A Comparative Study of Quality of Postoperative Analgesia After USG Guided Transversus Abdominis Plane Block vs USG Guided Quadratus Lumborum Block for Lower Abdominal Gynaecological Surgeries Using Ropivacaine (0.25%) with Clonidine

– Dr. Abik Mallik, Dr. Krishnendu Chandra, Dr. Jayanta Bhattacharya, Dr. Ashish Patra

Abstract :
Context : Optimizing pain management is an essential component of enhanced perioperative recovery for patients undergoing surgery. The transversus abdominis plane (TAP) block or quadratus lumborum (QL) block have been used as modality of post-operative analgesia in lower abdominal gynaecological surgeries. This comparative study examines the effect of USG guided TAP block vs USG guided QL block on analgesic requirment.

Aims : Toasses the analgesia between USG guided TAP block vs USG guided QL blockin first 24 postoperative hrs in lower abdominal gynaecological surgeries.

Settings and Design: It was a Prospective Single Blinded Randomized Clinical Trial, undertaken at tertiary care hospital in eastern India with 60 patients in each group, ASA I&II, aged 18 – 80 yrs, posted for lower abdominal gynaecological surgeries.

Methods & Material:
After Institutional Ethical & Scientific Committee approval and written informed consent, 120 women undergoing lower abdominal gynaecological surgeries under general anaesthesia were studied in 2 groups. The (T) group received USG guided TAP Block and the (Q) group received USG guided QL block with 25 ml of 0.25% Ropivacaine with Clonidine (75mcg) before Neuromuscular reversal bilaterally. Both groups received inj. Fentanly & inj. Paracetamol (1gm) in the intraoperative period.

In postoperative period both group received inj. Tramadol (100mg) IV on demand or VAS>5. Each patient was assessed in the PACU at 0, 1, 2, 4, 6, 9, 12 & 24 hrs and VAS score recorded. The time of 1st dose of rescue analgesic, total analgesic consumption in 1^st 24 hour and any event of adverse incident were noted.

Results:
The QL Block reduced VAS Score on various postoperative time points at 6 hrs, 12 hrs and 18 hrs than TAP Block.
Tramadol 100 mg dose requirement in first 24 hrs were significantly reduced in Q group.
No complications were noted in both the groups. In the postoperative period the (minutes) requirement of first dose of tramadol was significantly later in the QL group than the TAP group.

Conclusions:
The bilateral QL block provides more effective analgesia than bilateral TAP block.

Introductions:Effective post-operative analgesia is an essential part of post-operative care. Inadequate postoperative pain relief may lead to various adverse effects like patient discomfort, prolonged immobilization, pulmonary complications, and longer hospital stay. Traditionally systemic opioids are used for post-operative analgesia. However, opioids are associated with side effects like respiratory depression, pruritus etc.

Regional anaesthesia techniques are effective alternatives to achieve post-operative analgesia. Transversus Abdominis Plane Block or Quadratus Lumborum Block has emerged as a safe and effective regional anaesthesia modality for providing post-operative analgesia in lower abdominalgynaeological surgeries in adults.
Today improved understanding of Ultrasonography promotes vizualisation of anatomical structures in real time and TAP block given in between internal oblique and transversus abdominis thereby decreasing the chance of block failures.

In QL block at first quadratus lumborum muscle is identified where it borders the psoas major and attaches to the transverse process of the L4 vertebra. The needle is inserted in posterior to anterior direction through the QLM until the tip reaches in the plane between anterior surface of QLM and psoas major and drug deposited in this plane.
Objective of this study was to compare TAP block versus QL block for providing better postoperative analgesia in lower abdominal gynaecological surgeries.

Aim:
Toasses the analgesia in first 24 postoperative hrs in lower abdominal gynaecological surgeries.

Objectives :
a) Postoperatively to assess and compare the analgesic efficacy of USG guided TAP block versus USG guided Quadratus Lumborum(QL) block through the visual analogue scale (VAS) score for post-operative pain.
b) To assess the total rescue analgesic (Tramadol) consumption in first 24 postoperative hrs
c) To evaluate any associated side effects.

