Outpatient inguinal hernia repair under local anaesthesia: feasibility and efficacy of ultrasound-guided transversus abdominis plane block
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- Milone, M., Di Minno, M.N.D., Musella, M. et al. Hernia (2013) 17: 749. doi:10.1007/s10029-012-1022-2
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The aim of this prospective randomized study was to determine the utility of transversus abdominis plane (TAP) block to improve the efficacy of conventional local anaesthesia for hernia repair in order to achieve an adequate anaesthesia and to evaluate its post-operative analgesic effectiveness.
Hundred and fifty consecutive male patients undergoing outpatient hernia repair (Lichtenstein technique) were enrolled in this study. Patients were randomly allocated to undergo a combined TAP block and local anaesthesia (case group) or single conventional local anaesthesia (control group). The study was designed to obtain a 1:2 case–control ratio. The primary outcome was the evaluation of the proportion of patients achieving an adequate anaesthesia. The secondary outcome was the evaluation of pain on movement, pain at rest, rescue analgesia need, nausea and satisfaction.
An adequate anaesthesia was achieved in 8 % case and in 36 % control subjects (p = 0.001). At the 6 and 12 h post-operative evaluations, patients enrolled in the case group reported significantly less pain (evaluated by VAS score) both at rest and on movement (p always = 0.001). Moreover, the need of rescue analgesia resulted significantly higher in the control group (14 vs. 32 %, p = 0.01).
Our results demonstrated that, as compared with conventional local anaesthesia, the combination of TAP block with local anaesthesia showed a higher efficacy in the obtainment of an adequate anaesthesia and in the post-operative pain control for hernia repair.
Inguinal hernia repair is one of the most commonly performed operations world-wide . However, there is no common consensus among surgeons regarding the best choice of anaesthesia.
Several retrospective and randomized controlled trials demonstrated the clinical and pharmacoeconomic superiority of local anaesthesia as compared with spinal and general anaesthesia [2–6]. In spite of this, the use of local anaesthesia for inguinal hernia repair in Europe is not a common practice. Interestingly, the low utilization of local anaesthesia for inguinal hernia repair was noticed across Europe. Previous studies have revealed that, in the UK, only 5–10 % of inguinal hernias undergo surgery under local anaesthesia with the majority of cases being repaired under general (60–70 %) or regional anaesthesia (10–20 %) [7–11].
The transversus abdominis plane (TAP) block is a regional anaesthesia technique that provides analgesia to the parietal peritoneum as well as to the skin and muscles of the anterior abdominal wall [12, 13]. Despite a relatively low risk of complications and a high success rate using modern techniques, TAP block remains overwhelmingly underutilized. Although the block is technically straightforward, there is inertia regarding its adoption into clinical practice .
The aim of this prospective randomized study was to determine the utility of TAP block to improve the efficacy of conventional local anaesthesia for hernia repair in order to achieve an adequate anaesthesia and to evaluate its post-operative analgesic effectiveness.
After local ethical committee approval and written informed consent signature, all consecutive adult male patients undergoing outpatient elective inguinal hernia repair were screened for the enrolment in our study between January 2011 and March 2012.
Exclusion criteria were as follows: inability to consent to the study, age ≤ 18 years, BMI ≥ 40 kg/m2, contra-indication to local anaesthetic (LA) agents.
Patients were randomly allocated by sealed envelopes, according to a computer-generated sequence of random numbers, to undergo combined TAP block and local anaesthesia (case group) or single conventional local anaesthesia (control group). The study was designed to obtain a 1:2 case–control ratio.
All surgical procedures were performed by the same surgeon using the Lichtenstein tension-free technique. All patients (cases and controls) were premedicated with Midazolam (0.03 mg/kg) intravenously. All procedures were performed before operation by the same anaesthetist, experienced in ultrasound-guided loco-regional anaesthesia.
We have evaluated the average of patients achieving an adequate anaesthesia, pain on movement (elevation of the head and shoulders from the pillow, in the supine position), pain at rest, need of rescue analgesia, presence of nausea and patient satisfaction (defined according to validated criteria, see below). All these variables have been evaluated for each subject (cases and controls) at different time-points after surgery (6, 12 and 24 h).
Anaesthesia was defined adequate if not requiring a further anaesthetic procedure with analgosedation during the intervention. Before surgery, patients were instructed how to make use of a 10-mm Visual Analogue Scale (VAS) for pain graded from 0 (no pain) to 10 (most severe pain). The VAS scores were recorded at each time-point by an independent observer unaware of the patient allocation to case or control arm.
For post-operative analgesia, both case and control subjects received Paracetamol 1 g every 8 h. If rescue analgesia was needed (VAS score at rest > 4), Ketorolac (30 mg in single dose) was administered. In case of failure of the rescue analgesia with Ketorolac, the use of opioids has been taken into consideration.
