Repetitive hemodilution in chronic obstructive pulmonary disease and pulmonary hypertension: effects on pulmonary hemodynamics, gas exchange, and exercise capacity.
BACKGROUND
In cor pulmonale associated with severe chronic obstructive pulmonary disease (COPD), disturbances of pulmonary microcirculation may contribute significantly to hypoxemia, pulmonary hypertension, and exercise intolerance.


OBJECTIVE
It was tested whether reduction of blood viscosity induced by repetitive hemodilution might improve pulmonary hemodynamics and oxygen uptake.


METHODS
Seven patients with stable COPD (forced expiratory volume in 1 s 33 +/- 3 % of predicted, means +/- SE) and pulmonary hypertension were phlebotomized 5-6 times over a period of 3 months with substitution of 6% hydroxyethyl starch (molecular weight 40, 000). This resulted in a stepwise reduction of the hematocrit from 53.3 +/- 2.6 to 45.8 +/- 3.1% and a reduction of whole blood viscosity from 9.8 +/- 0.6 to 8.8 +/- 0.7 mPa x s at a shear rate of 2.0 s-1. Before and after the treatment period, patients underwent cardiopulmonary exercise testing and right heart catheterization.


RESULTS
Mean pulmonary artery pressure (PAm) decreased from 30 +/- 3 to 22 +/- 2 mm Hg and arterial oxygen partial pressure (PaO2) increased from 63.2 +/- 2.2 to 71.8 +/- 3.7 mm Hg at rest. During peak exercise, PAm decreased from 59 +/- 7 to 53 +/- 7 mm Hg and PaO2 increased from 54.0 +/- 5.7 to 63.2 +/- 2.4 mm Hg after hemodilution. Peak oxygen consumption rose from 573 +/- 84 to 750 +/- 59 ml x min-1, corresponding to an increase in cardiac index from 4.25 +/- 0.5 to 5.88 +/- 0.76 liters x min-1 x m-2. Pulmonary vascular resistance fell from 345 +/- 53 to 194 +/- 32 dyn x s x cm-5. The patients' peak exercise capacity increased from 9.2 +/- 2. 0 before to 13.5 +/- 3.2 kJ at the end of the study (p < 0.05 for all differences, paired t test).


CONCLUSIONS
The findings suggest that a prolonged improvement of pulmonary microcirculation by reducing blood viscosity may improve pulmonary gas exchange, central hemodynamics, and exercise tolerance in patients with severe COPD and pulmonary hypertension.
Borst
M M
MM
Department of Cardiology, Pneumology, and Angiology, Heinrich Heine University Medical Centre, Düsseldorf, Germany. mathias_borst@ukl.uni-heidelberg.de
Leschke
M
M
König
U
U
Worth
H
H
D000368:Aged; D001682:Biological Availability; D001809:Blood Viscosity / Q000502:physiology; D015444:Exercise / Q000502:physiology; D005260:Female; D006400:Hematocrit; D006438:Hemodilution; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D008137:Longitudinal Studies; D008168:Lung / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010807:Physical Endurance / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D012189:Retrospective Studies
D010100:Oxygen