Transversus Abdominis Plane (TAP) Block
Sean Logan, M.D.
Srinivas Chiravuri, M.D.
Director, Pain Medicine Fellowship
Department of Anesthesiology
University of Michigan Health System
Ann Arbor, MI
Introduction - TOP
Transversus abdominis plane (TAP) block is a regional anesthetic technique used to block sensation to the anterior abdominal wall. Prospective randomized trials have demonstrated analgesic efficacy of TAP block and cadaveric studies have shown reliable dye spread from T9-L1 (iliac crest to the costal margin), although the spread is dependent upon the technique of injection, single versus multiple injections.
Two injection techniques have been described. They are: 1) the classical landmark approach via the Triangle of Petit and 2) the ultrasound guided approach (classic, and subcostal approach).
The TAP block is an intermuscular plane block i.e., needle placed in the plane between the internal oblique and transversus abdominis muscles. The sensory fibers located in this plane is too small to be visualized by ultrasound or localized by nerve stimulation. The TAP block may be performed in patients under general anesthesia since nerve localization is not necessary. However, a preoperative informed consent is mandatory.
This block has a number of advantages which include technical simplicity, high analgesic effectiveness, opioid sparing, long duration of effect (~30 - 36 hour), minimal side effects in comparison to that associated with neuraxial analgesia (e.g., hypotension, motor blockade).
However, its disadvantages are the need to perform a bilateral block for midline incisions (e.g. c-section) and provision of somatic analgesia only without any effect on visceral pain.
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