Nerve Blocks of the Abdominal Wall

Fig. 53.1
Lumbar triangle (triangle of Petit) and the neurovascular plane targeted for landmark approach to TAP block. (1) External oblique, (2) internal oblique, (3) transversus abdominis, (4) latissimus dorsi, (5) serratus posterior inferior muscle, (6) erector spinae, (7) quadratus lumborum (8) psoas major, (9) iliac crest. Transversus abdominis plane is shaded orange (Original illustration by Michael Ee with permission)

Anatomy

The anterolateral abdominal wall muscles (external oblique, internal oblique, and transversus abdominis) are replaced by a well-defined aponeurosis, the linea semilunaris, at the lateral border of the rectus sheath (Fig. 53.2). This is an important sonoanatomical landmark for performing TAP and rectus sheath blocks [8, 9]. The rectus sheath contains the rectus abdominis muscles, the anterior rami of the lower sixth thoracic nerves (T7–T12), the superior and inferior epigastric vessels, and lymph vessels. It is formed by the fusion of the aponeuroses of the three anterolateral abdominal wall muscles. The abdominal wall is innervated by the T6–T11 intercostal and T12 subcostal nerves (Fig. 53.3). The intercostal nerves exit the intervertebral foramina and enter the paravertebral region related to the intercostal muscles posteriorly. Between the midline and the anterior axillary line, segmental nerves T6–T9 emerge from the costal margin to enter the TAP. The T10 segmental nerve is located caudal to the costal margin (rib 10) and T11, T12, and L1 are located in a caudal direction, toward the iliac crest. The TAP contains intercostal, subcostal, and first lumbar (L1) nerves and blood vessels (deep circumflex iliac, inferior epigastric, superior epigastric arteries) (Fig. 53.3). The lateral cutaneous branch of the intercostal nerves divides into anterior and posterior cutaneous branches. The origins of the lateral cutaneous nerves are proximal close to the costal angle. However, the point at which lateral cutaneous nerves pierces muscle layers is more anterior at the angle of rib or midaxillary line [10]. The lateral cutaneous branches are significant because they innervate much of the abdominal wall (T6–T12) and thorax (T1–T5). The anterior cutaneous nerve sends twigs to the external oblique muscle as well as skin to the lateral margin of the rectus abdominis. The posterior branch runs backward supplying the paravertebral region as well as the erector spinae.
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Fig. 53.2
Cross section of abdominal wall. (1) External oblique, (2) internal oblique, (3) transversus abdominis, (4) transversus abdominis plane (shaded orange), (5) rectus abdominis, (6) parietal peritoneum, (7) spinal cord, (8) ventral ramus, (9) dorsal ramus, (10) lateral cutaneous nerve, (11) anterior cutaneous nerve, (12) anterior branch of lateral cutaneous nerve, (13) posterior branch of lateral cutaneous nerve; linea semilunaris (orange-dotted lines) (Original illustration by Michael Ee with permission)
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Fig. 53.3
Nerves and vessels within transversus abdominis plane. (1) Deep circumflex iliac artery, (2) superior epigastric artery, (3) inferior epigastric artery (Original illustration by Michael Ee with permission)
The iliohypogastric nerve (IHN) and ilioinguinal nerve (IHN) are branches of L1 and these pass laterally through the psoas muscle, course anterior to the quadratus lumborum and travel caudally toward the iliac crest on the inner surface of the transversus abdominis muscle. The nerves pierce the transversus abdominis muscle to enter the TAP plane at variable locations (Fig. 53.4). They are located in the TAP for a short distance only. Medial to the anterior superior iliac spine, the IIN passes through internal oblique close to the inguinal ligament [11, 12]. It is at this location that landmark techniques usually aim to locate the IIN. The IHN is usually above and medial to it [13]. The IIN and IHN supply the skin and muscles of the pubic and inguinal region and genitalia. In summary, the IHN and IIN are located in the TAP close to the iliac crest and anterior superior iliac spine [14]. Medial and inferior to the anterior superior iliac spine, the nerves are located between the internal and external oblique muscles [15].
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Fig. 53.4
Course of subcostal, iliohypogastric, and ilioinguinal nerves. (1) External oblique, (2) internal oblique, (3) transversus abdominis, (4) quadratus lumborum; anterior superior iliac spine (ASIS); subcostal nerve (yellow); iliohypogastric nerve (blue); ilioinguinal nerve (green); diaphragmatic crura (black outline) (Original illustration by Michael Ee with permission)
The lower five intercostal nerves pierce the lateral margin of the linea semilunaris to enter the rectus sheath posterolaterally. The intercostal (T6–T9), subcostal, and L1 nerves terminate in the rectus abdominis muscle with three patterns: (1) terminate simply within the muscle, (2) supply the muscle and then terminate as a cutaneous branch, or (3) pass through the muscle and terminate as a cutaneous branch [10]. Rozen et al. [16] noted that as the nerves approach the posterior surface of the rectus abdominis, a longitudinal branch of fibers run craniocaudally with the deep inferior epigastric artery. In addition, the cutaneous branches were closely related to the perforating musculocutaneous vessels. Together T7–L1 supply the skin from the xiphoid sternum (T7 nerve root) to the pubic symphysis (L1 nerve root), with T10 nerve supplying the umbilical segment. The IHN nerve supplies the lowermost segment of the rectus abdominis muscle and overlying skin.
The posterior abdominal wall is composed of muscles bound by the thoracolumbar fascia (Fig. 53.5). The thoracolumbar fascia is an extensive tough membranous sheet that envelops the muscles of the posterior abdominal wall, dividing these into anterior, middle, and posterior layers. Key paired muscles of the posterior abdominal wall are psoas major, iliacus, and quadratus lumborum [17].
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Fig 53.5
Thoracolumbar fascia and relationship to posterior and lateral abdominal wall muscles. (1) External oblique, (2) internal oblique, (3) transversus abdominis, (4) latissimus dorsi, (5) serratus posterior inferior muscle, (6) erector spinae, (7) quadratus lumborum, (8) psoas major, (9) iliac crest (Original illustration by Michael Ee with permission)

