Am. J. Respir. Crit. Care Med., Vol 151, No. 2, 02 1995, 378-383.
The effects of oxygen and dopamine on renal and aortic blood flow in chronic obstructive pulmonary disease with hypoxemia and hypercapnia
TQ Howes, CR Deane, GE Levin, SV Baudouin and J Moxham
Department of Thoracic Medicine, King's College School of Medicine and Dentistry, London, United Kingdom.
Renal blood flow is reduced in patients with chronic respiratory failure
caused by chronic obstructive pulmonary disease (COPD), and changes in
renal hemodynamics are likely to be important in the pathogenesis of the
edematous state of cor pulmonale. We therefore examined the hypothesis that
this renal vasoconstriction is reversible by comparing the effects of
oxygen therapy and the renal vasodilator dopamine on renal hemodynamics in
both hypoxemic patients with COPD and those who were also hypercapnic. We
assessed renal hemodynamics noninvasively with color-flow Doppler
ultrasound. In order to validate the technique we recorded renal
hemodynamics in a group of healthy volunteers before and during a dopamine
infusion, and in a subgroup we simultaneously measured effective renal
plasma flow (ERPF) with para- aminohippurate clearance. In the healthy
volunteers there was a 22.5% rise in time-adjusted mean arterial velocity
(Tamx) measured by Doppler compared with a 22% rise in ERPF with dopamine.
This rise was significant (p < 0.05). In hypoxemic, normocapnic subjects
Tamx rose by 25% with oxygen (p < 0.005), 20% with dopamine (p <
0.005), and 24% with both therapies. There was no significant change in
aortic flow whether the subjects received air, oxygen, or dopamine (p =
0.77). In the hypercapnic patients there was no significant change in
aortic or renal velocities while receiving oxygen or dopamine (p = 0.85 and
0.86). We conclude that color-flow Doppler velocity measurements can
accurately detect changes in renal blood flow. Oxygen and dopamine are
equipotent renal vasodilators in hypoxic COPD, but the effect is not
additive.(ABSTRACT TRUNCATED AT 250 WORDS)
