Comparison of Bilateral Ultrasound guided Transversus abdominis plane block with dexamethasone and Magnesium sulphate as an adjuvant with Ropivacaine (0.25%) in patients undergoing lower segment cesarean section under subarachnoid block – A prospective randomized double blinded study.

· Lower segment cesarean section (LSCS) may result in significant postoperative pain, which can negatively impact ambulation, breastfeeding, and even maternal bonding. Pain after LSCS has a somatic component arising from nociceptors within the surgical wound and a visceral component originating from muscles.Inadequate postoperative analgesia after cesarean delivery delays ambulation with subsequent increased risk of thromboembolism, and harms motherbabyrelationship(1) .Goal standard for postoperative pain is opioids whether administered systemic or neuraxial but it is associated with manyside effects such as nausea, vomiting, pruritus, constipation, and respiratory depression(2). Multimodal approach of postoperative analgesia which combines parenteral analgesics with regional analgesic techniques may enhance analgesia of each component and decrease its side effects.(3)

· Transversus abdominis plane (TAP) block represents one of the most widely used regional analgesic techniques and important component of multimodal approach for postoperative analgesia.(4)Transversus abdominis plane (TAP) is a neurovascular plane between the internal oblique muscle and the transversus abdominis muscle through which pass the nerves supplying the anterolateral abdominal wall(5).Application of the local anesthetics in this plane will produce myocutaneous sensory block between T6 and L1 (TAP) block which is suitable for pain relief in abdominal surgeries(6).TAP block was described for the 1st time by Rafi in 2001; he called the technique as refined abdominal field block. TAP block hasbeen used successfully as an important element of multimodal postoperative analgesia for many abdominal procedures such as cholecystectomy, gynecological laparoscopy, appendectomy, nephrectomy, and cesarean delivery(7).Establishment of TAP block requires injection of large dose of LA in this relatively vascular plane which leads to potential neurotoxic plasma level of the LA ,specially during pregnancy which increases susceptibility of the pregnant women to local anesthetic toxicity.(8)

· Ropivacaine is longer acting than lignocaine and has a documented better safety profile than bupivacaine. It is common practice nowadays to use ropivacaine for nerve blocks and fascial plane blocks.  For regional anaesthesia, local anaesthetics alone provide good operative conditions but have shorter duration of post-operative analgesia. Hence, various adjuvants such as opioids, clonidine and ketamine are added to local anaesthetics to achieve a quick, dense and prolonged block, but their use is limited by side effects such as nausea, vomiting and pruritis.(9)

·      Dexamethasone is highly potent, long-acting glucocorticoid with analgesic, antiemetic, and anti-inflammatory properties, and when used as adjuvant in peripheral nerve blocks, increases the duration of analgesia with minimal side effects and has an added advantage in decreasing postoperative nausea and vomiting (PONV)(10). Dexamethasone when added as anadjuvant to Ropivacaine in ultrasound guided transversus abdominis plane block enhanced the duration of analgesia and decrease total rescue analgesic requirement.

  Â·      The presence of N-methyl -D -aspartate receptors in skin and muscles have led to the use of Magnesium sulphate.Magnesium helps to regulate the amount of intracellular calcium  and is known to be able to control pain. Magnesium sulphate (MgSO4 ) has analgesic, antihypertensive, anaesthetic sparing effects when used systemically(11,12).ln recent times, MgSO4 has been commonly used as an adjuvant to neuroaxial block, various peripheral nerve blocks as well as plane blocks.

 Â·      Thus, this study aims to compare the effects of dexamethasone and Magnesium sulphate as an adjunct to Ropivacaine in Transverse Abdominis Plane (TAP) block as post-operative pain management in patients undergoing Ceserean section.

  Sample size:

Group RD(n=36) :patients will receive bilateral USG Guided TAP Block with Ropivacaine0.25%  with Dexamethasone (8mg) 20 ml on each side.

Group RM (n=36): patients will receive bilateral USG Guided TAP Block with Ropivacaine0.25% with Magnesium sulfate (250mg) 20ml on each side.

 Methods:

  After obtaining approval by the institutional human Ethics Committee and CTRI registration, and written informed patient consent, 72 patients under ASA physical status,II,III patients scheduled for caesarean section both emergency and elective, will be included in a prospective, randomized, double-blinded clinical trial at Chettinad Hospital and Research Institute, Kelambakkam, Chennai.

In the preoperative waiting room, detailed history and physical examination will be done. Baseline datas like pulse rate, blood pressure, respiratory rate, and basic investigations will be collected. An  IV access with 18G size IV cannula secured for all patients.

Proper standard monitoring of pulse oximetry, Non invasive blood pressure, continuous electrocardiogram were established and baseline variable values will be noted before the procedure.

Under aseptic precautions,patients will undergo spinal anesthesiain sitting position with hyperbaric Bupivacaine 0.5% (2 ml)with fentanyl 0.5ml at L3-L4 or L4-L5 interstate with 26G or 27 G Quincke needle. Patient’s hemodynamic stability and level of motor and sensory blockade will be assessed and documented. The bilateral TAP block will be performed after skin closure under monitoring with ultrasound guidance ( a high frequency linear probe) with needle in-plane technique , wherein the  23G Quincke’s spinal needle will be inserted between the mid and anterior axillary line extending below the rib line to the highest point of the iliac crest. The needle is placed in between the plane of Internal Oblique muscle and transverse Abdominis muscle, and as per allocation, Group (RD) will receive 20 ml of 0.25%Ropivacaine with Dexamethasone (8mg)on each side and Group (RM) will receive 20 ml of 0.25%Ropivacaine with MgSO4 (1gram)on each side.

During the injection,the distribution of local anesthetics was observed as a hypoechoic enlargement upon USG.

 After completion of TAP block,hemodynamicstability of the patient assessed and each patient will be moved to the postoperative room for monitoring the vitals and adverse effects.Every patient will be inquired to state the post operative pain by means of VAS scale.Time to preliminary reporting of postoperative pain was noted.