This article aims to review the anatomy relevant to the ultrasound
techniques of the transversus abdominis plane (TAP) block and rectus sheath
block (RSB). We discuss their analgesic efficacy for various surgical
procedures, both as single shot and as a continuous infusion via
catheters.
Recent Findings
RSB provides superior analgesia to local infiltration and has an
opioid-sparing effect for umbilical surgery, laparotomy, and laparoscopic
surgery. There is no high-quality evidence comparing RSB with epidural
analgesia. Intermittent bolus through catheters appears to be more effective
than continuous infusion for prolonged analgesia. Similarly, ultrasound-guided
TAP block provides postoperative analgesic benefit after abdominal laparotomy or
laparoscopy and cesarean delivery when long-acting neuraxial opioids are not
used or contraindicated. Adding adjuvant such as dexamethasone and
dexmedetomidine to local anesthetic prolongs the duration of TAP and RSB blocks
and improves their efficacy.
Summary
Use of ultrasound guidance makes the RSB and TAP blocks more
reliable. Single-shot infiltration is useful for less extensive surgical
procedures, while catheters are a useful alternative when thoracic epidural
analgesia is contraindicated.
Hinweise
This article is part of the Topical Collection on Regional Anesthesia
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Anatomical Concepts
The rectus abdominis muscle (RAM) is a paired vertical muscle separated
in the midline by the linea alba, it is wide and thin superiorly, increasing in
thickness inferiorly. This muscle is surrounded by the rectus sheath, which is
comprised of the aponeurosis of the more lateral abdominal muscles. The posterior
layer becomes thin at the arcuate line, one-third of the way between the umbilicus
and the pubic crest. At this line, the aponeurosis of the internal oblique and
transversus abdominis goes anterior to the muscle, rather than posterior, leaving
only the thin transversalis fascia posterior. The deep inferior and superior
epigastric arteries run deep to rectus abdominis and superficial to the fibrous
layer that forms the posterior rectus sheath. Care should be taken to avoid
puncturing these blood vessels during the needle insertion.
Lateral to the RAM are the external oblique, internal oblique, and
transversus abdominis muscles (superficial to deep). The intercostal nerves run in a
plane between the internal oblique and transversus abdominis muscles, then penetrate
the posterolateral border of the rectus muscle, innervating the muscle (muscular
branch) and then the subcutaneous tissue and skin (anterior cutaneous branch). The
deep circumflex iliac artery can be seen in the posterior TAP plane, where needle
puncture can lead to hematoma.
Anzeige
Instillation of local anesthetic bilaterally between the rectus muscle
and the posterior sheath provides midline analgesia for several dermatomes around
the injection site. Injection between the internal oblique and transversus abdominis
muscles (TAP block) at the level of the iliac crest can provide analgesia for lower
abdominal surgery. Similarly, local anesthetic injection between the rectus
abdominis muscle and transversus abdominis muscle at subcostal level (subcostal TAP
block) can provide analgesia for upper abdominal surgery.
It is important to note that only the somatic components of pain are
covered when these blocks are utilized (skin, subcutaneous tissue, muscle). A
multimodal analgesics regimen is required to cover the visceral pain component.
Furthermore, bilateral blocks are required for midline incisions.
Rectus Sheath Block
Introduction
Rectus sheath block (RSB) was originally described in 1899 and was
used to provide abdominal wall relaxation during laparotomy before the
introduction of neuromuscular blocking agents [1]. Currently the block is generally performed for
postoperative analgesia, either as a single injection or with a continuous
catheter technique. While the block was traditionally used for procedures around
the umbilicus to provide analgesia from T9–T11, good clinical results are also
achieved for higher dermatomes, up to T6, when the injection is performed
higher. This makes the block useful for midline laparotomy, regardless of its
level in the abdomen.
Real-time ultrasound guidance is our preferred method for placing
rectus sheath blocks as it ensures the local anesthetic is efficiently placed
anterior to the posterior rectus sheath without being within the rectus muscle
[2]. A linear array ultrasound
transducer is placed on the abdomen in a transverse position congruent with the
surgical incision (generally between T8 and T11 dermatomes). In the middle of
the abdomen, the linea alba is observed on the ultrasound screen. The probe is
then moved laterally to identify the rectus muscle, along with the subcutaneous
tissue and the peritoneum.
Fig. 1
Rectus sheath block. The left image shows the ultrasound
probe position and in-plane needle insertion technique
(lateral-to-medial approach) for a rectus sheath block (RSB).
The image on right shows the sonogram during performance of RSB.
