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Comparison of eutectic mixture of local anesthetics cream with dorsal penile nerve block using lignocaine for circumcision in infants.

Byline: Sabeen Mujeeb, Jamshed Akhtar and Soofia Ahmed

ABSTRACT

Objective: Circumcision is a commonly performed surgical procedure but choice of anesthesia remained an issue of research and debate. This study was conducted to find out the effectiveness of the eutectic mixture of local anesthetic (EMLA) cream with dorsal penile nerve block (DPNB) using lignocaine, for reduction of pain during circumcision.

Methodology: This was comparative study carried out in Surgical Unit B of National Institute of Child Health Karachi, from May 2008 to October 2008. Patients under six month of age were randomized in to two groups (EMLA and DPNB) of fifty patients each. The effectiveness of pain control was assessed by measuring the baseline heart rate (HR), respiratory rate (RR) and Neonatal infant Pain Scale (NIPS scale) before the start of procedure and measuring of these parameters for each step of circumcision. Independent sample t -test was used to compare means and repeated ANOVA was used to compare means of HR, RR, oxygen (O 2) saturations and NIPS.

Results: The mean age in both the groups was 2.3 months. There was no statistically significant difference in baseline parameters in both the groups except the respiratory rate, which was significantly raised in DPNB group (33 breaths/min in EMLA and 38 in DPNB P (less than) 0.04). During circumcision there was significant increase in heart rate in DPNB group, especially in step three and step four (p (less than) 0.04). Oxygen saturation dropped in both the groups (baseline saturation 98% up to 91% in step 4). While assessing NIPS scores in both the groups, statistically significant difference was found between NIPS at step two and step four in two groups (p (less than) 0.04).

Conclusions: The overall pain control was equal in both the groups, although NIPS score was higher in DPNB in step two and four of circumcision. There was difference in application and cost. EMLA was easy to apply but has increased cost; while DPNB required expertise.

KEY WORDS: Circumcision, EMLA, Anesthesia- circumcision, Penile nerve block, Pain, Infant.

INTRODUCTION

Circumcision is one of the most commonly performed surgical procedures specially among Muslims and Jews.1 The understanding of the anatomy of the foreskin, pain perception and conditioning in infants changed the approach towards the procedure of circumcision in relation to anesthesia and analgesia.2 The neural pathways related to painful stimuli including the cortical and subcortical centers at which level pain is perceived, are well functional even at birth. Neonatal circumcision produces both physiologic as well as behavioral changes. Thus the need of some kind of anesthesia / analgesia for the procedure cannot be underestimated.3-5

The procedure of circumcision is mostly performed under dorsal penile nerve block. This is simple, safe and effective technique to reduce pain. DPNB is often associated with significant complications in case of intravascular injection.6

The injection itself is also painful. Some form of analgesia which is painless to use, effective and produces no side effects is thus searched for.7

EMLA cream is a eutectic mixture of local anesthetic. It contains 5% lidocaine-prilocaine cream (2.5% lidocaine and 2.5% prilocaine, Emla, Astra, Canada). Its properties allow increased absorption of the active ingredients through the skin.8 There are few studies available on the effectiveness of EMLA cream for neonatal circumcision.9 This study was undertaken to compare the effectiveness EMLA cream in terms of pain relief with that of DPNB in infants undergoing circumcision.

METHODOLOGY

Based upon the premise that EMLA cream would be equally effective in alleviating pain, in compari- son to penile dorsal nerve block a study was con- ducted in the Surgical Unit B, Department of Pae- diatric Surgery National Institute of Child Health Karachi from May 2008 to October 2008. The study included children up to six months of age. Fifty patients each were assigned to EMLA and DPNB groups. The infants with history of hemorrhagic disease, congenital anomalies, allergic reactions or sensitivity to local application etc were excluded. Consent was taken. For assigning into each group balloting was used on operation day. All circumci- sions were performed by Plastibell (Hollister Inc.) device in fully equipped operation theatre.

