COMPLICATIONS after DPNB Dorsal penile nerve block: “An accidental injection of epinephrine” MadhanKumar Sathyamoorthy1 MBBS,MS , Jerrold Lerman1,2 MD, FRCPC, FANZCA, James Foster1,2 MD, Doron Feldman1,2 MD From the Departments of Anesthesia1 , Women and Children’s Hospital of Buffalo and SUNY at Buffalo, and University of Rochester2, Rochester, New York CASE REPORT A 7yr old boy was scheduled for circumcision for phimosis. He weighed 39 kg, gave a history of seizures and an innocent heart murmur. His medications included tegretol. He had no drug allergies. The anesthetic plan included general anesthesia, an LMA and a dorsal penile nerve block (DPNB) for post op pain control. After induction of anesthesia, a DPNB was performed using a 2 inch 25G needle by piercing the penile fascia (Buck’s fascia) just below the pubic symphysis on either side of midline. After negative aspiration for blood, a total of 10 mL of 0.25% bupivacaine with epinephrine (1:200,000) was injected. Upon completion of the block, a medication error was immediately recognized and the surgeon was informed. Plain bupivacaine had been the intended solution for the block, but bupivacaine with epinephrine was used. The surgery proceeded while the child was monitored closely both intraoperatively and postoperatively until discharge. The block seemed effective as the child required only one dose of 4 mg morphine intra-operatively and none postoperatively. There was no evidence of hypo perfusion or ischemia of the penis or overlying skin at the time of discharge from hospital 6 h after surgery. At the follow-up urology appointment one week later, the surgical wound appeared normal and there was no evidence of tissue or penile damage. DISCUSSION This case report discusses the following issues. 1.Ischemic complications associated with DPNB 2.Use of epinephrine is contraindicated in end arteries…Myth or Fact? 3.Management of ischemia after an inadvertent injection of epinephrine around an end artery . COMPLICATIONS after DPNB There are few case reports of ischemic complications associated with the accidental use of epinephrine in DPNBs. In a 2 day old infant, transient ischemia occurred after an inadvertent injection of 1:1000 epinephrine in a DPNB.1 Gangrene of the skin of the glans has been reported after a DPNB after DPNB with a plain solution of 0.5% bupivacaine in two children.2 Gangrene was attributed to pressure effect from a hematoma. Transient ischemia of the glans penis has also been reported after DPNB with 0.75% ropivacaine.3 In contrast to the other amide local anesthetics, concentrated plain ropivacaine has vasoconstrictive properties. USE OF EPINEPHRINE IS CONTRAINDICATED IN END ARTERIES…IS IT MYTH OR FACT?  A review of the literature from 1880 to 2000 revealed 21 cases of digital gangrene after local anesthetic blocks that included epinephrine. Of those, 17 involved an unknown concentration of epinephrine that was based on manual dilution. 18 cases involved procaine and 2 with cocaine. None of the cases involved lidocaine with epinephrine. Multiple other concurrent treatments or medical conditions (hot soaks, tight tourniquets, and infection) existed in these case reports, precluding determining the exact cause of the gangrene.4 Epinephrine is rapidly metabolized in plasma by catecholamine O-methyl transferase and monoamine oxidase. Its half-life in plasma is only 1.7 minutes. Catecholamines preferentially vasoconstrict shunt blood flow in the skin, whereas they vasoconstrict nutrient circulation to a much lesser degree.  When epinephrine was injected into rabbit ear flaps with an end-artery, concentrations of 1/200,000 and 1/100,000 , produced no damage, although 1/50,000 concentration did cause tissue necrosis. Similar studies in human flaps have not been conducted.5 Color Doppler studies have demonstrated low-flow, not no-flow after epinephrine was injected as around a digital nerve in fingers.6 .   TREATMENT A number of treatments have been used successfully in previous case reports to manage ischemia following an accidental injection of epinephrine into an end-artery organ. 1.Phentolamine (1 mg/mL) subcutaneously at the same sites as the epinephrine had been injected7 2.Sympathetic block via an epidural or caudal block1 3.Intravenous infusion of iloprost (a PGI 2 analogue)3 CONCLUSION Epinephrine in concentrations <1:100,000 with local anesthetic has been used in digital nerve blocks in hand surgery without side effects where it provides benefits including surgical hemostasis, avoiding need for a tourniquet and additional anesthesia. These concentrations of epinephrine need to be studied in DPNB to determine the risk/benefit ratio. Ischemic complications from use of epinephrine can be successfully reversed with phentolamine.. REFERENCES 1. Berens R, Pontus SP. A complication of circumcision and dorsal penile nerve block of the penis. Reg Anesth Pain Med 1990;15:309-310 2. Sara CS, Lowry CJ. A complication of circumcision and dorsal nerve block of the penis. Anaesth Intens Care 1984;13:79-85 3. Burke D, Joypaul V, Fyffe M. Circumcision supplemented by dorsal penile nerve block with 0.75% ropivacaine: a complication. Regional Anesthesia and Pain Medicine 2000;25:424–7 4. A Comprehensive Review of Epinephrine in the Finger: To Do or Not to Do. Denkler K. Plastic & Reconstructive Surgery 2001;108:114-24 5. Hormozi AK, Zendehnam H, Hosseini SN, Rasti M, Rostami K, Hamraz H Epinephrine's effect in varying concentrations on the end artery organ in an animal model. J Coll Physicians Surg Pak. 2010;20:90-2 6. Altinyazar HC, Ozdemir H, Koca R, et al. Epinephrine in Digital Block: Color Doppler Flow Imaging. Dermatologic Surgery 2004;30:508–511 7. Heard C.M.B., et al. "An accidental ringblock of the great toe?” Pediatr Anesth 2001;11:123-123