|Year : 2021 | Volume
| Issue : 17 | Page : 34-39
Efficacy of preincisional versus post incisional unilateral ultrasound-guided transversus abdominis plane block in patients undergoing appendectomy under subarachnoid block
Uwadia Tony, Hanson Osazuwa Idehen, Charles Olumese Imarengiaye
Department of Anesthesiology, University of Benin Teaching Hospital, Edo State, Nigeria
|Date of Submission||03-Jun-2020|
|Date of Decision||11-Sep-2020|
|Date of Acceptance||21-Sep-2020|
|Date of Web Publication||24-Apr-2021|
Dr. Hanson Osazuwa Idehen
Department of Anesthesiology, University of Benin Teaching Hospital, Edo State
Source of Support: None, Conflict of Interest: None
Background: Transversus abdominis plane (TAP) block produces effective postoperative analgesia and reduces postoperative opioid consumption after abdominal surgeries. It could be instituted preoperatively or postoperatively. Objectives: This study determined which period of institution of TAP block is more efficacious in postoperative analgesia in patients undergoing open appendicectomy. Patients and Methods: Eighty patients undergoing open appendicectomy were randomized, of which eight were excluded for various reasons (these were; three for protocol violations, four declined further participations, while one for prolonged surgery). A total of 72 patients received SAB, of which half received (n = 36) TAP block with 20 ml of 0.375% plain marcaine before skin incision (preoperative TAP block group) while the other half (n = 36) received same volume and concentration of TAP block at the end of surgery (postoperative TAP block group). Pain was evaluated postoperatively at rest and on movement by numerical rating scale (NRS) over 24 h. Results: Pain scores were significantly lower in the preoperative TAP block group than in the postoperative TAP block group, especially in the first 6 h (P < 0.001) postoperatively; although, both demonstrated lower pain score. Furthermore, total analgesic consumption (paracetamol and tramadol) was significantly higher in the postoperative TAP block group (P = 0.001 and P = 0.002). Conclusion: Preoperatively, administered TAP block increases time to first analgesic request, provides a longer duration of analgesia and reduces total analgesic requirement in comparison to postoperative TAP block in patients undergoing open appendicectomy.
Keywords: Appendicectomy, postoperative pain management, transversus abdominis plane block
|How to cite this article:|
Tony U, Idehen HO, Imarengiaye CO. Efficacy of preincisional versus post incisional unilateral ultrasound-guided transversus abdominis plane block in patients undergoing appendectomy under subarachnoid block. N Niger J Clin Res 2021;10:34-9
|How to cite this URL:|
Tony U, Idehen HO, Imarengiaye CO. Efficacy of preincisional versus post incisional unilateral ultrasound-guided transversus abdominis plane block in patients undergoing appendectomy under subarachnoid block. N Niger J Clin Res [serial online] 2021 [cited 2021 Dec 4];10:34-9. Available from: https://www.mdcan-uath.org/text.asp?2021/10/17/34/314597
| Introduction|| |
Postoperative pain is best managed with a multimodal approach. Hence, transversus abdominis plane (TAP) block and subarachnoid block can be used as part of multimodal postoperative pain management. When using subarachnoid block (SAB) as an anesthetic mode for appendicectomy, the visceral peritoneal pain can be obtunded with addition of adjuncts like opioids (fentanyl, pethidine, etc.).
Preincisional analgesia, a clinical concept that involves the introduction of analgesic regimen before the onset of noxious stimuli, with the goal of preventing sensitization of the nervous system to subsequent stimuli that could amplify pain. TAP block when used as part of a multimodal postoperative pain management given before skin incision, after anesthesia (pre-emptive analgesia) may be more effective than when given at the end of surgery.
Evidence abounds in the literature indicating the institution of TAP block at the end of surgery with demonstrable analgesic efficacy. However, it is likely that postoperative analgesia may be improved if analgesia is provided prior to the surgical insult. Indeed, Shin et al. presented an effective and improved analgesia with a decreased incidence of side effects such as nausea, vomiting, dizziness, and itching by reducing the requirements of opioids after pre-incisional TAP block in patients undergoing gynecologic surgery through a transverse lower abdominal skin incision.
