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Rectus Sheath Block
Rectus Sheath Block
CHAPTER
57
See Video 57.1 on ExpertConsult.com.
The rectus abdominis is a vertical muscle of the anterior abdominal wall. The muscle is divided into compartments by the midline linea alba, paramedian linea semilunaris, and transverse fibrous bands.1 Muscles of the lateral abdominal wall (the external oblique, internal oblique, and transversus abdominis) become aponeurotic as they approach the midline, and the rectus sheath consists of the rectus abdominis muscles surrounded by these aponeuroses. Above the arcuate line, the transversalis fascia and the aponeuroses separate the rectus abdominis muscle from the abdominal cavity. Caudal to the arcuate line, the rectus abdominis muscle is in direct contact with the transversalis fascia. In this location, all three of the lateral abdominal wall muscles (external oblique, internal oblique, and transversus) have their aponeuroses pass anterior to the rectus abdominis muscle.2 Anterior cutaneous branches of the intercostal nerves enter the rectus sheath from the posterior and lateral sides.3 Epigastric arteries and veins are sometimes identified within the rectus sheath, and the epigastric arteries are usually accompanied by two flanking veins. The anterior intercostal nerves can run alongside these vessels before rising to the surface through the rectus abdominis muscle. The nerves of the rectus sheath are too small to be directly imaged with ultrasound. A few emerging nerve fibers can bypass the rectus sheath as they travel toward the midline. Rectus sheath block is useful as part of a combined anesthetic technique for outpatients.4,5 The usual indication for this block is to provide pain relief after repair of umbilical or incisional hernias. It provides an excellent alternative to straight general anesthesia or epidural blocks for surgical procedures around the midline of the abdominal wall.
SUGGESTED TECHNIQUE The rectus sheath block is usually performed after induction of general anesthesia for patient comfort and to reduce movement. The choice of ultrasound transducer is not critical to the success of the procedure. With the patient in the supine position, an in-plane approach from the lateral side of the patient is used, with the rectus abdominis muscle imaged in short-axis view (transverse); hand-on-needle provides excellent needle control. Tidal movement of the abdominal cavity with respiration or contraction of the abdominal wall muscles can make the procedure challenging. Rectus sheath block is a plane block that does not rely on direct nerve imaging. The goal is to have the injected local anesthetic layer underneath the rectus abdominis muscle where the anterior intercostal nerves enter the rectus sheath. The transversalis fascia and aponeurosis of the transversus muscle form a double-layer appearance on ultrasound scans (the peritoneal stripe).6 Therefore, the needle tip and injection should be placed between the rectus abdominis muscle and the double layer that constitutes the posterior aspect of the rectus sheath. To accomplish this view, the cephalocaudad placement of the transducer should be adjusted away from tendons to allow visualization of the double layer of the transversalis fascia. Because the nerves enter the sheath from the lateral side, the lateral aspect of the rectus abdominis muscle is targeted. The lateral edge of the rectus sheath is a potentially safer approach because it is over the abdominal wall muscles rather than the abdominal cavity. Injection of a small volume of local anesthetic on pullback of the needle through the rectus abdominis muscle gives more complete distributions. Because of the compartmental nature of the rectus abdominis muscle, two or four injections are usually performed for periumbilical surgery (right and left sides, and sometimes above and
249
Rectus Sheath Block
ABSTRACT
Rectus sheath block is a method of trunk analgesia most useful for midline surgical procedures at or above the umbilicus. Local anesthetic is injected at the lateral edge of the rectus sheath where branches of the intercostal nerves enter.