Indications

Surgical

TAP blocks have provided surgical anesthesia in high-risk patients for abdominal wall hernia repair, emergency laparotomy [18, 19], and elective Cesarean delivery [20]. The site of block insertion can be modified according to the anticipated site of surgical incision [21]. Despite these case reports, TAP blocks are rarely used for surgical anesthesia.

Therapeutic

Most commonly, TAP blocks are used as one component of multimodal postoperative analgesic technique. They have been effective following colorectal surgery [3], appendicectomy [22], cholecystectomy, prostatectomy, Cesarean section [23], gynecological surgery [24], hernia repair, and renal transplantation [25]. The TAP block is well described following pediatric surgery [26, 27] providing analgesia following ambulatory surgery including hernia repair [28]. A systematic review of studies has demonstrated clinically significant reductions of postoperative opioid requirements and pain [29]. In addition to reduced opioid-related side effects [30], TAP blocks have reduced postoperative opioid consumption in laparoscopic colorectal surgery [31]. A summary of current evidence is provided in Table 53.1. Continuous TAP blockade has been used for treatment of chronic pain [32], for complex traumatic pelvic fractures [33] and for rescue analgesia [34].
Table 53.1
Efficacy of TAP blocks reported in randomized controlled trials
Publication
Surgical procedure
N
Local anesthetic dosage
Comparator
Effect of TAP block on primary outcome
El-Dawlatly (2009) [35]
Laparoscopic cholecystectomy
42
15 ml 0.5 % bupivacaine bilaterally (n = 21)
No TAP (n = 21)
Decrease in PCA morphine use in PACU and ward 1st 24 h
Niraj (2009)
[36]
Open appendicectomy
52
20 ml 0.5 % bupivacaine unilaterally (n = 26)
No TAP (n = 26)
Reduced morphine use and reduced VAS score (at rest and cough) in 1st 24 h. Decreased PONV at 30 min but not at 24 h
Jankovic (2009*)
[37]
Renal transplant recipients
40
20 ml 0.375 % levobupivacaine then 0.15 % bupivacaine 10 ml/h (n = 7)
No TAP (n = 33)
TAP block reduced morphine requirement and duration of PCA use. No difference in pain scores
Griffiths (2010)
[24]
Gynecological cancer surgery
65
20 ml 0.5 % ropivacaine bilaterally (n = 32)
Normal saline placebo (n = 33)
No significant difference in opioid use
Mukhtar (2010)
[38]
Renal transplant recipients
20
20 ml 0.5 % bupivacaine unilaterally (n = 10)
No TAP (n = 10)
Decrease in morphine use. Decrease in pain up to 12 h. Less sedation up to 6 h. Lower PONV scores up to 6 h
Ra (2010)
[39]
Laparoscopic cholecystectomy
54
30 ml 0.25 % compared with 30 ml 0.5 % levobupivacaine bilaterally (n = 18, 18)
Normal saline placebo (n = 18)
In TAP groups: decrease in i.v. opioid use and pain up to 24 h. No difference between 0.25 % and 0.5 % levobupivacaine
Conaghan (2010)
[40]
Laparoscopic colorectal surgery
74
20 ml of 0.25 % levobupivacaine bilaterally (n = 40)
No TAP (n = 34)
Decrease in i.v. opioid use. Decreased length of hospital stay
Milan (2011)
[41]
Liver transplant
34
20 ml 0.5 % levobupivacaine bilaterally (n = 17)
No TAP (n = 17)
Reduced morphine consumption and median pain scores
Aniskevich (2011)a
[42]
