OBJECTIVE  To analyze the drying effect of durations of continuous blowing with a pressure air gun on the biopsy channels of gastroscopes and colonoscopes.

METHODS  Gastroscopes and colonoscopes used at the Second Hospital of Tianjin Medical University from May 2024 to Jan. 2025 were collected. For gastroscopes, there were 40 units each with biopsy channel inner diameters of 2.8 mm and 3.2 mm （both with a length of 1 030 mm）. For colonoscopes, there were 40 units each with biopsy channel inner diameters of 3.2 mm （length 1 330 mm）, 3.7 mm （length 1 330 mm）, and 3.7 mm （length 1 680 mm）. Each group was first subjected to continuous blowing with a pressure air gun for 30, 40, 50, 60 and 70 seconds. Subsequently, an endoscope drying machine was used to blow air for 5 minutes, followed by continuous blowing with the pressure air gun for 30, 40, 50, 60 and 70 seconds. The drying effectiveness of the biopsy channels was compared across the different processing methods.

RESULTS  After initial drying with the endoscope drying machine for 5 minutes followed by pressure air gun blowing, 100.00% drying rates were achieved for all gastroscope biopsy channels （regardless of diameter and length） with 40 seconds of blowing. For colonoscopes, 100.00% drying rates were observed with 60 seconds of blowing for biopsy channels of 3.2 mm （length 1 330 mm） and 3.7 mm （length 1 330 mm）, and with 70 seconds for the 3.7 mm channel （length 1 680 mm） （P＜0.05）.

CONCLUSIONS  When preceded by 5 minutes of drying machine treatment followed by pressure air gun blowing, gastroscopes of varying biopsy channel diameters and lengths achieved good drying effects with 40 seconds of blowing. For colonoscopes, drying effectiveness was influenced by increases in channel diameter and length, requiring correspondingly longer blowing times.