In Vitro Performance Testing of Legacy and ENFit Gastrostomy Tube Devices Under Gravity Flow Conditions

Changes in connector design for the gastrostomy tube were implemented to reduce the risk of misconnections. This study aimed to determine whether there are differences in gravity flow rates between legacy devices and the ENFit devices intended to replace them.

We compared 5 legacy gastrostomy tube brands with 3 corresponding ENFit brands, sized between 14 French (Fr) and 24 Fr. Seven commercial diets were used. One comparison involved low-profile devices.

Whether an ENFit device manifested a lower flow rate than a legacy device was not a strong function of diet. One 14-Fr ENFit device, because of its reduced distal inner tube diameter, produced an average feeding time of 56 (±13) minutes from a 20-minute baseline. For other 14-Fr ENFit devices, the increase was much less pronounced (25 ± 4 minutes). At larger sizes, both decreases and increases in feeding time were observed, depending on device type; on average, the 20-minute feeding time increased to 25 (±7) minutes. For low-profile devices, across all sizes, an increase in 20-minute feeding time occurred, but the difference was small (23 ± 2).

Statistically lower flow rates were observed for 70% of ENFit devices relative to their legacy counterparts. We estimate that 30% of the differences may be noticeable. In the scenarios studied, lower flow rates (relative to other devices at the same Fr number) arise from energy losses in straight tubing. This difference can be reduced by increasing the tube inner diameters in distal end of ENFit tubes.