Pulmonary hypertension (PH) is a well-recognized complication of chronic obstructive pulmonary disease (COPD). The impact of PH on exercise tolerance is largely unknown. We evaluated and compared the circulatory and ventilatory profiles during exercise in COPD-patients without PH, with moderate PH and with severe PH.
METHODS:Forty-seven patients, GOLD-stages II-IV, underwent cardiopulmonary exercise testing and right heart catheterisation at rest and during exercise. Patients were divided into three groups based on mean pulmonary artery pressure at rest: no PH (mPAP<25 mmHg), moderate PH (mPAP 25-39 mmHg) and severe PH (mPAP≥40 mmHg). Mixed venous oxygen saturation (SvO(2)) was used for evaluating the circulatory reserve. Arterial carbon dioxide tension (PaCO(2)) and the calculated breathing reserve were used for evaluation of the ventilatory reserve.
RESULTS:Patients without PH (n=24) had an end-exercise SvO(2) of 48±9%, an increasing PaCO(2) with exercise and a breathing reserve of 22±20%. Patients with moderate PH (n=14) had an exercise SvO(2) of 40±8%, an increasing PaCO(2) and a breathing reserve of 26±15%. Patients with severe PH (n=9) had a significantly lower end- exercise SvO(2) (30%±6), a breathing reserve of 37±11% and an absence of PaCO(2) accumulation.
CONCLUSION:Patients with severe PH showed an exhausted circulatory reserve at the end of exercise. A profile of circulatory reserve in combination with ventilatory impairments was found in COPD-patients with moderate PH or no PH. The results suggest that pulmonary vasodilation might only improve exercise tolerance in COPD patients with severe PH.
Authors: Boerrigter BG, Bogaard HJ, Trip P, Groepenhoff H, Rietema H, Holverda S, Boonstra A, Postmus PE, Westerhof N, Vonk-Noordegraaf A
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