How Long Does it Take Phentolamine to Reverse Adrenaline Induced Vasoconstriction in the Finger? A Prospective Randomized Blinded Study

            Twenty two subjects, including 18 certified hand surgeons, were injected with 1.8cc of 2% lidocaine with 1:100,000 adrenaline in three places in one finger of each hand. One hour later, the same sites of one hand were injected with phentolamine (1mg in 1cc), and the other hand was injected with saline. Subjects were blinded as to which hand received the phentolamine. It took and average of one hour and twenty-five minutes for adrenaline injected fingers to return to normal color after phentolamine injection. It took and average of five hours and twenty minutes for adrenaline injected fingers to return to normal color after saline injection (no phentolamine). We also observed that lidocaine with adrenaline provided an average of 9 hours and 9 minutes of anesthesia in non phentolamine injected fingers. Phentolamine consistently and reliably reversed adrenaline induced vasoconstriction in the finger.

Figure 1. Each hand was injected in 3 sites with 1.8cc of 2% lidocaine with 1:100,000 adrenaline. One hour later each 3 sites of one hand were injected with 1mg (1cc) of phentolamine, and the other hand 3 sites received 1cc of saline.