KEYWORDS
rectus sheath transversalis fascia tendinous intersections epigastric artery and veins arcuate line
249.e1
250
Trunk Blocks
below the umbilicus). About 5 to 10 mL of local anesthetic is injected per side per compartment in adult patients. Because the tendinous inscriptions of the muscles are not complete posteriorly,7,8 some communication between compartments is possible. If local anesthetic is observed to distribute between compartments, no further injection is necessary. The duration of rectus sheath blocks may not be as long as for transversus abdominis plane (TAP) blocks.9 The superior and inferior epigastric arteries anastomose through a vascular network. It is unlikely that large epigastric arteries will be found in the umbilical region because the contributing vessels course from above or below. Because of the lack of underlying bone, visible arterial pulsations are difficult to elicit with probe compression during rectus sheath blocks. Power Doppler can be useful during these procedures to confirm vascular identity. In one study, 21% of rectus sheath injections guided by traditional loss-of-resistance techniques were intraperitoneal.10 These intraperitoneal injections were detected by ultrasound imaging after initial needle placement. Although no complications were observed in this study, intraperitoneal injections are not clinically effective and presumably place patients at risk for injury.
KEY POINTS Rectus Sheath Block
The Essentials
Anatomy
The nerves of the rectus sheath enter the posterolateral side of the RA. The TA lies under the lateral aspect of the RA in the supraumbilical region. Epigastric arteries and veins usually lie deep within the midportion of the RA. Tendinous intersections divide adjacent rectus sheath compartments. These tendons are thought to be incomplete posteriorly. This should allow communication between adjacent compartments.
Positioning
Supine
Operator
Standing on the side of the patient
Display
Across the table
Transducer
High-frequency linear, 38- to 50-mm footprint
Initial depth setting
35–50 mm
Needle
20–21 gauge, 70–90 mm in length
Anatomic location
Begin by scanning the RA in transverse view. Slide transducer to midway between the tendinous intersections.
Approach
Transverse view of RA, in-plane from lateral to medial. Aim for the posterolateral corner of the RA. Place the needle tip between the RA and underlying fascial double layer. If necessary, scratch the needle tip against the fascial double layer. Bilateral injections are necessary for midline anesthesia.
Sonographic assessment
Desire side-to-side (medial-lateral) distribution over the double layer. “Swimming pool” or “smile” shaped appearance of distribution between RA and double layer. Desire cephalocaudad distribution between adjacent compartments. The “handlebar mustache” appearance of the longitudinal distribution between compartments.
Anatomic variation
Position of epigastric arteries and TA varies.
RA, Rectus abdominis muscle; TA, transversus abdominis muscle.
Rectus Sheath Block
Clinical Pearls • The extent to which the abdominal wall muscles underlie the lateral corner of the rectus abdominis muscle is variable. In some cases, there is no underlying muscle to separate the rectus from the abdominal cavity. • The needle tip should be scratched against the double layer without actually puncturing it so as to place the tip between the rectus muscle and the double layer. • A few milliliters of local anesthetic can be injected as the needle is removed to cover the path of nerves through the rectus muscle. • The best way to perform rectus sheath blocks is to inject forward on one side and back for the contralateral side. In this fashion, the ultrasound display screen and operator remain in one position for bilateral injections. • The fibers of the rectus abdominis course in a parallel direction with the muscle divided by transverse tendinous intersections. • The nerves of the rectus sheath are too small (100 µm diameter) to be directly imaged with ultrasound.3 Therefore, ultrasound-guided rectus sheath block relies on injecting between the rectus abdominis muscle and the underlying double layer of fascia at the point where the nerves are known to enter the rectus sheath. • The rectus abdominis muscle is slightly narrower near its ends at the xiphoid process and pubic bone. The rectus sheath narrows at its cephalad and caudad ends as the linea semilunaris tapers toward the midline. • Local anesthetic should be injected at the lateral edge of the rectus sheath for safe and effective rectus sheath blocks.11
