percutaneous endoscopic gastrostomy ( peg ) tube feeding is widely used for patients with swallowing dysfunction caused by a number of disease conditions or a history of repeated aspiration pneumonitis . aspiration pneumonitis caused by reflux of gastric contents including nutrients fed via peg is one of the most frequent and life - threatening inflammatory events during long - term peg feeding . solidification of nutrients is considered to be an effective method to prevent gastro - esophageal reflux ( ger ) of fed nutrients , and several studies have demonstrated that increased viscosity of nutrients reduces the risk of ger of nutrients in infants by mainly counting the occurrences of regurgitation and vomiting . however , the efficacy of solidification of nutrients for the prevention of aspiration pneumonitis in elderly patients with peg feeding was not yet fully investigated . kanie and coworkers previously demonstrated that half - solidification of nutrients was useful for decreasing ger of nutrients . they used computed tomography scan to study the presence of nutrients mixed with water - soluble contrast agent in the esophagus . it was , however , demonstrated that there was a zone of apparently unbuffered , highly acidic gastric juice above the ingested food at as early as 15  min after a meal , a phenomenon termed an  acid pocket  . the presence of an acid pocket above the nutrients calls into question the effectiveness of solidification for preventing aspiration pneumonitis , since it is well - known that the aspiration of acidic gastric contents induces more severe pneumonitis . we recently demonstrated that half - solidification of nutrients could not significantly decrease the frequency of ger events by using the esophageal multichannel intraluminal impedance ( mii ) and ph ( mii - ph ) monitoring method , which can detect any types of ger . however , the volume of ger of gastric contents , which the mii - ph monitoring system could nt measure , is considered to affect the occurrence of aspiration pneumonitis . we , therefore , performed this prospective multi - centre study to test the efficacy of half - solidification of nutrients for preventing aspiration pneumonitis in elderly patients with tube feeding via peg . the subjects were 42 elderly patients undergoing peg feeding ( female : 31 , mean age : 85.8 year , range : 56100 year ) in 8 hospitals in shimane prefecture , japan . peg feeding was started in these patients due to swallowing dysfunction caused by cerebral infarction , and almost all patients had a history of repeated aspiration pneumonitis . in all cases , feeding of liquid nutrients via peg had been performed for over 3 months before study enrollment . after enrollment in this study , all subjects were fed by half - solid nutrients for 8 weeks and by liquid nutrients for 8 weeks in a random order . medication for each patient was not changed between the periods of feeding . in this study , we used commercially available half - solid nutrients ( 150 or 200  g of medi - f pushcare from ajinomoto pharma co. , inc . , tokyo , japan ) . the volume of half - solid nutrients was determined by the total calories of the nutrients used in each patient before the study enrollment . the total calories , protein and lipids in 150  g of medi - f pushcare are 300  kcal , 14.0  g and 8.4  g , respectively . the volume of liquid nutrients was adjusted to equal the total calories , protein and lipids to those of medi - f pushcare. the quantity of basic minerals and vitamins was almost equal between the two kinds of nutrients . the water contents of medi - f pushcare and liquid nutrients were markedly different ( 81.3  g vs approximately 250  g ) . therefore , total water volume in one meal was adjusted to 400  g by modifying the volume of water administered with the meals . feeding of half - solid nutrients and liquid nutrients was done according to the schedule shown in fig .  1 . half - solid nutrients were infused into stomach by the hands of medical staffs , and liquid nutrients were fed by gravity . three hundred millilitres of water was given via the peg feeding tube in 10  min before administration of the half - solid nutrient . one hour after giving 300  ml water , half - solid nutrients and 20  ml of water were delivered through the peg tube in 10  min . patients were instructed to remain supine , and the bed head was elevated to 30 for 2  h. for administration of the liquid nutrient , 300  ml of nutrient was infused via the peg feeding tube in 1  h , followed by delivery of 150  ml water in 10  min . patients were instructed to remain supine , and the bed head was elevated to 30 for 2  h. feeding time for each patient and the days when fever , defecation and diarrhea were observed , were carefully recorded on sheets during the 16-week study period . the time necessary for feeding included the time for preparing nutrients and for administering nutrients and water , since medical staff frequently needed to observe the patients during nutrient feeding . we counted the number of days with fever caused by pneumonitis and unidentified origin to detect possible aspiration pneumonitis , since fever observed in elderly patients with peg feeding and a history of repeated pneumonitis is highly speculated to be caused by aspiration pneumonitis . in this study , fever was defined as a body temperature of over 37c , and watery or muddy stool was defined as diarrhea . the time necessary for feeding and the days with fever , defecation and diarrhea were compared between half - solid and liquid nutrient feeding periods . we used the percentages in all the observed days to compare the number of days with fever , defecation and diarrhea because some patients could not complete the study protocol for various reasons . the data of patients with at least a 4-week - long observation period using both half - solid nutrient and liquid nutrient were taken for analysis in this study . statistical analysis was performed using the wilcoxon signed rank test , and differences at p<0.05 were considered statistically significant . the study protocol was approved by the ethics committee of shimane university , faculty of medicine , and written informed consent was obtained from all study subjects or their family members . twenty - six of 42 study subjects completed the 16-week study protocol . sixteen patients could not complete the 16-week study protocol due to : transfer to another hospital or home ( n  =  4 ) , life threatening pneumonitis which necessitates fasting over several days ( n  =  7 ) , continuous severe diarrhea which necessitates a change of nutrients ( n  =  4 ) , or acute renal failure of unknown origin ( n  =  1 ) . of the 16 patients who could not complete the 16-week study , 6 completed at least the 4-week observational period in both types of nutrients . in this study , these 6 patients plus the 26 who completed the whole 16-week protocol were the 32 patients we analyzed . the necessary time for feeding half - solid nutrients was significantly shorter than that for feeding liquid nutrients ( 180.4    8.1 vs 329.7    14.8  min / day , p<0.0001 ) , as shown in fig .  