Subjects and Methods Approval of the Institutional Scientific and Ethical Committee was obtained. Written informed consent was obtained from the patients or patient relatives participating in this study. VAS score was explained to both the patients and their patient relatives before either of the procedures. The study was a prospective single blinded randomized control trial.

120 ASA physical status I, II female patients between the ages of 18-80 years posted for lower abdominal gynaecological surgeries were randomly allocated into two groups of 60 each,Group T and Group Q, using computer generated random numbers table.

Patients who were allergic to Ropivacaine, having coagulopathy, mental incapacity or language barrier precluding informed consent, a body mass index more than 35, currently using analgesics regularly for underlying disease such as arthritis was excluded from the study.

Both the groups were administered general anesthesia, one group received US-TAP block (group T) and the other group received US-QL block (group Q) with 0.25% ropivacaine and clonidine (75 µg), 25 ml on the left and right side each for a total of 50 ml .

In the Operation Theatre (OT), after establishing I.V access and attaching all standard monitors, premedicated with I.V. Inj. glycopyrrolate 4 µg/kg and lidocaine (2%) 1.5 mg/kg, fentany l2 µg/kg.

Induction of anesthesia done by Propofol (1%) @ 2mg/kg. Patient was intubated with Inj. Vecuronium. Both groups received injection paracetamol 1gm intraoperatively.
Anesthesia was maintained with 40%-50% oxygen with N2O and Sevoflurane with a total fresh gas flow of 2 L/min with controlled mechanical ventilation. The blood pressure was kept to within 20% of the blood pressure measured when arriving in the operation room. Also, the end-tidal carbon dioxide partial pressure was maintained within the range of 30 to 40 mmHg. Patients was actively warmed to keep core temperature normothermic. At the end of the surgical procedure and wound dressing, the patients in group T received the US-TAP block and the group Q was received the US-QL block.Patient was reversed from neuromuscular blocked after performing bilateral QL/TAP block.
A LOGIQe ultrasound machine equipped with a low frequency transducer 2-6 MHz probe was used for all patients. An exploratory scan was performed in each patient before the block. After proper antiseptic dressing and application of sterile transducer sheath and gel, linear USG probe was placed in the axillary plane in mid axillary line mid-way between costal margin and iliac crest. Three layers of the abdominal wall was identified. 10 cm Stimuplex needle was inserted until the tip was located on USG screen in between internal oblique and transversus abdominis layer. After negative aspiration of any fluid or blood, Inj. Ropivacaine with clonidine (75 mg), was injected bilaterally and confirmed by presence of hypo echoic layer on USG. The QL block was performed in lateral position. The low frequency transducer probe was placed on the lateral abdomen above the iliac crest and below the thoracic cage. The transducer is then gradually aligned in a more posterior and lateral direction parallel to the inter-crista line to visualize first transverse abdominis aponeurosis and will be followed until QL muscle (lateral and posterior to abdominal wall muscle) visualized. The quadratus lumborum muscle is identified where it borders the psoas major and attaches to the transverse process of the L4 vertebra. The needle is inserted in posterior to anterior direction through the QLM until the tip reaches in the plane between anterior surface of QLM and psoas major and drug deposited in this plane.

Each patient was assessed in the PACU at 0,1,2,4,6,9,12,18 & 24 hrs and VAS score recorded at rest and on movement (knee flexion).
Patients received Injection Tramadol (2mg/kg, maximum dose 100 mg) intravenous if VAS >5 or patients demanded analgesia.
The time of 1^st dose of rescue analgesic, total analgesic consumption in first 24 hour and any event of adverse incident were noted.

Tap Block

Image 1 : USG screen showing three distinct layers-external oblique, internal oblique and transversus abdominis

Image 2 : USG screen showing drug being infiltrated.

