|Ahead of print publication
Comparison of postoperative analgesic effect of transversus abdominis plane block versus direct wound infiltration with local anesthetic for lower segment cesarean section
Debashish Paul1, Sachin Narayan Kulkarni2, Nipun Gupta1, Tina Singh3, Deepak Dwivedi4, Shalendra Singh1
1 Department of Anaesthesiology and Critical Care, AFMC, Pune, Maharashtra, India
2 Department of Anaesthesiology and Critical Care, INHS Asvini, Mumbai, Maharashtra, India
3 Department of Obstetrics & Gynaecology, INHS Asvini, Mumbai, Maharashtra, India
4 Department of Anaesthesiology and Critical Care, Command Hospital (SC), Pune, Maharashtra, India
|Date of Submission||17-May-2020|
|Date of Decision||13-Jul-2020|
|Date of Acceptance||09-Aug-2020|
|Date of Web Publication||23-Sep-2020|
Department of Obstetrics and Gynaecology, INHS Asvini, Mumbai - 400 005, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Various drugs and regional blocks are available for providing suitable postoperative analgesia after lower segment cesarean section (LSCS), however commonly used techniques are conventional wound infiltration with local anesthetic and the current technique of transversus abdominis plane (TAP) block. This study aims to compare the analgesic efficacy of TAP block with that of direct infiltration of local anesthetic into a surgical incision in LSCS patients. Materials and Methods: A total of 80 patients for LSCS under subarachnoid block were allocated in two groups; Group A (TAP block, n = 40). TAP block was done by the Anesthesiologist and Group B (wound site infiltration, n = 40); wound site infiltration was done by the operating Surgeon. Postoperative pain, assessed by the Visual Analog Scale (VAS) levels at 2, 6, 12, and 24th h, the requirement of rescue analgesia and patient satisfaction was analyzed. Results: The VAS scores were lower at the 2nd and 4th h (statistically significant) of the postoperative period but at 6th, 12th, and 24th h, though VAS scores in Group A were lower in comparison to Group B, differences were statistically insignificant. The time to administer the first dose of rescue analgesia (421 ± 118.8 min) was longer in Group A in comparison to Group B (187 ± 148.3 min) with significantly fewer cumulative dose and delayed requirement of rescue analgesia in the first 24 h. Conclusions: Wound site infiltration and TAP block did not significantly differ regarding postoperative pain score in post-LSCS patients except the initial 4 h, but the TAP block showed an advantage with significantly reduced cumulative dose and delayed requirement of rescue analgesia in first 24 h.
Keywords: Cesarean section, obstetric analgesia, postoperative period, Visual Analog Scale
|How to cite this URL:|
Paul D, Kulkarni SN, Gupta N, Singh T, Dwivedi D, Singh S. Comparison of postoperative analgesic effect of transversus abdominis plane block versus direct wound infiltration with local anesthetic for lower segment cesarean section. J Mar Med Soc [Epub ahead of print] [cited 2020 Dec 4]. Available from: https://www.marinemedicalsociety.in/preprintarticle.asp?id=295895
| Introduction|| |
Lower segment cesarean section (LSCS) is the most commonly performed surgery all over the world. Pain remains the most common and dissatisfying problem experienced by a patient in the postoperative period, leading to increased morbidity, functional disability, and quality of life impairment., Various pharmacological agents are described in the literature to tackle this postoperative pain through a multi-modal approach.,, Transversus abdominis plane (TAP) block and local infiltration of the wound at the end of the surgery are the most commonly used techniques among them.,
Rafi first described the TAP block in 2001. A blind “double pop” technique or ultrasound-guided needle tracking through the external oblique and internal oblique (IO) muscles have been practiced for the TAP block. It works by blocking the thoracolumbar nerves (T6–L1) which supply sensory fibers to the anterior abdominal wall. It has been used to provide analgesia for various surgical procedures., Shibata et al. also reported the use of TAP block in gynecological procedures with sensory block up to T10, and they recommended its use only in lower abdominal surgeries.
Wound infiltration with local anesthetics is also used as multi-modal analgesia regimens and considered as a potentially useful method to decrease the consumption of postoperative analgesics mainly opioids and to decrease opioid-related side effects in the perioperative period. TAP block and incision site infiltration have opioid-sparing analgesic effects, but their relative efficacy is not well established. A clinical comparison between two methods in terms of quality of analgesia and patient satisfaction is warranted as both help in alleviating the incision site pain.