2 . the numbers of patients who did not show fever during the observational period of half - solid feeding and liquid feeding were only 5 and 7 , respectively . however , the percentage of days with fever during the half - solid nutrient feeding period was significantly lower than that during the liquid nutrient feeding period ( 15.3    0.3 vs 19.8    0.4% , p  =  0.030 ) . the percentage of days with spontaneous defecation during the half - solid nutrient feeding period was significantly higher than that during the liquid nutrient feeding period ( 54.6    3.5 vs 48.7    4.2% , p  =  0.013 ) . however , the number of patients who did not develop diarrhea during the half - solid nutrient feeding period was similar to that during the liquid nutrient feeding ( 15 vs 19 cases ) . the percentage of days with diarrhea was also not significantly different between the half - solid nutrient and liquid nutrient feeding periods ( 10.1    3.8 vs 7.2    3.2% , p  = aspiration pneumonitis induced by ger of gastric contents is an important and serious problem for patients with long - term peg feeding . the degree of ger during peg feeding is reported to be related to esophageal motor function , volume or rate of gastric infusion , gastric emptying , posture during feeding , accompanying diseases such as diabetes or scleroderma , and usage of drugs that affect esophageal motor function . solidification of nutrients is considered to be one of the most effective method to prevent gastro - esophageal reflux ( ger ) of nutrient itself . however , a zone of apparently unbuffered highly acidic gastric juice above the ingested food was observed after meals , and this was considered an important cause of postprandial acidic ger . the zone of acidic gastric juice after the administration of solid nutrients may be wider than that after liquid nutrients , since gastric juice could be easily mixed with liquid nutrients . recently , we demonstrated that half - solidification of nutrients could not decrease the number of ger events and half - solidification tends to increase acidic ger in patients with peg feeding using the esophageal mii - ph monitoring method . however , the results of this prospective multi - centre study showed that the usage of half - solid nutrients significantly decreases the percentage of days with fever in elderly patients with peg feeding . since fever in patients with peg feeding is mainly caused by aspiration of refluxed gastric contents , the result of this study seems not to fit with the results of our previous mii - ph monitoring study , which could not demonstrate the reduction of ger events during half - solid nutrient feeding . the larger volume of ger of gastric contents , which the mii - ph monitoring system could not investigate , may be more important as a risk factor of aspiration pneumonitis . although the half - solid nutrients were effective to decrease the number of days with fever , it did not completely prevent the occurrence of aspiration pneumonitis in patients with peg feeding . the therapeutic effect of anti - secretory therapy in combination with half - solidification of nutrients , which can decrease the zone of highly acidic gastric juice above ingested food , should be further investigated . half - solidification of nutrients is considered to have several advantages other than decreasing ger of nutrients . it could prevent the leakage of nutrients from the gaps between peg fistula and tubing . it may prevent diarrhea caused by rapid delivery of high - osmolar liquid nutrient into the small intestine . the results of this study clearly demonstrated that the usage of half - solid nutrient could decrease the workload of medical staff , since it can be easily administered in a short period . the shorter necessary time of feeding could also reduce the duration of bed head elevation of patients , and this might be effective for the prevention of pressure ulcers . the percentage of days with spontaneous defecation during half - solid nutrient feeding was significantly higher than that during liquid nutrient feeding , although we found no significant difference in the percentage of days with diarrhea in this study . the occurrence of diarrhea is considered to correlate with the speed of nutrient and water administration . although the solidification of nutrients has an advantage for preventing diarrhea , the increased frequency in defecation during half - solid nutrient feeding might be caused by the rapid infusion of 300  ml of water before the feeding of half - solid nutrients . the limitations of this study are the small number of enrolled cases and the uncertainty in the diagnosis of aspiration pneumonitis as a cause of fever . in the future , a large - scale study using more realistic diagnostic markers of aspiration pneumonitis is considered necessary to confirm the results of this study . in conclusion , this prospective multi - centre study demonstrated that half - solidification of nutrition is effective for a reduction of the days with fever in elderly patients using peg feeding .
percutaneous endoscopic gastrostomy tube feeding is widely used for patients with swallowing dysfunction and a history of repeated aspiration pneumonitis . however , liquid nutrient feeding via percutaneous endoscopic gastrostomy is not effective enough to prevent aspiration pneumonitis and related inflammatory responses . 
 we performed this prospective multi - centre study to clarify the efficacy of half - solidification of nutrients to prevent fever possibly caused by aspiration pneumonitis in elderly patients with percutaneous endoscopic gastrostomy . 
 the study subjects were 42 elderly patients undergoing percutaneous endoscopic gastrostomy feeding ( mean age 85.8 years ) . 
 all subjects were fed half - solid as well as liquid nutrients for 8 weeks respectively in a cross over design . 
 we counted the number of days with fever caused by pneumonitis and unidentified origin . 
 thirty - two of 42 patients were successfully observed in both nutrient periods . 
 fever was frequently observed in both nutrient periods , however , the percentage of observational days with fever during half - solid nutrient feeding was significantly lower than that during liquid nutrient feeding ( 15.3    0.3 vs 19.8    0.4% , p  =  0.030 ) . the percentage of observational days when patients had diarrhea was not significantly different ( 10.1    3.8 vs 7.2    3.2% , p  =  0.357 ) . in conclusion , 
 half - solid nutrient feeding was determined to be effective for reducing fever in patients with percutaneous endoscopic gastrostomy feeding .