A bilateral Rectus sheath block is a very useful technique for intra-op and postoperative analgesia in surgeries involving the middle anterior abdominal wall from xiphisternum to pubic symphysis. Hence it is preferable for surgeries with midline or paramedian abdominal incision.
Anatomy
The anterior rami T 7 to T 11, gives sensory innervation to the rectus muscle and overlying skin.
Clinical application
Deposition of the local anaesthetic within the posterior rectus sheath gives predictable analgesia for midline and paramedian abdominal surgeries. It gives somatic pain relief only for anterior abdominal wall structures, but for deep visceral intraperitoneal structures, for example for bowel resection then a rectus block should be supplemented with IV analgesia. The block gives excellent pain relief for major laparotomies making early walking within 48 hours possible without motor blockade and hence secondary complications like atelectasis and pneumonia, deep vein thrombosis, and pulmonary thromboembolism are all reduced.
Advantages over epidural
1. No haemodynamic instability
2. Can be given in sepsis
3. Can be given in anticoagulated patients
4. No motor blockade and hence early mobilisation
Block performance
1. Iv cannula / Standard monitoring
2. Sterile precautions including sterile usg probe cover
3. Local anaesthetic – 0.5 % Ropivacaine 20 mls on each side
4. The transverse probe ( 5 to 12 MHz ) is kept in a transverse position just above the umbilicus and moved laterally to see the rectus muscle. A 22 or 23 gauge spinal needle connected to a 10 cm extension is used. The needle is advanced under vision to the posterior part of the rectus muscle and the local anaesthetic is deposited between the posterior part of the muscle and the rectus sheath. Insertion of local anaesthetic will hydrodissect the muscle from the sheath.
Complications
1. Inadvertent intravascular injections in superior and inferior epigastric vessels
2. Rectus sheath haematoma
A rectus sheath block can be given blindly but the success rate is better with USG guidance which we normally do in our institution. A catheter also can be placed in the rectus sheath for intermittent boluses.
Dr. Velmurugan Deisingh
Consultant Anaesthesiologist and Head of the Department