References 1. Ali QM. Sonographic anatomy of the rectus sheath: an indication for new terminology and implications for rectus flaps. Surg Radiol Anat. 1993;15:349–353. 2. Monkhouse WS, Khalique A. Variations in the composition of the human rectus sheath: a study of the anterior abdominal wall. J Anat. 1986;145:61–66. 3. Rozen WM, Tran TM, Ashton MW, Barrington MJ, Ivanusic JJ, Taylor GI. Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall. Clin Anat. 2008;21:325–333. 4. Willschke H, Bösenberg A, Marhofer P, et al. Ultrasonography-guided rectus sheath block in paediatric anaesthesia: a new approach to an old technique. Br J Anaesth. 2006;97:244–249. 5. Sandeman DJ, Dilley AV. Ultrasound-guided rectus sheath block and catheter placement. ANZ J Surg. 2008;78:621–623. 6. Muradali D, Wilson S, Burns PN, Shapiro H, Hope-Simpson D. A specific sign of pneumoperitoneum on sonography: enhancement of the peritoneal stripe. AJR Am J Roentgenol. 1999;173(5):1257–1262. 7. Connell D, Ali K, Javid M, et al. Sonography and MRI of rectus abdominis muscle strain in elite tennis players. AJR Am J Roentgenol. 2006;187:1457–1461. 8. de Jose Maria B, Götzens V, Mabrok M. Ultrasound-guided umbilical nerve block in children: a brief description of a new approach. Paediatr Anaesth. 2007;17(1):44–50. 9. Murouchi T, Iwasaki S, Yamakage M. Chronological changes in ropivacaine concentration and analgesic effects between transversus abdominis plane block and rectus sheath block. Reg Anesth Pain Med. 2015;40(5):568–571. 10. Dolan J, Lucie P, Geary T, et al. The rectus sheath block: accuracy of local anesthetic placement by trainee anesthesiologists using loss of resistance or ultrasound guidance. Reg Anesth Pain Med. 2009;34:247–250. 11. Seidel R, Wree A, Schulze M. Does the approach influence the success rate for ultrasound-guided rectus sheath blocks? An anatomical case series. Local Reg Anesth. 2017;10:61–65.
251
252
Trunk Blocks
Spinal nerve trunk Meningeal branch Spinal sensory (dorsal root) ganglion Dorsal root Ventral root
Trapezius muscle Erector spinae muscle
Ventral (anterior) ramus of spinal nerve (intercostal nerve) Collateral branch
Medial branch Lateral branch Dorsal (posterior) ramus
External intercostal muscle Internal intercostal muscle Innermost intercostal muscle Latissimus dorsi muscle
Subcostal muscles
Serratus anterior muscle
Window cut in innermost intercostal muscle Communicating branch
Greater and lesser splanchnic nerves Sympathetic trunk Gray and white rami communicantes
Internal intercostal membranes anterior to external intercostal muscles Superior costotransverse ligaments
Lateral cutaneous branch Internal intercostal muscle
Collateral branch rejoining intercostal nerve
Transversus abdominis muscle Slip of costal part of diaphragm
Rectus abdominus muscle
Costal cartilage
Innermost intercostal muscle Internal intercostal muscle External intercostal muscle
Linea alba External intercostal membrane External oblique muscle Anterior cutaneous branch
FIGURE 57.1 Thoracoabdominal nerves. Note the path of the anterior cutaneous branch of the intercostal nerve through the rectus abdominis muscle. (From netterimages.com, with permission.)
Rectus Sheath Block
A
Double layer
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
253
B
FIGURE 57.2 External photograph showing the approach to rectus sheath block in supine position. An in-plane approach from across the midline is shown (A). The corresponding sonogram in shown (B). The best way to perform rectus sheath blocks on both sides of the midline is to inject forward on one side compartment and back for the opposite side, with the screen and operator in one position.
Trunk Blocks
Double layer
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A Loops of bowel
Subcutaneous tissue
Double layer
Lateral
Rectus abdominis muscle
Medial
254
B FIGURE 57.3 The double-layer sign indicates the presence of the aponeurosis of the transversus abdominis and transversalis fascia in transverse view (A). Closer to the midline, loops of bowel are visualized (B).
Rectus Sheath Block
Epigastric veins
Rectus abdominis muscle
Medial
Lateral
Subcutaneous tissue
A Epigastric artery Epigastric arteries
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
B FIGURE 57.4 The epigastric arteries have variable position within the rectus sheath. In these examples from different patients, the arteries are seen either below (A) or within (B) the rectus sheath in transverse view. Transversus abdominis muscle
Rectus abdominis muscle
Medial
Lateral
Subcutaneous tissue
FIGURE 57.5 The transversus muscle on the lateral edge of the rectus abdominis in transverse view. The extent to which the abdominal wall muscles underlie the lateral corner of the rectus abdominis muscle is variable. In some cases, there is no underlying muscle to separate the rectus from the abdominal cavity.
