Changes in superior mesenteric artery blood flow after oral, enteral, and parenteral feeding in humans.

OBJECTIVE: Alterations in splanchnic blood flow cause gut ischemia and may predispose to gut-derived sepsis. Increases in superior mesenteric artery (SMA) blood flow occur follow the oral ingestion of food, but the effects of enteral nutrition (EN) on splanchnic perfusion are poorly defined and those of parenteral nutrition (PN) are unknown in humans. The aim of this study was to investigate changes in SMA flow in healthy controls and patients receiving adjuvant nutrition. DESIGN: Qualitative before-after study. SETTING: Intensive care and general wards at Scarborough Hospital, Scarborough, United Kingdom. PATIENTS: Fourteen healthy volunteers and 20 consecutive hemodynamically stable patients receiving adjuvant nutrition. INTERVENTIONS: Oral, EN, or PN after an overnight fast. MEASUREMENTS AND MAIN RESULTS: Duplex ultrasonography was used to assess SMA flow after an overnight fast. Subjects were then rescanned 3 hrs later after commencement of the appropriate test feed so that postprandial flows could be determined. Of the 20 patients recruited, 10 were receiving EN (120 kcal) and 10 PN (175 kcal). Of the 14 volunteers, three received no feed before their second scan (controls), six received an oral meal (530 kcal), and five received EN (120 kcal). Changes in SMA flow within groups were assessed. The control (fasting) volunteers showed no change between the two scans (p = 1.000). All subjects fed intraluminally demonstrated significant increases in postprandial SMA blood flow. Conversely, all patients fed parenterally showed decreased postprandial SMA flows with a median (interquartile range) fasting SMA flow of 14.5 (4.8-24.8) mL/sec, which decreased to 6.1 (2.4-9.2) mL/sec postprandially (p = 0.013). CONCLUSIONS: Splanchnic flow is modulated by the route of feeding. The clinical significance of these findings requires further investigation as they may be important in the management of the critically ill patient, particularly in those with cardiovascular instability or any patient predisposed to gut ischemia.

Gastric colonization predisposes to septic morbidity in surgical patients: a prospective study.

OBJECTIVE: Several previous studies have suggested that pathological colonization of the proximal gastrointestinal (GI) tract may be associated with septic morbidity. However, the prevalence of this in surgical patients is unknown and there is little information on factors that might predispose to this phenomenon. The aim of this study was to assess the preoperative variables that are associated with pathological colonization of the proximal GI tract in surgical patients. METHODS: Nasogastric aspirates were obtained from 502 surgical patients to identify abnormal colonization. Several preoperative variables were tested to identify association with pathological colonization of the proximal GI tract. Postoperative septic morbidity was recorded prospectively in all patients. RESULTS: Enterobacteriaceae were identified in 78 of 502 patients (15.5%), 124 of 502 (24.7%) had multiple organisms, and 157 of 502 (31.3%) had Candida in the nasogastric aspirates. Age >70 y and emergency surgery were associated with presence of Enterobacteriaceae. Age >70 y was also associated with the presence of multiple organisms (with or without Enterobacteriaceae). Colonization with Enterobacteriaceae or presence of multiple organisms in the proximal GI tract was associated with postoperative septic morbidity. Preoperative total parenteral nutrition was associated with Candida colonization in the upper GI tract, but not with sepsis. CONCLUSION: Pathological colonization of the proximal GI tract with Enterobacteriaceae or multiple organisms is associated with increased incidence of postoperative sepsis. Age >70 y and emergency surgery were the two preoperative variables associated with pathological colonization in surgical patients. Preoperative total parenteral nutrition is associated with fungal colonization but this is not associated with septic morbidity.

Influence of synbiotic containing Lactobacillus acidophilus La5, Bifidobacterium lactis Bb 12, Streptococcus thermophilus, Lactobacillus bulgaricus and oligofructose on gut barrier function and sepsis in critically ill patients: a randomised controlled trial.

BACKGROUND & AIMS: Infective complications are a common cause of mortality and morbidity in critically ill patients. Many factors affect sepsis, one of which is gut barrier function. The aim of this study was to determine whether the oral administration of a synbiotic preparation could alter gut barrier function in critically ill patients and thus reduce sepsis. METHODS: A total of 90 patients admitted to an intensive care unit (ICU) were randomised to receive either synbiotic or placebo preparations (45 into each group). The synbiotic preparation consisted of Lactobacillus acidophilus La5, Bifidobacterium lactis Bb 12, Streptococcus thermophilus and Lactobacillus bulgaricus (probiotics) with oligofructose (prebiotic). Gut barrier function was assessed by measurement of intestinal permeability (lactulose/rhamnose test) and culture of nasogastric aspirate on days 1 and 8. All septic complications and mortality were recorded. RESULTS: There were no differences between the groups in terms of age, sex, APACHE II or POSSUM scores. After 1 week of therapy, patients in the synbiotic group had a significantly lower incidence of potentially pathogenic bacteria (43% versus 75%, P = 0.05) and multiple organisms (39% versus 75%, P = 0.01) in their nasogastric aspirates than controls. There were no significant differences between the groups in terms of intestinal permeability, septic complications or mortality. CONCLUSIONS: The administration of synbiotic in critically ill patients favourably altered the microbial composition of the upper gastrointestinal tract but had no effect on intestinal permeability and was not associated with measurable clinical benefit.