (CF).
- To assess the effectiveness of beta2-agonists in modifying airway diameter in CF patients using FOT.
- To compare FOT measurements with traditional spirometry in this population.
Main Methods:
- Pulmonary function tests including spirometry, body plethysmography, and FOT were performed.
- Measurements were taken before and after albuterol (salbutamol) inhalation in 20 stable CF patients.
- Key parameters assessed included FEV1, airway resistance (Raw), and respiratory system resistance and reactance at 6 Hz (Rrs6, Xrs6).
Main Results:
- Baseline FEV1, Raw, and Rrs6 showed poor correlation with each other.
- After bronchodilator, significant decreases in Raw (-16%) and Rrs6 (-16%) were observed.
- While FEV1 showed minimal change, FOT parameters indicated bronchodilation in most patients, with some exhibiting paradoxical FEV1 decreases.
Conclusions:
- Forced oscillation technique (FOT) measurements are not a substitute for baseline spirometry in CF.
- FOT can provide valuable insights into the effects of beta2-agonists on airway diameter in CF.
- Integrating FOT into the evaluation of bronchodilator response in CF is recommended.
Study Objectives:
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.
Design:
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.
Setting:
The study was set up at a university hospital with a CF population of 125 children and adolescents.
Patients:
Data were collected on 20 patients in stable condition able to perform the three lung function tests.
Measurements 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 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.