Exercise capacity in COPD patients with exercise-induced pulmonary hypertension

Area of Science:

• Cardiopulmonary Medicine
• Respiratory Physiology

Background:

• Pulmonary hypertension (PH) in COPD patients reduces exercise capacity.
• Exercise-induced pulmonary hypertension (EIPH) occurs in COPD patients with normal resting pressures but elevated pressures during exercise.
• EIPH is hypothesized to impact exercise capacity and CPET parameters.

Purpose of the Study:

• To determine if COPD patients with EIPH can be identified using CPET.
• To compare exercise capacity and CPET parameters between COPD patients with and without EIPH.

Main Methods:

• Ninety-three COPD outpatients underwent right heart catheterization during rest and exercise.
• EIPH was defined by resting mean pulmonary artery pressure (mPAP) <25 mmHg and a ΔmPAP/ΔCO slope >3 mmHg/L/min.
• CPET and pulmonary function tests were performed; data were analyzed using linear mixed models.

Main Results:

• EIPH was present in 45% of the study population.
• Maximal workload was lower in the COPD-EIPH group.
• COPD-EIPH patients showed greater increases in oxygen uptake, ventilation, heart rate, and lactate, and a greater decrease in pH per unit increase in workload.

Conclusions:

• CPET cannot reliably discriminate between COPD patients with and without EIPH.
• COPD patients with EIPH experience a higher physiological cost for a given workload.
• EIPH is associated with increased cardiorespiratory strain during exercise in COPD.