Pancreas transplant
1
20 ml 0.5 % ropivacaine bilaterally
n/a
Successful use of TAP block for postoperative rescue analgesia in chronic opioid user
Bharti (2011)
[43]
Colorectal surgery
40
20 ml 0.25 % bupivacaine bilaterally (n = 20)
Normal saline placebo (n = 20)
Decreased morphine use and rest and dynamic pain. Reduced sedation in TAP group (0 to 6 h). Improved patient satisfaction
Atim (2011)
[44]
Hysterectomy
55
20 ml 0.25 % bupivacaine bilaterally (n = 18)
Normal saline placebo (n = 18) and local wound infiltration 0.25 % bupivacaine (n = 19)
Reduced pain compared to both placebo and local infiltration
Sandeman (2011)
[26]
Pediatric
Laparoscopic appendicectomy
87
0.5 ml/kg 0.2 % ropivacaine bilaterally (n = 42)
Local infiltration to port sites only (n = 45)
No clinically important benefit
Niraj (2011)
[45]
Open hepatectomy and renal surgery
62
Bilateral TAP catheter (n = 29), 1 mg/kg 0.375 % bupivacaine
Epidural (n = 33)
No difference in pain scores and PONV
Melnikov (2011)
[46]
Major gynecological surgery for cancer
58
0.375 ml/kg 0.25 % bupivacaine with 5 mcg/ml adrenaline bilaterally (n = 19)
Bilateral thoracic paravertebral block (n = 19)
No difference in pain scores and PONV
Kadam (2011)
[47]
Major abdominal surgery
20
15 ml 0.5 % ropivacaine with continuous infusion 0.2 % ropivacaine bilaterally (n = 10)
No TAP (n = 10)
Reduced pain scores and fentanyl consumption
Petersen (2012)
[48]
Laparoscopic cholecystectomy
74
20 ml 0.5 % ropivacaine bilaterally (n = 37)
Normal saline placebo (n = 37)
Some reduction in VAS scores for pain on coughing and slightly less opioid requirement
Tan (2012)
[49]
Cesarean section
40
20 ml 0.25 % levobupivacaine bilaterally (n = 20)
No block (n = 20)
Reduction morphine consumption, increased patient satisfaction
Tolchard (2012)
[50]
Laparoscopic cholecystectomy
43
1 mg/kg bupivacaine unilaterally (n = 21)
Local infiltration to port sites only (n = 22)
Reduced VAS scores and fentanyl requirement in PACU
Walter (2013)
[31]
Laparoscopic colorectal
surgery
68
20 ml 0.2 % levobupivacaine bilaterally (n = 33)
No TAP (n = 35)
Reduced opioid use 1st 24 h
Albrecht (2013)
[51]
Laparoscopic
gastric-bypass surgery
70
30 ml 0.25 % bupivacaine with adrenaline bilaterally (n = 35)
Local infiltration to port sites only (n = 35)
No difference in opioid consumption during 1st 24 h. Rates of PONV equivocal
Sinha (2013)
[52]
Laparoscopic bariatric surgery
100
20 ml 0.375 % ropivacaine bilaterally
(n = 50)
No TAP (n = 50)
Reduced opioid requirements and VAS scores
Sahin (2013)
[53]
Pediatric inguinal hernia repair
57
0.25 % levobupivacaine 0.5 ml/kg unilaterally (n = 29)
Wound infiltration (n = 28)
Reduced pain, prolonged effect
Wu (2013)
[54]
Radical gastrectomy
82
20 ml 0.375 % ropivacaine bilaterally (n = 27)
Thoracic epidural (n = 29), GA only (n = 26)
TAP reduced opioid consumption than GA alone; equivocal pain scores. Thoracic epidural less opioid consumption than TAP block; equivocal pain scores
Parikh (2013)
[55]
Donor nephrectomy
60
25 ml 0.375 % bupivacaine unilaterally (n = 30)
Placebo control with saline (n = 30)
Reduced tramadol consumption in the 1st 24 h
Gasanova (2013)
[56]
Total abdominal hysterectomy
