European Journal of Cardiovascular Medicine

Cesarean delivery is one of the most commonly performed surgical procedures.(1) Adequate pain control after cesarean delivery is a major concern both for parturients and for obstetric anesthesiologists and may impair early postoperative maternal   recovery. Usually this comprises a combination of systemic and regional techniques.The transversus  abdominis plane (TAP) block, affecting the nerves supplying the anterior abdominal wall, is a promising regional analgesic technique for a variety of abdominal and pelvic surgeries including cesarean delivery.(2)

TAP block is a regional anesthetic technique that blocks the abdominal wall neural afferents (T7-L1) and significantly reduces the pain associated with lower abdominal surgery.

Local anesthetic agents are injected into the neurofascial plane between the internal oblique and transversus abdominis muscle. The block, first described by Rafi in 2001,(3) is a simple and safe technique for analgesia after cesarean section, whether guided by anatomic landmarks or by ultrasound. TAP block in cesarean section is carried out by local anesthetics (4)such as bupivacaine or ropivacaine with a limited duration of action. Levo isomers have less systemic toxicity than the racemic compounds and have frequently been used for TAP block.(5)

The present study was planned to investigate whether 0.25% levobupivacaine or 0.25% bupivacaine in TAP block and the duration of postoperative analgesia in lower uterine segment cesarean section.

Objectives:

The primary outcome measure in this study was duration of postoperative analgesia.

The secondary outcome measures included total analgesic consumption in the first 24 h after the block, patient satisfaction, and possible side effects (sedation, hypotension, and bradycardia).

After the Institutional Ethical Committee approval, this randomized, double-blind controlled trial was conducted in 100 parturients (American Society of Anesthesiologists' physical status Class II) scheduled to undergo elective  cesarean section (where no fetal or maternal compromise existed) through Pfannenstiel incision under spinal anesthesia (SA). The patients were recruited between November 2023 and June 2024.

Exclusion criteria

Patients who refused SA, had any contraindication to regional anesthesia, history of drug allergy or chronic pain, a coagulation disorder or infection at the needle insertion site, a body mass index of >30 kg/m², or were unable to communicate were excluded from this study. Patients in whom SA was inadequate for the conduct of surgery were also excluded from the study.

Patients were divided into two equal groups of fifty each to receive either:

• Group A (n = 50): TAP block with 20 mL of 0.25% levobupivacaine each bilaterally
• Group B (n = 50): TAP block with 20 mL of 0.25% bupivacaine each bilaterally.

Patients were allocated to the respective groups using a computer-generated random number table. Group allocation report was concealed in sealed, opaque envelopes that were opened in the operating theatre just before the administration of SA. The study drug was prepared and coded by an anesthesiologist or the OT technician who not involved in the study. The patient and the anesthesiologist administering the TAP block and involved in data collection were also blinded to group assignment. The code was broken after the completion of the study and statistical analysis. After written informed consent, patients were made familiar with 10-cm visual analog scale (VAS) with 0 representing no pain and 10 representing worst imaginable pain before administering the block. Patients received a standard SA comprising hyperbaric 0.5% bupivacaine (1.8 ml) with 25-μg fentanyl. Bilateral ultrasound-guided TAP blocks were performed under all aseptic precautions, in the lumbar triangle of Petit bilaterally. Once the surgery was over and the sensory block had receded to T₁₀ level by pinprick, TAP block was given with an S-Nerve™ transportable ultrasound device (Toshiba, Nemio XG SSA-580A, TOCHIGI-KEN, JAPAN) using a linear array transducer (7.5 MHz) at the level of the anterior axillary line between the 12^th rib and the iliac crest. The assigned drug was slowly injected under direct ultrasonographic guidance.

After completion of the surgical procedure and block, patients were transferred to the post anesthesia care unit. The duration of postoperative analgesia, defined as the time (in hours) from the giving of the TAP block to the time to the first analgesic request in the postoperative period, was recorded. The degree of pain was observed using the VAS in 2, 4, 6, 8, 12, 18, and 24 h. The time was noted when the patient demanded for the first dose of analgesia. The TAP block was deemed a failure if the patient requested analgesia within the first 2 h of administering the block, and the case was not included in analyses. Patients were given injection tramadol 100 mg slow intravenous (IV) injection on demand or if the VAS score was ≥4. Sedation was evaluated along with VAS using a four-point ordinal scale (1 = wide awake and alert, 2 = awake but drowsy, responding to verbal stimulus, 3 = arousable, responding to physical stimulus, and 4 = not arousable, not responding to physical stimulus). The presence of sedation was defined as a sedation score >1 at any postoperative time point. A four-point patient satisfaction score (1 = extremely satisfied, 2 = satisfied, 3 = dissatisfied, and 4 = extremely dissatisfied) was also noted. Other associated side effects such as hypotension (systolic blood pressure <20% of baseline), nausea, vomiting, and bradycardia (heart rate <50/min) were also observed. A note was made of the total analgesic consumption in the first 24 h after the block. All the observations were made by an anesthesiologist who was unaware of group allocation and blind to the study drug.