RAM, rectus abdominis muscle; TAM, transversus abdominis muscle;
green arrow, Needle path; yellow-shaded area denotes the site of
local anesthetic (LA) deposition
×
Anzeige
At the lateral border of the rectus muscle, the external oblique,
internal oblique, and transversus abdominus can be identified. The needle tip is
placed just deep to the posterolateral border of the rectus muscle. Correct
placement is confirmed when injection causes the rectus muscle to lift cleanly
off the rectus sheath deep to it (Fig. 1). Continuous hydrodissection during needle advancement is
invaluable for efficiently identifying the correct plane. Between 10 and 15 ml
of local anesthetic per side or 0.25 ml/kg in pediatrics is the usual dose.
Another approach is to use a smaller dose at two different levels on each side
when a large incision must be covered. Dexamethasone or dexmedetomidine can be
added to the local anesthetic to prolong the block duration [3].
Alternative Techniques for Rectus Sheath Block
Landmark techniques can be utilized by either the anesthesiologist
or the surgeon. A blunt bevel needle is advanced perpendicular to the abdominal
wall at the lateral edge of the rectus muscle. After the skin is penetrated, the
needle is withdrawn back to the skin then advanced through the first “pop” that
represents the anterior rectus sheath. Next, the needle is advanced until it is
pressed against the firm resistance of the posterior sheath. If performed by the
surgeon during surgery with an open abdomen, the blunt needle can be palpated
from within the abdomen. A correctly placed needle tip will have a distinctive
“close, but not too close” feeling on palpation. Alternatively, there has also
been a laparoscopically assisted approach described [4].
Catheter Technique
A catheter may be placed at the time of block performance to extend
the duration of analgesia. Catheter regimens vary, but intermittent bolus seems
to be more efficacious than continuous infusion [5]. For example, 10 ml of 0.2% ropivacaine in each catheter
every 4 h by a programmable pump is an efficacious and safe dose in
adults.
Analgesic Efficacy
Umbilical Hernia
One recent randomized control trial (RCT) has compared RSB with
placebo for umbilical hernia surgery in adults where they found lower 24-h
opioid consumption (mean morphine consumption 3.73 mg vs. 8.76 mg) and lower
pain scores [6]. A meta-analysis
of ten trials for RSB in pediatric umbilical surgery found a reduction in
opioid use for the first 6–8 h (-0.03 mg/kg) [7••].
Laparotomy
In laparotomy, RSB has been shown to significantly reduce morphine
use (0.7 mg vs. 6.4 mg) [8] and pain
scores (VAS score at 6 h, 2 vs. 3) when compared with placebo [9]. These studies either used a single-shot
technique [8‐11], combined
with TAP block [12, 13], or with continuous catheters
[13, 14•]. A retrospective case-control study
suggested the analgesic efficacy of RSB for open pyloromyotomy in infants
[15]. Some of the studies also
found significant reductions in postoperative nausea/vomiting, sedation, and
constipation, and improvements in patient satisfaction [9, 16].
Rectus sheath catheters have been compared with thoracic epidural
analgesia (TEA). One retrospective observational study for pancreas transplant
found there was no significant difference in rescue analgesia and the technique
was preferred due to their anticoagulation regimen [17]. Another observational study found
equivalent pain scores and faster time to mobilization in the rectus sheath
group [18].
Laparoscopy
Some recent studies have investigated the use of RSB for analgesia
after laparoscopic surgery with positive results (24-h fentanyl use, 189 vs. 286
μg [19]; and verbal and numeric
pain score at 6 h, 3 vs. 5 [20•]).
In gynecological procedures, 2 RCTs showed RSB to be superior to placebo
[19, 20•]. In one RCT of laparoscopic
cholecystectomy, RSB resulted in less rescue analgesia compared with placebo and
higher patient satisfaction compared with local infiltration [21]. For pediatric appendectomy, pain scores
were reduced compared with placebo [22] and compared with in local infiltration [23] with similar overall [22] or reduced overall [23] opioid use.
Complications
Given the large area available for absorption after RSB, care
should be taken to use appropriate doses and concentrations of local anesthetic
[24••]. Adding epinephrine to
reduce peak plasma concentration is also helpful [25].
The superior and inferior epigastric arteries are at risk of
puncture or injury during the performance of rectus sheath block. Using
ultrasound to avoid the arteries (and their attendant veins) can reduce the
chance of puncture or inadvertent intravascular injection. When using a landmark
technique, a lateral insertion point helps to avoid these vessels.
