Prolonged slow expiration technique (PSET) chest physiotherapy technique: alterations in lung mechanics in wheezing infants

Introduction: Chest physiotherapy techniques may assist in the removal of airways secretions. Infants suffering from pulmonary infections can be benefit from these techniques. A limited number of studies has already evaluated the efficacy of these techniques in children. Lung function measurements could improve the evaluation of such techniques. Prolonged slow expiration technique (PSET) is a passive physiotherapy technique used for the removal of expectorated secretions in infants. Although widely employed, some doubts remain regarding its effectiveness. Objective: To evaluate changes in respiratory parameters during and after the performance of PSET in infants, including expiratory reserve volume (ERV), passive respiratory mechanics and the presence of sighs. Methods: Infants attending the Infant Pulmonary Function Testing Laboratory (UNIFESP) for lung function testing participated in the study. Infants under two years of age and with history of recurrent wheezing were chosen for the study. Infants suffering from gastric reflux disease or recovering from abdominal or thoracic surgery were excluded. Infants were sedated with chloral hydrate (60 – 80 mg/Kg, orally). Measurements were performed during sleep, after sedation, with a mask sealed adapted to the child’s face and connected to a pneumotachometer. Several parameters from normal breathing (peak expiratory flow [PEF], tidal volume [TV], respiratory rate [RR]) and from passive respiratory mechanics (compliance, resistance and time constant of respiratory system) were recorded before, during and after the PSET. Three thoracic compressions (PSET), executed to prolong the expiratory phase, were carried out: A, B and C. Increase in TV over 100% was considered sighs, before, during or immediately after the PSET. Raised volume rapid thoracic compression technique was performed at the end of the test to measure ERV. Results: 18 infants were evaluated. Their mean age was 32,3 ± 11,4 weeks and they had, on average, 4,8 ± 1,9 previous wheezing exacerbations. After PSET, significant changes were observed for TV (79,3 ± 15,6 ml vs 82,7 ± 17,2 ml; p = 0,009) and for RR (40,6 ± 6,9 bpm vs 38,8 ± 5,9 bpm; p = 0,042). PEF and passive respiratory mechanics parameters did not change significantly after the PSET. An expressive reduction in TV was measured during PSET compressions (82,3 ±16,5 ml vs 48,5 ± 10,8 ml; p 0,05). Durante a realização da ELPr, observamos redução do VC: de 82,3 ± 16,5 ml para 48,5 ± 10,8 ml (p < 0,001). Houve maior frequência de suspiros durante a realização da ELPr, comparada à fase sem realização da mesma (p = 0,035). Houve maior eliminação no VRE a cada compressão realizada (32 ± 17,8% na sequência A, 40,9 ± 23,9% na B e 53 ± 19,6% na C; p = 0,035). Conclusões: confirmamos algumas suposições sobre a ELPr em lactentes sibilantes, aumenta o VC e reduz a freqüência respiratória ao final da sua realização. Não há aumento no PFE, confirmando ser técnica lenta. O VC é reduzido durante a ELPr. Predispõe a indução de suspiros. O VRE a cada compressão foi quantificado e é mais exalado quanto mais compressões sucessivas forem realizadas.TEDEBV UNIFESP: Teses e dissertaçõe