The analgesic effect of Laparoscopic (LAP) TAP block (LTAP) is non-inferior to ultrasound-guided TAP block (UTAP) in terms of time to 1st rescue analgesia, total morphine consumption, and safety blocking through low post-operative complications and patient satisfaction, in patients undergoing LAP bariatric surgery. According to these outcomes from a randomised controlled trial, by investigators from the Ain Shams University, Cairo, Egypt, both LATP and UTAP can be used whenever accessible.
The researchers hypothesised that LTAP block is non-inferior to UTAP block in patients who underwent bariatric surgery. This study aimed to compare the efficacy and safety of LTAP vs. UTAP block following LAP bariatric surgery. The primary outcomes were total post-operative opioid consumption and post-operative pain scores (using Visual Analogue Scale (VAS)) at rest and in movement. In contrast, the secondary outcomes were the time of the first analgesic requested by the patient and the surgical duration.
This non-inferiority randomised controlled single-blind study was conducted on 120 patients with obesity scheduled for bariatric surgery. Patients were allocated into two equal groups (n=60):
LTAP Group - under direct vision, the operative surgeon inserted an 18G LAP needle between the lower costal border and the iliac crest at the midaxillary line via a working port until the "pop" was felt. Then, 2 mL of normal saline was administered to confirm the right position. 20 mL of 0.25% bupivacaine was injected into each side after noting Doyle's internal bulge sign, which is the bulge that forms when the TAM with the peritoneum is pushed inside.
ULAP Group - the anaesthesiologist conducted the UTAP blocks. A high-frequency linear transducer was positioned in the midaxillary line to measure the area between the iliac crest and the lower costal margin. After the TAM was identified, the anaesthesiologist used in-plane US- guidance to insert a 22G Tuohy needle between the internal oblique and TAM, injecting 2 mL of saline to ensure proper needle placement before injecting 20 mL of 0.25% bupivacaine into each side.
After reversing muscular relaxation with neostigmine, Extubation was carried out in a semi-sitting position. The patient was transferred to the Post-Anethesia Care Unit and administered paracetamol 1gm/6h IV as routine analgesia.
Outcomes
There were no statistically significant differences in age (p=0.114), sex (p=0.459), weight (p=0.259), height (p=0.229), BMI (p=0.519), WHO classification of BMI (p = 0.056), ASA classification (p=0.315), duration of surgery (p=0.516). The mean duration of anaesthesia in the LTAP group (47.62 ± 4.27 min) was statistically significantly shorter than in the UTAP group (54.23 ± 5.60 min) (p<0.001). The mean block performance in the LTAP group (2.8±0.8min) was statistically significantly shorter than in the UTAP group (7.13±1.76 min) (p<0.001).
In addition, there was no statistically significant difference in the post-operative heart rate between the two groups during all times of measurement (p>0.05). One-way repeated measures analysis in each group revealed a statistically significant change in heart rate among the different times of measurement (p<0.001).
There was no statistically significant difference in the post-operative Mean Arterial Blood Pressure (MABP) between the two groups during all times of measurement (p>0.05) except at 12 h post-operative, where the MABP was statistically significantly higher in the LTAP group (95.32±11.11 mmHg) when compared with UTAP group (91.40±10.09 mmHg) (p=0.046). One-way repeated measures analysis in each group revealed a statistically significant change in MABP among the different times of measurements (p<0.001).
There was no statistically significant difference in time to the first rescue analgesia between the UTAP group (12.60±6.43h) when compared with the LTAP group (14.29±5.84h) (p=0.384).
The mean of total morphine consumption is statistically not different between the UTAP group (1.22±1.93mg) and LTAP group (1.30±1.94 mg) when calculated for all included patients (n=60 per group) (p=0.814). In the UTAP group, 20/60 (33.33%) needed morphine compared with 21/60 (35.00%) in the LTAP group, with no statistically significant difference (p=0.849). Also, there was no statistically significant difference in the total morphine consumption between the two groups when calculated for only patients who need morphine (p=0.848).
There was no statistically significant difference in Post-operative Pain by Visual Analogue Scale (VAS) score for pain between the two groups during all times of measurement (p>0.05). One-way repeated measures analysis revealed a statistically significant change in VAS score among the different times of measurements in both the UTAP group and LTAP (p<0.001, p=0.001; respectively).
The incidence of adverse effects was not significantly different between both groups. No patients developed any signs of local anaesthetic toxicity. There was no statistically significant difference between both groups as regards post-operative nausea and vomiting (p=0.307), post-operative hypotension (p=0.509) and post-operative bradycardia (p=0.509). In the LTAP group, the patient satisfaction score (4.70±0.50) was statistically significantly higher when compared with the UTAP group (4.25±0.77) (p<0.001).
“Additional studies comparing different additives with different doses and concentrations of these blocks and examining the effect of varying block techniques on the post-operative outcome and the longer duration of post-operative follow-up will be valuable to verify these results. Also, in LAP group, there was no confirmation in the right position by US and cannot detect the spread of local anaesthetic drug in LTAP,” the researchers concluded. “Further studies need to compare different types, volumes and concentrations of local anaesthetic with local infiltration and other blocks.”
The findings were reported in the paper, 'Laparoscopic assisted versus ultrasound guided transversus abdominis plane block in laparoscopic bariatric surgery: a randomized controlled trial, published in BMC Anesthesiology. To access this paper, please click here