Using the forced oscillation technique to evaluate bronchodilator response in healthy volunteers and in asthma patients presenting a verified positive response.
OBJECTIVE
To use the forced oscillation technique to evaluate asthma patients presenting positive bronchodilator responses (confirmed through spirometry) and compare the results with those obtained in healthy individuals.


METHODS
The study sample consisted of 53 non-smoking volunteers: 24 healthy subjects with no history of pulmonary disease and 29 asthmatics presenting positive bronchodilator response, as determined through analysis of spirometry findings. All of the subjects were submitted to forced oscillation technique and spirometry immediately before and 20 minutes after the administration of salbutamol spray (300 g). The parameters derived from the forced oscillation technique were total respiratory resistance, total respiratory reactance, resistance extrapolated to the y axis, the slope of resistance, and dynamic compliance. The parameters measured in the spirometry evaluation tests were forced expiratory volume in one second and forced vital capacity.


RESULTS
In the control group, bronchodilator use produced a significant alteration in the resistance extrapolated to the y axis (p < 0.001), although no significant differences were observed in the slope of resistance or in dynamic compliance. Analysis of the asthma patients revealed significant differences between the prebronchodilator and postbronchodilator values for all spirometry and forced oscillation technique parameters. Values of p < 0.001 were obtained for all comparisons between the two groups.


CONCLUSIONS
The modifications provoked by use of the forced oscillation technique were in direct concordance with the pathophysiology of the bronchodilator response in asthma patients, indicating that the forced oscillation technique could be useful as a complement to spirometry in these patients.
Cavalcanti
Juliana Veiga
JV
Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil. julianaveiga@hotmail.com
Lopes
Agnaldo José
AJ
Jansen
José Manoel
JM
de Melo
Pedro Lopes
PL
D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000494:pharmacology*; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D013147:Spirometry; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology
D001993:Bronchodilator Agents; D000420:Albuterol