A randomized crossover study of sputum induction by physiotherapy and hypertonic saline techniques in asthmatic children

Background: Hypertonic saline (HS) is widely used on sputum induction (SI). However, in some asthmatic children, this induction is difficult. Physiotherapy (P) can solve the disadvantages of HS and facilitate the collection of mucus by applying specific techniques and maneuvers. Aims: To analyze whether physiotherapy is efficient in sputum induction and in evaluation of pulmonary inflammation in asthmatic children. Methods: We collected 90 samples from 30 children (7-18 years old) with well or partly controlled asthma from “Children’s Institute of the Clinical Hospital–University of Sao Paulo”. They performed spirometry and were underwent to a randomized crossover study for SI by 3 techniques: 1) hypertonic saline (3%)–HS; 2) physiotherapy (oscillatory positive expiratory pressure, forced expiration and acceleration of expiratory flow)–P; 3) hypertonic saline+physiotherapy–HSP. Data were analyzed by repeated measures analysis of variance (RM ANOVA). Results: Total cells (mL) and the percentage (%) of (macrophages, neutrophils, lymphocytes and eosinophils) had the same inflammatory profile in all techniques. The sputum weight (mg) in HSP were higher compared with HS (median) [0.41(0.37-0.46)] vs [0.37(0.19-0.40)], p=0.02. In all techniques the % of viable cells was superior to 50% and there was no difference between HS and P [94.55(84.22-99.55)] vs [80.05(74.25-94.36)]. Moreover, the SI did not cause any alterations on pulmonary function of patients. Conclusion: All techniques were safe when performed in asthmatic children and were useful to study inflammation in these patients. In addition, children were more collaborative and enthusiastic with physiotherapy.