Peripheral Nerve Blocks of the Trunk: Transversus Abdominis Plane Block

Transversus Abdominis Plane Block

The transversus abdominis plane (TAP) block is most often used to provide surgical anesthesia for minor, superficial procedures on the lower abdom-inal wall, or postoperative analgesia for procedures below the umbilicus. For hernia surgeries, intrave-nous or local supplementation may be necessary to provide anesthesia during peritoneal traction. Potential complications include violation of the peritoneum with or without bowel perforation, and the use of ultrasound is highly recommended to minimize this risk.The subcostal (T12), ilioinguinal (L1), and iliohypogastric (L1) nerves are targeted in the

TAP block, providing anesthesia to the ipsilateral lower abdomen below the umbilicus (Figure 46–63). For part of their course, these three nerves travel in the muscle plane between the internal oblique and transversus abdominis muscles. Needle placement should be between the two fascial layers of these muscles, with local anesthetic filling the transversus abdominis plane. The patient is ideally positioned in lateral decubitus, but if mobility is limited the block may be performed in the supine position.

A. Ultrasound

With a linear or curvilinear array transducer ori-ented parallel to the inguinal ligament, the layers of the external oblique, internal oblique, and transver-sus abdominis muscles are identified just superior

to the anterior superior iliac spine (Figure 46–64). Muscles appear as striated hypoechoic structures with hyperechoic layers of fascia at their borders.long (10-cm) needle is inserted in-plane just lat-eral (posterior) to the transducer and advanced, noting tactile feedback from fascial planes, to the hyperechoic effacement of the deep border of inter-nal oblique and the superficial border of transver-sus abdominis. Following careful aspiration for the nonappearance of blood, 20 mL of local anesthetic is injected, observing for an elliptical separation between the two fascial layers (Figure 46–64).