|Year : 2014 | Volume
| Issue : 3 | Page : 400-405
Ultrasound-guided bilateral transversus abdominis plane block versus conventional systemic analgesia after cesarean section
Yahia A Hemimi, Ayman M Kamaly, Sahar M Talaat, Mohamed A Nosseir
Department of Anesthesiology, Intensive Care, and Pain Management, Faculty of Medicine, Ain Shams University, Cairo, Egypt
|Date of Web Publication||27-Aug-2014|
Sahar M Talaat
Department of Anesthesiology, Intensive Care, and Pain Management, Faculty of Medicine, Ain Shams University, Cairo
Source of Support: None, Conflict of Interest: None
The aim of this study was to test whether the ultrasound (US)-guided continuous transversus abdominis plane (TAP) block, as a part of a multimodal analgesic regimen, would result in decreasing systemic analgesic consumption and improving analgesia in the first 24 h after cesarean section in comparison with conventional systemic analgesia.
Patients and methods
Sixty-two healthy parturients scheduled for elective cesarean delivery under general anesthesia were included in this double-blinded randomized prospective study. Participants were randomly assigned into one of two groups. In the TAP group (n = 31), TAP catheter was inserted bilaterally immediately after completing the surgery and before recovery from general anesthesia under US guidance. Bupivacaine (0.25%) 15 ml was then injected on each side and then every 6 h for the first 24 h. In the systemic analgesia group (Sys group; n = 31), patients received intravenous ketolac (20 mg) before recovery to be repeated every 8 h. The assessment of both groups was performed at 1, 2, 4, 6, 12, and 24 h postoperatively. The assessment included heart rate and blood pressure, visual analog score at rest and during movement, frequency of giving paracetamol to patients, and total morphine requirement throughout the 24 h. Salivary α-amylase was measured 4 h postoperatively. Complications were also recorded.
The TAP group showed significantly lower visual analog score at rest and during movement. A significantly higher percentage of patients among the systemic analgesia group required more rescue paracetamol analgesia than those in the TAP group. The total morphine consumption in 24 h was highly significantly greater in the systemic analgesia group. Salivary α-amylase showed significant increase in the systemic analgesia group in comparison with the TAP group.
US-guided continuous TAP block decreased systemic analgesic consumption and improved analgesia in the first 24 h after cesarean section. US-guided continuous TAP block is recommended to be incorporated to the multimodal analgesia protocol.
Keywords: cesarean section, conventional systemic analgesia, ultrasound-guided transversus abdominis plane block
|How to cite this article:|
Hemimi YA, Kamaly AM, Talaat SM, Nosseir MA. Ultrasound-guided bilateral transversus abdominis plane block versus conventional systemic analgesia after cesarean section. Ain-Shams J Anaesthesiol 2014;7:400-5
|How to cite this URL:|
Hemimi YA, Kamaly AM, Talaat SM, Nosseir MA. Ultrasound-guided bilateral transversus abdominis plane block versus conventional systemic analgesia after cesarean section. Ain-Shams J Anaesthesiol [serial online] 2014 [cited 2019 Sep 19];7:400-5. Available from: http://www.asja.eg.net/text.asp?2014/7/3/400/139579
| Introduction|| |
Cesarean section (CS) is a common surgical procedure, after which postoperative pain and discomfort can be anticipated. In modern anesthetic practice, postoperative pain relief is considered as an extension of the anesthetic technique, facilitates early ambulation, and lessens postoperative complications and hospital stay. The analgesic postoperative regimen should be effective with minimal side effects and should ensure the safety of the lactating mother and her child . The standards of the Royal College of Anesthetists (RCoA) suggest that more than 90% of women should score their worst pain as less than 3 on visual analog score (VAS) of 0-10. It was found that 39.8% of women had VAS score of greater than 3 . This raises the question of the need to reconsider pain relief and its assessment in postcesarean patients.