We hypothesized that the TAP block will provide better patient satisfaction and postoperative analgesia compared to direct surgical incision site infiltration with local anesthetics.
The primary outcome was the difference in pain scores at 2, 6, 12, and 24 h between the two groups. The secondary outcomes were the difference in the cumulative consumption of additional analgesia in 24 h in both the groups, in addition to the difference in patient satisfaction at 24 h between the two groups.
| Materials and Methods|| |
After obtaining the approval of the ethics committee and the informed consent of the patients, an observational comparative study was conducted in patients who underwent elective LSCS in a tertiary level hospital. A total of 126 patients reporting to the Antenatal OPD were enrolled in the study with the following inclusion criteria: (1) Antenatal patients between 19 and 40 years, (2) with viable pregnancy confirmed by ultrasound, (3) at term planned for elective LSCS, (4) patients consenting to participate in the study, and (5) patients in American Society of Anesthesiology (ASA) physical Status I and II. Patients for emergency LSCS, having contraindication for subarachnoid block (SAB), allergic to Local Anaesthetic, patients of chronic pain syndrome, or not consent for the study were excluded from the study.
During the study period using the consecutive sampling technique, initial 40 patients fulfilling study protocol were given ultrasonography (USG)-guided TAP block (Group A) and the next 40 patients were given wound infiltration locally (Group B).
Both the groups received the same dose of 30 ml of 0.25% bupivacaine within 30 min of completion of surgical wound closure. An experienced anesthesiologist performed a SAB who was not involved in performing USG-guided TAP block. USG-guided TAP block was performed by an anesthesiologist having experience in regional anesthesia techniques under USG guidance, and he was not involved in the collecting data or allocating the groups. The same anesthesiologist performed the TAP block in all the patients to remove the performance bias, whereas wound site infiltration was done by the operating surgeon after the surgery.
USG-guided TAP block was performed with a linear transducer placed in the axial plane on the midaxillary line between the subcostal margin and the iliac crest. After confirming three layers of abdominal wall muscles, the needle was inserted in the anterior axillary line and was advanced until it reached the fascial plane between the IO and transversus abdominis (TA) muscles approximately in the midaxillary line where half of the drug was deposited. The needle tip was then advanced (medial to the anterior superior iliac spine) until it was placed between the IO and TA muscles adjacent to the deep circumflex iliac artery (with a linear transducer pointing toward the umbilicus with a caudad tilt) and rest of the drug was deposited. The same procedure was repeated on both sides.
The SAB was performed with the patient in the sitting position with a midline approach by a 26-G Quincke needle (Exel Int, Los Angeles, CA, USA). 10 mg of hyperbaric bupivacaine (Heavy Marcaine 0.5%; Astra Zeneca, London, UK) was injected intrathecally. Any patient requiring general anesthesia or supplementation to SAB due to inadequate effect was excluded from the study.
A 100 mm 21-G peripheral nerve block needle (B. Braun) was used for the TAP block. 15 mL of 0.25% bupivacaine on each side of the abdomen (total 30 mL) was administered after the completion of the surgery. In Group B, a total of 30 mL of 0.25% bupivacaine was used for subcutaneous wound site infiltration (15 ml on each side of the incision, near right and left angles) of the patients by the surgeon only.
Intraoperative complications (nausea, vomiting, hypotension, and bradycardia) and postoperative complications for the same symptoms along with the complaint of headache were noted. Furthermore, the time for the first postoperative analgesic requirement was recorded. Postoperative pain was assessed by the Visual Analog Scale (VAS) score for the initial 24 h at different intervals (2, 6, 12, and 24 h) when the patient is in rest.
The patients were asked to provide a number, with ten being the most violent pain they had ever had, and zero being no sensation of pain for VAS.
Patient satisfaction was determined by asking the patients to express in terms of quality of pain relief (Excellent/Good/Fair).
Patients were evaluated at the 2, 6, 12, and 24 h by an observer who was blinded to the allocation of groups of the patient. All patients were administered injection paracetamol 1 g IV 8 hourly for analgesia in both the groups as an institutional protocol for postoperative pain relief, the first dose was given at the end of the surgery. If any of the patients complained of inadequate pain relief or observed for VAS score ≥ 4, injection diclofenac sodium 75 mg was administered intramuscularly, and the log of the same was maintained in the postoperative monitoring chart along with the time of administration.