255
Trunk Blocks
Subcutaneous tissue
Caudad
Cephalad
Rectus abdominis muscle
A Rectus abdominis muscle
Subcutaneous tissue
Caudad
Cephalad
256
B Tendinous intersection
FIGURE 57.6 Longitudinal views of the rectus abdominis muscle within a single muscular compartment (A) and in separate rectus compartments (B). The fibers of the rectus abdominis course in a parallel direction, with the muscle divided by transverse tendinous intersections that are typically incomplete posteriorly.
Rectus Sheath Block
Local anesthetic
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A
Cephalad
Rectus abdominis muscle
Needle tip Local anesthetic
Subcutaneous tissue
Caudad
Double layer
B FIGURE 57.7 Image sequence showing rectus sheath block. An in-plane approach is demonstrated where the needle tip is placed between the rectus muscle and the double layer (A). Before injection, the needle tip is gently scratched against the double layer so as to place the tip between the rectus muscle and the double layer. Local anesthetic is seen to layer underneath the muscle, giving a swimming pool appearance of successful rectus sheath injection in transverse view. A few milliliters of local anesthetic can be injected as the needle is removed to cover the path of nerves through the rectus muscle. The corresponding longitudinal view is shown (B).
257
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A Transversus abdominis muscle
Double layer Subcutaneous tissue
Rectus abdominis muscle
Medial
Lateral
Needle tip
B Local anesthetic
Double layer Subcutaneous tissue
Caudad
Cephalad
Rectus abdominis muscle
C Local anesthetic
FIGURE 57.8 Image sequence showing rectus sheath block. Before needle tip placement, the double layer is identified (A). An in-plane approach is demonstrated where the needle tip and local anesthetic are placed between the rectus muscle and the double layer (B). After rectus sheath injection, longitudinal views can be used to assess the distribution (C). The “handlebar mustache” appearance verifies that local anesthetic has distributed to the adjacent compartment of the rectus abdominis muscle.
CHAPTER
57
See Video 57.1 on ExpertConsult.com.
The rectus abdominis is a vertical muscle of the anterior abdominal wall. The muscle is divided into compartments by the midline linea alba, paramedian linea semilunaris, and transverse fibrous bands.1 Muscles of the lateral abdominal wall (the external oblique, internal oblique, and transversus abdominis) become aponeurotic as they approach the midline, and the rectus sheath consists of the rectus abdominis muscles surrounded by these aponeuroses. Above the arcuate line, the transversalis fascia and the aponeuroses separate the rectus abdominis muscle from the abdominal cavity. Caudal to the arcuate line, the rectus abdominis muscle is in direct contact with the transversalis fascia. In this location, all three of the lateral abdominal wall muscles (external oblique, internal oblique, and transversus) have their aponeuroses pass anterior to the rectus abdominis muscle.2 Anterior cutaneous branches of the intercostal nerves enter the rectus sheath from the posterior and lateral sides.3 Epigastric arteries and veins are sometimes identified within the rectus sheath, and the epigastric arteries are usually accompanied by two flanking veins. The anterior intercostal nerves can run alongside these vessels before rising to the surface through the rectus abdominis muscle. The nerves of the rectus sheath are too small to be directly imaged with ultrasound. A few emerging nerve fibers can bypass the rectus sheath as they travel toward the midline. Rectus sheath block is useful as part of a combined anesthetic technique for outpatients.4,5 The usual indication for this block is to provide pain relief after repair of umbilical or incisional hernias. It provides an excellent alternative to straight general anesthesia or epidural blocks for surgical procedures around the midline of the abdominal wall.
