• Juliana Veiga Cavalcanti, Agnaldo José Lopes, José Manoel Jansen, and Pedro Lopes de Melo.
• Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil. julianaveiga@hotmail.com
• J Bras Pneumol. 2006 Mar 1; 32 (2): 91-8.

ObjectiveTo 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.MethodsThe 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.ResultsIn 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.ConclusionThe 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.

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