The subcostal transversus abdominal plane (TAP) approach is very useful for supraumbilical procedures.
The most cephalad sensory dermatomal spread is T8.
The bilateral continuous catheter infusion can be used in the upper abdominal surgeries where epidural analgesia is contraindicated or failed.
The key for the success of this technique is the proper identification of the fascial plane between the transversus abdominis and rectus abdominis muscles.
There are four paired muscles of the anterolateral abdominal wall: the anterior rectus abdominis muscles and, from deep to superficial, the three lateral muscles: transversus abdominis, internal oblique, and external oblique muscles. It is only in the lateral abdomen that the three fleshy muscle bellies overlie one another because medially they become an aponeurosis. Under ultrasound the rectus abdominis can be easily identified, and by moving laterally, the transversus abdominis muscle will appear beneath the rectus abdominis muscle. The transversus abdominis has two key features on ultrasound imaging. It is usually darker (more hypoechoic) than other muscles, and it passes beneath the rectus abdominis muscle ( Fig. 37.1 ).