SUGGESTED TECHNIQUE The rectus sheath block is usually performed after induction of general anesthesia for patient comfort and to reduce movement. The choice of ultrasound transducer is not critical to the success of the procedure. With the patient in the supine position, an in-plane approach from the lateral side of the patient is used, with the rectus abdominis muscle imaged in short-axis view (transverse); hand-on-needle provides excellent needle control. Tidal movement of the abdominal cavity with respiration or contraction of the abdominal wall muscles can make the procedure challenging. Rectus sheath block is a plane block that does not rely on direct nerve imaging. The goal is to have the injected local anesthetic layer underneath the rectus abdominis muscle where the anterior intercostal nerves enter the rectus sheath. The transversalis fascia and aponeurosis of the transversus muscle form a double-layer appearance on ultrasound scans (the peritoneal stripe).6 Therefore, the needle tip and injection should be placed between the rectus abdominis muscle and the double layer that constitutes the posterior aspect of the rectus sheath. To accomplish this view, the cephalocaudad placement of the transducer should be adjusted away from tendons to allow visualization of the double layer of the transversalis fascia. Because the nerves enter the sheath from the lateral side, the lateral aspect of the rectus abdominis muscle is targeted. The lateral edge of the rectus sheath is a potentially safer approach because it is over the abdominal wall muscles rather than the abdominal cavity. Injection of a small volume of local anesthetic on pullback of the needle through the rectus abdominis muscle gives more complete distributions. Because of the compartmental nature of the rectus abdominis muscle, two or four injections are usually performed for periumbilical surgery (right and left sides, and sometimes above and
249
Rectus Sheath Block
ABSTRACT
Rectus sheath block is a method of trunk analgesia most useful for midline surgical procedures at or above the umbilicus. Local anesthetic is injected at the lateral edge of the rectus sheath where branches of the intercostal nerves enter.
KEYWORDS
rectus sheath transversalis fascia tendinous intersections epigastric artery and veins arcuate line
249.e1
250
Trunk Blocks
below the umbilicus). About 5 to 10 mL of local anesthetic is injected per side per compartment in adult patients. Because the tendinous inscriptions of the muscles are not complete posteriorly,7,8 some communication between compartments is possible. If local anesthetic is observed to distribute between compartments, no further injection is necessary. The duration of rectus sheath blocks may not be as long as for transversus abdominis plane (TAP) blocks.9 The superior and inferior epigastric arteries anastomose through a vascular network. It is unlikely that large epigastric arteries will be found in the umbilical region because the contributing vessels course from above or below. Because of the lack of underlying bone, visible arterial pulsations are difficult to elicit with probe compression during rectus sheath blocks. Power Doppler can be useful during these procedures to confirm vascular identity. In one study, 21% of rectus sheath injections guided by traditional loss-of-resistance techniques were intraperitoneal.10 These intraperitoneal injections were detected by ultrasound imaging after initial needle placement. Although no complications were observed in this study, intraperitoneal injections are not clinically effective and presumably place patients at risk for injury.
KEY POINTS Rectus Sheath Block
The Essentials
Anatomy
The nerves of the rectus sheath enter the posterolateral side of the RA. The TA lies under the lateral aspect of the RA in the supraumbilical region. Epigastric arteries and veins usually lie deep within the midportion of the RA. Tendinous intersections divide adjacent rectus sheath compartments. These tendons are thought to be incomplete posteriorly. This should allow communication between adjacent compartments.
Positioning
Supine
Operator
Standing on the side of the patient
Display
Across the table
Transducer
High-frequency linear, 38- to 50-mm footprint
Initial depth setting
35–50 mm
Needle
20–21 gauge, 70–90 mm in length
Anatomic location
Begin by scanning the RA in transverse view. Slide transducer to midway between the tendinous intersections.
Approach
Transverse view of RA, in-plane from lateral to medial. Aim for the posterolateral corner of the RA. Place the needle tip between the RA and underlying fascial double layer. If necessary, scratch the needle tip against the fascial double layer. Bilateral injections are necessary for midline anesthesia.
Sonographic assessment
Desire side-to-side (medial-lateral) distribution over the double layer. “Swimming pool” or “smile” shaped appearance of distribution between RA and double layer. Desire cephalocaudad distribution between adjacent compartments. The “handlebar mustache” appearance of the longitudinal distribution between compartments.
Anatomic variation
Position of epigastric arteries and TA varies.
RA, Rectus abdominis muscle; TA, transversus abdominis muscle.
