Transversus Abdominis Plane Blocks: A Pilot Study of Feasibility and Ascension up the Learning Curve

Deborah S Keller, MS, MD1, Sergio Ibarra, MD1, Juan R Flores-Gonzalez, MD1, Nisreen Madhoun, DO1, Oscar I Moreno-Ponte, MD1, Eric M Haas, MD, FACS, FASCRS2. 1Colorectal Surgical Associates, Houston, TX, 2Colorectal Surgical Associates, Houston Methodist Hospital, The University of Texas Medical School, Houston, TX

Background: Transversus Abdominis Plane (TAP) blocks are advocated to reduce perioperative pain, narcotic requirements, and improve clinical outcomes. However, no previous work has investigated the learning curve of TAP block placement. Our goal was to evaluate the learning curve for TAP block placement in novices, identify issues that may impede successful placement, and their solutions.

Methods: Three novices were prospectively evaluated performing an ultrasound-guided TAP block in 10 consecutive patients undergoing laparoscopic colorectal surgery. Operators were assessed on medication knowledge, set-up and placement, technical steps of the procedure, and performance time. Set-up time, time for placement on each side, and total procedure time were compared to an expert’s time to determine efficiency and competence. Feasibility was determined by proper knowledge of the medication and set-up, and placement within 2 standard deviations of expert time. The main outcome measures were the procedures needed for competence and variables associated with increased coaching/procedure time.

Results: The 3 operators each performed 10 consecutive TAP blocks. In the patient sample, the mean age was 56.9 years (SD 15.6), and the mean body mass index (BMI) was 30.9 (SD 5.79). Fifteen patients (50.0%) were obese (BMI > 30), seven (23.3%) were super obese (BMI>35), and 15 had prior abdominal surgery. The overall mean set-up time was 107.5 (SD 87) seconds, the right-side placement time was 131.8 (SD 60.3) seconds, the left-side placement was 114.8 (SD 40.5) seconds, and total time 354 (SD 111) seconds. By the 2nd attempt, all operators were fluent in the medication and set-up.  At block 3, operators 1 and 3 reached competence in performance time; by block 4, all 3 operators reached time competence. After reaching competence, outliers in procedure times were only experienced for extremes in BMI (<20 and >35). Additional coaching was needed in 4 patients with prior abdominal surgery to decipher the correct planes.

Conclusions: Our pilot study demonstrates it is safe and feasible for novice surgeons to place TAP blocks. By 4 placements, novices were competent, and continued to improve their times with experience. Extremes of BMI and prior abdominal surgery were found to impact procedural time, and required additional coaching to facilitate placement in some cases. Given the promising results, further work on developing best practices for education and implementation is warranted.

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