Immediate changes in blood-gas tensions during chest physiotherapy with positive expiratory pressure and oscillating positive expiratory pressure in patients with cystic fibrosis.

OBJECTIVE To assess and compare immediate effects of chest physiotherapy with positive expiratory pressure (PEP) versus oscillating PEP on transcutaneously measured blood-gas tensions in patients with cystic fibrosis. METHODS Fifteen patients (mean age 12.5 y, range 6.9-21.5 y) participated. The treatments were randomized and performed on 2 separate occasions, 8 weeks apart. Spirometry was conducted before and after each treatment. We transcutaneously measured oxygen tension (P(tO2). RESULTS There were no changes in spirometry values. During PEP, different trends in blood-gas tension were seen, and there were no consistent changes. During oscillating PEP, P(tO2) increased and P(tCO2) decreased. During oscillating PEP, P(tCO2) was lower and the intra-individual change in P(tCO2) was more pronounced than during PEP. The results obtained immediately after oscillating PEP showed a higher P(tO2) and a lower P(tCO2) than with PEP. CONCLUSION PEP and oscillating PEP can both cause transitory effects on blood gases in patients with cystic fibrosis. However, oscillating PEP alters blood-gas tensions more than does PEP, and hyperventilation during oscillating PEP may reduce treatment time.