Rectus Sheath Block
Clinical Pearls • The extent to which the abdominal wall muscles underlie the lateral corner of the rectus abdominis muscle is variable. In some cases, there is no underlying muscle to separate the rectus from the abdominal cavity. • The needle tip should be scratched against the double layer without actually puncturing it so as to place the tip between the rectus muscle and the double layer. • A few milliliters of local anesthetic can be injected as the needle is removed to cover the path of nerves through the rectus muscle. • The best way to perform rectus sheath blocks is to inject forward on one side and back for the contralateral side. In this fashion, the ultrasound display screen and operator remain in one position for bilateral injections. • The fibers of the rectus abdominis course in a parallel direction with the muscle divided by transverse tendinous intersections. • The nerves of the rectus sheath are too small (100 µm diameter) to be directly imaged with ultrasound.3 Therefore, ultrasound-guided rectus sheath block relies on injecting between the rectus abdominis muscle and the underlying double layer of fascia at the point where the nerves are known to enter the rectus sheath. • The rectus abdominis muscle is slightly narrower near its ends at the xiphoid process and pubic bone. The rectus sheath narrows at its cephalad and caudad ends as the linea semilunaris tapers toward the midline. • Local anesthetic should be injected at the lateral edge of the rectus sheath for safe and effective rectus sheath blocks.11
References 1. Ali QM. Sonographic anatomy of the rectus sheath: an indication for new terminology and implications for rectus flaps. Surg Radiol Anat. 1993;15:349–353. 2. Monkhouse WS, Khalique A. Variations in the composition of the human rectus sheath: a study of the anterior abdominal wall. J Anat. 1986;145:61–66. 3. Rozen WM, Tran TM, Ashton MW, Barrington MJ, Ivanusic JJ, Taylor GI. Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall. Clin Anat. 2008;21:325–333. 4. Willschke H, Bösenberg A, Marhofer P, et al. Ultrasonography-guided rectus sheath block in paediatric anaesthesia: a new approach to an old technique. Br J Anaesth. 2006;97:244–249. 5. Sandeman DJ, Dilley AV. Ultrasound-guided rectus sheath block and catheter placement. ANZ J Surg. 2008;78:621–623. 6. Muradali D, Wilson S, Burns PN, Shapiro H, Hope-Simpson D. A specific sign of pneumoperitoneum on sonography: enhancement of the peritoneal stripe. AJR Am J Roentgenol. 1999;173(5):1257–1262. 7. Connell D, Ali K, Javid M, et al. Sonography and MRI of rectus abdominis muscle strain in elite tennis players. AJR Am J Roentgenol. 2006;187:1457–1461. 8. de Jose Maria B, Götzens V, Mabrok M. Ultrasound-guided umbilical nerve block in children: a brief description of a new approach. Paediatr Anaesth. 2007;17(1):44–50. 9. Murouchi T, Iwasaki S, Yamakage M. Chronological changes in ropivacaine concentration and analgesic effects between transversus abdominis plane block and rectus sheath block. Reg Anesth Pain Med. 2015;40(5):568–571. 10. Dolan J, Lucie P, Geary T, et al. The rectus sheath block: accuracy of local anesthetic placement by trainee anesthesiologists using loss of resistance or ultrasound guidance. Reg Anesth Pain Med. 2009;34:247–250. 11. Seidel R, Wree A, Schulze M. Does the approach influence the success rate for ultrasound-guided rectus sheath blocks? An anatomical case series. Local Reg Anesth. 2017;10:61–65.
251
252
Trunk Blocks
Spinal nerve trunk Meningeal branch Spinal sensory (dorsal root) ganglion Dorsal root Ventral root
Trapezius muscle Erector spinae muscle
Ventral (anterior) ramus of spinal nerve (intercostal nerve) Collateral branch
Medial branch Lateral branch Dorsal (posterior) ramus
External intercostal muscle Internal intercostal muscle Innermost intercostal muscle Latissimus dorsi muscle
Subcostal muscles
Serratus anterior muscle
Window cut in innermost intercostal muscle Communicating branch
Greater and lesser splanchnic nerves Sympathetic trunk Gray and white rami communicantes
Internal intercostal membranes anterior to external intercostal muscles Superior costotransverse ligaments
Lateral cutaneous branch Internal intercostal muscle
Collateral branch rejoining intercostal nerve
Transversus abdominis muscle Slip of costal part of diaphragm
Rectus abdominus muscle
Costal cartilage
Innermost intercostal muscle Internal intercostal muscle External intercostal muscle
Linea alba External intercostal membrane External oblique muscle Anterior cutaneous branch
FIGURE 57.1 Thoracoabdominal nerves. Note the path of the anterior cutaneous branch of the intercostal nerve through the rectus abdominis muscle. (From netterimages.com, with permission.)