It is not clear if similar results will be obtained in patients after open appendicectomy. Therefore, this study determined the effect of pre-incisional versus postincisional TAP block on post appendicectomy pain.
| Patients and Methods|| |
The study was conducted in a tertiary Hospital in Nigeria. Patients scheduled for appendicectomy under SAB were recruited after institutional clearance and approval for the study has been obtained from the Hospital Research and Ethics Committee and informed and written consent given by the patient.
This is a randomized, double-blinded study. All patients had pre- and post-operative pre-procedural ultrasound scan performed by the principal investigator irrespective of the group they were randomized into in other to prevent patient bias. The assessment of outcome measurement was carried out by an assistant who was unaware of the group patient were randomized into.
The American Society of Anesthesiologists (ASA) I or II patients undergoing open appendicectomy, ages 18–50 years in both elective and emergency cases were approached. Exclusion Criteria were patient's refusal, patients with known allergy to bupivacaine or study medication. Extension of surgical wound incision, any contraindication to regional anaesthesia. History of chronic pain. Failed spinal anaesthesia, morbid obesity with BMI>35. Sensory block height less than T4.
Sample size estimation
Sample size estimation came up to 79 patients. This was derived from our data gotten from our departmental audit of appendicectomy under SAB shows that 80% of the patients requested analgesia within the first 4 h. A study of ultrasound-guided unilateral post incisional TAP block for postappendicectomy pain management by Imarengiaye showed that 61% were pain free at the 6th h (i.e., 39% requested analgesia). We hope to achieve a 45% improvement in the proportion of patients who will be pain free at the 6th h.
Preoperative assessment and routine investigations (full blood court, urinalysis, electrolyte, and urea) were carried out. Patients did not receive any premedication in the ward. The patients were educated on the SAB as an anesthetic technique, ultrasound-guided TAP block as postoperative analgesic adjunct and the use of the Numerical rating score(NRS) for postoperative pain assessment. The absence of pain was rated zero (0), mild pain was 1–3, moderate pain was 4–6 and severe pain was 7–10. All patients were fasted following the fasting guidelines.
The patients that gave consent were randomly allocated to either group I or II with each patient picking from numbers kept in opaque sealed envelopes. Group 1 – Unilateral ultrasound guided TAP block using 20 ml 0.375% bupivacaine i.e., pre incision after SAB and before skin incision. Group 2 – Unilateral ultrasound guided TAP block using 20 ml of 0.375% bupivacaine postoperatively, i.e., after closure of surgical site (post incision).
On arrival in the theatre, baseline vital signs were noted and recorded. Resuscitation drugs made available. All patients received a preload of 15 ml/kg normal saline before institution of the SAB.
Every patient was placed in the traditional sitting position (patients feet placed on the stool, knees flexed and higher than the flexed hip). Under aseptic condition L3-L4 or L4-L5 interspace was identified and infiltrated with 1 ml of 2% lidocaine. A combination of 3 ml of 0.5% hyperbaric bupivacaine (MacaineR spinal heavy 0.5%) and 10 mg (0.2 ml) of preservative free pethidine (PethisomR 100 mg/2 ml) was deposited using a 25G pencil point needle into the subarachnoid space to establish spinal anesthesia. Postprocedure vital signs were checked and recorded and sensory block assessed for loss of cold sensation. The maximal level of sensory block was evaluated within 5 min until the same level is obtained twice and this was recorded as the maximum block height. Required block height for appendicectomy is T4 which is capable of preventing pain from the manipulation of the peritoneum. For the purpose of this study, block height level than T4 were excluded from the study. No additional analgesic was given intraoperative.
