|Year : 2019 | Volume
| Issue : 2 | Page : 74-79
Prospective randomized study comparing transversus abdominus plane block and spinal fentanyl added to bupivacaine for postoperative analgesia after cesarean section
Ahmed E Nasef, Lubna M Abo-Elnasr, Nabil A El-Sheikh, Ahmed E Mohamed
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||26-Apr-2017|
|Date of Acceptance||08-Apr-2018|
|Date of Web Publication||18-May-2020|
Ahmed E Nasef
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Tanta University, Tanta
Background Cesarean section is a very common surgery and so postoperative pain in cesarean section is a major problem; different modalities of analgesia exist. Transversus abdominus plane (TAP) block is a simple and safe technique and can be used for postoperative analgesia after lower abdominal surgeries.
Aim The aim of this study was to compare between postoperative analgesic effect of TAP block and spinal fentanyl added to bupivacaine in patients undergoing cesarean section.
Participants and methods This study was carried out on 80 pregnant women presented for elective cesarean section who met the American Society of Anesthesiology II status. The patients were randomized into two equal groups (40 patients in each group). − Group I (spinal fentanyl group): patients received intrathecal 2.5 ml heavy bupivacaine 0.5% plus 25 µg fentanyl. Group II (TAP block group): patients received intrathecal 2.5 ml heavy bupivacaine 0.5% and then TAP block with 40 ml bupivacaine 0.25% (20 ml each side). Heart rate and mean arterial blood pressure were recorded postoperatively; postoperative pain was assisted by visual analog scale (VAS) score, time of postoperative first rescue analgesia, and total amount of rescue analgesia consumption.
Results As regards hemodynamics (heart rate and mean arterial blood pressure) there was significant difference between both groups; at 2 h in group II it was lower than group I. Comparison of VAS score among both groups have shown that there was significant difference at 2 h as group II showed extended postoperative analgesia as the VAS score started to elevate at 6 h. Time of first rescue analgesia was significantly shorter in group I than in group II. Pethidine consumption was significantly lower in group II than in group I.
Conclusion TAP block is a simple and safe technique and may be a potential alterative to spinal opioid for analgesia after cesarean section with no or minimal effects on hemodynamics, more prolonged analgesia, and less pethidine consumption and no or minimal complications.
Keywords: cesarean section, fentanyl, spinal anesthesia, transversus abdominus plane block
|How to cite this article:|
Nasef AE, Abo-Elnasr LM, El-Sheikh NA, Mohamed AE. Prospective randomized study comparing transversus abdominus plane block and spinal fentanyl added to bupivacaine for postoperative analgesia after cesarean section. Tanta Med J 2019;47:74-9
|How to cite this URL:|
Nasef AE, Abo-Elnasr LM, El-Sheikh NA, Mohamed AE. Prospective randomized study comparing transversus abdominus plane block and spinal fentanyl added to bupivacaine for postoperative analgesia after cesarean section. Tanta Med J [serial online] 2019 [cited 2020 Sep 23];47:74-9. Available from: http://www.tdj.eg.net/text.asp?2019/47/2/74/284498
| Introduction|| |
Cesarean section is one of the most commonly performed surgical procedures , but the optimum form of postoperative analgesia is not known. Many procedures are carried out under spinal anesthesia . Spinal anesthesia is the most commonly used technique for lower abdominal surgeries as it is very economical and easy to administer. However, postoperative pain control is a major problem because spinal anesthesia using only local anesthetics is associated with relatively short duration of action, and thus early analgesic intervention is needed in the postoperative period ,. The addition of fentanyl to hyperbaric bupivacaine improves the quality of intraoperative and early postoperative subarachnoid block but the addition of opioids to local anesthetic solution has its disadvantages, such as pruritus and respiratory depression .
The transversus abdominus plane (TAP) block is a regional analgesic technique which blocks T6–L1 nerve branches and has an evolving role in postoperative analgesia for lower abdominal surgeries ,,. However, there are few studies comparing TAP block with spinal opioids or with epidural analgesia. If superior to spinal opioids, TAP block would have the advantage of improved analgesia and also reduction in opioid-associated adverse effects, and the absence of motor blockade .
| Aim|| |
The purpose of this study was to compare between postoperative analgesic effect of TAP block and spinal fentanyl added to bupivacaine in cesarean section.
| Participants and methods|| |
After obtaining the research ethics committee approval and informed written consent, this study was carried out on 80 pregnant women presented for elective cesarean section in Tanta University Hospital, Obstetrics and Gynecology Department during a period of 6 months. Patients with refusal of guardians, history of allergy to local anesthetics, local infection or anatomic malformation at the site of the block, and coagulopathies were excluded from the study. Patients were randomized into two equal groups by using sealed opaque envelope (40 patients in each group) − group I (spinal fentanyl group): patients received intrathecal 2.5 ml heavy bupivacaine 0.5% plus 25 µg fentanyl and group II (TAP block group): patients received intrathecal 2.5 ml heavy bupivacaine 0.5% followed by TAP block with 40 ml bupivacaine 0.25% (20 ml each side).
