Vasodilation from Sufentanil in Humans

Sufentanil is a potent opioid that occasionally has been associated with hypotension. The mechanism behind this hypotension is unclear. We hypothesized that sufentanil had a direct effect on vascular smooth muscle to cause vasodilation. Sufentanil was infused into the brachial artery of 10 young, healthy volunteers at rates of 0.083, 0.167, 0.333, and 0.833 microg/min. Forearm blood flow was measured in both the experimental and control arms with venous occlusion plethysmography. The forearm blood flow in the infused arm increased in a dose-dependent fashion from 3.2 to 5.2 mL/min per 100 mL of tissue whereas simultaneous measurements in the control (non-infused) arm did not increase. Heart rate and mean arterial blood pressure were unchanged during the infusions. Furthermore, respiratory rate did not change at any infusion level and sedation did not occur. Thus, the data support that significant systemic "spillover" of sufentanil did not occur. We conclude that sufentanil has a direct, vasodilatory effect on human vascular tissue that is likely independent of a neurogenic or systemic mechanism.