Do pH and temperature play a role in gastrostomy tube deterioration?

The effects of pH and temperature over time on percutaneous endoscopic gastrostomy (PEG) tube longevity were examined in an in vitro model. Two sets of tubes were obtained from 7 major US PEG manufacturers. Using scissors, each PEG tube was cut cross-sectionally 8 cm from the bumper end of the tube. Both qualitative (photographs) and quantitative (mass) measurements were taken at baseline. Median physiologic gastric acidity was approximated by completely submerging 1 set of each cut PEG tube in a 250-mL glass jar containing a 0.050-N (pH 1.3) solution of hydrochloric acid. As a control, another set of each PEG tube was completely submerged in a 250-mL glass jar containing a buffer solution of pH 6. Each jar was then submerged in the waterbath so that the water completely covered the tube but did not enter the jar. The waterbath was covered and maintained at a constant temperature of 37 degrees C. Measurements taken at baseline were repeated at 168 days and again at 375 days. On qualitative examination, no dilations, brittleness, obstruction, nodularity, tears, loss of elasticity, color changes, tube fracturing, kinking, loss of resilience, or variation in external diameter was observed. Quantitative examination showed no change in mass. Tubes removed from the pH 1.3 solution appeared identical to the tubes removed from the pH 6 solution. In all cases, there were no apparent changes from baseline. These findings suggest that temperature and pH can be excluded as predominant factors in tube deterioration and lend further support to a microbial hypothesis of PEG tube deterioration.