Use of a vegetable model as a training tool for PCNL puncture

Abstract

Introduction: Training residents to perform a PCNL puncture is hampered by the non-availability of a good inanimate model that can be used for demonstration and practice. The ethics of surgical training during actual surgeries is being questioned and the role of simulation is increasingly important. Virtual reality trainers, however, are prohibitively expensive and the use of animal models is fraught with regulatory and ethical concerns. We have devised a model that can be used to teach the concept of depth perception during a PCNL puncture.

Methods: A bottle gourd was used to mimic the posterior abdominal wall. Cotton pledgets dipped in intravenous contrast were fitted into 4 mm holes made at staggered levels in the bottle gourd which was strapped onto the operating table with the cotton pledgets facing away from the surgeon. Surgeons with varying degrees of experience made fluoroscopy-guided punctures onto the cotton pledgets. We recorded the time taken for puncture in seconds and the distance of the needle exit site from the center of the cotton ball. Speed was measured by recording the fluoroscopy time in seconds on the C-arm. Accuracy was documented by using a Vernier caliper to measure the distance from the edge of the target to the actual puncture. One second of fluoroscopy time and 0.1 mm distance were each given one point. The total points accumulated over a set of 10 punctures was added to give a total score. Longer fluoroscopy times and inaccurate punctures resulted in higher scores.

Results: A surgeon with more than 1000 PCNLs to his credit had a score of 99. The average score of five residents was 555.

Conclusion: The bottle gourd model provides an ethically acceptable, inexpensive, easy to replicate model that can be used to train residents in the PCNL puncture.

Keywords: Bottle gourd; PCNL; puncture.

Figure 1

Raw materials needed include the bottle gourd, cotton pledgets, radiographic contrast, needles and a measuring scale

Figure 2

The model after punctures

Figure 3

Radiographic appearance of model before puncture

Figure 4

Radiographic appearance of model with the needle punctures

Figure 5

The surgeon stands on the side away from the targets to make the punctures

Figure 6

Direct visualization of the exit site in incorrect punctures helps the trainee orient himself to the information provided by the fluoroscopic images