ABSTRACT
Frequently the blood flow to an area of low is also reduced as a result of hypoxic vaso-constriction. However, the reduction in blood flow often is inadequate to match the reduction in ventilation. Certain vasoactive drugs reduce hypoxic vasoconstriction and cause significant worsening of arterial oxygenation. Inhaled nitric oxide in COPD patients has been shown to increase hypoxemia, as have other systemic vasodilators (nitroprusside).