Participants were asked to rate the severity of nausea on a 4-point scale (none, mild, moderate and severe) during the first 24 h after surgery.
Overall patient satisfaction was evaluated by an independent observer during the physical examination performed 7 days after surgery. It was assessed by questioning the patient to give a grade for his operation on a 3-point scale (good, fair or bad).
Lichtenstein hernia repair
The mesh is fashioned to fit the posterior wall of the inguinal canal. A slit of 2 cm long is made in the lateral aspect of the mesh, and the spermatic cord placed between the 2 tails of the mesh. The cord is then tagged in the cephalic direction, and the medial end of the mesh is made to overlap the pubic bone by approximately 2 cm. The mesh is then sutured to the fibro-periosteum of the pubic bone using interrupted polypropylene 3/0 suture. The interrupted sutures are continued laterally, suturing the inferior edge of the mesh to the shelving edge of the inguinal ligament, to a point 2 cm lateral to the deep inguinal ring. The superior edge of the mesh is then secured likewise to the internal oblique aponeurosis or muscle approximately 2 cm from the aponeurotic edge, while the lower edges of the 2 tails are sutured to the shelving edge of the inguinal ligament to create a new deep ring made of mesh. Finally, the cord is allowed to fall back on the strengthened posterior wall of the canal, the aponeurosis of the external oblique repaired with continued polyglactin 910 2/0 suture and the superficial ring reconstructed to fit snugly around the cord.
Conventional local anaesthesia
As regarding anaesthetic agents, our choice has been a 50–50 mixture of mepivacaina 2 % and ropivacaine hydrochloride monohydrate 7.5 mg/ml. Approximately 8 ml of the mixture is infiltrated along the line of the incision using a 2-inch-long 25-gauge needle into the subdermic and intradermic tissue parallel with the surface of the skin. Approximately 10 ml is injected deep into the subcutaneous adipose tissue by vertical insertions of the needle (perpendicular to the skin surface) 2 cm apart. Finally, approximately 10 ml is injected immediately underneath the aponeurosis of the external oblique through a window created in the subcutaneous adipose tissue at the lateral corner of the incision. Occasionally, infiltration of a few millimetres of the mixture at the level of the pubic tubercle is required to achieve complete local anaesthesia.
Statistical analysis was performed with SPSS 15.0. The Yates corrected Chi square test was used as a means of evaluating differences in categorical variables, and the independent t test was used for continuous variables. To make predictions and to adjust for all the other variables, a multivariate logistic regression was performed with effective anaesthesia as the dependent variable, age, BMI, operative time and hernia types as independent variables. A separate multivariate logistic regression analysis was performed to evaluate the need of rescue analgesia use in the postoperative period. Statistical significance was accepted when the p value was less than 0.05.
As to the sample size evaluation, planning a study of independent cases and controls with two controls per case, with a >2.0 pre-defined OR, an α error <5 % and a power >90 %, we will need to enrol at least 38 experimental subjects and 76 control subjects.
Of the 186 subjects screened for the enrolment in this study, 36 patients were excluded because of the exclusion criteria. In particular, 10 were ≤18 years old, 13 showed a BMI > 40 kg/m2, 8 denied their consensus to the study, 5 referred contra-indication to LA agents.
Among the 150 consecutive patients enrolled in our study, 50 underwent hernia repair under combined TAP block and conventional local anaesthesia (case group), and 100, under single conventional local anaesthesia (control group).
Baseline demographic characteristics and outcome measurements
49.5 + 12.8
50.3 + 13.2
29.1 + 4.5
28.5 + 4.8
18 (36 %)
41 (41 %)
23 (46 %)
41 (41 %)
9 (18 %)
18 (18 %)
7 (14 %)
11 (11 %)
4 (8 %)
9 (9 %)
29 (58 %)
43 (43 %)
16 (32 %)
32 (32 %)
5 (10 %)
25 (25 %)
Operative time (min)
47.6 + 11.3
51.6 + 13.4
5 (10 %)
14 (14 %)
4 (8 %)
9 (9 %)
3 (6 %)
3 (3 %)
1 (2 %)
4 (4 %)
Adequate anaesthesia (pts)
46 (92 %)
64 (64 %)
Rescue analgesia use (pts)
7 (14 %)
32 (32 %)
5 (10 %)
16 (16 %)
10 (20 %)
26 (26 %)
35 (70 %)
58 (58 %)
43 (86 %)
79 (79 %)
7 (14 %)
21 (21 %)
The TAP block procedure added to the surgery 14.4 ± 3.1 min.