Balanced (multimodal) analgesia uses two or more analgesic agents or techniques that act by different mechanisms to achieve superior analgesic properties without increasing adverse effects compared with increased doses of single agents. Therefore, balanced analgesia is the method of choice wherever possible, based on paracetamol and NSAIDs for low-intensity pain and opioid analgesics and/or local analgesic techniques for moderate and high-intensity pain . Analgesia for abdominal surgery is traditionally provided by systemic drugs such as opioids, ketamine, NSAIDs, and paracetamol. Peripheral nerve blockade is an alternative method of providing analgesia by anesthetizing the sensory nerves conducting pain impulses from the incision site to the spinal cord and higher centers . Peripheral nerve blocks were previously performed by eliciting paresthesia according to anatomical landmarks, which was not really effective and safe, and recently under ultrasound (US) guidance with increased success and reduced complications .
The transversus abdominis plane (TAP) block involves block of the sensory nerve supply of the anterolateral abdominal wall, where T7-T12 intercostal nerves, ilioinguinal and iliohypogastric nerves, and the lateral cutaneous branches of the dorsal rami of L1 are blocked. This block is performed by injection of local anesthetic drug between the internal oblique and transverse abdominal muscles . The efficacy of single-shot, blind TAP block in comparison with systemic conventional analgesia was established . Posterior US-guided TAP block technique for postoperative analgesia was described by Hebbard  and proved good quality and safety. However, the use of indwelling bilateral catheters inserted under US guidance in TAP block, which allow repeated and timed injections, and its efficacy and safety after CS in comparison with conventional systemic analgesia are not yet studied.
In this study, we investigated whether the US-guided continuous TAP block, as a part of a multimodal analgesic regimen, would result in decreased systemic analgesic consumption and improved analgesia in the first 24 h after cesarean delivery in comparison with conventional systemic analgesia.
| Patients and methods|| |
This double-blinded randomized prospective study was conducted in Ain Shams University Obstetrics and Gynecology Hospital on 62 patients scheduled for elective CS with pfannenstiel incision under general anesthesia, after they gave their informed consent after approval of the ethical committee. Randomization was performed by preselected closed envelopes. The inclusion criteria included age of 18-40 years, ASA I or II, BMI of 20-40, and single-term pregnancies. The exclusion criteria included known sensitivity to local anesthetics or US conduction gel, history of psychological disorders and/or chronic pain, emergency CS, and previous abdominal surgery.
All patients were monitored with five-lead ECG, NIBP, pulse oximetry, and end-tidal CO 2 . Anesthesia was induced by rapid sequence induction with thiopental (5 mg/kg) intravenously and succinylcholine (1-1.5 mg/kg) intravenously followed by endotracheal intubation. Anesthesia was maintained by isoflurane 0.6-1.2 vol% in oxygen air mixture and atracurium for muscle relaxation. After delivery of the baby, morphine (10 mg) was given intravenously and oxytocin (30 IU) was infused. No more narcotics or analgesics were given rather than the protocol of postoperative analgesia according to allocation of patient grouping.
The patients were divided randomly into two groups. In group I (the TAP group, n = 31), bilateral TAP catheters were inserted under US guidance immediately after the end of surgery and before recovery from general anesthesia. A Voluson-i US machine with a high frequency (5.7-13.3 MHz) 45 mm linear array US probe (GE Healthcare, Milwaukee, Wisconsin, USA) was used. The catheters were inserted under complete aseptic conditions, and the probe was covered by a sterile disposable cover. The external oblique, internal oblique, and transverse abdominis muscles and the plane between the internal oblique and transverse abdominis muscles were identified. Along the midaxillary line above the iliac crest, a 17-G, 8.5 cm long Tuohy needle (B. Braun Medical Inc., Bethlehem, Pennsylvania, USA) was placed under US guidance, using an in-plane approach, between the transverse abdominis and internal oblique muscles. The tip of the catheter was localized by injecting 1 ml of saline under sonographic vision after negative aspiration of fluid or blood, and hydrodissection was confirmed. Thereafter, 5 ml of bupivacaine (0.25%) was injected and the spread of the injectate in the appropriate plane was confirmed sonographically. A 20-G B. Braun epidural catheter was then passed 4 cm beyond the tip of the needle, keeping the bevel of needle lateral. After negative aspiration of any fluid or blood, a test dose of 3 ml of lidocaine (1%) with 1 : 200 000 epinephrine was used to exclude intravascular injection, then 10 ml bupivacaine (0.25%) was injected. The described procedure was then repeated on the other side. Both catheters were secured and fixed by adhesive tape. After recovery from anesthesia, ketolac (20 mg) was injected slowly and intravenously. Timed injections of 15 ml bupivacaine (0.25%) were given bilaterally every 6 h for 24 h. The catheters were removed after the last injection.
