Efficacy of intravenous versus perineal dexamethasone as an adjuvant in transverse abdominis plane block for post operative analgesia following elective cesarean section - A randomised double blinded clinical trial

Cesarean delivery (CD) is one of the most commonly performed lower abdominal surgeries. CD pain has both a somatic component due to the surgical incision and a visceral component due to uterine contractions. Blocking both components leads to decreased maternal morbidity, early mobilization,and increased patient satisfaction.

The infra-umbilical portion of the anterior abdominal wall is supplied by T7-L1 nerves, which travel in the plane between the transverse abdominus muscle and the internal oblique muscle- the transversus abdominis plane (TAP).The nerves in addition give out a lateral cutaneous branch, which arises proximal to the angle of the rib, runs a short distance with the main nerve, and emerges obliquely through the overlying muscles in the mid axillary line to supply the respective dermatomes. The transverse abdominal plane (TAP) block, is used to block these nerves and their branches in the TAP.

Dexamethasone is a synthetic glucocorticoid with anti-inflammatory and immunosuppressive properties. With 20 to 30 times the binding affinity for glucocorticoid receptors of endogenous cortisol, which causes vasoconstriction and reduce absorption of administered local anesthetic, decreases the inflammatory response and blocking k + channel used for pain transmission and transduction. Various studies have been done in dexamethasone for prevention of post-operative nausea and vomiting (PONV) in caesarean section.Even though dexamethasone is one of the most commonly used antiemetics, its mechanism of action remains unclear. Post-operative pain relief using dexamethasone as an adjuvant in perineural TAP block has been studied in caesarean sections. IV dexamethasone has been studied for post-operative pain management in patients undergoing caesarean section.Various studies have been done comparing IV dexamethasone and perineural dexamethasone for post-operative pain relief in peripheral nerve block, supraclavicular block, interscalene block.

 A literature search revealed that there is only one study related to comparing IV dexamethasone and dexamethasone as adjuvant in the TAP block in elective LSCS and that was done without using ultrasound guidance. There is lack of study using ultrasound guided TAP block, Hence this study is being done to compare the ultrasound guided TAP block using dexamethasone as an adjuvant to 0.25% bupivacaine and IV dexamethasone for post-operative analgesia following elective caesarean section