Statistical analysis

The data were compiled, tabulated, and statistically analyzed using SPSS version 24 (IBM, Chicago, IL, USA). Unpaired Student's t-test was used for analysis of the duration of analgesia at the time of administration of injection tramadol. For analysis of nonparametric variables, such as the level of sedation and patient satisfaction score, Mann–Whitney U-test was used. Results were presented as mean ± standard deviation. P < 0.05 has been considered statistically significant.

One hundred patients were enrolled and randomized for the study. Baseline clinical characteristics are given in Table 1.

Table 1: Baseline clinical characteristics

BMI-Body mass index    MAP- Mean arterial pressure   SBP- Systolic blood pressure

DBP -Diastolic blood pressure

Groups were comparable in terms of age, weight, duration of surgery, and body mass index. Intraoperative blood pressure and heart rate were also comparable in  both the groups. The triangle of Petit was located easily on palpation; the TAP block performed without complication in all patients. Thus, a total of 50 patients each were analyzed in Group A and Group B.

100 patients were analyzed. Postoperative clinical outcome parameters were compared in Table 2.

Postoperative outcome parameters

Duration of analgesia was significantly longer in Group B (10.94 ± 0.56 h) compared to Group A (6.16 ± 0.61 h) (P < 0.001). Mean consumption of tramadol was 135.78 ± 14.90 mg and 88.89 ± 28.77 mg in Groups A and B (P < 0.001), respectively. All patients in Group B were extremely satisfied (P < 0.01) while those in Group A were satisfied. In Group B, 12 (28%) patients were sedated but arousable (P = 0.01) compared to 8 (19.5%) in Group A. None of the patients experienced hypotension or bradycardia.

This randomized, double-blind, controlled trial demonstrated that the bupivacaine in single-shot TAP block for cesarean section under SA prolongs analgesia by 10–12 h and reduces overall postoperative analgesic requirements in comparison to levobupivacaine alone. Although long-acting neuraxial or patient-controlled epidural/IV opioids produce effective analgesia, they are frequently associated with nausea, vomiting, and pruritus, which reduce overall patient satisfaction.(6) In addition, hydrophilic opioids such as morphine may cause delayed maternal respiratory depression due to the rostral spread.(7) The use of neuraxial opioids may be limited by logistic issues and/or the presence of medical contraindications.(8) (9)Systemically administered lipophilic opioids  may be secreted in breast milk and cause transient adverse neurobehavioral effects in the neonate. Given these issues, there is considerable potential for a regional technique such as TAP blockade to provide effective and long-lasting postcesarean section analgesia.(10) Many previous investigators have reported the analgesic benefit of TAP block in patients undergoing a wide variety of lower abdominal surgeries,(11) including cesarean section.(12) Sanjay et.al  (13) investigated the effect of TAP block with 0.5% ropivacaine 20 ml with dexmedetomidine bilaterally in patients undergoing cesarean section and reported  the increase in post op duration of analgesia and improved postoperative pain scores. In a recent study, nedeljkovic(14)concluded that  TAP block using LB plus bupivacaine HCl as part of a multimodal analgesia protocol incorporating intrathecal morphine resulted in reduced opioid consumption after cesarean delivery in the PCA set. Results suggested that with the correct TAP block placement and adherence to a multimodal postsurgical analgesic regimen, there is an opioid-reducing benefit of adding LB to bupivacaine TAP blocks after cesarean delivery. A meta-analysis by Abdallah et al.(15) concluded that TAP block can provide effective analgesia when spinal morphine is contraindicated or not used in patients undergoing lower segment cesarean section under SA. A study by John et al. showed that the TAP block as a part of a multimodal analgesic regimen definitely has a role in providing superior analgesia in the postoperative period.(16)

Varshney Aman et al. concluded that the addition of Bilateral TAP block with 0.25% levobupivacaine provides good quality analgesia for early postoperative period. Adding dexmedetomidine further improves pain control and gives higher patient satisfaction without any added side effects.(17)