In group II [the conventional systemic analgesia group (Sys group), n = 31], patients received ketolac (20 mg) intravenously before recovery from the same anesthetic technique, and it was repeated every 8 h.
For both groups, a rescue analgesic in the form of paracetamol (1 g) was given intravenously when VAS score at rest was greater than 4, for maximum four doses a day with 6-h interval. If VAS was still greater than 4, 20 min after paracetamol infusion, morphine (3 mg) was given intravenously.
Heart rate, mean arterial blood pressure, and pain severity at rest and during movement using VAS from 0 to 10 were assessed in both groups at 1, 2, 4, 6, 12, and 24 h postoperatively, by a person who does not know the nature of the injected drug or the technique. In addition, the frequency of morphine and paracetamol injections throughout 24 h was recorded and salivary α-amylase (sAA) sample was collected 4 h postoperatively. Measurement of sAA was carried out by unstimulated passive droll to collect samples after rinsing mouth thoroughly with water for 10 min. Samples were refrigerated within 30 min and freezed at or below -20°C within 4 h. The Salimetrics sAA assay kit was validated for the kinetic measurement of sAA activity. Nausea was assessed using the category scoring system (none = 0, mild = 1, moderate = 2, and severe = 3), and it was recorded in addition to vomiting.
Statistical data analysis
Before the study, a power analysis was performed to determine the necessary number of patients in each group on the basis of postoperative VAS score for pain, with a type I error of 5% and study power of 90%, and it was estimated that the minimal sample size for the study was 62 patients for both study groups.
Statistical analysis was performed using SPSS v 12.0 computer software. Numerical variables were presented as mean and SD, median, and percentile, whereas categorical variables were presented as number of cases and percentage. Between-group comparisons of numerical variables were performed with one-way analysis of variance (ANOVA) test and the Wilcoxon rank sum test, whereas repeated measures of ANOVA test was used for within-group comparisons of these variables; Tukey's highly significant difference test was used as a post-hoc test if pairwise comparisons were indicated. If the assumptions of both ANOVA tests were not fulfilled, the Kruskal-Wallis test and Friedman's test were used as appropriate instead. Between-group comparisons of categorical data were performed with the χ2 -test. Any difference with P value less than 0.05 was considered statistically significant.
| Results|| |
The two groups were comparable (P > 0.05) regarding age, BMI, and ASA physical status [Table 1].
The difference in the heart rate between the two groups was statistically significant throughout the study except at 1 h record [Figure 1].
|Figure 1: Changes in the heart rate recorded with respect to baseline (bpm).Data are presented as mean values. bpm, beats per minute .|
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The difference in the mean arterial blood pressure was statistically significant throughout the studied times between the two groups [Figure 2].
|Figure 2: Column chart showing changes in mean arterial blood pressure. Data are presented as mean values. TAP, transversus abdominis plane|
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Regarding the pain assessment, the VAS showed statistically highly significant difference between the two groups at rest and during movement ([Figure 3] and [Figure 4].
|Figure 3: Column chart showing pain at rest assessed by VAS. Data are presented as mean and SD. TAP, transversus abdominis plane; VAS, visual analog score .|
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|Figure 4: Column chart showing pain on movement assessed by VAS. Data are presented as mean and SD. TAP, transversus abdominis plane; VAS, visual analog score .|
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There was a significant difference between baseline measure of sAA and 4 h measure in the systemic analgesia group (P < 0.001), indicating significant increase in sAA level, whereas there was no significant change in the TAP group [Table 2].
