In vitro security of 3 surgical knots placed by novice veterinary students

Abstract

Objective: To determine the most secure knot when tied by veterinary students in a ligation model. Study design: Prospective study. Sample population: Sixteen first-year veterinary students. Methods: Veterinary students were taught 3 knots: surgeon's, Miller's, and strangle. After having demonstrated competence, students tied each knot twice in a vascular ligation model at physiologic pressure. The system was tested for completeness of occlusion and volume of fluid lost over 10 seconds. Time, reattempts, repositioning, correctness, and difficulty score were documented. Students were surveyed before and after training regarding their experience. Results: Students correctly tied 75% of all knots and achieved complete occlusion of the model with 56% of knots. No difference was identified among knot types in correctness, difficulty, complete occlusion, or time to construct the knot. The first surgeon's knot placed by students had more fluid loss than the Miller's knot, but this was not true of the second knot. Conclusion: Incomplete occlusion was common among all knot types, but students generally achieved similar knot security when placing surgeon's, Miller's, and strangle knots on a model. More surgeon's knots failed catastrophically during the first attempt, evidenced by a greater volume of fluid loss. Clinical significance: This study does not provide evidence to recommend any of the 3 tested knots as superior to the others to improve the security of ligatures during surgeries performed by students. The prevalence of incomplete occlusion among student knots illustrates the requirement for education regarding knot security and vigilant monitoring of students performing live animal surgeries.

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