Influence of the incremental step size in work rate on exercise response and gas exchange in patients with pulmonary hypertension

Sven Gläser¹ , Sven Lodziewski¹ , Beate Koch¹ , Christian F Opitz² , Henry Völzke³ and Ralf Ewert¹

¹Division of Cardiology and Pneumology, University of Greifswald, Greifswald, Germany

²Department of Cardiology, DRK-Kliniken Berlin|Westend, Berlin, Germany

³Institute of Epidemiology and Social Science, University of Greifswald, Greifswald, Germany

author email corresponding author email

BMC Pulmonary Medicine 2008, 8:3doi:10.1186/1471-2466-8-3


Published:	23 February 2008

Abstract

Background

Cardiopulmonary exercise testing (CPET) has become increasingly important as a routine procedure in daily clinical work. So far, it is generally accepted that an individualized exercise protocol with exercise duration of 6 to 12 minutes is preferable to assess maximal exercise performance. The aim of this study was to compare an individualized NYHA adapted exercise protocol with a fixed standard protocol in patients with severe pulmonary arterial hypertension.

Methods

Twenty-two patients (17 female, 5 male; mean age 49 ± 14 yrs) underwent symptom limited CPET on a bicycle. On two consecutive days each subject performed a stepwise CPET according to a modified Jones protocol (16 Watt per minute stages) as well as an individualized NYHA adapted protocol with 5 or 10 Watt/min stages in a randomized order. Oxygen uptake at peak exercise (peakVO₂) and anaerobic threshold (VO₂AT), maximal ventilation (VE), breathing reserve (VE/MVV), ventilatory efficiency (VE vs. VCO₂slope), exercise time, maximal power and work rate were assessed and compared between both protocols.

Results

Comparing both, adapted NYHA protocol and standardized Jones protocol, we found significant differences in maximal power (56.7 ± 19 W vs. 74 ± 18 W; p < 0.001) and exercise time (332 ± 107 sec. vs. 248 ± 72 sec.; p < 0.001). In contrast, no significant differences were obvious comparing both protocols concerning work rate, VE, VE/MVV, peakVO₂, VO₂AT and VE vs. VCO₂slope.

Conclusion

Variations of incremental step size during CPET significantly affect exercise time and maximal power, whereas relevant parameters for clinical judgement and prognosis such as oxygen uptake, ventilation and ventilatory efficiency remain unchanged. These findings have practical implications for the exercise evaluation of patients with pulmonary hypertension. To reach maximal results for ventilation, oxygen uptake and gas exchange an individualization of incremental step size appears not to be mandatory.