The Effect of Local Wound Infiltration Versus Caudal Block on Wound Infection and Healing After Inguinal Herniotomy Paediatrics

THE EFFECT OF LOCAL WOUND INFILTERATION VERSUS CAUDAL BLOCK ON WOUND INFECTION AND HEALING AFTER INGUINAL HERNIOTOMY IN PAEDIATRICS

INTRODUCTION Since the introduction of cocaine in 1884, local anesthetics have been used as a mainstay of pain management. However, numerous studies over the past several decades have elucidated the supplemental role of local anesthetics as antimicrobial agents. In addition to their anesthetic properties, medications, such as: bupivacaine and lidocaine have been shown to exhibit bacteriostatic, bactericidal, fungistatic, and fungicidal properties against a wide spectrum of microorganisms.(1) Johnson et al.(2)made a comprehensive literature search using MEDLINE 1950-present for in vitro and in vivo studies pertaining to the antimicrobial activity of various local anaesthetics on a broad range of bacterial and fungal pathogens. Studies testing the effect on microbial growth inhibition of local anaesthetics alone and in combination with other agents, such as: preservatives and other medications, as well as the effect of conditions, such as: concentration and temperature were included for review. Evidence suggests that local anesthetics as a class possess inherent antimicrobial properties against a wide spectrum of human pathogens. Limited studies attribute the mechanism of action of antimicrobial activity of local anesthetics to a disruption of microbial cell membrane permeability, leading to leakage of cellular components and subsequent cell lysis.(2) Multiple local anesthetics at concentrations typically used in the clinical setting (e.g.:- bupivacaine 0.125%-0.75%; lidocaine 1%-3%) inhibit the growth of numerous bacteria and fungi under various conditions. Different local anesthetics showed various degrees of antimicrobial capacity; bupivacaine and lidocaine, for example, inhibit growth to a significantly greater extent than does ropivacaine.(2) In 1943 Lofgren (3) developed lidocaine. This was an amide and had a low risk of allergic reactions in comparison to ester local anesthetics. This was followed by mepivacaine (1957), prilocaine (1960), bupivacaine (1963), ropivacaine (1997) and levobupivacaine (2000).(3) Bupivacaine has been used in clinical practice for more than 40 years. It is remarkably stable in solution and is commercially available in 0.25% and 0.5% solutions (with and without epinephrine). Spinal heavy bupivacaine (0.5% bupivacaine + 6% glucose) is also manufactured. It is four times more potent than lidocaine. Therefore, 0.25% bupivacaine is equipotent with 1% lidocaine. Bupivacaine is particularly cardiotoxic and should never be used in Biers blocks. Bupivacaine binds tightly to tissues and thus has a long duration of action (up to 24 hours in some cases). Adding epinephrine will decrease its toxicity by delaying the drug absorption but, will have minimal effect on the duration of the block.(3)

The recommended maximum safe doses of bupivacaine are as follows:

BUPIVACAINE WITHOUT EPINEPHRINE ------- 2.0 mg/kg BUPIVACAINE WITH EPINEPHRINE ------- 2.5 mg/kg.(3) Caudal anesthesia is one of the most used-popular regional blocks in children. This technique is a useful adjunct during general anesthesia and for providing postoperative analgesia after infraumbilical operations. The quality and level of the caudal blockade is dependent on the dose, volume, and concentration of the injected drug.(4) Prophylactic analgesia with local anesthetics is an attractive concept, especially in pediatric practice, because the evaluation of pain can be very challenging in young children.(5) In contrast to opioids, local anesthetics can be administered safely, and in recent guidelines regional anaesthesia is accepted as the cornerstone of post-operative pain relief in the pediatric patients.(6) Although regional anaesthesia holds a good safety record overall, the global experience with pediatric regional anaesthesia is still quite low; even the most commonly performed procedure, caudal block, represents only 2.5% of all central neuroaxial blocks performed.(7,8) Determining the risk-benefit ratio is rather difficult for techniques that are relatively rarely performed. Wound infiltration can produce reliable analgesia for superficial skin surgery. Infiltration itself is extensively used by pediatricians, surgeons and emergency physicians for skin laceration repair or minor superficial surgery.(5) Several studies have compared the local anesthesia so far, including: ilio-inguinal and iliohypogastric nerve block plus subcutaneous injection by the surgeon against the caudal anesthesia.(9,10) But to our knowledge, there is still no study comparing the local wound infiltration by itself and caudal anesthesia for postoperative analgesia as regard their effect on wound infection and healing.

AIM OF THE WORK The aim of the present study is to assess effect of local wound infiltration in comparison with caudal block by bupivacaine 0.25% after inguinal herniotomy in pediatrics on: Wound infection and healing (primary outcome) and postoperative analgesia (secondary outcome).