Comparative study between Bupivacaine versus Bupivacaine with Pethidine in Bilateral Transversus Abdominis Plane Block for Postoperative Pain Relief in Patients Undergoing Cesarean Deliveries

INTRODUCTION

Among the most prevalent surgical procedures in the world is the Caesarean section (CS). Both the mom and the newborn experience post-surgical pain, especially in the first 48 hrs after delivery. The pain might be excruciating, disrupting mother-child bonding.¹ In a dose-dependent way, the analgesic morphine's well-known adverse effects of nausea, vomiting, itchiness, and sedation could interact with the interaction between mom and baby, breastfeeding, and post-partum experience. However, several alternative strategies for reducing morphine consumption after surgery were described.² One of these has been the (TAP) block, which is a regional anesthetic method that offers sensory and motor block of the anterior abdominal wall from T7 to L1, but has no visceral impact. It's utilized in lower abdominal surgeries like CS.³ Since the advent of ultrasound into anesthetic procedures, there has been an increase in the importance of the (TAP) block.⁴ Multiple benefits for mother and baby obtained by TAP block include: long and effective analgesia, earlier oral nutrition, earlier mobilization, and a brief

stay in the hospital.⁵ Recent researches have focused on prolongation of the analgesia provided by the block.⁶ Pethidine is a local anesthetic opioid that binds to peripheral opioid receptors and impacts voltage-gated sodium channels.⁷ Pain in inflamed tissues is linked to peripheral opioid receptors. According to studies, opioid antinociception is triggered by the stimulation of opioid receptors outside the CNS, and the analgesic impact of opioids administered systemically is largely mediated by peripheral opioid receptors.⁸ According to electrophysiological studies, pethidine administration is followed by a sensory and motor block caused by peripheral nerve action. Pethidine is useful in a variety of regional anesthesia methods, including subarachnoid, epidural, intraarticular, as well as regional intravenous.⁹

PATIENTS AND METHODS

A total of 60 patients with American Society of Anesthesiologists (ASA) physical status I or II who were scheduled for Caesarean deliveries were enrolled in this randomized, prospective, double-blind clinical study. The research took place at Al-Azhar University Hospitals (Al-Husein and Sayed Galal Hospitals) between October 2018 and October 2020.

Patients have been split into 2 equal groups: Group (B) got an ultrasound guided TAP blocks with 20 ml of 0.25 % bupivacaine bilaterally, and Group (BP) received an ultrasound guided TAP blocks with 20 ml of 0.25 % bupivacaine bilaterally and 50 mg of pethidine bilaterally.

Inclusion Criteria: Patients with ASA I to II range in age from 21 to 45 years.

Exclusion Criteria: Refusal by the patient, allergy to local anesthetics, BMI >35 kg/m2, chronic opioid use history, emergency CS, coagulopathy, infection at puncture site, and physical status ASA III or more.

Sample size: According to a prior study evaluating bupivacaine versus bupivacaine with pethidine in bilateral TAP blocks for postsurgical pain alleviation in women having undergone caesarean delivery, the alpha error was set at 5% and the power was set at 80% utilizing the STATA program.

Ethical considerations:

The study was performed following the approval of the ethical committee and obtaining the patients' informed consent. The study protocol was explained to the patients after taking their consent to the type of anesthesia and surgical procedure.

All patients were subjected to:

Monitor for vital signs: Noninvasive blood pressure (NIBP), electrocardiograph (ECG), oxygen saturation (SpO₂).

Ultrasound machine (sonosite M turbo).

Spinal anesthesia needle (25G).

Bupivacaine 0.5% - Lidocaine 2%.

Resuscitation equipment and drugs.

The pre-anesthetic assessment was performed with history, clinical examination and investigations. Furthermore, all patients have been given 0.01 mg/kg atropine as a premedication, 1 mg of metoclopramide, and 20 mg of famotidine intravenously before the operation. As a preload, 15 min were spent infusing 20 mL/kg of Ringer's lactate solution. Prior to surgery, mean arterial blood pressure (MAP), oxygen saturation (PO) and heart rate (HR) have been measured and documented. A standard spinal anesthetic containing 10-12 mg of 0.5 % hyperbaric bupivacaine was used on all study participants who obtained spinal anesthesia. After that, the patients were moved to a supine position with a 15° head elevation. Abdominal surgery has been conducted with continuous hemodynamic monitoring of BP and HR following confirmation of an adequate level of anesthesia. If the systolic blood pressure drops by 20% or < 90 mmHg, 6 mg of ephedrine is administered intravenously. Furthermore, 0.6 mg of atropine has been administered IV if the HR has been lowered to 50 bpm or less.

After completion of surgery, fascial plane block was applied to reduce and control pain following the surgery. With the patient supine, a linear US probe (high frequency probe, 10–12 MHz) linked to a portable US unit (SonoSite, USA)  has been positioned in the mid-axillary plane midway between the lower costal margin and the highest point of the iliac crest. After disinfecting the skin, a 23-G 50-mm needle with an injection line has been inserted in the probe's plane. After placing the needle tip in the space between the internal oblique abdominal muscle and the transversus abdominis muscle, and after negative aspiration, 5 ml of saline (0.9%) has been injected to distend the TAP, followed by 20 ml of bupivacaine (0.25%), and the procedure has been repeated on the other side.