The calculation was done using the SPSS software version 13.0. (IBM, USA), and graphs were produced using Microsoft Excel for MAC 2011 (version 14.1.2, Microsoft Corporation, USA). The sample size calculation was based on a recommendation from a previous study where the two-point difference in VAS between the two groups was considered clinically significant. To detect an observed difference of 20% in between the groups, with a power of study 80% and a type I error of 0.05, the minimum sample size required was 36 in each group with a suggested difference of standard deviation (SD) of 4. Total no. of allocation of patients in various groups was kept more than 40 assuming a drop out of maximum 10% of patients. Demographic parameters were analyzed using the Chi-square test. Patient characteristic data were presented using mean and SD and were analyzed using a t-test. Nonnumerical data such as the VAS score was analyzed using the Mann-Whitney test. The results were considered statistically significant when the P value was under 0.05.
| Results|| |
In this study, a total of 126 patients underwent LSCS during the study period (January 2017 to June 2017). Data of 80 patients were analyzed, whereas 34 patients did not meet inclusion criteria, 06 patients expressed their unwillingness to participate in the study, and 6 patients were excluded as could not be followed up [Figure 1]. Demographics such as age, body weight, status in terms of postcesarean pregnancy, or not along with ASA status were compared and were found out to be comparable [Table 1]. Both groups had predominantly ASA-I patients [Table 1]. All values expressed as mean ± SD or as expressed otherwise.
|Table 1: Demographic profile and baseline clinical characteristics of patients in both the groups|
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All applied TAP blocks were successful. Postoperative VAS scores in Group A were significantly reduced at 2 h (1.8 ± 1.3 in Group A vs. 2.24 ± 0.8; P = 0.047) and 4 h (2.41 ± 0.3 in Group A vs. 3.12 ± 0.8; P = 0.019) as compared to those of Group B [Table 2]. The VAS score of Group A at 6, 12, and 24 h was found to be clinically lower than those of Group B (P ≥ 0.05) but statistically insignificant. When we look at the time for the first demand of analgesics, it was significantly increased in Group A (mean 421 ± 118.8 min) in comparison to Group B (mean 187 ± 148.3 min), (P = 0.001) [Table 2].
|Table 2: Comparisons of Visual Analog Scale in between the groups and the time to demand for the first rescue analgesia|
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When we analyzed the requirement of additional analgesia over the first 24 h in the postoperative period, we observed a significant difference in both the groups. Patients in Group A consumed less amount of additional analgesia in the first 24 h in comparison to Group B (93.75 ± 32.8 in Group A vs. 127.5 ± 34.8 in Group B; P = 0.041) [Figure 2].
|Figure 2: Cumulative amount of additional analgesia in first 24 h (in mg) (P = 0.041)|
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There was no significant difference between the groups in terms of patient satisfaction for postoperative pain relief [Table 3]. While, 46.25% of patients expressed either of the technique as an excellent method to get pain relief in the postoperative period, 51.25% of our study population from both the groups considered either of the methods as good options for postoperative analgesia. A small proportion of patients (0.5%) labeled them as fair, interpreted as unsatisfactory [Table 3].
|Table 3: Comparison of patient satisfaction level with the method of postoperative analgesia|
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The results of complications in both groups were comparable. In both groups, postoperative complications were noted for hypotension, bradycardia, and nausea and vomiting only. There was no statistically significant difference between these two groups in the incidences of postoperative complications (P > 0.05) [Table 4].
| Discussion|| |
This study compared the TAP block with the local wound infiltration method for postoperative analgesia in patients undergoing LSCS under SAB because both are commonly clinically practiced techniques for postoperative analgesia. The advantage of local infiltration over the TAP block is that it requires no technical expertise and specialized equipment like ultrasound and can be performed by the operating surgeon himself. The advantage of TAP block for postoperative pain relief in patients undergoing LSCS, abdominal surgeries, laparoscopic cholecystectomy, and appendicectomy has been described in the literature. Most studies compared TAP block with placebo or other pharmacological agents. However, limited literature is available comparing TAP block with local infiltration at the surgical wound site.
