Research and Opinion in Anesthesia & Intensive Care

: 2018  |  Volume : 5  |  Issue : 1  |  Page : 21--26

Postoperative analgesia by a surgically inserted transversus abdominis plane catheter versus a thoracic epidural catheter after flank incision: randomized-controlled trial

Fathi M Heba1, Elgalaly Hazem2, Eliwa M Ahmed2, Abdelwahab Khalid2,  
1 Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Zagazig University, Zagazig, Egypt
2 Department of Urology, Faculty of Medicine, Zagazig University, Zagazig, Egypt

Correspondence Address:
Fathi M Heba
Department of Anesthesia and Surgical Intensive Care, Zagazig University Hospitals, Zagazig, 44519


Introduction Transversus abdominis plane (TAP) block has been reported to be an effective method of analgesia after abdominal surgery. This prospective randomized study compared the analgesic effect by a surgically inserted TAP catheter versus a thoracic epidural catheter in the postoperative period after a flank incision. Patients and methods Sixty-four American Society of Anesthesiologists physical status I and II patients, 18–59 years of age scheduled for renal surgery for a nonmalignant lesion with a flank incision, were allocated randomly to two equal groups. The group E (n=29; three excluded) received 0.125% bupivacaine with fentanyl 2 µg/ml at the rate of 5–8 ml/h, whereas the group T (n=30; two excluded) received 1 mg/kg bupivacaine 0.375%/8 h. Rescue analgesia of 5 mg morphine bolus doses was administered upon patients’ requests with a maximum dose of 10 mg/4 h. Visual analog scale, morphine consumption in 48 h, and incidence of postoperative complications were assessed. Results Visual analog scale and morphine consumption were comparable in the two groups. No significant complications were found in the TAP group, whereas the incidences of hypotension and motor block were higher in the epidural group. Conclusion A surgically assisted-TAP catheter is an easy, safe and effective method for analgesia after a flank incision and can be a good alternative to epidural analgesia, especially when the latter is contraindicated.

How to cite this article:
Heba FM, Hazem E, Ahmed EM, Khalid A. Postoperative analgesia by a surgically inserted transversus abdominis plane catheter versus a thoracic epidural catheter after flank incision: randomized-controlled trial.Res Opin Anesth Intensive Care 2018;5:21-26

How to cite this URL:
Heba FM, Hazem E, Ahmed EM, Khalid A. Postoperative analgesia by a surgically inserted transversus abdominis plane catheter versus a thoracic epidural catheter after flank incision: randomized-controlled trial. Res Opin Anesth Intensive Care [serial online] 2018 [cited 2018 Feb 21 ];5:21-26
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Full Text


Postoperative pain is a major obstacle for early postoperative ambulation. It increases the risk of venous thromboembolism and respiratory complications, and prolongs hospital stay [1]. Inadequately treated postoperative pain may lead to chronic pain [2],[3]. A high incidence of chronic postsurgical pain has been reported after a flank incision [4],[5],[6].

Conventional practice has involved the use of opioids as well as neuraxial analgesic techniques for the treatment of postoperative pain. Unfortunately, these therapies are not without potential risks and side effects [7].

Although epidural analgesia is an effective method for postoperative pain control, it is contraindicated in patients with coagulopathies and sepsis. It poses technical difficulties in positioning, decreases splanchnic blood supply, and can precipitate hemodynamic instability [8].

The transversus abdominis plane (TAP) was first described by Rafi in 2001 [9] and involves the injection of a local anesthetic into the plane between the internal oblique and transversus abdominis muscle layers using surface landmarks. Afterwards, ultrasonography is used to guide the delivery of the anesthetic drug into the appropriate plane, thereby increasing the accuracy of the technique [10]. Cases of inadvertent liver injury secondary to needle insertion have been reported in both traditional landmark and ultrasonography-guided TAP blocks [11],[12]. Accidental intraperitoneal infiltration has also been reported in obese patients and in those with reduced muscle tone, even with ultrasonography guidance [13]. Surgically administered TAP block has been described and enables a more accurate placement [14],[15]. We assumed that analgesia through a surgically inserted TAP catheter is an easy and available method for pain control and compared it with thoracic epidural analgesia as a conventional method for pain relief after flank incision.

 Patients and methods

This prospective randomized study was carried out at the Anesthesiology and Urology Departments of Zagazig University hospitals after approval of the local ethical committee and written informed consent was obtained from all patients. The study included 64 patients scheduled for renal surgery for a nonmalignant lesion, in which a primary flank incision was planned as pyelolithotomy, pyeloplasty, nephrectomy, and ureterolithotomy. The study excluded patients with recurrent wounds, a history of allergy to the study drugs, chronic pain, chronic preoperative opioid consumption, bleeding tendency with prothrombin time greater than 14 s, partial thromboplastin time greater than 45 s, and international normalized ratio greater than 1.25, chronic hepatic and/or renal disease, malignancy, sepsis, immune deficiency, and psychiatric disorders that prevent postoperative assessment and emergencies. The patients included were 18–59 years old with American Society of Anesthesiologists physical status I and II.