The procedure was divided into four standard steps for the purpose of comparison. It included 1: application of forceps and separation of adhesions between prepuce and glans penis, 2: dorsal prepu- tial incision after crushing of skin with hemostat, 3: insertion of Plastibell and tightening of encircling thread and finally 4: excision of prepuce skin. On day of circumcision the baseline physiological pa- rameters such as HR, RR, and oxygen saturation were measured. In EMLA group 1-2 gm of EMLA cream was applied over the glans and prepuce. An occlusive Opsite (Smith and Nephew, Inc USA) dress- ing was applied, one hour prior to the procedure. In DPNB group injection was given by infiltrating 1ml of 1% (plain) lignocaine at penile base.

An assessor recorded the physiological parameters and pain by using NIPS score during each standard step of the procedure. According to this scale Infants having intense pain would score between 5 and 6, infants receiving a somewhat effective anesthetic would score between 3 and 4, and infants receiving very effective anesthetic would score between 0 and 2.

At the conclusion of the procedure baby was shifted to recovery room and kept under observation for one hour. On discharge, all patients were prescribed paracetamol drops. Baby was re-evaluated after one week. Side effects if any were recorded.

The data was analyzed by SPSS-10. Frequency and percentages were computed for categorical variables. Mean and standard deviations were calculated for quantitative variables. Independent sample t-test was used to compare means. Repeated measure ANOVA was used to compare mean of HR, RR, oxygen saturation, NIPS score and for differences within subjects and between subject effects. P value (less than) 0.05 was considered significant.

RESULTS

Mean age of patients in each group was two months (range one month to six months). Mean baseline heart rate, respiratory rate, oxygen satu- ration and NIPS score observed are given in Fig.1. There was no statistically significant difference in base line parameters in both the groups except for the respiratory rate, which was significantly raised in DPNB group ( (less than) .01). There was no statistical dif- ference in step one parameters. There was statisti- cally significant difference in NIPS score between two groups which showed a higher NIPS score in DPNB group (p=.003) while rest of the parameters did not show any statistical significance in step 2.

During step three, mean heart rate was 166/min in EMLA group and 155/min in DPNB group which was statistically significant ((p=0.04). NIPS score was 6 in EMLA group (range 5-7, SD=0.37) and in 6.14 in DPNB (range 4-7, SD=0.72). During step 4, heart rate in EMLA group was 178/min while it was 165/min in DPNB group which was statistically significant (p=.048). NIPS score was 6.06 in EMLA group (range 5-7) and 6.2 (range 5-7) in DPNB group which was statistically significant (p=.035).

The data is given in Table-I. The parameters were also compared within the group at different steps and are shown in Fig. 1 and 2.

DISCUSSION

According to WHO approximately 30% males are estimated to be circumcised globally.1 The safety of procedure is very much dependent upon pain man- agement. The procedure is smooth in an adequately anesthetized baby. Thus a technique which is sim- ple and least technically demanding is desirable. Though DPNB has been reported to be one such approaches it is still associated with complications though negligible like needle prick and minor inci- dence of local and systemic complications.10 EMLA cream thus appears to be more patient friendly by avoiding needle pricks.11

The results of this study showed the mean base- line heart rate was slightly raised in DPNB group (eight beats) versus EMLA group which could be due to the pain experienced during the block. There was no significant difference in base line parame- ters in both the groups except the respiratory rate which was significantly raised in DPNB group (p (less than) .01). Measurement of pain scores began three min- utes after the DPNB. None of the reported studies measured the difference between the baseline phys- iological and behavioural parameters before and after the application of nerve block. It is observed that various factors can lead to physiological and behavioural changes in infants. Interpretation of pain score thus can be inaccurate.

The mean HR during whole procedure in this study was159/min in EMLA group, for which the baseline was 122/min (difference of 37 beats per min) and 155/min in DPNB which increased from 130 beats per minutes (difference of 25 beats per min) at baseline level. Howard et al in their study compared heart rate and found that average rise in heart rate, above baseline was only 9 /min in DPNB group while it was (greater than) 50/min in EMLA group.12 The heart rate increased five times greater in EMLA group than the DPNB group. In present study similar results with increase in heart rate up to 12 times higher in EMLA group noted. Benani et al compared EMLA with placebo and found attenu- ated pain response in infants receiving EMLA.13 In a study by Howard et al EMLA was compared with DPNB. Distress score was significantly higher in in- fants treated with the EMLA. They concluded that DPNB with lidocaine was a more efficacious means of providing anesthesia for neonatal circumcision.12

