Use of a sensitive multi‐sugar test for measuring segmental intestinal permeability in critically ill mechanically ventilated adults: A pilot study

BACKGROUND Increased intestinal permeability (IP) is associated with sepsis in the Intensive Care Unit (ICU). This study aimed to pilot a sensitive multi-sugar test to measure IP in critically ill patients in the non-fasted state. METHODS Critically ill mechanically ventilated adults were recruited from two ICUs in Australia. Measurements were completed within three days of admission using a multi-sugar test measuring gastroduodenal (sucrose recovery), small bowel (lactulose-rhamnose [L-R] and lactulose-mannitol [L-M] ratios) and whole gut permeability (sucralose-erythritol [S-E] ratio) in 24-hour urine samples. Urinary sugar concentrations were compared at baseline and post-sugar ingestion, and IP sugar recoveries and ratios were explored in relation to known confounders including renal function. RESULTS Twenty-one critically ill patients (12 males, median 57 years) participated. Group median concentrations of all sugars were higher following sugar administration; however, sucrose and mannitol increases were not statistically significant. Within individual patients, sucrose and mannitol concentrations were higher in baseline than post-sugar ingestion in nine (43%) and four (19%) patients, respectively. Patients with impaired (n = 9) versus normal (n = 12) renal function had a higher L-R ratio (median 0.130 versus 0.047,p = 0.003), a lower rhamnose recovery (median 15 versus 24%,p = 0.007) and no difference in lactulose recovery (median 2.5 versus 2.4%,p = 0.508). CONCLUSION Small bowel and whole gut permeability measurements are possible to complete in the non-fasted state, while gastroduodenal permeability could not be measured reliably. For small bowel IP measurements, the L-R ratio is preferred over the L-M ratio. Alterations in renal function may reduce the reliability of the multi-sugar IP test, warranting further exploration. This article is protected by copyright. All rights reserved.