A randomised controlled trial to compare the efficacy of clonidine versus dexamethasone as an adjunct in ultrasound guided transversus abdominis plane block in children undergoing laparotomy

INTRODUCTION

Postoperativepain relief is an essential component of modern anaesthesia practice that greatlyreduces the stress response of surgery and the perioperative morbidity insurgical patients. With the greater availability of portable ultrasound (USG) inrecent years, a surge in the use of regional blocks for management ofpostoperative pain is evident. The use of USG guidance allows real-timevisualisation of anatomical structures and shows the spread of anaestheticsolution injected. This is an attractive option in paediatric patients as mostregional anaesthetic techniques are performed while under general anaesthesia. Evidence-basedliterature shows that USG guided regional blocks provide better postoperativepain control, reduce opioid requirements, decrease hospital stay and improveoutcomes in paediatric patients1. Therefore, USG guided regionalblocks are becoming the standard of care for postoperative pain relief inpaediatric patients2.

Peripheral nerve blocks are usually favoured overcentral neuraxial blocks as they cause minimal haemodynamic alterations andcomplications, as well as short hospital stay.  The transversus abdominis plane (TAP) block isone of the most popular peripheral nerve blocks and provides adequatepostoperative analgesia for a range of abdominal proceduresby blocking the lowerintercostal (T6-11) nerves, ilioinguinal, and iliohypogastric nerves3,4.Local anaesthetic agents (LA) are deposited in the neurovascular plane betweenthe internal oblique and transversus abdominis muscle. The transversusabdominis plane block has been given with LAs like bupivacaine and ropivacaine butthey have a limited duration of action. Adjuvant drugs are oftenadded to LAs in peripheral blocks to achieve a quick, dense and prolonged block5.Alpha 2 agonists, like clonidine and dexmedetomidineare commonly added to LAs in TAP block6. Their clinical use ishowever limited by the occurrence of hypotension and bradycardia which can bedetrimental in small children in the postoperative period. Dexamethasone, avery potent and highly selective glucocorticoid has also been used an adjuvantto LAs in various nerve blocks resulting in a prolonged duration of analgesiaand motor block. Dexamethasone helps by attenuating the release of inflammatorymediators, reducing ectopic neuronal discharge and inhibiting potassiumchannel-mediated discharge of nociceptive C-fibres. Addition of steroids to LAseffectively and significantly prolongs the duration of analgesia as well asproducing earlier onset of action7.

RATIONALE FOR STUDY

Transversus abdominis plane block has emerged as a safe, reliableand efficient technique to provide postoperative analgesia for a range ofabdominal procedures. Although many studies have described the successful usageof TAP block and the use of adjuncts for the same in adults, no data isavailable regarding the use of adjuncts such as dexamethasone or clonidine inTAP block in paediatric patients. Thus, the present study is aimedto compare the efficacy (in terms of duration of postoperative analgesia)of clonidine with dexamethasone as an adjunct in ultrasound guided TAP block inchildren undergoing laparotomy.