To assess the hemodynamic changes to exercise in patients with COPD and normal control using impedance cardiography (ICG).
We studied 10 COPD patients (FEV1 = 36% predicted) and 5 controls (FEV1 = 90% predicted). Hemodynamic monitoring was done non invasively before and after 6 minute walking test using impedance cardiography byBioZ ® ICG Monitor (Cardio dynamics Inc, San Diego, CA).
The increase in cardiac out put and cardiac index post exercise was only 7% and 8% respectively in COPD patients as compared to normal (34%, p= 0.01). The systemic vascular resistance increased by 1% after exercise in COPD, whereas in normal controls it came down by 16 %. There was no difference in heart rate and blood pressure response.
Ventilatory limitations and cardiac impairment seem to be the cause of limited exercise capacity in COPD. Possible explanations, such as dynamic hyperinflation with intra-thoracic pressures limiting cardiac contractility and stroke volume and/or decreased pulmonary vascular capacitance remain to be explored.
Limitation of exercise capacity in COPD patients is thought to be due to a decreased ventilatory reserve. Based on our data, the role of the cardiovascular system may be more important in exercise limitation than previously thought. Pre ExerciseCOPDControlp ValuePost ExerciseCOPDControlp ValueCO5.365.42.29CO5.727.24.04*CI2.913.12.07CI3.154.18.01*SVR14991313.32SVR16691107.19HR8378.89HR93108.29VAS3.90.002*VAS7.43.8.001*MAP9793.47MAP111102.896M walk976 ft2167 ft.01*
G. Hoskere, None.