Bronchodilator response in wheezing infants assessed by the raised volume rapid thoracic compression technique

BACKGROUND

Bronchodilator response (BDR) analyzed by the raised volume rapid thoracic compression (RVRTC) in wheezing infants is not yet well described, although bronchodilators (BD) are routine in the treatment of this population.

OBJECTIVE

To evaluate BDR by RVRTC technique in infants with recurrent wheezing and compare to control group.

METHOD

Cross sectional study, 45 infants, age 56 weeks (38-67 weeks). Two groups: wheezing group (WG: history of recurrent wheezing) and control group (CG). RVRTC was evaluated, FVC, FEV_0.5, FEF₅₀, FEF₇₅, FEF_85, FEF_25-75 were measured. Salbutamol was delivered to infants and RVRTC evaluated again. BDR was determined by the increase greater than two standard deviation from the mean change in the CG.

RESULTS

In WG (n = 32) lung function was worse than in CG (n = 13): FEV_0.5: 0.0(-0.9-0.9z score) vs 0.8(0.2-1.4z score); FEF₅₀: 0.2(-0.3-1.1z score) vs 0.9(0.5-1.4z score); and FEF_25-75: 0.2(-0.5-1.1z score) vs 1.1(0.6-1.6z score), respectively, p < 0.05. Both groups had similar increase after BD. In WG 11 patients (34%) were responder and these had worse lung function compared to nonresponder (n = 21) (p < 0.05). The increase in lung function after BD in responder was higher than in nonresponder: FEV_0.5: 6.5(2.1-7.1%) vs -0.5(-2.5-0.7%), FEF₅₀: 5.1(2.7-11.7%) vs 0.4(-1.1-2.8%), FEF₇₅: 20.7(4.7-23.6%) vs -1.3(-6.4-3.9%), FEF_25-75: 9.9(3.8-16.4%) vs 0.0(-1.5-1.0%), respectively, p < 0.05.

CONCLUSION

34% WG showed BDR measured by the RVRTC. The best variables to detect BDR were FEF₇₅, FEF_25-75 and FEV_0.5. Patients with worse lung function showed better response to BD.