Safety Profile of Ropivacaine in Dorsal Penile Nerve Block for Male Circumcision: a Large Cohort Study in Children

Overview

Dorsal penile nerve block (DPNB) according to Dalens' technique by using local anesthetics (LAs) is a fundamental part of a multimodal analgesic approach following circumcision. Ropivacaine has a favorable cardiovascular and neurological toxicity profile. However, its application in DPNB is limited because of the theoretical concerns about its vasoconstrictive properties and the potential risks of ischemia of the glans. The aim is to evaluate the incidence of necrosis of the glans penis and the safety profile of ropivacaine following its use in the DPNB in a large pediatric population.

Circumcision is one of the most practiced surgical procedures in childhood causing significant postoperative pain in the infant. Perioperative and postoperative pain management at this age ideally should be managed by a combination of general anesthesia with regional anesthesia techniques such as caudal block, dorsal penile nerve block or subcutaneous ring block of the penis. The dorsal nerves of the penis can be anesthetized at the level of the penile root through different approaches. Kirya and Wertgmann described for the first time dorsal penile nerve block. Since then, many studies have been realized and have been showed its benefits and safety in the clinical use. Ring Blok is also known for its safety and low incidence of complications and has been used primarily for postoperative pain management in circumcision. This block is easy to perform but it has been identified that it has a greater failure compared to the dorsal penile block. In the study of Holder who compares dorsal penile block and ring block, most of the children who has had a ring block also received opioids postoperatively. Implementation of local or regional anesthesia techniques is inevitably associated with risks and complications. For DPNB, this is estimated around 0.18%. Those complications may include urethral injuries, accidental injection of an incorrect drug or drug dose, accidental intravascular injection of local anesthetics, ischial osteomyelitis, hematoma, and ischemia and necrosis of the glans penis. The dorsal nerves of the penis also lies close to de corpora cavernosa and the Buck's fascia. Given the rich vascularized features of these structure, DNPB may increase the risk of intravascular injection, systemic absorption of local anesthetics or hematoma. Ischemia or even necrosis of the glans due to the placement of a penile block is a very rare complication that is not seen in the daily practice. Endothelial injury and necrosis is a serious complication that can be caused due to vascular compression because of the mass effect of anesthetic solution or hematoma, perforation of a vein or artery, excessive cauterization, a very tight suture, veno/vasospasm at the glans; secondary to surgery or the dorsal penile nerve block. Ischemia or necrosis may also be due to the vasoconstrictive effect of local anesthetics, especially if they contain epinephrine. Cases of ischemia of the glans have been described after the application of the dorsal penile nerve block, this was related to anesthetics that contained epinephrine or another type of vasoconstrictor agent. Ropivacaine is a local anesthetic drug with a remarkable safe cardiologic and neurologic toxicity profile specially in children. Its administration for dorsal penile nerve block (DPNB) in male penile surgeries, however, has been discouraged because of the fear to cause necrosis of the glans due to its vasoconstrictor properties. In Universitair Ziekenhuis Brussel, we use ropivacaine for this purpose for more than 20 years now with seemingly no significant complications. We want to evaluate the safety of our practice that is associated with the use of ropivacaine in DPNB in the pediatric population, as well as the incidence and type of potential complications. The impact may be important because there are no studies that verify the safety of this local anesthetic for those type of procedures. This cohort study could eventually also serve as quality improvement. Ropivacaine is a local anesthetic amide-type that has been shown to have vascular biphasic effects, with vasoconstrictive qualities. These properties have been verified in Dahl's study. Where they identified a decrease in epidural blood flow of 37%, compared to the increase in blood flow that they identified after the administration of bupivacaine. The vasoconstrictive qualities have been related with low ropivacaine concentrations like 0.063% and 0.125%. At higher concentrations like 0.75% has been showed just a little decrease in blood flow comparing with saline. There are currently no other studies in the literature that indicate the risk of using ropivacaine in children for Dorsal Penile Nerve Block (DPNB).