Chest
Volume 119, Issue 4, April 2001, Pages 1073-1078
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Clinical Investigations: Cystic Fibrosis
Prolonged Oxygen Kinetics During Early Recovery From Maximal Exercise in Adult Patients With Cystic Fibrosis

https://doi.org/10.1378/chest.119.4.1073Get rights and content

Study objectives

To explore the significance of oxygen kinetics during early recovery after maximal cardiopulmonary exercise testing (CPET) in the assessment of functional capacity and severity of the disease in cystic fibrosis (CF) patients.

Participants

Eighteen patients with CF (9 male/9 female; mean ± SD age, 23 ± 13 years) and 11 healthy subjects (3 male/8 female; mean age, 29 ± 4 years) underwent maximum CPET on a treadmill. Breath-by-breath analysis was used for measuring oxygen consumption ( V˙o2), carbon dioxide production, and ventilation. Maximum V˙o2 ( V˙o2peak) and the first-degree slope of V˙o2 decline during early recovery ( V˙o2/t-slope) were calculated. To assess the severity of the disease, we used standard indexes like FEV1 (% predicted), V˙o2peak, and a widely accepted system of clinical evaluation, the Schwachman score (SS).

Results

V˙o2/t-slope was significantly lower in CF patients compared to healthy subjects (0.61 ± 0.31 L/min/min vs 1.1 ± 0.13 L/min/min; p < 0.01) and was closely correlated to FEV1(r = 0.90, p < 0.001), V˙o2peak (r = 0.81, p < 0.001), and the SS (r = 0.81, p < 0.001). The multivariate analysis showed that the only independent predictor of the SS is the V˙o2/t-slope.

Conclusion

We conclude that in CF patients, the prolonged oxygen kinetics during early recovery from maximal exercise is related to the disease severity.

Section snippets

Subjects

This study involved 18 patients with CF (9 male and 9 female; mean ± SD age, 23 ± 13 years) attending the outpatient CF clinic of Athens Chest Hospital and 11 healthy subjects (3 male/8 female; mean age, 29 ± 4 years). All subjects were physically active but were not engaged in regular training. Table 1 lists the characteristics of both groups. All patients were in clinically stable condition and optimally treated at the time of the study. Those with recent pulmonary infection, respiratory

Results

The V˙o2/t-slope was significantly lower in CF patients compared to healthy subjects (0.61 ± 0.31 L/min/min vs 1.1 ± 0.13 L/min/min; p < 0.01), and was closely correlated to FEV1(r = 0.90, p < 0.001; Fig 2), V˙o2peak (r = 0.81, p < 0.001; Fig 3), and SS (r = 0.81, p < 0.001; Fig 4) in CF patients.

The mean values of V˙o2peak of the CF patients were also significantly lower than those of healthy subjects (24.8 ± 7.3 mL/kg/min vs 35.4 ± 7.3 mL/kg/min; p < 0.001). V˙o2peak was

Discussion

Our results showed a significant correlation between the severity of CF and prolonged V˙o2 kinetics during early recovery. The value of the V˙o2/t-slope was significantly lower in CF patients and significantly correlated with FEV1, V˙o2peak, and the SS. The V˙o2peak value of CF patients was also significantly lower than that of healthy subjects. The sample of patients included a 61-year-old woman; there was no difference in the result when the analysis was performed with or

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