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Hypoxemia and hypercapnia during exercise and sleep in patients with cystic fibrosis


Bradley, S and Solin, P and Wilson, J and Johns, DP and Walters, EH and Naughton, MT, Hypoxemia and hypercapnia during exercise and sleep in patients with cystic fibrosis, Chest, 116 pp. 647-654. ISSN 0012-3692 (1999) [Refereed Article]

DOI: doi:10.1378/chest.116.3.647


Background: In patients with cystic fibrosis (CF), it has been proposed that hypoxemia and hypercapnia occur during episodes of stress, such as exercise and sleep, and that respiratory muscle weakness because of malnutrition may be responsible. Methods: Pulmonary function, respiratory muscle strength, and nutrition were assessed and correlated with the degree of hypoxemia and hypercapnia during exercise and sleep in 14 patients with CF and 8 control subjects. Results: Despite no differences in maximum static inspiratory pressure (PImax) between the two groups, the CF group developed more severe hypoxemia (minimum oxyhemoglobin saturation [Spo2], 89 ± 5% vs 96 ± 2%; p < 0.001) and hypercapnia (maximum transcutaneous CO2 tension [PtcCO2], 43 ± 6 vs 33 ± 7 mm Hg; p < 0.01) during exercise. Similarly, during sleep, the CF group developed greater hypoxemia (minimum Spo2, 82 ± 8% vs 91 ± 2%; p < 0.005), although CO2 levels were not significantly different (maximum PtcCO2, 48 ± 7 vs 50 ± 2 mm Hg). Within the CF group, exercise-related hypoxemia and hypercapnia did not correlate with FEV1, residual volume/total lung capacity ratio (RV/TLC), PImax, or body mass index (BMI). Hypoxemia and hypercapnia during sleep correlated with markers of gas trapping (RV vs minimum arterial oxygen saturation [r = -0.654; p < 0.05]), RV vs maximum PtcCO2 (r = 0.878; p < 0.001), and RV/TLC vs maximum PtcCO2 (r = 0.790; p < 0.01) but not with PImax or BMI. Conclusion: Patients with moderately severe CF develop hypoxemia and hypercapnia during exercise and sleep to a greater extent than healthy subjects with similar respiratory muscle strength and nutritional status. Neither respiratory muscle weakness nor malnutrition are necessary to develop hypoxemia or hyercapnia during exercise or sleep.

Item Details

Item Type:Refereed Article
Research Division:Biomedical and Clinical Sciences
Research Group:Cardiovascular medicine and haematology
Research Field:Respiratory diseases
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Johns, DP (Associate Professor David Johns)
UTAS Author:Walters, EH (Professor Haydn Walters)
ID Code:34540
Year Published:1999
Web of Science® Times Cited:64
Deposited By:Medicine
Deposited On:2005-07-28
Last Modified:2005-07-28

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