| Abstract: | OBJECTIVE: To evaluate changes in respiratory mechanics and tidal volume (VT) in
wheezing infants in spontaneous ventilation after performing the technique known
as the prolonged, slow expiratory (PSE) maneuver. METHODS: We included infants with a history of recurrent wheezing and who had had no
exacerbations in the previous 15 days. For the assessment of the pulmonary
function, the infants were sedated and placed in the supine position, and a face
mask was used and connected to a pneumotachograph. The variables of tidal
breathing (VT and RR) as well as those of respiratory
mechanics-respiratory system compliance (Crs), respiratory system resistance
(Rrs), and the respiratory system time constant (prs)-were measured before and
after three consecutive PSE maneuvers. RESULTS: We evaluated 18 infants. The mean age was 32 ± 11 weeks. After PSE, there was a
significant increase in VT (79.3 ± 15.6 mL vs. 85.7 ± 17.2 mL; p =
0.009) and a significant decrease in RR (40.6 ± 6.9 breaths/min vs. 38.8 ± 0,9
breaths/min; p = 0.042). However, no significant differences were found in the
variables of respiratory mechanics (Crs: 11.0 ± 3.1 mL/cmH2O vs. 11.3 ±
2.7 mL/cmH2O; Rrs: 29.9 ± 6.2 cmH2O • mL−1 •
s−1 vs. 30.8 ± 7.1 cmH2O • mL−1 •
s−1; and prs: 0.32 ± 0.11 s vs. 0.34 ±0.12 s; p > 0.05 for all).
CONCLUSIONS: This respiratory therapy technique is able to induce significant changes in
VT and RR in infants with recurrent wheezing, even in the absence of
exacerbations. The fact that the variables related to respiratory mechanics
remained unchanged indicates that the technique is safe to apply in this group of
patients. Studies involving symptomatic infants are needed in order to quantify
the functional effects of the technique. |
