Comparing the use of a needle guidance device with free-hand technique in performing ultrasound-guided transversus abdominis plane (TAP) blocks: a prospective randomized trial.

This is a crossover study, where participants are randomly assigned to two groups. Group 1 participants will receive the transversus abdominis plane (TAP) block via the needle guided technique and then followed by free hand technique whilst Group 2 participants will receive the TAP block via free hand technique and then followed by needle guided technique. The intervention is the use of an ultrasound needle guide (Infiniti, CIVCO Medical Solutions, Kalona, Iowa, USA) when performing an ultrasound-guided TAP block. The ultrasound needle guide consists of two parts, a reusable bracket that is placed beneath the probe cover, and disposable needle guides that attach to the brackets. The needle is passed through the attached needle guide, which holds the needle in the plane of the ultrasound probe. The TAP block will be performed with a 21-gauge 100 mm Stimuplex needle and 200 mg of ropivacaine for patients more than or equal to 70 kg (20 ml of 0.5% ropivacaine each side) or 150 mg of ropivacaine for patients less than 70 kg (20 ml of 0.375% ropivacaine each side). The ultrasound probe will be placed in a transverse plane to the lateral abdominal wall in the midaxillary line, between the lower costal margin and iliac crest. The needle will then be introduced in-plane of the ultrasound probe and advanced until the tip reaches the plane between the internal oblique and transversus abdominis muscles. At this point 20 ml of ropivacaine solution will be injected in 5 ml aliquots after negative aspiration. The transversus abdominis plane will be visualized expanding with the injection. The intervention will be completed within 5-10 minutes. The duration of the wash-out period is 5 minutes.