combination of pectin solution and liquid nutrient during the first 2 h after the start of feeding. GER events associated with delivery of the combination of pectin solution and liquid nutrient were observed most frequently at 1–2 h after the end of feeding. Discussion PEG tube feeding is widely used for patients with swallowing dysfunction caused by a number of disease conditions. Survival after PEG placement is reported to be influenced by several factors, such as advanced age, complicated diseases and presence of malnutrition before PEG placement.(15–17) Aspiration pneumo- nitis caused by reflux of gastric contents is also demonstrated to affect the survival in patients with long-term PEG feeding.(1–4,18,19) Half-solidification or increased viscosity of a nutrient have been demonstrated to be effective for decreasing GER of the nutrient.(8,10,11) In this study using the MII-pH method, we made a comparison of GER events associated with the use of half-solid nutrient with relatively high viscosity and a combination of pectin solution and liquid nutrient in patients undergoing PEG feeding. The results of this study showed that the use of liquid nutrient with pectin solution was able to decrease acidic GER in compar- ison with half-solid nutrient, although there was no significant difference in the total number of reflux events between the two nutrient delivery methods. Previously, Fletcher and colleagues had demonstrated that there was a zone of apparently unbuffered highly acidic gastric juice above the ingested food at 15 min after a meal, a phenomenon that they termed an ‘‘acid pocket’’.(20) The median pH in this zone was 1.6, compared with 4.4 in the meal-buffered region in the stomach, and this was considered an important cause of postprandial acidic GER.(20) In addition, the acid pocket in patients with GER has been demonstrated to persist for longer than in healthy volunteers, remaining highly acidic for up to 2 h postprandially relative to the body of the stomach. The zone of acidic gastric juice after delivery of half-solid nutrient with high viscosity may be wider than that after liquid nutrient, since gastric juice could become easily mixed with liquid nutrient. Indeed, we have previously demonstrated that the number of acid reflux events after half-solid nutrient feeding tended to be higher than that after liquid nutrient feeding.(21) In contrast to the delivery of half-solid nutrient with high viscosity, pectin solution can be easily infused into the stomach via the PEG tube and increase the viscosity of intragastric liquid nutrient. It is also considered to reduce the width of the acid pocket, since the solution can also easily mix with the gastric acidic liquid contents. GER of highly acidic gastric contents has been reported to cause severe aspiration pneumonitis.(2) Therefore, the use of pectin solution with liquid nutrient may effectively reduce the incidence of aspiration pneu- monitis caused by GER events in comparison with half-solid nutrient. The results of this study also demonstrated that the use of pectin solution and liquid nutrient might decrease the incidence of GER extending as far as the upper portion of the esophagus in comparison with half-solid nutrient. The viscosity of reflux contents after the feeding of pectin solution and liquid nutrient may be higher than that after the feeding of half-solid nutrient, since the viscosity is important factor to influence the volume and speed of reflux contents. The pattern of the changes in GER with time showed a difference between delivery of the half-solid nutrient and the combination of pectin solution and liquid nutrient. Acidic GER was frequently observed after injection of 300 ml water and after the injection of half-solid nutrient. This indicated that both liquid and half-solid materials easily cause frequent GER when they are infused quickly. The number of weakly acidic GER events increased markedly from 2 to 3 h after the start of delivery of pectin solution and liquid nutrient. This time point corresponded to that when the bed head was returned from an elevated to a flat position. GER at this time point may be caused by the remaining mixture of liquid nutrient and acidic gastric juice in the stomach even 1 h after the completion of liquid nutrient delivery, and GER of retained liquid gastric contents could be easily induced by this postural change. Gastric emptying associated with combined delivery of pectin solution and liquid nutrient should be investigated in a future study in comparison with half-solid nutrient. There are some limitations in this study. The number of study subjects was relatively small. In addition, we did not compare GER events during administration of liquid nutrient with and without the usage of pectin solution, although the combined usage of pectin solution with liquid nutrient has been reported to prevent GER of liquid nutrient in patients undergoing PEG feeding.(10,11) In this study, the order in which the water and the nutrient were given differed for each nutrient dosage. Water was administered 60 min before administration of the half-solid nutrient to retain the viscosity and small volume of the latter. On the other hand, water was administrated after administration of the pectin solution and liquid nutrient to further increase the intragastric volume. We examined GER events using the MII-pH method, which can detect all types of GER. However, this method did not allow investiga- tion of GER volume, which may be one of the most important factors associated with the occurrence of aspiration pneumonitis. Therefore, a further prospective long-term study should be per- formed to clarify the efficacy of pectin solution in combination with liquid nutrient for preventing the occurrence of aspiration pneumonitis. In conclusion, delivery of liquid nutrient with pectin solution, REF-P1®, is able to reduce the incidence of both acidic GER and GER that extends as far as the upper portion of the esophagus, in comparison with half-solid nutrient with high viscosity, during PEG feeding. Acknowledgment This study was supported by the funding from the Grants-in- Aid from Science Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan, No. 22590681. None of the authors had a personal or financial conflict of interest. Abbreviations GER LES MII MII-pH PEG gastro-esophageal reflux lower esophageal sphincter multichannel intraluminal impedance multichannel intraluminal impedance and pH percutaneous endoscopic gastrostomy 1 Coben RM, Weintraub A, DiMarino AJ Jr., Cohen S. Gastroesophageal reflux during gastrostomy feeding. Gastroenterology 1994; 106: 13–18. 2 Marik PE. Aspiration pneumonitis and aspiration pneumonia. N Engl J Med 2001; 344: 665–671. 3 Sanders DS, Carter MJ, D’Silva J, McAlindon ME, Willemse PJ, Bardham KD. Percutaneous endoscopic gastrostomy: a prospective analysis of hospital support required and complications following discharge to the community. Eur J Clin Nutr 2001; 55: 610–614. 4 Carnes ML, Sabol DA, DeLegge M. Does the presence of esophagitis prior to PEG placement increase the risk for aspiration pneumonia? Dig Dis Sci 2004; 49: 1798–1802. 5 Penna FJ, Norton RC, Carvalho AS, et al. Comparison between pre-thickened and home-thickened formulas in gastroesophageal reflux treatement. J Pediatr (Rio J) 2003; 79: 49–54. References K. Adachi et al. J. Clin. Biochem. Nutr. | May 2012 | vol. 50 | no. 3 | 193 ©2012 JCBN