In adherence to CONSORT guidelines, this prospective, randomized study was conducted, after obtaining Hospital Ethics Committee approval and informed written consent was taken for every patient, the study was carried out according to the principles of the Declaration of Helsinki guidelines seventh revision (2013). We studied prospectively 58 patients, undergoing elective abdominoplasty surgery from 2017 to 2020 at Al Kindi Specialised Hospital, Bahrain.
Inclusion criteria were patients undergoing elective abdominoplasty surgery with rectus sheath plication and ASA (I-II) patients. Exclusion criteria were patient’s refusal, patients with a history of known hypersensitivity to local anesthesia and psychiatric disorders, or use of psychiatric medications.
Patients were randomly assigned using computer-generated numbers using random allocation software QuickCals (GraphPad Software Inc., La Jolla, CA, USA) into two equal groups of 29 patients each. Transversus abdominis plane block (TAPB) group and non-blocked group.
Preoperatively, the patients were educated to the use of the incentive spirometer and visual analog scale (VAS) to monitor their pain postoperatively (where 0 represented no pain, and 10 meant the worst possible pain).
The anesthesia management of all patients was the same. On arrival at the operating theatre, the patients were monitored by electrocardiography, non‑invasive blood pressure, and pulse oximetry. Intravenous infusion of warm ringer’s lactate solution was initiated. All patients received general anesthesia; midazolam 0.03 to 0.05 mg/kg was given intravenously. After adequate pre-oxygenation, anesthesia was induced by IV fentanyl 1 to 2 μg/kg, propofol 1.5 to 2mg/kg, and cisatracurium 0.15 to 0.2 mg/kg. Tracheal intubation was done and ventilator settings were adjusted to maintain the end‑tidal carbon dioxide tension at 30 to 35 mm Hg.
Anesthesia was maintained using 1.2 MAC isoflurane, oxygen–nitrous oxide mixture, and IV cisatracurium incremental doses. Incremental doses of morphine 0.01 to 0.03 mg/kg were given intraoperatively with an interval of 30 min between each dose or when needed to avoid any increase in vital signs > 20% of basic vitals preoperatively.
A standard abdominoplasty technique was performed for all patients including rectus sheath plication with or without liposuction. The procedure starts with liposuction, if indicated, by infiltrating the subcutaneous abdominal layer with normal saline mixed with adrenaline, followed by suctioning most of the fat layer using a 2-4 mm cannula through small skin incisions.
Proceeding with abdominoplasty; initially the umbilicus is separated from the abdominal wall through a circular incision & dissecting along the umbilicus stalk. Then, an incision is made horizontally at the pubic hair boundary to approximately 3–4 cm caudal to the anterior superior iliac spine on both sides. The flap is dissected cranially along the superficial fascia, in a lateral direction as far as the xiphoid process and the costal arch. While ensuring immediate hemostasis at all times.
To achieve a good result for the tightening of the abdominal wall, plication of the rectus sheath is routinely carried out by doubling the fascia longitudinally. The first layer, by using an interrupted mattress sutures, while the second layer, which forms sort of a mesh layer, by using a continuous loop suture. The flap is then pulled down, & the excess skin/fat layer is excised. The wound is closed in three layers. Finally, the new umbilicus site is created.
By the end of the surgery, for the blocked group after wound closure and keeping dressing, a bilateral subcostal and bilateral posterior TAPB has done to provide a sensory block for the anterior abdominal wall dermatomes from T6 to L1. Ultrasound-guided block using a high-frequency linear probe 7-15 MHZ, a 22 G needle for injection, and an isobaric bupivacaine 0.25% dosage 2mg/kg as local analgesia with additive dexamethasone 0.1 to 0.2 mg/kg to increase the duration of LA. For the subcostal TAPB the transversus abdominis muscle identified starting beneath rectus abdominis muscle, the target is to visualize the fascial plane between the internal oblique and transversus abdominis muscle where LA has injected 10 ml on each side. While for the posterior TAPB the three layers of abdominal wall muscles (external and internal oblique as well as the transversus abdominis muscles) were visualized, the target is the fascial plane between the internal oblique and the transversus abdominis muscles where LA was injected 15 to 20 ml on each side.
Using the ultrasound gives the chance of performing the block under the complete clear vision of the needle tip, and also for observing the LA spread which allows us to avoid structures injury (intestine/vascular) and to give the less amount of LA to achieve the wanted effect without the risk of dose-related toxicity.
After finishing the block, isoflurane was discontinued, Neuromuscular blockade was antagonized with 0.025 to 0.05 mg/kg neostigmine and 0.01 to 0.02 mg/kg atropine, and then extubation was done for all patients
In PACU, where patient observed and monitored for 1 hour. ECG, NIBP, pulse oximetry, respiratory rate and effort were monitored also VAS was assessed. All patients have received IV pethidine 50 mg when VAS ≥ 4.
In the ward all patients' data were recorded for 72 hours postoperatively. Including the opioids consumption, pain assessed at rest and during movement (or with knee flexion) using VAS in 1 hour (H1), 3 hours (H3), 6 hours (H6), 12 hours (H12), 24 hours (H24), 36 hours (H36), 48 hours (H48), 60 hours (H60) and 72 hours (H72) postoperatively. Also time to the first ambulation and time to first incentive spirometer when the patient was able to reach 900 ml/min.
For all patients analgesic regimen consisted of IV Paracetamol 1 g every 6 hours, values of VAS were recorded postoperatively, once the patient had a VAS ≥ 4 pethidine 50 mg IV was administered and VAS was recorded every 30 min until the pain improved with an interval of 3 to 4 hours between each pethidine dose.
Based on previous study , the reduction in the mean dose of postoperative analgesics opioids was 39%. Authors considered a 25% increase in the reduction of the mean dose of opioids consumption postoperatively to 64% is considered to be clinically significant. Assuming an α error of 0.05, β error of 0.1, and power of study 90%, 24 patients were needed in each group to detect the clinical effect, we enrolled 29 patients in each group to accommodate for any dropout.
Data entry and analyses were performed using the SPSS statistical package, version 27 (SPSS, Inc., Chicago, IL, USA). The data were examined for normal distribution using Shapiro-Wilk’s test. For parametric data, a t-test was used for mean ± SD, while nonparametric data Wilcoxon Signed Ranks Test was applied for median or frequency. The statistically significant level was set a p-value ≤ 0.05, post-hoc power test SPSS was performed also using G power 184.108.40.206 to determine the sample size. All calculated P-values were two-tailed.