Rectus Sheath Block
A
Double layer
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
253
B
FIGURE 57.2 External photograph showing the approach to rectus sheath block in supine position. An in-plane approach from across the midline is shown (A). The corresponding sonogram in shown (B). The best way to perform rectus sheath blocks on both sides of the midline is to inject forward on one side compartment and back for the opposite side, with the screen and operator in one position.
Trunk Blocks
Double layer
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A Loops of bowel
Subcutaneous tissue
Double layer
Lateral
Rectus abdominis muscle
Medial
254
B FIGURE 57.3 The double-layer sign indicates the presence of the aponeurosis of the transversus abdominis and transversalis fascia in transverse view (A). Closer to the midline, loops of bowel are visualized (B).
Rectus Sheath Block
Epigastric veins
Rectus abdominis muscle
Medial
Lateral
Subcutaneous tissue
A Epigastric artery Epigastric arteries
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
B FIGURE 57.4 The epigastric arteries have variable position within the rectus sheath. In these examples from different patients, the arteries are seen either below (A) or within (B) the rectus sheath in transverse view. Transversus abdominis muscle
Rectus abdominis muscle
Medial
Lateral
Subcutaneous tissue
FIGURE 57.5 The transversus muscle on the lateral edge of the rectus abdominis in transverse view. The extent to which the abdominal wall muscles underlie the lateral corner of the rectus abdominis muscle is variable. In some cases, there is no underlying muscle to separate the rectus from the abdominal cavity.
255
Trunk Blocks
Subcutaneous tissue
Caudad
Cephalad
Rectus abdominis muscle
A Rectus abdominis muscle
Subcutaneous tissue
Caudad
Cephalad
256
B Tendinous intersection
FIGURE 57.6 Longitudinal views of the rectus abdominis muscle within a single muscular compartment (A) and in separate rectus compartments (B). The fibers of the rectus abdominis course in a parallel direction, with the muscle divided by transverse tendinous intersections that are typically incomplete posteriorly.
Rectus Sheath Block
Local anesthetic
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A
Cephalad
Rectus abdominis muscle
Needle tip Local anesthetic
Subcutaneous tissue
Caudad
Double layer
B FIGURE 57.7 Image sequence showing rectus sheath block. An in-plane approach is demonstrated where the needle tip is placed between the rectus muscle and the double layer (A). Before injection, the needle tip is gently scratched against the double layer so as to place the tip between the rectus muscle and the double layer. Local anesthetic is seen to layer underneath the muscle, giving a swimming pool appearance of successful rectus sheath injection in transverse view. A few milliliters of local anesthetic can be injected as the needle is removed to cover the path of nerves through the rectus muscle. The corresponding longitudinal view is shown (B).
257
Subcutaneous tissue
Medial
Lateral
Rectus abdominis muscle
A Transversus abdominis muscle
Double layer Subcutaneous tissue
Rectus abdominis muscle
Medial
Lateral
Needle tip
B Local anesthetic
Double layer Subcutaneous tissue
Caudad
Cephalad
Rectus abdominis muscle
C Local anesthetic
FIGURE 57.8 Image sequence showing rectus sheath block. Before needle tip placement, the double layer is identified (A). An in-plane approach is demonstrated where the needle tip and local anesthetic are placed between the rectus muscle and the double layer (B). After rectus sheath injection, longitudinal views can be used to assess the distribution (C). The “handlebar mustache” appearance verifies that local anesthetic has distributed to the adjacent compartment of the rectus abdominis muscle.