enteral nutrition is the preferred method to provide nutritional support in critically ill patients . despite the advantages of enteral feeding , enteral nutrition may not be tolerated by all patients and may cause complications such as diarrhea , constipation , aspiration and bowel ischemia . we describe two patients who manifested fatal complication of bowel ischemia associated with enteral feeding . a 53-year - old man with hypertension and diabetes mellitus , who was a hepatitis b virus carrier visited the hospital due to abdominal discomfort . computed tomography scanning showed a liver mass . upon opening his abdomen for mass resection , we found that the lesions were multiple and not resectable . two days after rfa , he was transferred to the intensive care unit ( icu ) due to sepsis with acute respiratory distress syndrome , probably caused by rfa - related liver abscess . , he continued to receive 30 kcal / kg of enteral nutrition via a feeding tube with regular bowel movement . on icu 15th day , however , we observed new onset leukocytosis , tachycardia and fever . moreover , his fever became worse and his intra - abdominal pressure increased to up to 17 mmhg . the next day , he showed unstable vital signs , with a sudden drop of blood pressure . cultures of his blood , catheter tip , and ascites samples revealed no infection . after excluding other causes of septic shock , we began to suspect that it was of bowel origin . during exploration of his abdomen , we observed mucosal infarction and congestion of the entire intestine , which was filled with mud - like contents ( fig . 1 ) . we therefore performed a total colectomy and small bowel resection for bowel necrosis , but the patient died of hepatic failure soon afterward . after operation , we can confirm pathologic findings of specimen , we could n't find an evidence of acute vessel obstruction ( fig . 2 ) . a 77-year - old man , who had been diagnosed with chronic obstructive pulmonary disease ( copd ) on both lower lungs with underlying emphysema , visited asan medical center with mid common bile duct cancer that had been diagnosed at another hospital . after we performed a bile duct resection and cholecystectomy , he was admitted to the icu for pneumonia caused by exacerbation of his copd . with recovery of his condition , he was administered enteral nutrition , consisting of a 25 kcal / kg of formula rich in dietary fiber via a feeding tube for 5 days . on icu 10th day , however , he experienced septic shock , with tachycardia , fever and a stuporous mental state . we hypothesized that the bowel ischemia of this patient was associated with enteral nutrition due to abdominal tenderness and a rectum filled with mud - like stool even with regular bowel movement . a sigmoidofiberscopy showed increased vascularity of the rectal mucosa , as well as increased bowel edema , hyperemia and submucosal hemorrhage ( fig . he underwent an emergency hartmann 's operation , resulting in progressive improvement in his general condition . pathologic finding of the resected bowel specimen did n't show the evidence of vessel injury or ischemia ( fig . however , the finding of thinning and diffuse flattening with hemorrhagic necrosis of mucosal layer and congestion of submucosa is suggesting hemorrhagic infarction caused by direct pressure of mucosal wall . a 53-year - old man with hypertension and diabetes mellitus , who was a hepatitis b virus carrier visited the hospital due to abdominal discomfort . computed tomography scanning showed a liver mass . upon opening his abdomen for mass resection , we found that the lesions were multiple and not resectable . two days after rfa , he was transferred to the intensive care unit ( icu ) due to sepsis with acute respiratory distress syndrome , probably caused by rfa - related liver abscess . , he continued to receive 30 kcal / kg of enteral nutrition via a feeding tube with regular bowel movement . on icu 15th day , however , we observed new onset leukocytosis , tachycardia and fever . moreover , his fever became worse and his intra - abdominal pressure increased to up to 17 mmhg . the next day , he showed unstable vital signs , with a sudden drop of blood pressure . cultures of his blood , catheter tip , and ascites samples revealed no infection . after excluding other causes of septic shock , we began to suspect that it was of bowel origin . during exploration of his abdomen , we observed mucosal infarction and congestion of the entire intestine , which was filled with mud - like contents ( fig . 1 ) . we therefore performed a total colectomy and small bowel resection for bowel necrosis , but the patient died of hepatic failure soon afterward . after operation , we can confirm pathologic findings of specimen , we could n't find an evidence of acute vessel obstruction ( fig . a 77-year - old man , who had been diagnosed with chronic obstructive pulmonary disease ( copd ) on both lower lungs with underlying emphysema , visited asan medical center with mid common bile duct cancer that had been diagnosed at another hospital . after we performed a bile duct resection and cholecystectomy , he was admitted to the icu for pneumonia caused by exacerbation of his copd . with recovery of his condition , he was administered enteral nutrition , consisting of a 25 kcal / kg of formula rich in dietary fiber via a feeding tube for 5 days . on icu 10th day , however , he experienced septic shock , with tachycardia , fever and a stuporous mental state . his blood pressure decreased despite receiving vasopressor and inotropic agents . we hypothesized that the bowel ischemia of this patient was associated with enteral