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ORIGINAL RESEARCH |
From the Blodgett Memorial Medical Center, Grand Rapids, Michigan.
Address reprint requests to: Charles Newton, MD, Blodgett Memorial Medical Center, 1840 Wealthy, SE, Grand Rapids, MI 49506, E-mail: charles_newton{at}blodgett.com
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Abstract |
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Methods: One hundred ninety-four newborn males were studied in a randomized trial using two dorsal penile nerve block preparations for circumcision. Ninety-two received plain lidocaine, and 102 received buffered lidocaine. The infants were evaluated at timed intervals before the procedure, during anesthetic injection, and during circumcision. Objective measurements of heart rate and oxygen saturation, and subjective determinations of behavioral state were recorded. Using heart rate as the major outcome variable, it was determined that 65 subjects per group would be needed to achieve a power of .08. Complications also were noted.
Results: Heart rates and oxygen saturations were similar in the two groups at each timed interval. The behavioral characteristics and amount of crying also were comparable in both groups. The only complication was minor bleeding, seen in each group.
Conclusion: Adding a buffering agent to lidocaine did not provide a more effective level of anesthesia in a short time.
Pain relief for circumcision is a growing expectation because parents are learning that anesthesia is available. Although circumcision is painful and parents want their newborns protected from pain, anesthesia or analgesia is used infrequently. It was shown that a dorsal penile nerve block with injected lidocaine gives satisfactory pain relief,1–3 but despite the fact that it is a simple, safe, and effective technique, many clinicians do not use it.4,5 Objection to using anesthesia has a variety of reasons, including risks of the anesthetic and belief that newborn neuroanatomy is immature and does not experience pain the same way as an adult, which have been shown to be without merit.5 Continued resistance might come from concern that anesthesia causes additional stress for infants because lidocaine stings at the injection site. Further objection might be due to increased time required to provide anesthesia. Amending those potential obstacles might induce clinicians to provide anesthesia more readily for newborn circumcision. The objective of our study was to find an anesthetic technique that caused less pain on administration, and provided more effective anesthesia in a short time.
Buffering lidocaine with sodium bicarbonate was shown to decrease the burning sensation of injection16 and speed the anesthetic effect.7 We hypothesized that buffered lidocaine would have a similar effect in newborns. This study was designed to compare lidocaine 1% alone and lidocaine 1% with an added buffer, in pain experienced during injection and pain relief during neonatal circumcision a short time after dorsal penile nerve block.
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Materials and Methods |
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AbstractMaterials and MethodsResultsDiscussionReferences |
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One hundred ninety-four healthy newborn males were assigned to one of two groups. Group assignment, based on a computer-generated random sequence, prepared before the start of enrollment, was made just before circumcision. Procedural personnel were unaware of the randomization sequence. Ninety-two infants received lidocaine 1%, and 102 lidocaine 1% with buffer. Using a 30-gauge needle on a 1-mL syringe, each subject received a dorsal penile nerve block, with 0.4 mL anesthetic solution injected in each side of the penis. The solution for the lidocaine 1% with buffer group was prepared by adding 5 mL 8.4% sodium bicarbonate solution to a pristine 50-mL vial of plain lidocaine. A fresh sodium bicarbonate solution was prepared in the nursery by the operating physician just before each circumcision. No other comfort measures were given.
During circumcision, each infant was placed on a plastic molded board and restrained in the usual fashion. The Mogen clamp technique was used for all of the circumcisions. Each infant was monitored with a pulse oximeter transducer attached to one foot. The heart rate and the oxygen saturation were monitored continuously, and these data were entered into a desktop computer.
Data were collected at 10-second intervals, and time marks were made at six predetermined points in the procedure. The first point was application of a povidone iodine solution, the second when the baby calmed, the third when anesthetic was given, the fourth when the foreskin was grasped with hemostats, the fifth when the clamp was closed on the foreskin, and the sixth when the penis was dressed with petrolatum and gauze. In addition to recordings of heart rates and oxygen saturations, the infants were evaluated by the operating physicians and attending nurses, using a modified Brazelton Neonatal Behavioral Assessment Scale.8 The behavioral scale is categorized into six levels: 1) deep sleep, 2) light sleep, 3) drowsy, 4) quiet alert, 5) active alert, and 6) crying. These evaluations were made at three points during the procedure. The first observation was made after the infant was placed and restrained on the circumcision board (baseline); the second when the anesthetic was injected (injection); and the last when the Mogen clamp was closed (clamp application). Interrater reliability between physician and nurse for behavioral assessment was done by consensus. Complications of the procedures were noted. Race, gestational age, Apgar scores, newborn age, and birth weight were recorded for each infant.