Anzeige
Conclusion
RSB has a proven analgesic benefit for umbilical surgery,
laparoscopy, and laparotomy. It can provide midline abdominal analgesia anywhere
from the symphysis pubis to the xiphoid process for several dermatomes around
the injection point. RSB has few complications, which can be reduced by using
ultrasound guidance. Single injection provides good analgesia for the first 6 h,
with a waning effect up to 24 h. Continuous catheters can provide effective
analgesia for extended durations.
Tap Block
Introduction
Rafi first described a technique of transversus abdominis plane
(TAP) block using a landmark approach in 2001. However, it was only after the
introduction of the ultrasound-guided technique in 2007 that the TAP block was
more widely adopted in clinical practice. In the past 20 years, it has been one
of the most widely investigated regional anesthesia technique. Since the
original description of ultrasound-guided technique, various technical
modifications have been described including lateral [26], posterior [27], subcostal [28], and continuous catheter techniques
[29] .
The exact technique used should be suited for a surgical incision,
as each provides different dermatomal coverage. Lateral TAP block typically
gives a T10–T12 dermatomal coverage while the posterior TAP approach covers
T9–T12 and is shown to provide a longer duration of analgesia with possibly some
visceral analgesia [30]. The
subcostal TAP approach provides T6–T9 dermatomal coverage and is usually
suitable for upper abdominal surgeries.
Ultrasound-Guided TAP Block
The ultrasound-guided techniques are recommended over the landmark
technique to ensure precise deposition of local anesthetic between the
transversus abdominis muscle and internal oblique muscle. Further, ultrasound
may be helpful in reducing the risk of complications such as a vascular or
visceral puncture.
A linear high-frequency probe is generally ideal for performing
the block. However, a curved array lower frequency probe may be needed in
morbidly obese patients. After wide skin preparation with antiseptic, we
recommend starting the scanning similar to the rectus sheath block
(described earlier) to identify the rectus muscle. On sliding the ultrasound
probe laterally towards iliac crest parallel to Tuffier’s line, three
lateral abdominal wall muscles (external oblique, internal oblique, and
transverse abdominus muscle) can be easily visualized. Scanning more
posteriorly the transversus abdominis muscles can be observed to taper.
Since posterior TAP block is shown to provide longer analgesia and more
extensive spread than lateral TAP block, posterior approach should be the
preferred approach in clinical practice.
Fig. 2
Posterior transversus abdominis plane (TAP) block.
The left image shows the ultrasound probe and in-plane
needle insertion technique (medial-to-lateral or
anterior-to-posterior approach) for a posterior TAP block.
The image on the right shows the sonogram during performance
of a posterior TAP block. EOM, external oblique muscle; IOM,
internal oblique muscle; TAM, transversus abdominis muscle;
green arrow, needle path; yellow-shaded area denotes the
site of local anesthetic (LA) deposition
×
An 8–10-cm echogenic needle is inserted anterioposteriorly
in-plane to ultrasound beam towards TAP plane (plane between transverse
abdominus muscles and internal oblique). The main difference between the
lateral and posterior TAP block is the final point of injection:
mid-axillary line in lateral TAP block versus posterior axillary line for
posterior TAP block. Hydrolocation is useful in determining that the needle
tip is in correct plane; the clear separation of transversus abdominis
muscle from internal oblique on injection is a good endpoint. At least 15–20
ml of local anesthetic is required to produce a successful block in adult
patients.
As the name suggests, the ultrasound probe position in the
approach is parallel to the subcostal margin. For identification of the TAP
plane, a similar scanning approach is followed with identification of the
rectus muscle. On sliding the ultrasound probe laterally, the transversus
abdominis muscle is usually seen underlying the lateral part of rectus
abdominis muscle. On further lateral scan, the three lateral abdominal wall
muscles can be visualized.
Fig. 3
Subcostal transversus abdominis plane (TAP) block.
The left image shows the ultrasound probe position and
in-plane needle insertion technique (lateral-to-medial or
caudad-to-cephalad approach) for a subcostal TAP block. The
image on the right shows the sonogram during performance of
subcostal TAP block. RAM, rectus abdominis muscle; EO,
external oblique; IO, internal oblique; TAM, transversus
abdominis muscle; green arrow, needle path; yellow-shaded
area denotes the site of local anesthetic (LA)
deposition
×
The exact point of local anesthetic injection depends on the
dermatomal coverage required. A more medial injection (between rectus muscle
and transversus abdominis muscle) will produce analgesia of T6–T8
dermatomes. On the other hand, a more lateral injection between transverse
abdominus muscles and internal oblique will more consistently result in
T8–T10 dermatomal analgesia. Both medial-to-lateral and lateral-to-medial
in-plane needling techniques have been described [31]. We prefer a lateral-to-medial
approach as it is more ergonomic to perform the technique and catheter
insertion is away from the surgical field.
