Objective
The purposes of this study are to estimate the proper replacement time of percutaneous endoscopic gastrostomy Foley catheter for prevention of accidental expulsion from the stomach, and to identify factors influencing deflation of balloon.

Method
Silicone Foley catheters (22 Fr) were placed and compared in the different environments: 1) different acidity (pH 1, 2, 3, 4, 7), 2) static versus dynamic (100 RPM) environment. The balloon capacity of 30 ml versus 5 ml inflated with 5 ml of normal saline were compared. Mean time interval of deflation of balloon down to the capacity of 2.5 ml and 1 ml was estimated and compared respectively.

Results
The results showed no significant difference of the decrease of the balloon of the Foley catheters in each acidity except for pH 1 and dynamic environment. But capacity of balloon could affect deflation. The mean days of deflation of total Foley catheter down to 2.5 ml and 1 ml were 23.5⁑5.3 and 42.2⁑7.2 days respectively.

Conclusion
Physiological gastric acidity and dynamic environment did not affect the deflation of the Foley catheter significantly, but the capacity of the balloon affected it. And suggested proper time of the replacement of the Foley catheter gastrostomy tube is ranged from 24 to 42 days after exchange.