Group BP: received spinal anesthesia according to the same protocol as in group B and US guided TAP block bilaterally following surgery with 20 ml of 0.25% bupivacaine and 50 mg of pethidine.

The following parameters were assessed and recorded:

Hemodynamic monitoring: The first postoperative hour's MAP and HR have been documented every 15 minutes, followed by 2, 4, 6, 12, and 24 hrs.

Respiratory monitoring: For the first hour after surgery, peripheral oxygen saturation (SPO2) was recorded every 15 minutes, then at 2, 4, 6, 12, and 24 hrs.

Assessment for post-operative pain using a visual analogue scale score every 15 minutes for the first hour postoperative, then 2, 4, 6, 12, and 24 hrs later.

Analgesic requirements (Rescue analgesic): The time to first rescue analgesic Nalbuphine (0.1 mg/kg) has been recorded in both groups. VAS reached 4 and the total amount of analgesia consumed in the first 24-h following surgery was recorded in both groups.

Post operative nausea and vomiting: In both groups, the prevalence of postsurgical nausea and vomiting has been assessed in the first 24 hours, and average consumption of rescue antiemetic doses of Granisetron (1mg) was recorded in both groups.

The time to hospital discharge was recorded.

Statistical analysis:

Using the SPSS statistical computer package, the gathered data was organized, tabulated, and statistically analyzed (IBM Corp., Armonk, NY, USA). Age and body weight were numerical variables with a normal distribution, and the mean ± SD have been utilized to summarize them. The mean values of the two groups have been compared utilizing an independent t-test. Other non-normally distributed variables are expressed as the median and interquartile range (IQR). As a significance test, the Mann–Whitney U-test has been utilized. The Chi-square test has been utilized to determine the significance of qualitative data, which was expressed as a number and a percentage. A statistically significant P-value of

RESULTS

The study enrolled 60 patients, 30 of whom had been randomized to receive TAP block with 20 ml of 0.25 % bupivacaine bilaterally + 2 ml of normal saline and the remaining 30 patients received TAP block with 20 ml of 0.25 % bupivacaine bilaterally + 50 mg of Pethidine (meperidine) bilaterally.

The demographics between groups B (bupivacaine) and BP (bupivacaine-Pethidine) exhibited  no statistically significant differences as shown in (Table 1).

Table 1: Demographic data comparison between groups B (TAP block) and BP (TAP block).

According to mean arterial blood pressure, the two study groups' baseline MAPs were comparable, with no statistically significant differences. When contrasted to group B, the MAP in group BP was significantly lower after 15 minutes, 30 minutes, and 45 minutes in PACU. Following that, no statistically significant differences among both groups were found in subsequent recordings, as displayed in (Table 2) and (Figure 1).

Table 2: Comparison of mean arterial blood pressure (mmHg) between group B (TAP block) and group BP (TAP block) 

Fig. 1: Comparison between Group B and Group BP according to Mean arterial blood pressure.

Regarding heart rate, baseline heart rate was comparable between the two study groups with no statistically significant differences. In subsequent recordings, no statistically significant differences among both groups were found, as displayed in (Table 3).

Table 3: A comparison of postoperative heart rate (beats/min) between groups B (TAP block) and BP (TAP block).

According to pain VAS S score, postoperative pain was evaluated at rest through assessment of the mean VAS score, at PACU, 2, 4, 8, 12, and 24 hrs after surgery. The average VAS S scores in the BP group showed a significant decrease during recovery time at 2 and 8 hrs postoperatively. At other time points, however, no significant differences in mean pain intensity among both groups have been noticed (P > 0.05) (Table 4) and (Figure 2).

Table 4: Comparison of VAS S scores between group B (TAP block) and group BP (TAP block).

Fig. 2 : Comparison between Group B and Group BP according VAS S score

According to pain VAS D score, postoperative dynamic pain score was evaluated through assessment of the mean VAS score, at PACU, 2, 4, 8, 12, and 24 hours postoperatively. During the first two hours, the dynamic pain score can not be assessed, due to the inadequate motor activity. The mean dynamic VAS scores in the BP group showed a significant decrease throughout recovery time at 4 and 8 hours postoperatively. At other time points, however, no significant differences in mean pain intensity among both groups have been noticed (P > 0.05) (Table 5) and (Figure 3).

Table 5: Comparison of VAS D scores between group B (TAP block) and group BP (TAP block)

Fig. 3: Comparison between Group B and Group BP according VAS D score

According to the time of first postoperative analgesia, the time to postsurgical analgesia has been measured and contrasted between the two groups. The time to first postoperative analgesia in the BP group has been reported to be significantly longer than in the B group (256.9 vs. 160.5 minutes, P=0.0005) (Table 6) .

Table 6: Comparison of study groups based on time to first postoperative analgesia with nalbuphine (minutes)

According to the total analgesic requirements, the amount of diclofenac and nalbuphine consumed in 24 h by both the groups were compared. We found that the consumption of diclofenac and nalbuphine was significantly lower among the BP group (Table 7).

Table 7 : Comparison of analgesic requirements between groups B (TAP block) and BP (TAP block).

According to adverse effects, there was no difference in the occurrence of nausea (P=0.25), vomiting (P=0.14), hypotension (P=0.66), or bradycardia (P=0.17) between the groups. When compared to the B group, the occurrence of pruritus was significantly higher in the BP group (P=0.01) (Table 8).

Table 8: A comparison of the adverse effects of groups B (TAP block) and BP (TAP block)