Oblique subcostal TAP block has been described as a
modification of the subcostal technique. In this technique, an extra-long
(15–20 cm) needle is used to inject local anesthetic in TAP plane from
subcostal region to iliac crest with a potential to provide T6-L1 dermatomal
coverage. The technique is difficult to perform, and therefore, has not
gained popularity [28].
Catheter Technique
Continuous catheters have been described for all of the above
techniques. The technique of catheter insertion involves hydrodissection of the
planes. The number and site of catheters needed depend on the site and extent of
surgical incision. Four-quadrant TAP catheters (bilateral subcostal and
bilateral posterior TAP) can be used for midline abdominal incision extending
from xiphisternum to pubic symphysis [29]. It must be stated that four catheters can be tedious to
insert and maintain with further issues of local anesthetic systemic absorption
and failure/dislodgement of one of the four catheters is high.
Evidence Base
A literature search of key databases for systematic reviews on TAP
block for postoperative analgesia revealed more than 30 systematic reviews in
different surgical populations. These include colorectal surgery, cesarean
section, cholecystectomy, hysterectomy, appendectomy, donor nephrectomy,
retropubic prostatectomy, and bariatric surgery.
TAP Blocks Versus No Block/Placebo
All recent reviews [32, 33••,
34, 35] suggest that the ultrasound-guided TAP
blocks reduce postoperative pain scores in the first 6–24 h postoperatively
(mean difference of 1.4 to 2 points on a scale of 0–10) and reduce the morphine
requirement in the first 24 h (mean difference 7–15 mg) compared with placebo
[33••, 34]. Further, TAP block may delay the time
to first analgesic request (mean difference 2 h) [32] and may reduce the incidence of nausea/vomiting
[36, 37]. However, heterogeneity of type of
surgery, block approaches, drugs, doses, and volumes warrant that the findings
should be interpreted with caution.
Multiple systematic reviews have confirmed the analgesic efficacy
of TAP block for open and laparoscopic colorectal surgeries [38, 39, 40•,
41‐43].
Similarly, ultrasound-guided TAP block has been found to be an effective
analgesic intervention in patients undergoing laparoscopic cholecystectomy
[44, 45] and hernia surgery [46]. TAP blocks have also been shown to
significantly lower intraoperative and cumulative postoperative 24-h opioid
consumption, provide better pain control, and decrease the 24-h incidence of
postoperative nausea vomiting for renal transplant recipients [47].
Anzeige
TAP Blocks Versus Intrathecal Morphine
TAP blocks do not appear to provide additional analgesic benefit in
patients who also received intrathecal morphine [34]. Therefore, the TAP block may be particularly useful when
neuraxial techniques or opioids are contraindicated. Some of the older reviews
(conducted before 2012) found a limited benefit of TAP block in the context of
multimodal analgesia [48‐50].
TAP Blocks Versus Thoracic Epidural Analgesia
A recent review synthesized the data comparing TAP block with TEA.
Pain scores at rest on postoperative day 1 were equivalent for TAP block and TEA
groups in children and in adults. However, the TEA group experienced a higher
rate of hypotension and longer hospital length of stay compared with the TAP
block group, without a difference in functional outcomes [51•].
TAP Block Versus Local Anesthetic Wound Infiltration
Three different reviews have synthesized the evidence comparing TAP
blocks with local anesthetic would infiltration [52‐54]. The evidence from these reviews indicates that TAP
blocks provide superior and longer lasting analgesia when compared with local
anesthetic wound infiltration.
TAP Blocks in Different Surgical Populations
Cesarean Delivery
Three systematic reviews on TAP blocks in the cesarean delivery
population show similar results to the general surgical population
[55, 56, 57••]. The reviews consistently show analgesic benefit of
TAP blocks in patients who did not receive intrathecal morphine. No
analgesic benefit of TAP block was observed when intrathecal morphine was
used. Intrathecal morphine was associated with longer duration of analgesia
compared with TAP block alone at the expense of an increased incidence of
side effects such as pruritus [57••].