74
Group 1, 20 ml 0.5 % bupivacaine bilaterally (n = 25) with multimodal analgesia; Group 2, TAP block only (n = 24)
Group 3, multimodal analgesia only, no TAP block (n = 25)
Pain on coughing less variable where TAP block was combined with multimodal analgesia. No difference in pain at rest
Sivapurapu (2013)
[57]
Lower abdominal gynecological surgery
52
0.3 ml/kg 0.25 % bupivacaine bilaterally (n = 26)
Direct wound infiltration (n = 26)
Reduced VAS and increased time to request first rescue analgesia
Gomez-Rios (2014)b
[58]
Major gynecological and obstetric surgery
6
Continuous infusion of 0.125 % levobupivacaine 2 ml/h bilaterally for 50 h
n/a
Reduced opioid requirements and improved postoperative mobility
Niraj (2014)
[59]
Laparoscopic cholecystectomy
61
Four-quadrant TAP block 2.5 mg/kg 0.375 % levobupivacaine plus continuous infusion 0.25 % levobupivacaine (n = 30)
Epidural (n = 31)
No difference between groups in VAS scores at rest or with coughing
Aniskevich (2014)
[60]
Laparoscopic assisted nephrectomy
21
20 ml 0.5 % ropivacaine, lateral approach bilaterally (n = 10)
Placebo saline control (n = 11)
Reduced opioid requirements and lower pain scores at 24 h
Mckeen (2014)
[61]
Post-Cesarean delivery
74
Spinal anesthetic and post-op US-guided TAP, low-dose ropivacaine (n = 35)
Control (n = 39)
No statistically significant difference in pain scores, sedation, or opioid consumption
Soltani (2014)
[25]
Renal transplant recipients
44
Post-induction under US guidance
15 ml 0.25 % bupivacaine and adrenaline (n = 22)
Placebo control with saline (n = 22)
Decreased morphine consumption and lower pain scores in 1st 24 h. Reduced intraoperative fentanyl consumption in TAP group
Calle (2014)
[62]
Laparoscopic hysterectomy
197
Bilateral with 0.25 % bupivacaine
Placebo control with saline
No difference in opioid requirements at 24, 48, 72 h postoperatively
Marais (2014)
[63]
Open total abdominal hysterectomy
30
20 ml 0.25 % bupivacaine bilaterally (n = 15)
Placebo control with saline (n = 15)
Reduced PCA morphine use
Chandon (2014)
[64]
Post-Cesarean analgesia
65
20 ml 0.375 % levobupivacaine bilaterally (n = 36)
Continuous wound infusion (n = 29)
No difference in rest and dynamic pain scores between groups. Study terminated early due to generalized seizure in 1 patient in TAP group
Bhatacharjee (2014)
[65]
Total abdominal hysterectomy
90
1 ml/kg 0.25 % bupivacaine bilaterally (n = 45)
Placebo control with saline (n = 45)
Lower rest and dynamic VAS scores in immediate postoperative period
Heil (2014)
[66]
Hernia surgery
20
20 ml 0.5 % ropivacaine bolus plus continuous infusion 0.2 % ropivacaine (n = 10)
Placebo control with saline infusion (n = 10)
No significant difference in dynamic pain scores on postoperative day 1
De Oliveira Jr (2014)
[67]
Laparoscopic gastric banding
19
20 ml 0.5 % ropivacaine bilaterally (n = 10)
Placebo control with saline (n = 9)
Improved quality of postoperative recovery and reduced opioid use
*Retrospective audit, acase report, bcase series. PACU post anesthetic care unit, VAS visual analog scale, PCA patient-controlled analgesia, PONV postoperative nausea and vomiting, n/a not applicable, i.v. intravenous