nutrition due to abdominal tenderness and a rectum filled with mud - like stool even with regular bowel movement . a sigmoidofiberscopy showed increased vascularity of the rectal mucosa , as well as increased bowel edema , hyperemia and submucosal hemorrhage ( fig . he underwent an emergency hartmann 's operation , resulting in progressive improvement in his general condition . pathologic finding of the resected bowel specimen did n't show the evidence of vessel injury or ischemia ( fig . however , the finding of thinning and diffuse flattening with hemorrhagic necrosis of mucosal layer and congestion of submucosa is suggesting hemorrhagic infarction caused by direct pressure of mucosal wall . enteral nutrition is regarded as a preferred route for nutrition support of the critically ill patient with functioning digestive tract . enterally administrated nutritional support has been found to prevent mucosal weight loss , to increase endothelial proliferation , and to improve the maintenance of gut mucosal integrity , with maintenance of trophism apparently being the key to the prevention of bacterial translocation . in addition , because the gut is the largest producer of humoral antibodies in the body , it is believed that improved immune responses to bacterial challenge in enterally , compared with parenterally , fed individuals may be important in preventing septic complications . despite these advantages , enteral nutrition may not be tolerated by all patients and may cause fatal complications such as diarrhea , constipation , aspiration and bowel ischemia . especially , nasoenteric feeding in critically ill patients is often complicated by diarrhea . when diarrhea develops in critically ill patients , it adversely affects their nutritional status , electrolyte imbalance and nursing care and places them at increased risk for infection in the recovery phase . attempts to control the diarrhea that accompanies tube feeding include either changing the enteral formula which is containing fiber . the nutritional formulas they were fed contained plenty of fiber , they received postoperative mechanical ventilatory support due to poor lung function , and they have no underling vascular disease which cause acute bowel ischemia . in both patients , however , several mechanisms have been proposed as contributing towards the development of enteral tube feeding associated diarrhea , which are discussed below . first , the inspissated bowel contents may have put direct pressure on the mucosa of the bowel wall , leading to local impairment of mucosal blood flow with subsequent ischemic changes in the bowel . both patients were supplied dietary fiber daily for several days . this commercially available formula ( jevity ) , contains soy polysaccharide , which has up to 94% insoluble dietary fiber with no soluble dietary fiber . dietary fiber has become a standard component of enteral nutrition formulas to prevent and treat chronic constipation . the increase in stool bulk is thought to result from the residual , unfermented fiber , as well as from water held by gel formed by unfermented fibers . pathologic finding showed no acute vessel occlusion , atherosclerosis of arterial vessels , or thrombosis . mucosal thinning and diffuse flattening with hemorrhagic infarction are indicators of direct pressure from the lumen . generally , in critically ill patient who have risks of bowel ischemia , most guideline recommend to supply soluble fiber - rich enteral formula . next , increased energy demand from enterocytes may also have contributed to enteral nutrition - associated bowel ischemia , in association with ischemic bowel change , resulting in mismatches in the oxygen demand to supply ratio in the intestinal mucosa . splanchnic blood flow increases up to 200% that of baseline in response to the augmented demand of the intestinal mucosa , resulting in a regional blood - flow redistribution known as postprandial hyperemia . in conclusion , enteral nutrition has many benefits for critically ill patients and dietary fiber is important for stimulating the structural and functional trophism of the mucosa , preventing diarrhea by absorption of sodium and water   and preventing bacterial translocation . stool bulkiness resulting from insoluble dietary fiber and low transit time may result in inspissated bowel contents . especially , in patients who are hemodynamically unstable and hypoxic , bowel ischemia could also exacerbated . in these situations physician in icus should be aware of enteral nutirtion associated non - occlusive bowel ischemia in patients with fever , tachycardia , leukocytosis , and septic shock of unknown origin .
we describe two patients , with no previous history of vascular problems but poor lung function , who experienced septic shock due to bowel ischemia . both were fed an enteral formula rich in fiber using a feeding tube and experienced septic shock with regular enteral feeding . 
 surgical finding showed hemorrhagic ischemia in the bowel . 
 the pathologic finding suggests these changes may have been due to inspissations of bowel contents , which may put direct pressure on the mucosa of the bowel wall , leading to local impairment of mucosal and submucosal blood flow with subsequent bowel necrosis . 
 bowel ischemia may have been precipitated by an increased mesenteric blood flow requirement in combination with a metabolically stressed bowel . 
 patients in the intensive care unit fed a fiber - rich enteral formula may have inspissated bowel contents , leading to bowel ischemia , suggesting that the use of fiber - rich formula should be limited in patients at high - risk of bowel ischemia .