As to the efficacy of these anaesthesia methods, 4 of the 50 (8 %) patients from the case group and 36 of 100 (36 %) from the control group (p = 0.001) needed intraoperative analgosedation with remifentanil (0.05 μg/kg/min) for inadequate anaesthesia (abdominal pain). None of the cases and of the controls required general anaesthesia. After adjusting for all the other variables (logistic regression analysis), the use of the combined TAP block and local anaesthesia was associated with a 5.85 Odds Ratio (95 % CI: 1.89–17.86, p = 0.002) to obtain an adequate anaesthesia as compared with the conventional local anaesthesia.
During the first postoperative day, because of abdominal pain, the need of rescue analgesia resulted significantly higher in the control group as compared with the case group (14 vs. 32 %, p = 0.01). None of the subjects (case and controls) needed drugs other than ketorolac (30 mg) for analgesia. A multivariate logistic regression analysis showed that the need of rescue analgesia was significantly higher in subjects undergoing conventional local anaesthesia as compared with those in the TAP block and local anaesthesia combination group (odds ratio 2.89, 95 % CI: 1.17–7.12, p = 0.021). None of the patients had analgesic requirement during the first week after surgery.
After all, as to the patients’ satisfaction rate after surgery, in this study, we achieved good results among our patients in either groups (p = 0.2) and no one referred bad this period (Table 1).
This is the first prospective, randomized study showing that the combination of TAP block and local anaesthesia is associated with a more adequate anaesthesia achievement and with a better post-operative pain control as compared with the conventional local anaesthesia.
The TAP is an intermuscular plane between the internal oblique and transversus abdominis muscles. The terminal branches of the lower thoracic and first lumbar nerves course through the lateral abdominal wall within this plane [14, 15]. Injection of LA in the TAP may possibly provide unilateral analgesia of the anterior abdominal wall (skin, muscles and parietal peritoneum) from the T7 to L1 dermatomes [15–17].
The TAP block was first described as a landmark-guided technique involving needle insertion at the triangle of Petit and the elicitation of two tactile fascial “pops” to indicate entry into the transversus abdominis muscles [15, 16, 18]. More recently, ultrasound has been used successfully to guide needle insertion [15, 19–21], and it may help prevent complications related to inadvertent visceral perforation [15, 22]. The muscle layers and peritoneum are readily visualized using a linear transducer, even in moderately obese subjects .
Transversus abdominis plane block has been described as an effective component of multimodal postoperative analgesia for a wide variety of abdominal procedures including large bowel resection, open/laparoscopic appendectomy, caesarean section, total abdominal hysterectomy, laparoscopic cholecystectomy, open prostatectomy, renal transplant surgery, abdominoplasty with/without flank liposuction and iliac crest bone graft . Most reports demonstrate the effectiveness of TAP block by highlighting a reduced postoperative opioid-related requirement, lower pain scores and/or reduction in opioid-related side effects [12, 23]. Moreover, the efficacy of the TAP block in the induction of an effective analgesia during the first 24 h after surgery has been reported [17, 18, 24–29].
However, we were the first authors, in our best knowledge, prospectively evaluating the utility of TAP block to improve the efficacy of conventional local anaesthesia for hernia repair with respect to achieving adequate anaesthesia. In our setting, the proportion of patients achieving an adequate anaesthesia was higher among the patients who underwent combined TAP block and local anaesthesia. In fact, only 8 % of patients of case group required analgosedation while 36 % patients of the control group required analgosedation for inadequate anaesthesia, being this difference statistically significant.
Then, it has shown that TAP block could be an effective and feasible anaesthesia method to obtain an adequate local anaesthesia for hernia repair, although more patients should be enrolled in further randomized controlled research.
Moreover, our results demonstrate that this anaesthesia method is more effective than conventional local anaesthesia in the pain management after hernia repair because patients who underwent combined TAP block and local anaesthesia expressed significantly less pain on VAS score at rest and on movement and a less analgesic requirement.
Some limitations of the present study need to be addressed. The relatively small sample size and the presence of uncertain factors impacting on the clinical outcome involve that it is unlikely to define conclusive results. Namely, all subjects enrolled were males, so these results cannot be extrapolated to female patients. Finally, this procedure needs availability of ultrasound device and an experienced provider who can perform the procedure. On the other hand, the results were adjusted for all the other variables in the multivariate regression analysis and all p values are highly significant. Moreover, the control population selection needs to be further commented. A sampling frame of patients is often used to select controls; however, selection method can lead to an over-estimation of the population exposure to some risk factors. This concern should be taken into consideration being particularly relevant where the number of cases is small. In our study, by using multiple controls for each case (1:2 case–control ratio) and, in turn, by giving the study a greater power, we are confident to have overcome this type of issue .
Further studies are needed to address the relevant issue of the TAP block use in the anaesthetic and analgesic management of hernia surgery. On the other hand, our results appear to encourage the use of TAP block in hernia surgery.
Conflict of interest
All the authors have nothing to declare.