The duration of sensory block was timed from intrathecal injection to regression to T12 segment. Patients that complained of pain in the course of surgery had subhypnotic dose of 0.25–0.5 mg/kg of ketamine and the patients were excluded from the study.
An ultrasound-guided TAP block using SonoAce R3R was performed after SAB in Group I while post incisional ultrasound-guided TAP block was performed at the end of the surgery for Group II using 20 ml of 0.375% plain bupivacaine (15 ml of bupivacaine added to 5ml of water) for each group, respectively. The right anterolateral abdominal wall was prepared and a high frequency 10 MHz ultrasound probe was placed transversely between the iliac crest and the subcostal margin. Views were considered satisfactory if subcutaneous fat, external oblique muscle, internal oblique muscle, transversus abdominis muscle, peritoneum, and intraperitoneal structure are identified. After identification of the neuro-fascial plane between the internal oblique and the transversus abdominis muscle, a 23G 60 mm needle (Top neuropole needle, TOP Corp. Tokyo Japan) was introduced anteriorly from medial to lateral in the plane of the ultrasound beam. The needle was directed to approach the TAP and on entering the facial plane, the 20 ml of plain bupivacaine with concentration of 0.375% for the two groups (I and II) was injected after negative aspiration. The injectate was observed spreading in the TAP as a dark oval shape. At the end of the TAP block, baseline numerical rating score (NRS) was taken and recorded, 20 min elapsed between blocks and surgical incision in Group I in whom the block was performed before surgical incision (to allow the local anesthetic agent take effect). Patients were transferred to postanesthesia care unit at the end of surgery. Postoperative analgesic regimen consisting of intravenous (IV) Tramadol 100 mg 6 h, IV Paracetamol 15 mg/kg 6 h in 24 h was used in both groups when NRS was >3. The patient's postoperative analgesics were converted to oral medication after 24 h.
The presence and severity of pain, nausea, and hemodynamic variability (variations in blood pressure [BP], heart rate [HR], and SpO2) were assessed in the recovery room at 30 min, 60 min, 2 h, 3 h, 4 h, 5 h, 6 h, and 24 h after operation. The anesthetist assessing pain scores was different from the one who performed the TAP block so as to avoid bias. The TAP blocks were established by the researcher for uniformity. All patients were asked to give score for their pain at rest and on flexing the right hip. The patients were observed in the recovery room for 45 min after the procedure and be dispersed (transferred) from the recovery room when the vital signs were within normal range, with absence of nausea and vomiting and absence of pain (NRS < 3).
Patient's satisfaction with pain relief and overall quality were also evaluated 24 h postoperatively using a 5-point Likert's scale. Surgeons' satisfaction was assessed 24 h postoperatively, for their views about the patients' postoperative pain control using the 5-point Likert's scale.
Data were entered into the IBM Statistical product and service solution (SPSS) version 20. Armonk, New York. USA. Continuous data were summarized as means and standard deviation, and dichotomous data as counts and frequency. Continuous data such as age, systolic BP, HR, weight, and height were compared using the unpaired t-test. The association between the different groups with respect to time to request for analgesia and total analgesic consumption were tested using unpaired t-test. Dichotomous data were compared using Fisher's exact test. P < 0.05 was considered statistically significant. All statistical tests were two tailed.
| Results|| |
A total of 84 patients were recruited to participate in the study. Eighty were randomized while eight (8) were excluded from the analysis. The eight patients included 3 for Protocol violations, four for declining further participation after randomization and one for prolonged surgery. A total of 72 patients completed the study.
The patients were similar in weight, height, male/female ratio, and ASA distribution but the postoperative TAB block group appeared to be marginally older and higher in BMI [Table 1].