QL BLOCK

Image 3 : Showing transverse process of vertebra, quadratus lumborum, erector spinae, psoas major.

Image 4 : Showing infiltration of drug in QL BLOCK

Statistical analysis used:
Statistical Analysis was performed with help of Epi Info (TM) 3.5.3 which is a trademark of the Centers for Disease Control and Prevention (CDC).

Using this software, basic cross-tabulation and frequency distributions will be prepared. Chi square test was used to test the association between different study variables under study. Corrected Chi square test was used in case of any one of cell frequency less than 5 in the bivariate frequency distribution.

Test of proportion (Z-test) was used to test the significant difference between two proportions. t-test was used to test the significant difference between means. p≤0.05 was considered statistically significant.

From the sample size Table, to detect an effect size of 0.23 there is a need of at least 60 study subjects per group with 90% power at 5% level of significance. The number of patients in each group was in the ratio 1:1. Thus the required samplesize for the study was 120.

Results:
Table-1: Demographic variable of the patients of the two groups

Parameters	QL Block (n=60) (Mean±s.d)	TAP Block (n=60) (Mean±s.d)	p-value
Age (in years)	38.22±6.90	38.53±7.24	>0.05
Weight (in kg)	55.22±8.63	56.93±8.36	>0.05
Height (in cm)	150.62±9.63	151.23±8.54	>0.05
BMI(in kg/m²)	24.25±2.19	24.84±2.62	>0.05

t-test showed that there was no significant difference in mean age, mean weight, mean height and mean BMI of the patients of the two groups (p>0.05). Thus the patients of the two groups were matched for their base parameters. Chi-square test showed that there was no significant association between ASA physical status and groups (p=0.46). Thus the patients of the two groups were comparable in respect of their ASA physical status.
t-test showed that there was no significant difference in mean heart rate, mean mean arterial blood pressure (MAP), mean SPO2 at different time interval of the two groups (p>0.05).

Results:
Table-9: Comparison of VAS at rest at different time and groups

VAS	QL Block (n=60) (Mean±s.d)	TAP Block (n=60) (Mean±s.d)	p-value
End of surgery	2.42±0.50	2.42±0.50	>0.05
Post-operative (hours)
After 1 Hour	2.42±0.50	2.42±0.50	>0.05
After 2 Hours	2.42±0.50	2.42±0.50	>0.05
After 4 Hours	2.42±0.50	2.88±0.58	>0.05
After 6 Hours	2.60±0.59	6.02±0.50	>0.001*
After 9 Hour	5.42±0.50	5.00±0.18	>0.05
After 12 Hours	2.72±0.61	5.53±0.68	>0.001*
After 18 Hours	5.35±0.52	7.03±0.88	>0.001*
After 24 Hours	5.07±0.31	5.15±0.40	>0.05

* Statistically Significant

Mean VAS on movement of TAP block was significantly higher after 6 hours, 12 hours and 18 hours (p>0.01). But there was no significant difference in mean VAS of the two groups for all other time intervals (p>0.05).

Table-10 : Comparison of VAS on movement at different time and groups

VAS	QL Block (n=60) (Mean±s.d)	TAP Block (n=60) (Mean±s.d)	p-value
End of surgery	2.42±0.50	2.42±0.50	>0.05
Post-operative (hours)
After 1 Hour	2.42±0.50	2.42±0.50	>0.05
After 2 Hours	2.42±0.50	2.42±0.50	>0.05
After 4 Hours	2.62±0.64	3.42±0.59	>0.05
After 6 Hours	2.75±0.75	6.25±0.44	>0.001*
After 9 Hour	5.48±0.54	5.28±0.45	>0.05
After 12 Hours	2.90±0.75	6.12±0.58	>0.001*
After 18 Hours	5.38±0.56	7.18±0.75	>0.001*
After 24 Hours	5.27±0.45	5.50±0.54	>0.05

* Statistically Significant

Table-11: Time to requirement of analgesic (in minutes)

	QL Block (n=60) (Mean±s.d)	TAP Block (n=60) (Mean±s.d)	p-value
Time (in minutes)	552.17±28.23	353.00±26.06	<0.001*

* Statistically Significant

Time to requirement of tramadol was significantly higher in QL block was significantly higher than that TAP block (p<0.001).