Preoperative assessment was done by history taking, clinical examination, laboratory investigations including: complete blood count, bleeding time, and clotting time. Patients fasted according to American Society of Anesthesiologists guidelines. Oral midazolam 0.5 mg/kg was given 30 min before induction. On arrival to operating room (OR), the patients were attached to the monitor displaying the following: ECG, pulse oximetry, noninvasive blood pressure; an intravenous line was established with an 18 G cannula and then fluid preload of 500 ml of lactated Ringer’s solution was administered before starting the procedure.
Group I (spinal fentanyl)
Spinal needles (22 G) were introduced in sitting position in which the patient sat on the edge of the operating table leaning forward arching her back and then after skin disinfection with povidine iodine, iliac crest was palpated and thumb extended to meet the midline, feeling the space between L4 and L5. When spinal needle has gone through the dura matter, a pop was often appreciated and then after the needle puncture into the subarachnoid space and the appearance of clear cerebrospinal fluid, the intrathecal local anesthetic was injected. All patients received 2.5 ml heavy bupivacaine 0.5% plus 25 µg fentanyl to total volume of 3 ml.
Group II (spinal with transversus abdominus plane block)
Spinal needles (22 G) were introduced in sitting position using aseptic precautions. All patients received 2.5 ml heavy bupivacaine 0.5% plus 0.5 ml normal saline with a total volume of 3 ml and then at the end of the surgery a linear, high-frequency transducer was recommended for this block, as the relevant anatomical structures are relatively shallow. Following skin and transducer preparation, the transducer was placed in an axial (transverse) plane, above the iliac crest, and in the region of the anterior axillary line. Identify the three muscular layers of the abdominal wall, the external oblique (most superficial), the internal oblique and transversus abdominis muscles. Among the three muscles, the internal oblique muscle is usually the most prominent layer. In the lower medial aspect of the abdominal wall, the external oblique muscle gives way to the external oblique aponeurosis and may therefore appear as a layer of fascia instead of muscle. The peritoneal cavity lies deep in the transversus abdominis muscle layer and may be identified by the peristaltic movements of bowel loops.
If there is difficulty in distinguishing the three muscle layers, it is helpful to start the scan in the midline over the rectus abdominis muscle. The rectus abdominis muscle is the only muscular layer in the midline. The rectus abdominis muscle tapers laterally to a junction that leads to the three muscle layers of the lateral abdominal wall. The internal oblique, transversus abdominis, and intervening TAP are easily identified at this point, and can be traced laterally to the region above the iliac crest where the block was performed.
A 120 mm 22 G short beveled block needle was inserted in-plane with the transducer, in an anterior–posterior direction. Choosing an insertion point some distance away from the transducer permits a shallower needle and thus improves needle shaft and tip visualization. The needle was used and connected to the syringe through a short extension tubing. In patients with a protuberant abdomen, manual retraction of the abdominal wall by an assistant is a useful maneuver to facilitate needle insertion; it is important to deposit local anesthetic deep into the fascial layer that separates the internal oblique and transversus abdominis muscles.
Accurate placement of the needle tip was facilitated by injection of a small amount of fluid (1–2 ml of saline or local anesthetic) to ‘hydro dissect’ the appropriate plane. Correct needle tip position and deposition of local anesthetic were indicated by the appearance of a hypoechoic fluid pocket immediately deep into the hyperechoic fascial plane below the internal oblique, and above the transversus abdominis. If the needle tip was intramuscular instead of in the correct plane, a pattern of fluid spread consistent with intramuscular fluid injection was seen instead. A total of 20 ml of bupivacaine 0.25% was injected into this plane on each side. The maximum recommended dose (3 mg/kg of bupivacaine 0.5%) should not be exceeded. During local anesthetic injection, the abdomen was scanned cephalic and caudal to determine the extent of longitudinal spread. Medial and lateral scanning was determined by the extent of horizontal spread.