There was significantly higher percentage of patients who required rescue paracetamol analgesia in the systemic analgesia group in comparison with the TAP group [Table 3]. The total morphine consumption was highly significantly greater in the systemic analgesia group [Table 4].
|Table 3 Percentage of patients who required paracetamol among both groups|
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There was a significant statistical difference between the groups with respect to postoperative nausea and vomiting at 6 and 12 h record [Table 5].
|Table 5 Incidence and grade of postoperative nausea and vomiting between both groups|
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No signs of local anesthetic toxicity or other complications were recorded within the TAP group.
| Discussion|| |
TAP block is a regional technique that blocks stimuli arising from anterolateral abdominal wall. The posterior approach used in this study mainly blocks T10-L1, which supply lower abdominal wall; thus, it is suitable for surgeries below the umbilicus. Therefore, it can be used as a part of multimodal analgesia .
The duration of single-shot TAP block in providing analgesia shows to be between 8 and 10 h . To avoid this disadvantage, a catheter could be inserted for repeated local anesthetic injection [11-13]. Intermittent boluses injections technique was preferred in this study because it has been shown that it works better than the continuous infusion technique because of wider spread of the local anesthetic . The total dose required also is less, reducing the risk for local anesthetic toxicity with intermittent injection technique. Furthermore, bolus injections allow hydrodissection and facilitate the spread of local anesthetic .
In the current study, VAS score was low both at rest and on movement in the TAP block group as compared with the systemic analgesia group throughout 24 h. This was similar to the observations by McDonnell et al.  who compared TAP block to placebo. Our results also are in accordance with the findings of Niraj et al.  and Bharti et al.  who used TAP block for patients who underwent appendectomy and colorectal surgery, respectively. Baaj et al.  found as well lower 24-h VAS scores in the local anesthetic TAP block group in comparison with the control group.
In contrast, Costello et al.  found no difference in VAS scores and morphine requirements between local anesthetic and placebo TAP blocks, but the patients in the study received intrathecal morphine, which had prolonged period of analgesia.
Previous reports suggested that increased sAA may reflect increased physical stress, and it was closely associated with increased plasma norepinephrine , and thus it represented an objective method for stress assessment. In our study, we determined the usefulness of sAA measurement as an objective biomarker of stress. There was no statistically significant difference between baseline and postoperative measurements among the TAP group, whereas there was a significant difference among the systemic analgesia group, which reflects the efficacy of TAP block to control postoperative pain in lower abdominal surgery. This finding is in agreement with several studies [21,22] that showed significant correlation between sAA levels and VAS for pain.
In the present study, there was a statistically significant decrease in the number of patients who required rescue analgesic and in the total morphine dosage in the TAP group in comparison with the systemic analgesia group through the 24 h assessment, which reflects the efficacy of TAP block to alleviate postoperative pain.
These results are consistent with the results of the studies conducted by Belavy et al.  and McDonnell et al.  who showed that TAP block reduced mean total morphine requirements in the first 24-48 h. In addition, a meta-analysis by Siddiqui et al.  showed that TAP block reduced the need for postoperative opioid use and increased the time of first request for analgesia. Another study by Kadam and Field  evaluated US-guided continuous TAP block for abdominal surgery and detected reduction in postoperative pain scores and fentanyl requirement.
In contrast, Costello et al.  showed that there was no statistically significant difference between US-guided TAP block with ropivacaine and placebo block regarding postoperative morphine requirements and the visual analog pain score at 6, 12, 24, and 48 h, but, on closer inspection of the results during the first 3 h, more patients who had received the placebo block required morphine earlier.
The present study showed significant decrease in incidence and severity of postoperative nausea and vomiting in the TAP group at 6 and 12 h in comparison with the other group.
The present study showed no inadvertent intravascular injection, manifestations of local anesthetic toxicity, pruritis, or internal organ injury, which reflects the safety of TAP block when performed by US guidance. Farooq and Carey  reported needle perforation of the liver with blind TAP block technique. Peritonitis was reported once in a case of US-guided TAP block .
| Conclusion|| |
The current study showed that administration of repeated bolus doses of bupivacaine through the catheters inserted with US guidance for TAP block, as a part of a multimodal analgesic regimen, resulted in acceptable postoperative pain scores and relatively lower analgesic requirements. As the TAP block has no effect on visceral pain or on pain deriving from the pelvic floor, we expect the TAP catheters to be incorporated in multimodal analgesia.
| Acknowledgements|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]