METHODOLOGY

After obtaining clearance from the institutional ethics committee and CTRI , 56 patients aged between 20- 59 years posted for lower abdominal surgeries will be included in the study. Patients will be randomly allocated into two groups (group A and B) using computerized randomization  technique.  Written informed consent will be taken from all the patients. Standard anesthesia monitors ECG, HR, NIBP, SPO2 will be connected. Intravenous access will be secured with 18G. The patients will be given spinal anaesthesia according to standard protocol, once the surgery is over and the level regresses to T12, ultrasound guided TAP block or QL block will be given under aseptic precautions. Ultrasound guided TAP block will be given for patients belonging to group A and QL block will be given to group B.

In patients belonging to group A ultrasound guided TAP block will be performed in the triangle of Petit. The triangle is bounded by the external oblique anteriorly, the latissimus dorsi posteriorly and the iliac crest inferiorly. The floor of the triangle, from superficial to deep is composed of subcutaneous tissue, and the fascial borders of external oblique, the internal oblique and the transversus abdominis muscles respectively. The iliac crest will be taken as a fixed landmark. A linear transducer will be positioned in the mid axillary line in this triangle, between the iliac crest and the costal margin. Under SAP, a needle will be introduced anteriorly, in plane under real-time ultrasound guidance to lie in the fascial planes between the internal oblique and transversus abdominis muscle. The position of the needle will be confirmed following which 20ml of 0.125% bupivacaine + 4mg dexamethasone will be injected on each side after aspiration. Spindle-shaped echo lucent shadow in the space between the two muscles would confirm a successful injection.

In patients belonging to group B, type 1 QL block will be performed. For the type 1 QL block, a linear transducer will be placed in the axial plane in the midaxillary line and moved posteriorly until the posterior aponeurosis of the transversus abdominis muscle becomes visible. The needle will be inserted from either the anterior or the posterior end of the transducer and advanced until the needle tip penetrates the posterior aponeurosis of the transversus abdominis muscle. The position of the needle will be confirmed following which 20ml of 0.125% bupivacaine + 4mg dexamethasone will be injected on each side after aspiration. Spindle-shaped echo lucent shadow in the space between the two muscles would confirm a successful injection

All patients would receive analgesics according to institutional multimodal analgesia protocol. The patients after receiving block will be monitored for the need for first rescue dose of intravenous pethidine 0.5mg/kg body weight and subsequent doses required over 24 hours. All patients will be monitored in the recovery room for 30 min after the procedure for parameters like heart rate, blood pressure, respiratory rate, SpO2, NPIS score and for loss of pain and temperature sensations at 0, 30 minutes and 1 hour in the dermatomal areas corresponding to the anterior abdominal wall. The patients will be shifted to surgical ward for postoperative monitoring. All patients will be monitored at 0,1, 4,  8, 12 and 24 hours for the above-mentioned parameters. Patients will be asked to rate the pain they experience on a visual analogue scale (NPIS) from zero to ten, 0 being ‘no pain’ and 10 being ‘very severe pain’, time for first rescue dose of intravenous pethidine 0.5mg/kg body weight will be noted in both the groups and subsequent number of doses required over 24 hours will also be noted. Any complications arising as a result of TAP block or QL block will be recorded. The results will be compared and tabulated on a excel sheet and analysed using SPSS software.