Cutaneous Sensory Block Area, Muscle-Relaxing Effect, and Block Duration of the Transversus Abdominis Plane Block. Issue 4 (July 2015)

• Record Type: Journal Article
• Authors: Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V.; Aasvang, Eske K.; Lundstrøm, Lars H.; Lange, Kai H. W.
• Is Part Of: Regional anesthesia and pain medicine. Volume 40:Issue 4(2015)
• Publication Date: 2015-07
• Subjects: Conduction anesthesia -- Periodicals; Pain medicine -- Periodicals; 617.964
• DOI: 10.1097/AAP.0000000000000252
• Languages: English
• ISSNs: 1098-7339

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Background and Objectives</title> <p>The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration.</p> </sec> <sec> <title>Methods</title> <p>Sixteen healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block and the abdominal muscle–relaxing effect.</p> </sec> <sec> <title>Results</title> <p>The lateral part of the cutaneous sensory block area was a median of 266 cm<sup>2</sup> (interquartile range, 191–310 cm<sup>2</sup>) and the medial part 76 cm<sup>2</sup> (interquartile range, 54–127 cm<sup>2</sup>). In all the volunteers, lateral wall muscle thickness decreased significantly by 9.2 mm (6.9–15.7 mm) during a maximal contraction. Sensory block and muscle-relaxing effect duration were 570 minutes (512–716 minutes) and 609 minutes (490–724 minutes), respectively.</p> </sec> <sec> <title>Conclusions</title> <p>Cutaneous sensory block area of the TAP block is predominantly located lateral to a vertical line through the anterior superior iliac spine. The distribution is nondermatomal and does not cross the midline. The muscle-relaxing effect is significant and consistent. The block duration is approximately 10 hours with large variation.</p> </sec> </abstract>