Differences between treatment groups were analyzed using several statistical tests. Continuous demographic variables and procedure times were analyzed using t test. Apgar scores were analyzed with Mann-Whitney U test, and complications with the Fisher exact test. Continuous repeated measures were analyzed using repeated measures of analysis of variance, ordinal repeated measures with Friedman two-way analysis of variance, and categoric repeated measures with Cochran Q test. The level of statistical significance was P 
.05. Using heart rate as the major outcome variable and a clinically significant difference of 10 beats/minute, it was determined that 65 subjects per group would be needed to achieve a power of .08.
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Discussion |
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Our study showed that plain lidocaine 1% and lidocaine 1% with buffer provided similar results. The measured responses at the time of injection were the same with both agents. There was no difference in objective and subjective evaluations at the times marked during the circumcision procedure. This suggests that both agents had similar onsets of action and provided the same levels of pain relief at the timed intervals.
The physicians and nurses were not blinded with respect to the buffer status of the anesthetic solution; however, the expectation was for a significant difference favoring the lidocaine with buffer, and any bias from this lack of blinding could have led us to a difference in outcome. The physicians and nurses were consistent in their ratings of the behavioral state.
A placebo group was not used in our study, because it is considered unethical to withhold a known beneficial anesthetic agent for a painful procedure.13 Studies comparing the dorsal penile nerve block to placebo during circumcision found significant differences in pain relief.1,3
The Brazelton scores in our study indicate that neither method was completely successful in eliminating pain. Allowing more time after administration of the anesthesia before starting the circumcision could have provided a better block, but the aim of our study was to find an anesthetic technique that would be effective in a short time. We did not try to determine the exact rate of onset of action.
Our study evaluated needle placement and infiltration of anesthesia together, with respect to the amount of pain experienced. There were no differences in heart rate, oxygen saturation, and behavioral state. We viewed the insertion of the needle as a constant for both arms of the study, because the needle placement technique was the same for each. Evaluating the infiltration separately from the needle placement might have shown a difference, but it would not be clinically relevant. Other authors showed that speed of infiltration is more significant than adding a buffering agent. Less pain is produced when the anesthesia is administered slowly.14 The amount of anesthetic solution used for the dorsal penile nerve block might have been too small to cause a measurable difference in effect.
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Footnotes |
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Received May 7, 1998. Received in revised form August 24, 1998. Accepted September 10, 1998.
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References |
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2. Kirya C, Werthmann MW. Neonatal circumcision and penile dorsal nerve block—a painless procedure. J Pediatr 1978;92:998–1000.[Medline]
3. Maxwell LG, Yaster M, Wetzel RC, Niebyl JR. Penile nerve block for newborn circumcision. Obstet Gynecol 1987;70:415–9.[Medline]
4. Toffler WL, Sinclair AE, White KA. Dorsal penile nerve block during newborn circumcision: Underutilization of a proven technique? J Am Board Fam Pract 1990;3:171–3.
5. Myron AV, Maguire DP. Pain perception in the neonate: Implications for circumcision. J Prof Nurs 1991;7:188–95.[Medline]
6. Christoph RA, Buchanan L, Begalla K, Schwartz S. Pain reduction in local anesthetic administration through pH buffering. Ann Emer Med 1988;17:117–20.[Medline]
7. DiFazio CA, Carron H, Grosslight KR, Moscicki JC, Bolding WR, Johns RA. Comparison of pH-adjusted lidocaine solutions for epidural anesthesia. Anesth Analg 1986;65:760–4.
8. Brazelton TB. Neonatal behavioral assessment scale. Rev. ed. Philadelphia: JB Lippincott, 1984:17–20.
9. Shapiro C. Pain in the neonate: Assessment and intervention. Neonatal Netw 1989;8:7–21.
10. Rawlings DJ, Miller PA, Engel RR. The effect of circumcision on transcutaneous PO2 in term infants. Am J Dis Child 1980;134:676–8.[Abstract]
11. Taddio A, Goldbach M, Ipp M, Stevens B, Koren G. Effect of neonatal circumcision on pain responses during vaccination in boys. Lancet 1995;345:291–2.[Medline]
12. Anand KJS, Phil D, Hickey PR. Pain and its effects in the human neonate fetus. N Engl J Med 1987;317:1321–9.[Medline]
13. Walco GA, Cassidy RC, Schechter NL. Pain, hurt, and harm: The ethics of pain control in infants and children. N Engl J Med 1994;331:541–4.
14. Richtsmeier AJ, Hatcher JW. Buffered lidocaine for skin infiltration prior to hemodialysis. J Pain Symptom Manage 1995;10:198–203.[Medline]
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