Comparison of Ultrasound-Guided Transversus Abdominis Plane Block with Sub-Arachnoid Block for Open Inguinal Hernia Repair
Authors: Mowar Ashita , Singh Vishwadeep , Pahade Akhilesh , Karki Geeta 
Published: December 2021

Background:
Open inguinal hernia repair is one of the routine day-care procedures performed across the world. A multitude of anesthetic techniques have been outlined for painless inguinal hernia repair, comprising general anesthesia and regional anesthesia such as spinal, epidural, and nerve blocks; with regional anesthetic techniques often favored for uncomplicated open inguinal hernia repair. Ultrasound-guided peripheral nerve blocks have made rapid strides and are gaining popularity because of the reduced incidence of adverse events.

Aims:
We aim to compare the efficacy of two regional anesthesia techniques to compare the adequacy of surgical anesthesia and their efficacy to ease postoperative pain with least potential side effects.

Settings and Design:
This prospective, interventional, single-centric, double-blind, randomized, parallel-group, active-controlled, Helsinki protocol-compliant clinical study was registered with the Clinical Trial Registry of India (CTRI/2021/04/033109). It was conducted after obtaining written informed consent from all patients and approval from the institutional review board.

Materials and Methods:
Sixty patients of American Society of Anesthesiologists physical status classes I/II, in the age group of 18–60 years of either sex, scheduled for elective open inguinal hernia repair, were enrolled into two groups of 30 patients each according to the anesthetic technique used. Group T comprised patients receiving ultrasound-guided transversus abdominis plane block (TAP block), whereas the Group S comprised patients administered spinal anesthesia for elective open inguinal hernia repair. The primary end points of this study were to assess the adequacy of surgical anesthesia and duration of postoperative analgesia, whereas the secondary end points included assessment of patients’ hemodynamic profile post institution of the block and comparing the incidence of adverse events associated with the two techniques.

Statistical Analysis:
SPSS version 20.0 was used for analysis. Frequency, mean distribution, standard deviation, Chi Square test and student t Test were calculated to p value. P < 0.05 was considered statistically significant. Continuous variables were expressed as mean + SD, whereas categorical variables were expressed as absolute numbers and percentages. Intergroup nominal categorical data were compared by Chi-square test.

Results:
The visual analog scale score was found significantly lower in Group T at all time points except immediate postsurgery (3, 6, 12, 24, and 48 h) as compared to Group S (0.357 ± 0.4880 vs. 1.393 ± 1.8527; P = 0.006, 1.393 ± 0.4973 vs. 2.893 ± 2.3148; P = 0.001, 2.429 ± 0.9201 vs. 3.321 ± 2.0377; P = 0.039, 1.214 ± 0.4179 vs. 2.286 ± 1.9217; P = 0.006, and 1.143 ± 0.3563 vs. 1.643 ± 1.5685; P = 0.106, respectively), and the duration of postoperative analgesia was highly significant (P < 0.001) in Group T (724.00 ± 103.2914 min) as compared to Group S (256.643 ± 73.4218 min). Difference in the number of rescue analgesics administered over the first 24 and 24–48 h was significantly higher in the spinal group which comprised patients administered with the TAP block.

Conclusion:
Ultrasound-guided TAP block provides better intra-operative and postoperative analgesia as compared to subarachnoid block especially in respiratory and cardiovascular cripples without any significant adverse events and hemodynamic changes.