Transversus Abdominis Plane Block: How Safe is it?

To the Editor: Transversus abdominis plane (TAP) block is a new regional anesthetic technique that blocks the abdominal wall neural afferents by introducing local anesthetic into the neurofascial plane between the internal oblique and transversus abdominis muscles.1 Initially, no complications were attributable to TAP block, but there was an awareness of the possibility of visceral damage if the needle was inadvertently advanced too far.1 We have used the TAP block as a component of multimodal postoperative pain treatment for various abdominal procedures. During one open nephrectomy, wherein continuous TAP block was used, the tip of the TAP catheter was found to be in the abdomen, (without any visceral organ damage) and 20 mL 0.375% levobupivacaine (3.75 mg/mL) had been injected intraperitoneally. A study using ultrasound to check the actual location of local anesthetic placement during TAP block revealed that intraperitoneal injection had occurred in 2% of patients.2 Additional reported complications of TAP block include bowel hematoma, enlarged liver laceration, and transient femoral nerve palsy.3–5 Other organs that can be punctured during TAP block are the spleen (particularly if enlarged) and kidney. Suggestions for minimizing these types of complications include using a fine-gauge, blunt-tipped, short-bevel needle to minimize risk of visceral damage, directing the needle obliquely instead perpendicularly to increase the resistance of each aponeurosis, and using smaller volume of local anesthetic to decrease the incidence of femoral nerve block.2,3 Accidental intravascular injection of local anesthetic, infection, and catheter breakage should also be considered as potential complications of TAP block. Zorica Jankovic, MD, PhD Niaz Ahmad, MD Nagaraja Ravishankar, MD St James's University Hospital, Lincoln Wing Leeds LS9 7TF, UK [email protected]