Compared with bupivacaine, levobupivacaine is thought to be less toxic to the cardiovascular systems.(18) The quality of sensory and motor block appears to be similar in most studies after equal doses of levobupivacaine and bupivacaine.(19) The minimum effective local anesthetic concentration of levobupivacaine for motor block is significantly greater than that of bupivacaine, indicating that levobupivacaine is less potent at motor block than bupivacaine when administered in epidural analgesia for labor.(20) At this similar dose, levobupivacaine showed significantly less myocardial contractility and atrioventricular conduction depressant effect than bupivacaine.(21) Levobupivacaine reversibly blocks the transmission of action potential in sensory, motor, and sympathetic nervous fibers by inhibiting the passage of sodium through voltage-sensitive ion channels in the neuronal membrane. Whereas the inhibitory action is intended to be localized at the site of administration, excessive doses or accidental intravascular injection may lead to activity at the level of other ion channels in the excitable tissues, followed by unwanted central nervous and cardiovascular adverse effects. (22)The current pharmacodynamic evidence from animal and human studies suggests that levobupivacaine has a potentially greater margin of safety than the racemic bupivacaine. Hence, we used levobupivacaine as the local anesthetic which causes less motor blockade and comparatively safer drug than its congener bupivacaine.

Limitations of study

 First, the study was not large enough to assess safety. Second, there is a risk of inadvertent peritoneal puncture with this block, however, small. We, however, have not encountered this complication in the TAP blocks; we perform under ultrasonography guidance.

We conclude that  20 ml bupivacaine 0.25% in TAP block bilaterally for cesarean section provides 10–12 h of postoperative analgesia, decreases postoperative analgesic requirement, and increases maternal comfort compared to 20 ml of levobupivacaine 0.25% alone with minimal side effects.