Demographic data (age, weight, and length), mean arterial blood pressure (MAP), and heart rate (HR) were measured at 1, 2, 4, 6, 8, and 12 h postoperatively. Visual analog pain score (VAS) between 0 and 10 (0=no pain, 1–3=mild pain, 4–6=moderate pain, and 7–10=severe pain) was recorded at 1, 2, 4, 6, 8, and 12 h postoperatively. First time of rescue analgesia: this is defined as the time from onset of sensory block till the time of first requirement of analgesia. The total amount of rescue analgesia consumption in the form of intravenous pethidine→1 mg/kg if VAS greater than or equal to 4. Any undesirable postoperative side effects (as nausea, vomiting and pruritus) were recorded and managed
Statistical presentation and analysis of the present study was conducted, using the mean, SD, and Student’s paired t-test and unpaired t-test and Mann–Whitney test by SPSS v.24 (SPSS Inc., Chicago, IL, USA). Value of P less than 0.05 was considered significant.
| Results|| |
Regarding the demographic data such as age, weight, and length, there was no significant difference between both groups as shown in [Table 1].
Comparison of the mean value of HR among the studied groups showed that there was significant difference at 2 h as the mean value of HR in group I was 92.15 beats/min in comparison of 79.02 beats/min in group II with a P value of less than 0.001 and there was no significant difference at any other time point as shown in [Figure 1].
Comparison of the mean value of mean arterial pressure among the studied groups showed that there was significant difference at 2 h as the mean value of blood pressure in group I was 90.2 mmHg in comparison of 75.95 mmHg in group II with a P value of less than 0.001 and there was no significant difference at any other time point as shown in [Figure 2].
|Figure 2 Comparison of the changes in mean blood pressure in the two groups.|
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Comparison of the mean value of VAS score among the studied groups showed that there was significant difference at 2 h with a P value of less than 0.001 as the VAS score started to elevate at 2 h in group I, but group II showed extended postoperative analgesia as the VAS score started to elevate at 6 h; there was no significant difference at any other time point as shown in [Figure 3].
|Figure 3 Comparison of 1st time rescue analgesia requirement in the two groups.|
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The mean value of first time of analgesic request was 362.325 min in group II which was statistically prolonged in duration than the other group which was 135.225 min with a P value of less than 0.05 as shown in [Figure 4].
|Figure 4 Comparison of total rescue analgesia consumption in the two groups.|
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The mean value of pethidine consumption was significantly reduced in group II with a mean value of 134.55 mg in comparison to 208.975 in group I (P<0.05) as shown in [Figure 5].
| Discussion|| |
Cesarean section is one of the most commonly performed surgical procedures. It is estimated that 15% of births worldwide and 21.1% in the developed world occur by the cesarean section . The optimum form of postoperative analgesia is not known, but many procedures are carried out under spinal anesthesia . The addition of fentanyl to hyperbaric bupivacaine improves the quality of intraoperative and early postoperative subarachnoid block but the addition of opioids to local anesthetic solution has its disadvantages, such as pruritus and respiratory depression . The TAP block is a regional analgesic technique which blocks the T6–L1 nerve branches and has an evolving role in postoperative analgesia for lower abdominal surgeries ,,.
As regards postoperative pain comparison of the mean value of VAS score among the studied groups (the primary outcome of our study) it has been observed that there was significant elevation in VAS score greater than or equal to 4 in group I at 2, 6, and 12 h postoperatively compared with the other studied group that showed extended postoperative analgesia as the VAS score started to elevate at 6 h and rescue analgesia consumption was lower in the TAP group than in the spinal fentanyl group postoperatively.
In agreement with our study Eslamian  performed TAP block with 30 ml 0.25% bupivacaine in a group and no TAP in the other group. He found that there was a significantly longer time to the first request for analgesic in the TAP block group and women in the TAP block group had significantly less tramadol than women in the no TAP block group (50 vs. 25 mg). Hebbard and Barrington  found similar results in their study in which the TAP blockade with 1.5 mg/kg ropivacaine bilaterally in a parturient undergoing cesarean delivery successfully decreased the postoperative patient-controlled intravenous morphine requirement. McDonnell and Curley , performed TAP block with ropivacaine (150 mg) versus placebo in addition to patient controlled analgesia (PCA) morphine, diclofenac, and acetaminophen after spinal anesthesia. They proved that the first request for analgesia in patients who did not have TAP was after 90 min, whereas in patients who received landmark TAP block was after 220 min McDonnell and Curley  proved that the TAP block reduced total morphine consumption in first 48 h postoperatively (66±26 vs. 18±4 mg). Carney and McDonnell  found that the TAP block has been demonstrated to be effective in patients undergoing abdominal hysterectomy; VAS pain score was lower in the TAP block group in most time points assessed. Ahmed et al.  compared the efficacy of ultrasound-guided TAP block with placebo for postoperative analgesia after retropubic radical prostatectomy. They found that TAP block is efficient in postoperative analgesia after retropubic radical prostatectomy.
