Ultrasonic cleaning is effective in removing carbonized clots and tissue from the insulation-tipped diathermic knife-2

Objectives: Since carbonized clots and tissue (debris) tend to adhere firmly to the tip of the endoscopic submucosal dissection (ESD) knife as the procedure proceeds, manual removing the firm debris is often challenging and time-consuming. Recently, effective ultrasonic cleaning for other medical devices has been reported. The aim of the present study was to clarify whether ultrasonic cleaning is effective in removing the debris on the insulation-tipped diathermic (IT) knife-2. Methods: This study was an ex-vivo experimental randomized study. A total of 40 IT knife-2 knives with debris on their tip surfaces were prepared and randomly assigned to two groups (Group A and Group B). The knives in Group A were cleaned using the conventional scrubbing method for 30 s (conventional cleaning method), while those in Group B were cleaned using a combined method of scrubbing for 20 s and ultrasonic cleaning for 10 s (combined ultrasonic cleaning method). The tip electrode of the knife after cleaning was photographed under a microscope (40x). The 40 images of the knives were evaluated by independent three endoscopists and two clinical engineers using the five-step evaluation criteria ranging from cleaning score 1 (dirty) to 5 (clean). Results: The mean cleaning score of 3.78 (range: 2.33-4.67) in Group B was significantly higher than that of 1.68 (range: 1.00-2.83) in Group A. Conclusions: The combined ultrasonic cleaning method could remove debris adhering to the IT knife-2 more effectively than the conventional cleaning method. Ultrasonic cleaning may be applied for real-world ESD.