A recent review concluded that low-dose TAP blocks (bupivacaine
equivalents less than or equal to 50 mg per side) for cesarean delivery
provide analgesia and opioid-sparing effects comparable with high-dose TAP
blocks. Therefore, a lower dose TAP block should be used to reduce the risk
of local anesthetic toxicity without compromising the analgesic efficacy
[58]. Another systematic
review comparing TAP blocks with wound infiltration for cesarean delivery
demonstrated no statistically significant difference in analgesia or side
effects for patients who received multimodal analgesia but no intrathecal
morphine [59].
Hysterectomy
Three recent systematic reviews found that TAP blocks provide
significant postoperative early and 24-h pain control compared with placebo
or no block among women who undergo a hysterectomy. There was reduced
morphine consumption among patients who underwent total abdominal
hysterectomy but not for total laparoscopic hysterectomy [60‐62].
Pediatric Population
A recent review synthesized the evidence on rectus sheath and
transversus abdominis plane blocks in children. Data from ten RCTs (n = 599) suggests that patients receiving TAP and
RSB have a small but significant reduction in pain score and opioid use 6–8 h
after surgery. However, a high level of heterogeneity in the included studies
warrant caution in the interpretation of results [7].
Dexamethasone as an Adjuvant
Two recent systematic reviews have shown that dexamethasone added
to local anesthetics in ultrasound-guided TAP block significantly decreased
visual analogue pain scores by 1 point on a scale of 0–10 at rest for first 12
h, prolonged the time to the first request for additional analgesics by 3 h, and
reduced the incidence of postoperative nausea and vomiting significantly (risk
ratios = 0.40) without any increase in reported complications compared with the
control group [63, 64••].
Dexmedetomidine as an Adjuvant
Another recent review that included twenty published trials found
that the addition of dexmedetomidine significantly reduced rest pain scores for
8 h postoperatively (mean difference 0.8/10) and 4 h postoperatively on
movement. Adjuvant dexmedetomidine significantly prolonged the duration of the
TAP block by 3.3 h and did not affect the incidence of postoperative nausea and
vomiting, hypotension, bradycardia, somnolence, or pruritus [65].
Liposomal Bupivacaine
Currently, there is a lack of data to support or refute the use of
liposomal bupivacaine in TAP blocks for the management of postoperative pain
[66].
Continuous TAP Catheters
A recent systematic review on TAP catheters included twelve small
randomized controlled trials. The studies were extremely heterogeneous regarding
the type of surgery, control group, and technique of catheter insertion and
infusion. The authors concluded that TAP catheters have the potential to provide
effective and safe analgesia. A few studies have demonstrated effects comparable
with TEA, while TAP catheters are shown to be consistently superior to systemic
analgesia alone. Common complications of TAP catheters include catheter
dislodgement, block failures, and catheter leakage [67•].
Complications
It has been shown that the local anesthetic systemic concentrations
commonly exceed accepted thresholds after both TAP blocks and RSB [24••]. Although there are case reports of
seizures and ventricular arrhythmias, the incidence of local anesthetic systemic
toxicity is extremely low. However, efforts should be made to not exceed the
maximum recommended milligrams per kilogram local anesthetic dose [68]. This may be accomplished by using a
lower concentration of local anesthetic as 0.375% ropivacaine and 0.5%
ropivacaine have been shown to be equally effective for TAP block [69]. The risk of hematoma or visceral damage
is extremely rare with ultrasound guidance. Femoral nerve block has been
reported after TAP block, leading to 6–8 h of quadriceps weakness especially
with larger volume of injectate [70].
Conclusion
Ultrasound-guided TAP block provide 12–24 h of postoperative analgesic
benefit after abdominal laparotomy, laparoscopy, and cesarean delivery when
long-acting neuraxial opioids are not used or contraindicated. It appears to be a
safe technique, especially with ultrasound guidance. Consideration should be given
to adding an adjuvant to prolong its duration of action and improve efficacy of
single-shot TAP blocks. Although continuous TAP catheters have been used, they
require maintenance of multiple catheter infusions and risk of failure. The studies
evaluating its impact on the long-term and functional outcomes are lacking.
Compliance with Ethical Standards
Conflict of Interest
Vishal Uppal, Sushil Sancheti, and Hari Kalagara declare that he
has no conflict of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal
subjects performed by any of the authors.
Open Access This article is distributed
under the terms of the Creative Commons Attribution 4.0 International License
(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give appropriate
credit to the original author(s) and the source, provide a link to the Creative
Commons license, and indicate if changes were made.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Mit e.Med Anästhesiologie erhalten Sie Zugang zu CME-Fortbildungen des Fachgebietes AINS, den Premium-Inhalten der AINS-Fachzeitschriften, inklusive einer gedruckten AINS-Zeitschrift Ihrer Wahl.