The patient's vital signs were similar in pulse rate, systolic BP, diastolic BP, mean arterial BP and oxygen saturation in both the groups, but marginally higher in respiratory rate for the preoperative group [Table 2].
|Table 2: Baseline vital signs before establishing transversus abdominis plane block|
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Time taken to perform TAP block and duration of surgery were similar for both groups (61.44 ± 23.713 vs. 62.78 ± 19.439). Similarly, there was no difference in time taken to perform the TAP block in both the groups (6.850 ± 3.4837 vs. 7.094 ± 2.9861) [Table 3].
|Table 3: Time to perform transversus abdominis plane block and duration of surgery|
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The proportions of patients requiring analgesia at NRS > 3 in the first 12 h postoperative is shown in [Table 4]. At the end of surgery, up to the 2nd h post operatively, all the patients in both groups were pain free. At the 3rd h, only two patients in the postoperative group requested for analgesia, while none requested in the preoperative group. There was significant increase in patients request for analgesia in the postoperative group compared with the preoperative group at the 4th h (P = 0.008) and 5th h (P = 0.001) respectively. Subsequently, analgesic request was similar in both groups with the total dose being more in the post group.
|Table 4: Proportion of patients requiring analgesia at Numerical Rating Scale >3 in the first 12 h postoperative|
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Proportion of patients requiring analgesia NRS at movement (NRS > 3) at the different hour. The analgesic request was more in the fourth (P = 0.014) and 6th h (P = 0.001), with more request in post group. Subsequently, analgesic request were similar, but with more request in post group [Table 5].
|Table 5: Proportion of patients requiring analgesia Numerical Rating Scale at movement >3 at the different hour|
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[Table 6] shows that the time to first analgesic request was significantly prolonged in the preoperative group compared to postoperative group (P = 0.002). There was no significant difference in time of establishment of SAB to patient's first analgesic request. There was significant increase in the proportions of patients with NRS > 3 at the 6th h, in the postoperative group, compared to the preoperative group (P < 0.001). There was consistent higher consumption of paracetamol (P = 0.001) and tramadol (P = 0.002) in the preoperative group.
|Table 6: Time to first analgesic request and analgesics consumption in the first 24 h|
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The patients in the two groups were satisfied with the technique of TAB block. Excellent/very good were rated by 75% (preoperative group) and 88.9% (postoperative group). P = 0.088 [Table 7].
The surgeons in the two groups were satisfied with the technique of TAB block. Excellent/very good were rated by 72.2% (preoperative group) and 80.5% (postoperative group). P = 0.067 [Table 8].
| Discussion|| |
This study shows that the administration of TAP block preoperatively provides superior analgesia than when TAP block is conducted postoperatively. This is evidenced by the longer duration of pain-free period postoperatively and a longer time to first analgesic request and lower pain scores in the preoperative group. These parameters were achieved with minimal side effect profile.
The longer duration to patient's first analgesic request in the preoperative TAP block group compared to postoperative TAP block as seen in this study could be attributable to lesser nociceptive input to the central nervous system. This ultimately led to a better postoperative pain profile compared to postoperatively administered TAP. Superiority of preoperatively administered analgesia as seen in other works diminished sensitivity to pain (hyperalgesia) and reduces feeling of pain from non-painful stimuli (allodynia) in the postoperative period. The analgesic effect of preoperative TAP block was also supported by Shrokri et al.
There are a number of studies in the literature advancing the relevance of the analgesic effect of preincisional TAP block.,,, Nonetheless, the superiority of preoperative conduct of TAP block over postoperative administration has been demonstrated. Amr et al. showed superior analgesia in women who had hysterectomy. These findings are similar to our results especially in the first 6 h with lower pain scores in the preoperative TAP block group. However, deposition of local anesthetic bilaterally was indicated for laparotomy unlike our study on appendicectomy and thus unilateral injection of local anesthetics. Twenty minutes interval after the establishment of TAP block was allowed before skin incision. They used general anesthesia and landmark technique, these differences notwithstanding preoperative TAP appears superior to postoperative TAP despite the different surgical procedures. In contrast to the previous studies, Dirican et al. found that postoperatively administered TAP was superior to preoperative approach. This may be as a result of longer duration of surgery and short interval between establishment of TAP block and skin incision.