In index study it was observed that NIPS was not a good scoring system for the evaluation of pain in infants, although it is reported to be a non intru- sive, replicable and objective tool and has shown high internal consistency in different studies.14 As evidenced by present study infants persistently had high NIPS scores as compared to study by Howard et al where it was 2.3 for DPNB and 4.8 for EMLA groups.12 This difference could be due the inter ob- server variability in assessing the behavioral com- ponent. The observation of present study was dif- ferent from that reported by Howard et al in which they found that the maximum NIPS was observed

Table-I: Comparative Data of Physiological Parameters (Mean values).

###EMLA Group###DPNB Group

###HR (n/min)###RR (n/min)###O2 Saturation (%)###NIPS (n)###HR (n/min)###RR (n/min)###O2 Saturation (%)###NIPS (n)

Base Line###122###33###98###5###130###38###98###5.6

Step 1###143###39###97###5.6###147###40###97###5.8

Step 2###152###44###95###5###153###42###97###6

Step 3###166###46###93###6.06###155###41###94###6.1

Step 4###178###48###91###6.06###165###44###92###6.2

Statistically significant

in step one (adhenolysis), than foreskin cutting. Similar observation was made regarding respira- tory rate and oxygen saturation. One interesting ob- servation was the persistent maximum NIPS score throughout the procedure above the baseline level. Benini F et al, used different scale (neonatal facial coding scale), found that the lidocaine-prilocaine group spent less time crying during the procedure than the placebo group.13 Same are the observations and recommendations based upon present study.

In 2004 Brady-Fryer B et al conducted a Cochrane systemic review to evaluate the efficacy of different analgesia during circumcision. They concluded that DPNB was the most frequently studied intervention and was the most effective for circumcision pain. Compared to placebo, EMLA was also effective, but was not as effective as DPNB. Both interventions according to them appear safe to be used for new- borns circumcision. It was also noted that complete elimination of pain during circumcision was not achieved.15 Same were the findings in this study.

An important learning through this study is re- lated to steps of the procedure of circumcision. It appeared that the procedure of circumcision cannot be categorized into phases which could be assessed separately. Secondly NIPS score was difficult to ap- ply in children already crying because of the separa- tion from parents, environment and manipulation. It was difficult to differentiate whether behavioral changes were due to pain or simple crying. There was difficulty in recording both the physiological and behavioral components in this study.

Although both EMLA cream and lidocaine ap- peared to have similar efficacy in pain control (though DPNB has probably better efficacy in pain control as suggested by the results) there exist a difference in their cost and method of application. EMLA cream costs more than an ampoule of lido- caine. EMLA cream also requires proper tempera- ture requirement to be stored. For complete absorp- tion and action, EMLA cream needs to be applied for at least one hour while lidocaine starts working in less than three minutes of application. The de- gree of absorption in EMLA cream cannot be pre- dicted as it depends on many factors such as skin thickness and amount of ointment applied.16 There are less chances of systemic toxicity like methe- moglobinemia in case of systemic absorption with EMLA cream.17 No measurable changes in the level of methemoglobin is reported in literature. The use of EMLA in premature and term infants is reported as safe.18 Similarly no untoward effects of EMLA cream were reported in this study.

CONCLUSION

Both EMLA cream and DPNB were equally effec- tive for pain control during circumcision however difference of cost and duration of application may be a constraint in using EMLA cream.

REFERENCES

1. Male circumcision: global trends and determinants of prevalence, safety and acceptability. WHO Library Cataloguing-in-Publication Data 2007. [Internet] Accessed on January 21, 2011 Available from whqlibdoc.who.int/publications/2007/9789241596169_eng.pdf

2. Snell RS. Clinical Anatomy for Medical Students. 5th Ed. Little Brown and Co, Boston 1995:358.

3. Halata Z, Munger B. The neuroanatomical basis for the protopathic sensibility of the human glans penis. Brain Res. 1986;371:205-230.

4. Light AR, Perl ER. Peripheral sensory systems. In Dyck PJ, Thomas PK, eds, Peripheral Neuropathy. 3rd ed. Philadelphia: Saunders; 1993:150.

