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) and carbon dioxide tension (P_tCO2) 20 min before, during, and 10 min after each treatment.

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.