The superiority of preoperative TAP over postoperative TAP is further reinforced by the low scores in numerical rating scale (NRS) especially in the first 4–6 h. This observation is similar to report of Amr et al. that postoperative pain assessment scores at rest and on movement were reduced after TAP block. Pain assessment at rest and on movement was also less in patients administered preoperative TAP block over the first 24 h postoperatively. This is similar to the work done by Amr et al. (preemptive TAP block) and Kundra et al. (on preemptive caudal analgesia), but not similar to the work done by Dirican et al.
In this study, pain assessment using the numerical rating scale (NRS) was reduced in both groups. However, the NRS scores on movement (coughing) where higher than at rest for both preincisional TAP block groups and postincisional TAP block groups. This is because dynamic pain is worse than that at rest, and the addition of TAP block to the postoperative analgesic regimen improved dynamic pain relief.
Total analgesic consumption (Paracetamol and tramadol) in the first 24 h was higher in postoperative TAP block group. This shows the importance of preoperative administration of TAP block in the management of postoperative pain. This is similar to the work by Niraj et al. The author evaluated analgesic efficacy of unilateral ultrasound-guided TAP block in patients undergoing open appendicectomy, in which total analgesic consumption (morphine) in the first 24 h postoperatively was significantly reduced (50 mg), due to the preoperative effect of the TAP block. However, this is contrary to the work of Dirican et al. where total analgesic consumption was more in preoperative TAP block group than postop TAP block group, which fails to demonstrate the effect of preoperative analgesia. This could be as a result of short time interval between preoperative TAP block and skin incision, which is shorter than the onset of action of the local anesthetic used for TAP block.
The hemodynamic variation following TAP block for both groups were not significantly different. This shows that TAP technique does not seem to affect the hemodynamic parameters of patients, whether when conducted preoperatively or postoperatively.
There were no complications (hematoma formation and visceral injury) associated with TAP block in both groups. This is because the technique was done under ultrasound guidance, thus, visceral structures and the plane were identified before deposition of drugs. Moreover, this makes it similar to other TAP block studies under ultrasound guidance with little or no complications and less failure rates. However, this is not the case with landmark techniques where complications and failures are bound to occur. Farooq and Carey reported a liver laceration after a landmark-based TAP block. The failure rate associated with TAP block (landmark technique) is evidenced by McDermott and coworkers in their work on whether to stop doing blind TAP block, showed that incidence of failure rates were high (76.4%).
The patients were satisfied with the TAP block in both pre incisional TAP block and post incisional TAP block. There was no significant difference in the rating, despite superiority of preoperative analgesic profile. This infers that beside pain, there are other modalities that affect patient's satisfaction which were not assessed in this study. These are interpersonal manner, technical quality, accessibility/convenience, finances, efficacy/outcomes, continuity of care, physical environment, and availability of care and resources.
There was no significant statistical difference in the surgeon's level of satisfaction between the preincisional and postincisional TAP block. Perhaps because both groups had postoperative analgesia according to the departmental postoperative protocol when NRS score was > 3 (NRS > 3). Surgeon's satisfaction was assessed at the end of 24 h and by this time they have all received analgesic as per departmental protocol. It will be difficult then to assess the superiority of each, since they were not without analgesia. There might have been a difference in the level of surgeons satisfaction if they did not have post op analgesia when NRS > 3 but this practice will not be ethical as you cannot deprive a patient analgesic because of ongoing research.
Limitation of the study
Pain assessments were often done during the odd hours when patients may be asleep thus affecting patients comfort. Second, the level of the TAP block could not be assessed because patients were under spinal anaesthesia before establishing the TAP block.
| Conclusion|| |
Preoperatively, administered TAP block is more effective than that done post operatively for the management of post appendicectomy pains. The superiority of preoperatively administered TAP block was possible for the reason that surgical time for appendicectomy is relatively short. This con not be said of other surgeries lasting several hours.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]