5. Rosen M. Anesthesia for ritual circumcision in neonates. Paediatr Anaesth. 2010;20:1124-1127.

6. Menif K, Khalidi A, Bouziri A, Hamdi A, Belhadi S, Jaballah NB. Lidocaine toxicity secondary to local anesthesia administered in the community for elective circumcision. Fetal Pediatr Pathol. 2011;30(6):359-362.

7. Shockley RA, Rickett K. Clinical inquiries. What's the best way to control circumcision pain in newborns? J Fam Pract. 2011;60:233a-b.

8. Cassidy KL, Reid GJ, McGrath PJ, Smith DI, Brown TL, Finley GA. A randomized double-blind, placebo-controlled trial of the EMLA patch for the reduction of pain associated with intramuscular injection in four to six-year-old children. Acta Paediatr. 2001;90:1329-1336.

9. Taddio A, Stevens B, Craig K, Rastogi P, David SB, Shennan A, et al. Efficacy and safety of lidocaine prilocaine cream for pain during circumcision. N Engl J Med. 1997;336(117):1197-1201.

10. Soh CR, Ng SB, Lim SL. Dorsal penile nerve block. Paediatr Anaesth. 2003;13(4):329-333.

11. Taddio A, Ohisson K, Ohisson A. Lidocaine-prilocaine cream for analgesia during circumcision in newborn boys. Cochrane Database Syst Rev. 2000:(2)CD000496.

12. Howard CR, Howard FM, Fortune K, Generelli P, Zolnoun D, tenHoopen C, et al. A randomized, controlled trial of a eutectic mixture of local anesthetic cream (lidocaine and prilocaine) versus penile nerve block for pain relief during circumcision. Am J Obstet Gynecol. 1999;181:1506-1511.

13. Benini F, Johnston C, Faucher D, Aranda J. Topical anesthesia during circumcision on newborn infants. J Am Med Assoc. 1993;270(7):850-853.

14. Lawrence J, Alcock D, McGrath P, Kay J, MacMurray S, Dulberg C. The development of a tool to assess neonatal pain. Neonatal Network. 1993;12:59-66.

15. Brady-Frayer B, Weibi N. Pain relief for neonatal circumcision. Cochrane Database Syst Rev. 2004;18(4):CD004217.

16. Gazarian M, Taddio A, Kent G, Koren G. Penile absorption of EMLA cream in piglets: implications for use of EMLA in neonatal circumcision. Biol Neonate. 1995;68:334-341.

17. Couper RT. Methaemoglobinaemia secondary to topical lignocaine/ prilocaine in a circumcised neonate. J Pediatr Child Health. 2000;36(4):406-407.

18. Biran V, Gourrier E, Cimerman P, Walter-Nicole E, Mitanchez D, Carbajal R. Analgesic effects of EMLA cream and oral sucrose during venipuncture in preterm infants. Pediatrics. 2011;128:e63-70.

Authors Contribution:

Dr. Sabeen Mujeeb worked with two co-authors from data collection, literature search, write up, and final drafting and approval of manuscript. The present material of manuscript is tailored out of main dissertation with some addition in discussion part and references sections. No other study has been carved out of main dissertation. No submission of this article is made to other journals.

How to cite this:

Mujeeb S, Akhtar J, Ahmed S. Comparison of eutectic mixture of local anesthetics cream with dorsal penile nerve block using lignocaine for circumcision in infants. Pak J Med Sci 2013;29(1):27-30. doi: http://dx.doi.org/10.12669/pjms.291.2944

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Sabeen Mujeeb,

2. Jamshed Akhtar,

3. Soofia Ahmed,

1-3: Dept. of Paediatric Surgery, National Institute of Child Health,

Rafiquee Shaheed Road, Karachi-75510, Pakistan.

Correspondence:

Dr. Sabeen Mujeeb,

E mail: sabeenmujeeb@yahoo.com jamjim88@yahoo.com

Received for Publication: September 16, 2012

1st Revision Received: September 22, 2012

2nd Revision Received: November 19, 2012

Final Received Accepted: November 20, 2012
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Publication:Pakistan Journal of Medical Sciences
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Date:Feb 28, 2013
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