1. Pandey, A.K., Raushan, M.R., Gautam, D., and Neogi, S.B. "Alarming Trends of Cesarean Section—Time to Rethink: Evidence From a Large-Scale Cross-sectional Sample Survey in India." Journal of Medical Internet Research, vol. 25, no. e41892, 13 Feb. 2023.
2. Erol, M.K., Şengel, A., Tammo, Ö., Seçilmiş, S., and Kaya, F. "The Effect of TAP Block Use in Postoperative Analgesic in Cesarean Section." European Review for Medical and Pharmacological Sciences, vol. 27, no. 7, Apr. 2023, pp. 2786–93.
3. Rafi, A.N. "Abdominal Field Block: A New Approach via the Lumbar Triangle." Anaesthesia, vol. 56, no. 10, Oct. 2001, pp. 1024–26.
4. Aydogmus, M., Sinikoglu, S., Naki, M., Ocak, N., Sanlı, N., and Alagol, A. "Comparison of Analgesic Efficiency Between Wound Site Infiltration and Ultrasound-Guided Transversus Abdominis Plane Block after Cesarean Delivery under Spinal Anaesthesia." Hippokratia, vol. 18, no. 1, Jan. 2014, pp. 28–31.
5. Jadon, A., Jain, P., Chakraborty, S., Motaka, M., Parida, S.S., Sinha, N., et al. "Role of Ultrasound Guided Transversus Abdominis Plane Block as a Component of Multimodal Analgesic Regimen for Lower Segment Caesarean Section: A Randomized Double Blind Clinical Study." BMC Anesthesiology, vol. 18, no. 1, 14 May 2018, p. 53.
6. McDonnell, J.G., Curley, G., Carney, J., Benton, A., Costello, J., Maharaj, C.H., et al. "The Analgesic Efficacy of Transversus Abdominis Plane Block after Cesarean Delivery: A Randomized Controlled Trial." Anesthesia & Analgesia, vol. 106, no. 1, Jan. 2008, pp. 186–91.
7. Sharpe, E.E., Molitor, R.J., Arendt, K.W., Torbenson, V.E., Olsen, D.A., Johnson, R.L., et al. "Intrathecal Morphine Versus Intrathecal Hydromorphone for Analgesia after Cesarean Delivery: A Randomized Clinical Trial." Anesthesiology, vol. 132, no. 6, Jun. 2020, pp. 1382–91.
8. Carney, J., Finnerty, O., Rauf, J., Bergin, D., Laffey, J.G., and McDonnell, J.G. "Studies on the Spread of Local Anaesthetic Solution in Transversus Abdominis Plane Blocks." Anaesthesia, vol. 66, no. 11, Nov. 2011, pp. 1023–30.
9. Gehling, M., and Tryba, M. "Risks and Side-Effects of Intrathecal Morphine Combined with Spinal Anaesthesia: A Meta-Analysis." Anaesthesia, vol. 64, no. 6, Jun. 2009, pp. 643–51.
10. Fusco, P., Cofini, V., Petrucci, E., Scimia, P., Pozone, T., Paladini, G., et al. "Transversus Abdominis Plane Block in the Management of Acute Postoperative Pain Syndrome after Caesarean Section: A Randomized Controlled Clinical Trial." Pain Physician, vol. 19, no. 8, 2016, pp. 583–91.
11. Pratheeba, N., Remadevi, R., Raajesh, I.J., Bhavani, V., Tripathy, D.K., and Bhat, R.R. "Comparison of Postoperative Analgesic Efficacy of Wound Site Infiltration and Ultrasound-Guided Transversus Abdominis Plane Block with 0.5% Ropivacaine in Lower Abdominal Surgeries under Spinal Anesthesia." Anesthesia Essays and Research, vol. 12, no. 1, 2018, pp. 80–84.
12. Bm, M., Rb, G., and As, H. "Transversus Abdominis Plane Block for Analgesia after Cesarean Delivery: A Systematic Review and Meta-Analysis." Canadian Journal of Anesthesia/Journal Canadien D'anesthésie, Nov. 2012, vol. 59, no. 8.
13. Nag, D.S., Gehlot, P., Sharma, P., Kumar, H., and Kumar Singh, U. "Comparative Study of Ropivacaine and Ropivacaine with Dexmedetomidine in Transversus Abdominis Plane (TAP) Block for Post-Operative Analgesia in Patients Undergoing Cesarean Sections." Cureus, vol. 16, no. 7, 2024, e65588.
14. Nedeljkovic, S.S., Kett, A., Vallejo, M.C., Horn, J.L., Carvalho, B., Bao, X., et al. "Transversus Abdominis Plane Block with Liposomal Bupivacaine for Pain After Cesarean Delivery in a Multicenter, Randomized, Double-Blind, Controlled Trial." Anesthesia & Analgesia, vol. 131, no. 6, Dec. 2020, pp. 1830–39.
15. Abdallah, F.W., Halpern, S.H., and Margarido, C.B. "Transversus Abdominis Plane Block for Postoperative Analgesia after Caesarean Delivery Performed under Spinal Anaesthesia? A Systematic Review and Meta-Analysis." British Journal of Anaesthesia, vol. 109, no. 5, Nov. 2012, pp. 679–87.
16. John, R., Ramachandran, G., and George. "Analgesic Efficacy of Transverse Abdominal Plane Block after Elective Cesarean Delivery - Bupivacaine with Fentanyl versus Bupivacaine Alone: A Randomized, Double-Blind Controlled Clinical Trial." Anesthesia Essays and Research, vol. 11, no. 1, Nov. 2017, pp. 181–84.
17. Varshney, A., Prabhu, M., Periyadka, B., Nanjundegowda, D.C., and Rao, A. "Transversus Abdominis Plane (TAP) Block with Levobupivacaine versus Levobupivacaine with Dexmedetomidine for Postoperative Analgesia Following Cesarean Delivery." Journal of Anaesthesiology Clinical Pharmacology, vol. 35, no. 2, Jun. 2019, p. 161.
18. Yıldırım Ar, A., Erdoğan Arı, D., Yiğit Kuplay, Y., İşcan, Y., Karadoğan, F., Kırım, D., et al. "Ultrasound-Guided Transversus Abdominis Plane Block in Patients Undergoing Laparoscopic Cholecystectomy: Comparison of Efficacy of Bupivacaine and Levobupivacaine on Postoperative Pain Control." Brazilian Journal of Anesthesiology, vol. 68, no. 5, Sept. 2018, pp. 455–61.
19. S.S., T.K., and Alalamath, S. "Comparative Efficacy of Intrathecal Hyperbaric Levobupivacaine with Fentanyl Versus Hyperbaric Bupivacaine with Fentanyl in Elective Cesarean Section." Cureus, vol. 16, no. 9, Sept. 2024, e70476.
20. El-Shaarawy, A.M., Asfour, M.S., Rashwan, D.A., Amer, M.M., El-Menshawe, S.F., and Elkomy, M.H. "Comparison of Three Different Concentrations of Levobupivacaine for Epidural Labor Analgesia: Clinical Effect and Pharmacokinetic Profile." Anesthesia Essays and Research, vol. 12, no. 1, 2018, pp. 60–66.
21. McClellan, K.J., and Spencer, C.M. "Levobupivacaine." Drugs, vol. 56, no. 3, Sept. 1998, pp. 355–62, discussion 363-364.
22. Miranda, P., Corvetto, M.A., Altermatt, F.R., Araneda, A., Echevarría, G.C., and Cortínez, L.I. "Levobupivacaine Absorption Pharmacokinetics with and Without Epinephrine during TAP Block: Analysis of Doses Based on the Associated Risk of Local Anaesthetic Toxicity." European Journal of Clinical Pharmacology, vol. 72, no. 10, Oct. 2016, pp. 1221–27.