These patients were allocated randomly into two groups by a computer-generated sequence to receive postoperative analgesia either by a thoracic epidural catheter (group E) or by a surgeon-assisted tube that was inserted into the TAP during closure of the wound (group T).

General anesthesia was standardized for all study patients. They were monitored by ECG, pulse oximetry, and noninvasive arterial blood pressure and premedicated with intravenous midazolam 3–5 mg, atropine 0.5 mg, metoclopramide 10 mg, and ranitidine 50 mg.

Before induction of anesthesia, a thoracic epidural catheter was inserted preoperatively in the in the group E, while they were awake, in the thoracic (T7-T9) region using a paramedian approach 1–1.5 cm lateral to the inferior tip of the spinous process corresponding to the vertebra above. An 18 G Tuohy needle was inserted after the injection of a local anesthetic both to the skin and to the lamina of the vertebral body below. The approach of the needle was about 15° to the midline and 60–65° from the coronal plane. We identified the thoracic epidural space by loss of resistance to saline. After identifying the space, a multiorifice 20 G epidural catheter (Perifix® complete set; B. Braun Melsungen AG, Melsungen, Germany) was placed 3–4 cm within the epidural space. After removal of the needle, a sterile sponge or gauze was applied at the epidural insertion site and an occlusive clear dressing was placed over the catheter and sponge. The induction of general anesthesia was performed by intravenous propofol (2 mg/kg) with fentanyl (1–2 mg/kg), whereas intratracheal intubation was performed after the administration of atracurium 0.5 mg. Anesthesia was administered by isoflurane in oxygen and air, atracurium 0.1 mg/kg/30 min, and fentanil1 2 µg/kg/h. Oxygen saturation was maintained more than 98% and end tidal CO2 was maintained between 32 and 36 mmHg. At the end of the procedure, the halogenated agent was switched off and 100% oxygen was administered with an 8 l/min fresh gas flow. A residual neuromuscular block was reserved, if needed, with a mixture of neostigmine and atropine. In the TAP group, at the end of the operation, the surgeon identified the transeversus abdominis muscle at the upper and lower end of the wound flap. The muscle was grasped by Allis clamps and a plane was developed between the transeversus abdominis and the internal oblique muscle using both blunt and sharp dissection, ensuring preservation of the facial plane over all the wound edges. At the end of the dissection, a small mosquito clamp was passed through the wound layers with a skin exit ∼2 cm from the upper end of the incision. A 4 French open tip ureteric catheter was passed and situated in the dissected space. The catheter was fixed to the skin using 3/0 silk suture. Excess length of the catheter was cut. Finally, a catheter injector was applied and the flank incision was closed as usual ([Figure 1]).{Figure 1}

Following emergence from anesthesia, the patients were transferred to the recovery room and then to the surgical ward. The patients in group E received epidural analgesia with 0.125% bupivacaine and fentanyl 2 µg/ml at the rate of 5–8 ml/h. The TAP group received 1 mg/kg bupivacaine 0.375%/8 h. Rescue analgesia of 5 mg morphine bolus doses were administered upon patients’ requests with a maximum dose of 10 mg/4 h.

Patients were assessed in the postoperative period by an individual not involved in other data handling for the following:Pain using a visual analog scale (VAS) 10 cm unmarked line with 0 cm=no pain and 10 cm=worst pain at 1, 6, 12, 24, and 48 h postoperatively.Morphine consumption in the 48 h postoperative period.Incidence of postoperative complications such as nausea and/or vomiting, hypotension (mean arterial blood pressure ≤60 mmHg), bradycardia (heart rate <60), motor block, delayed bowel motility, and toxicity.

Statistical analysis

Using open Epi version 3 (Open Source Epidemiologic Statistics for Public Health, Version 3; available at, the sample size was calculated to be 29 patients in each group on the basis of previous data assuming a SD of 2 mm of VAS with a minimal confidence limit of 1.5 mm [16]. This yielded 80% power and a 95% confidence interval with type-1 error rate of 0.05. We decided to recruit 64 patients (32 per group) to account for possible study dropouts or lost data. Data were tabulated and subjected to a computer-assisted statistical analysis using the statistical package for the social sciences version 18.0 (SPSS; SPSS Inc., Chicago, Illinois, USA). Continuous data were expressed as mean±SD, whereas categorical data were expressed as frequency and percentage. Student’s t-test was used to compare the mean of continuous data. Categorical data were compared using Fisher’s exact test. A P value less than 0.05 was considered statistically significant.


