Intestinal failure defined by measurements of intestinal energy and wet weight absorption

Abstract

Background and aims: Intestinal failure defined by the minimal energy and wet weight absorption required to avoid home parenteral nutrition (HPN) is not well described. Thus the aim of this study was to identify the minimal level of gut function necessary to avoid parenteral support using objective measurements of intestinal function.

Methods: Energy (bomb calorimetry) and wet weight absorption were measured during 48 hour balance studies in 45 HPN patients with intestinal failure and in 44 non-HPN borderline patients with a short bowel or malabsorption exceeding 2 MJ/day.

Results: In the non-HPN patients, the lower 5% confidence interval of the absorption of energy was 84% of the basal metabolic rate (BMR, the Harris-Benedict equations), equivalent to 4.9 MJ/day. Wet weight absorption was 1.4 kg/day. The HPN patients absorbed less of either or both. The non-HPN patients absorbed 24-86% (range) of the energy and 23-95% of the wet weight. Absorption in the HPN patients ranged from below 0% (net secretion) in patients with very short bowels to 100% absorption of an insufficient oral intake in patients with pseudo-obstruction. Non-HPN patients who absorbed less than half of their intake avoided HPN by hyperphagia (200-400% of BMR equivalent to 10-24 MJ/day, and 3-7 kg/day of wet weight).

Conclusion: Intestinal failure was accurately measured as absorption below 1.4 kg/day of wet weight and 84% of the calculated BMR (depending on weight, sex and age), which is equal to 4.9 MJ/day. Intestinal absorption, expressed as a percentage of intake, did not discriminate between patients with and without intestinal failure, except for patients who absorbed less than 25% of their intake.

Figure 1

Absorption of wet weight and energy in relation to basal metabolic rate (BMR) calculated by the Harris-Benedict equations in 44 non-HPN patients and in 45 HPN patients. The 5% confidence limits of the non-HPN patients, defining intestinal failure, are given by the lines. Energy absorption/BMR was 84% and wet weight absorption 1.41 kg/day.

Figure 2

Relative energy absorption in relation to dietary energy intake/basal metabolic rate (BMR) in 44 non-HPN patients and 45 HPN patients. The open triangles indicate HPN patients who received HPN due to a wet weight absorption of less than the 5% limit (1.41 kg/day).

Figure 3

Relative wet weight absorption in relation to the dietary wet weight intake in 44 non-HPN patients and 45 HPN patients. The open triangles indicate HPN patients who received HPN because of energy absorption less than the 5% limit for basal metabolic rate (BMR) (84%).