Also in consistent with our results, Melnikov  demonstrated the analgesic effectiveness of both paravertebral block and TAP block after major gynecological cancer surgery. Both regional anesthetic techniques demonstrated significant reductions in opioid requirements and pain scores during early and late postoperative periods. Shin , proved that the ultrasound (US)-TAP block provided more effective analgesia after gynecological surgery. And Tan  also agreed with our study; in his study 40 women who underwent cesarean delivery under general anesthesia were allocated to receive TAP block using 20 ml levobupivacaine 2.5 mg/ml or no block with PCA morphine used postoperatively for both groups. Patients in the TAP block group consumed less morphine in 24 h than those in the no block group (12.3 vs. 31.4 mg).
In disagreement with our results Loane  showed that the TAP block was associated with greater supplemental morphine requirements than intrathecal morphine (7.5 vs. 2.7 mg; P<0.003) in 24 h. This study was conducted on 66 women undergoing elective cesarean delivery under spinal anesthesia. They were randomized to receive either intrathecal morphine 100µg plus TAP or a TAP block with 0.5% ropivacaine 1.5 mg/kg to each side. Also Mcmorrow et al.  studied 80 patients who were randomized to one of the four groups to receive (in addition to spinal anesthesia) either spinal morphine (SM) 100 mg or spinal saline (SS) and a postoperative bilateral TAP block with either bupivacaine (TLA) 1–2 mg/kg or saline (TS). They compared the analgesic efficacy of the TAP block with and without SM after cesarean section in a prospective, randomized, double-blinded placebo-controlled trial. They concluded that SM − but not TAP block − improved analgesia after cesarean section. The addition of TAP block with bupivacaine 1–2 mg/kg to SM did not further improve analgesia.
The disagreement is most probably due to the use of morphine intrathecally, which increases the duration of analgesia as intrathecal morphine is very potent with a prolonged period of analgesia but its usage is accompanied by many side effects like itching, nausea, vomiting, and respiratory depression.
Recently, two studies have not been able to show any differences between pain intensity or postoperative analgesic requirement when a TAP block was used as a multimodal analgesic regimen in cesarean delivery parturients under spinal anesthesia ,. However, both studies were performed on parturients who underwent spinal anesthesia, and in one of them, intrathecal morphine was used. It seems that the design of these studies mainly differed from ours.
As regards hemodynamic effect, both groups had stable hemodynamic with no occurrence of hypotension or bradycardia that required medications, but the TAP group showed a significant decrease in HR and MAP for prolonged time postoperatively in comparison to spinal fentanyl group; this is due to the analgesic effect of the TAP block reducing pain intensity, which stimulates the sympathetic system and causes increase in HR and MAP of the patient.
Our results are in agreement with Bhattacharjee et al. , who found that TAP block decreases intraoperative fentanyl requirements, prevents hemodynamic responses to surgical stimuli, and provides effective postoperative analgesia. Also Belzerena  studied the effects of different dosages of intrathecal fentanyl and observed no difference in the incidence of hypotension.
As regards side effects (nausea and vomiting) there was no significant difference in the incidence of nausea, vomiting, itching, and urine retention in group I versus group II.
Our results are in agreement with Carney et al. , who compared the analgesic efficacy of ipsilateral TAP block after appendectomy in children versus placebo. They did their study on 40 child undergoing appendectomy randomized into two groups who underwent TAP block versus placebo in addition to PCA morphine. They found that there was no significant difference in the incidence of nausea or distribution of nausea scores between the two studied groups at any time interval.
| Conclusion|| |
TAP block is a simple and safe technique and may be a potential alterative to spinal opioid for analgesia after cesarean section with no or minimal effects on hemodynamics, more prolonged analgesia, and less pethidine consumption and no or minimal complications.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]