As per some previous study, the efficacy of the TAP block for postoperative analgesia depends upon the simultaneous use of intrathecal morphine. When intrathecal morphine was used, TAP block as compared to placebo had better pain scores in the postoperative period in cases of LSCS, increased time to rescues analgesia, reduced overall postoperative opioid consumption. However, in contrast to this study, McMorrow et al. described no advantage of TAP block (with 0.375% bupivacaine) when added to subarachnoid morphine (100 mcg) in patients who underwent LSCS. The possible reason suggested by that study was that intrathecal morphine is effective both at the visceral and parietal levels; however, the TAP block acts only on the nerves supplying the anterior abdominal wall and thereby attenuate parietal component of pain only. However, the use of intrathecal morphine as compared to TAP block alone was associated with an increased incidence of side effects.
Local wound infiltration has also been studied extensively in patients undergoing LSCS. A meta-analysis revealed that the use of local anesthetic wound infiltration for cesarean section pain relief leads to decreased postoperative morphine consumption and lower incidence of PONV. The confounding factor in analyzing studies on local wound infiltration for postoperative pain relief is that the technique of infiltration used is varied. Many studies have also used a wound catheter with either intermittent local anesthetic bolus or continuous infusion with or without priming bolus.
In the present study, the VAS score at 2 h and 4 h postoperatively was significantly lower in Group A (TAP) as compared to Group B (Local Infiltration). The VAS scores at 6, 12, and 24 h postoperatively were more in Group B, however not significantly different between the two groups. This finding is supported by a randomized controlled trial conducted by Aydogmus MT which showed numeric pain score values of infiltration group at 2, 6, 12, and 24th h statistically significantly higher than those of TAP block group.
A randomized controlled trial by Naveen S showed that in patients undergoing LSCS mean time to first analgesic rescue was significantly prolonged in TAP group as compared to control (88.02 min vs. 525.27 min). Similar observation has been obtained in our study; however, the difference is not as marked as seen in the study by Naveen S. The difference can be explained by the fact that their study compared TAP group with control and added dexmedetomidine as an additive to hyperbaric bupivacaine for SAB.
We demonstrated a significant difference in the cumulative consumption of additional analgesia in the form of injection diclofenac (intramuscular) in the first 24 h in patients in between the groups. There is less requirement of a total dose of additional analgesia in Group A receiving bilateral TAP block than in the patients receiving wound infiltration in Group B. Our findings differ from the study done by Tawfik et al. in their randomized controlled trial of TAP block versus wound Infiltration for analgesia after cesarean delivery. They reported no significant difference in cumulative fentanyl consumption at 24 h in parturient receiving bilateral TAP block or subcutaneous wound infiltration after cesarean delivery performed under spinal anesthesia.
For postoperative patient satisfaction, both the groups had similar results with no significant difference. The results are supported by similar results in the previous study which showed no statistically significant difference between the TAP block and infiltration group for patient satisfaction. Mankikar et al. in their analysis compared USG-guided TAP using 0.5% ropivacaine and placebo and assessed the efficacy of TAP with ropivacaine for a period of 24 h postoperatively in patients undergoing LSCS. This finding was same as it was in our study except for the fact that they used ropivacaine in their study. Our findings are supported by the study done by Petersen et al. and Skjelsager et al. who also reported that there was no statistically significant difference in the mean rate of PONV at 24 h between the TAP group and local anesthetic infiltration group., We, too, concluded no difference between two groups in the incidence of nausea and/or vomiting or incidences of hypotension and bradycardia within 24 h after cesarean delivery (P > 0.05). Carney et al. also observed no decrease in the incidence or severity of PONV in the TAP block group as compared to the placebo group in patients undergoing total abdominal hysterectomy.
Small sample size and nonrecording of the VAS score of the patients when ambulant are the main limitations of our study. VAS scores inpatient while ambulant has a clinical significance as both visceral and parietal components of pain would have influenced the duration of analgesia.
| Conclusions|| |
TAP block, when compared with direct wound infiltration, has shown better pain relief in the initial few hours after cesarean delivery and has the added advantage with significantly reduced cumulative dose and delayed requirement of rescue analgesia in first 24 h. This study also brings out that combining with standard nonopioid drugs; both the technique provided comparable satisfactory analgesia with no significant difference in side effects. So, we recommend that all patients should be exposed to either of the technique before leaving the operating room; USG guided TAP block being the better choice to cut down the requirement of additional analgesia. This study is certainly asking for a randomized controlled trial with a larger sample size, preferably a multicentre study for an authoritative answer to the better modality for postoperative pain relief in cesarean section.
The authors would like to thank Surg Cmde (Dr) Rahul Ray VSM, Commanding Officer, INHS Kalyani.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]