Side Effect :
Table-13: Comparison of side effects

Post-operative Side Effect	QL Block (n=60) (Mean±s.d)	TAP Block (n=60) (Mean±s.d)	Z-value	p-value
Nausea	7(11.7%)	7(11.7%)	0.01	0.99
Vomiting	3(5.0%)	4(6.7%)	0.38	0.69
Convulsion	0(0.0%)	0(0.0%)	0.01	0.99
Hypotension	0(0.0%)	0(0.0%)	0.01	0.99
Chest Pain	0(0.0%)	0(0.0%)	0.01	0.99

Test of proportion showed that there was no significant difference in the proportion of patients with nausea and vomiting of the two groups (p>0.05).

No patient had convulsion hypotension and chest pain in both the groups.

Discussion :

The US-guided QL Block represents the continued evolution of the US-guided TAP Block.The promise of more extensive abdominal analgesia compared with the TAP Block accounts growing interest in this block.

Carney J et al^[1], in 2008 concluded that the TAP block provided superior analgesia as reduced VAS score when compared to placebo block after elective total abdominal hysterectomy. The total morphine requirements in post-operative hours were also reduced.
In comparison to PCA pump (inj. fentanyl) Hyun- Jung Shin et al^[2], concluded as The US-TAP block with standard care provide more effective analgesia after gynaecologic surgery via a transverse lower abdominal skin incision. In another randomized control, trial conducted by Laleh Eslamian et al^[3], in 2012 concluded as the women in the TAP block group had significantly lower VAS pain scores at rest and during coughing and consumed significantly less tramadol as rescue analgesia than the women in no blocked group.

F.W. Abdallah et al^[5], in 2013 investigated analgesic effectiveness of posterior TAP block (Quadratus lumborum block) versus lateral TAP block in lower abdominal transverse incision surgery. They concluded as the posterior TAP (QL BLOCK) block appears to produce more prolonged analgesia than the TAP block. Murouchi T et al^[6], in 2016 compared a prospective cohort of 11 patients undergoing laparoscopic gynaecologic surgery who received bilateral QL block to a historical cohort of patient who received bilateral TAP blocks. Those in the QL group had a significantly prolonged time to first request for rescue analgesia. The QL group ad a sensory level from T7-T8 to L1 compared to T10 to L1 in the TAP group.

All these studies formed the premise for our study of finding a comprehensive technique of post-operative analgesia in women posted for lower abdominal gynaecological surgeries. In our study we observed that there was no significant difference in mean pain scores (in VAS score) of the two groups, i.e. group receiving TAP block and group receiving QL block at initial 4 hours. However, the mean pain scores of Group T was higher at 6 hours, 12 hours and 18 hours. A prospective study done by F.W. Abdallah et al^[5] showed reduced rest pain scores at 24, 36, and 48 h, and also dynamic pain scores at 12, 24, 36, and 48 h. Reduced pain score in 6 hr and 18 hr was a unique finding in our study. In our study, proportion of patient who demanded their first rescue analgesia at 552 minutes time period after neuromuscular revarsal was significantly higher for Group Q than group T at 353 minutes. This finding is corroborated with study done by Murouchi T et al^[6] in 2016.

The rescue analgesia consumption was significantly lower in Q group than T group. Mean total dose of tramadol given in QL block was 138.33 mg than 233.37 mg in TAP block in first 24 postoperative period. It is also seen in study done by F.W. Abdallah^[5] where requirement of rescue analgesia was less in quadratus lumborum group.
Thus, we can conclude that QL block provided better post-operative analgesia as compared to TAP block and it is devoid of any significant side effects.

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