Contraindications

Infections and skin diseases in the injection area
Surgical dressings obstructing access
Patient refusal

Advantages/Disadvantages

TAP blocks reduce side effects associated with epidural or opioid analgesia failure rate and need for re-siting of block or catheter.
Inadequate analgesic coverage for visceral pain.

Procedure

Preparation

As with all regional anesthesia procedures, requirements include emergency equipment, monitoring, and assistance.

Materials and Disposables

We recommend a 38–50-mm intermediate frequency probe for adult patients.
Sterile ultrasound probe cover and gel for all procedures.
Routine disposables including fenestrated drape and dressings.
21- or 18-gauge short-bevel needles for single-injection or continuous catheter techniques, respectively, 100–150-mm needle required for in-plane technique
20–30 ml of local anesthetic for block (see section on Local Anesthetic Dosage, Volume, and Spread)

Patient Positioning

Supine however consider lateral or lateral tilt for more posterior approach

Ergonomics

We suggest positioning the ultrasound machine on the opposite side of the patient to the proceduralist, so that he/she directly faces the screen. We suggest first scanning by identifying the rectus abdominis muscles, then the linea semilunaris aponeurosis (separating the rectus abdominis from the three anterolateral abdominal wall muscles), and then the anterolateral muscles (Fig. 53.6). Dynamic scanning from medial to lateral or vice versa helps with correct identification of muscle layers (Fig. 53.7). In many patients, the rectus abdominis muscle is displaced further away from the midline than expected. To identify the TAP, it is useful to appreciate: (1) the transversus abdominis muscle may appear hypoechoic, and (2) the transverse abdominis muscle passes under the rectus abdominis close to the xiphisternum. Therefore, scanning in the upper part of the abdomen toward the midline is very helpful in locating the transverse abdominis muscle. Injecting between the rectus abdominis and transverse abdominis muscles close to the xiphisternum may increase the likelihood of anesthetizing T6–8 segmental nerves.
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Fig. 53.6
Linea semilunaris under ultrasound. Linea semilunaris (white arrow), rectus abdominis (RA), internal oblique (IO), transversus abdominis (TA), transversus abdominis plane (bold white arrow)
Oct 18, 2016 | Posted by in ANESTHESIA | Comments Off on Nerve Blocks of the Abdominal Wall

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