Sixty-four patients were enrolled in this prospective study. They were divided into two groups: an epidural group (group E) and a surgically inserted TAP group (group T). After allocation, three patients were excluded from the epidural group: two patients had an unintentional dural puncture during insertion of the catheter and one patient experienced catheter dislodgement during the first 2 h postoperatively. Also, two patients were excluded from the TAP group because of catheter occlusion and catheter dislodgement postoperatively ([Figure 2]).{Figure 2}

There was no significant difference between the two groups in the demographic data ([Table 1]).{Table 1}

The morphine consumption reported, as mean±SD, during the first postoperative 48 h was higher in the TAP group (44±5 mg) than in the epidural group (42±4.1 mg), but this difference was not statistically significant (t=1.7 and P=0.09) at a 95% confidence interval and a significance level of 0.05. No significant difference was found in the VAS between the two groups either at rest ([Table 2]) or on coughing ([Table 3]).{Table 2}{Table 3}

Both techniques had little adverse effects, but group E had a significantly higher incidence of motor blockade and hypotension whereas other adverse effects did not differ significantly between the two groups ([Table 4]).{Table 4}


The importance of surgically administered TAP blocks is the ability to infiltrate the correct anatomical layer under direct vision, avoiding the potential complications of transabdominal peritoneal puncture [13].

Epidural analgesia is a well-established technique that is commonly considered the gold standard in postoperative pain management. However, newer, evidence-based outcome data showed that the benefits of the epidural analgesia are not as significant as believed previously [17]. There are well-known side effects and potentially catastrophic risks to the use of the epidural technique. The reported epidural therapeutic failure rate ranges from 17 to 37% [18].

This study compared an epidural regimen with 0.125% bupivacaine with fentanyl 2 µg/ml at the rate of 5–8 ml/h as a postoperative analgesia with a surgically inserted TAP catheter analgesia administered on the basis of a bolus schedule as 1 mg/kg bupivacaine 0.375%/8 h. Data using TAP catheter boluses suggested that this was an effective technique for providing analgesia in patients undergoing major upper abdominal surgery [19],[20]. This technique enables greater patient mobility, where no pump attachment is required [10]. In the TAP block, the local anesthetic agent, volume, concentration, and delivery method differ between studies, whereas 1 mg/kg/side bupivacaine was used to produce sufficient postoperative analgesia either at a concentration of 0.375% [10],[19] or 0.5% [21],[22].

The insertion of the TAP catheter under direct vision should theoretically be safer than the blinded technique or the ultrasound-guided technique that is currently practiced [20]. We experienced easy insertion with no complications during or/and after a surgically administered TAP block. This is consistent with previous reports that have shown that surgeons can help to facilitate TAP blocks. Araco et al. [21], during abdominoplasty, described a surgical TAP block in which blunt dissection involves an injection of 1 mg/kg/side of 0.5% bupivacaine under direct visualization. Chetwood et al. [23] described a laparoscopic-assisted technique where the anatomical landmarks-guided TAP block was performed, while the injection area was observed with an intra-abdominal laparoscopic camera. Bharti et al. [15] during colorectal surgery, and Owen et al. [14], in a cesarean section, described a transperitoneal approach in which a blunt-tipped needle was advanced from inside the abdominal wall to the transversus abdominis muscle, and then to the TAP space.

The infrequent studies comparing an ultrasound-guided TAP catheter with an epidural catheter analgesia reported on the superiority of either technique in terms of pain control and the amount of rescue opioid analgesia. Rao Kadam et al. [24] found no difference between the two techniques in pain scores, Likert satisfaction scores, and total opioid consumption after abdominal surgeries. Niraj et al. [10] observed similar pain control between epidural and TAP catheter analgesia after open hepatobiliary and renal surgeries, but the total opioid consumption was significantly higher in the TAP group. However, Wahba and Kamal [25], in their study on ischemic patients after a laparotomy, found that the epidural analgesia is superior to TAP catheter analgesia, with higher significant VAS and opioid consumption in the TAP group. The results of the current study are in agreement with the study of Rao Kadam et al. [24], where we found no significant difference in VAS and opioid consumption between postoperative analgesia by a TAP catheter and an epidural catheter. The under vision insertion helped by the surgeons in our study that insures correct placement of the TAP catheter may explains the better quality of analgesia compared to the two studies done by Niraj et al. [10] and Wahba and Kamal [25].

Wahba and Kamal [25] found no significant incidence of complications in the TAP group, whereas patients in the epidural group experienced a significantly higher incidence of hypotension that responded to conventional treatment and significantly higher incidence of delayed postoperative ambulation because of motor blockade, which is consistent with our results.

The limitations of this study were that it was an open-label study (not double blinded) which was inevitable because of the nature of the technique.


The surgically assisted-TAP analgesia is easy, safe, and effective. It can be a good alternative to epidural analgesia, especially when the latter is contraindicated. Studies to investigate the best anesthetic agents and its volume and concentration for best analgesia are needed.

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Conflicts of interest

There are no conflicts of interest.


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