Transversus abdominis plane blocks: pilot of feasibility and the learning curve

Our goal was to evaluate the learning curve for transversus abdominis plane (TAP) block placement and identify issues that impede successful placement.

Three novices were prospectively evaluated performing ultrasound-guided TAP blocks in 10 consecutive patients. Operators were assessed on medication knowledge, setup/placement, procedural steps, and performance time. Times were compared to an expert for efficiency and competence. The main outcome measures were procedures needed for competence and variables associated with increased coaching/procedure time.

In the 30 patient sample, the mean body mass index (BMI) was 30.9 (standard deviation [SD], 5.79). Fifteen patients were obese (BMI > 30), seven (23.3%) super obese (BMI > 35), and 15 had prior abdominal surgery. The mean setup time was 107.5 s (SD, 87), right-side placement was 131.8 s (SD, 60.3), left-side placement 114.8 s (SD, 40.5), and total time 354 s (SD, 111). By the second attempt, all operators were fluent in the medication and setup. At block 3, operators 1 and 3 reached competence in performance time; by block 4, all three 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 four patients with prior abdominal surgery to decipher the correct planes.

Based on our pilot, by four attempts, novices reach appropriate speeds with progressively less coaching to safely and efficiently place TAP blocks. Extremes of BMI and prior abdominal surgery impact procedural time and may required additional coaching to facilitate placement. Given the promising results, further work on developing best practices for education and implementation is warranted.