Investigating the pathophysiology and nutritional requirements of patients with mesenteric infarction following restoration of bowel continuity
Creators: name: Adaba, Franklin Uchechukwu
Publisher: name: Imperial College London
Year: 2016

description: Acute mesenteric infarction results from insufficient mesenteric arterial inflow or poor venous drainage to the small bowel. It is known to have a high mortality rate between 60 to 90%. The aetiological factors for acute mesenteric infarction are divided into primary (venous, arterial and non-occlusive) vascular pathology and a secondary extravascular pathology. This thesis focuses on the primary causes of acute mesenteric infarction. In this study, we show that the mortality rate for mesenteric infarction due to a primary vascular pathology is high and the rate has not changed in the last decade. This study also shows mortality rate for venous mesenteric infarction is better compared to arterial or non-occlusive mesenteric infarction. An emergency operation is required to resect the infarcted bowel. In most cases, this would result in removal of significant lengths of small bowel with the patients having short lengths of small bowel (short bowel). In this situation, long term parenteral nutrition is required to maintain nutrition and improve survival but this is not without complications as well as reduced quality of life. The alternative has been a small bowel transplant but this is now considered only when patients have life threatening complication from parenteral nutrition and or failure of parenteral nutrition. Restoring bowel continuity has been proposed as another alternative treatment for patients with a short bowel. In the present study, restoring bowel continuity is shown to result in stopping or reducing the need for parenteral nutrition. The risk of chronic cholestasis, a complication of the liver associated with long term parenteral nutrition may be reduced and survival is likely to be better if patients have their bowel continuity restored. Quality of life is an important when assessing the value of a treatment. In this study we show that there is an overall improvement in quality of life after bowel continuity is restored. Studies on animals have shown that the short bowel undergoes functional and structural adaptation to improve absorption of nutrients and water. Human studies especially in patients who have had their bowel continuity restored are limited. The timing of adaptation is not known. Glucagon like peptide 2 (GLP -2) and peptide YY (P-YY) which are gut hormones secreted by the L-cells in the colon may play a role in bowel adaptation. P-YY causes a decrease in gastric emptying and reduces small bowel motility. GLP-2 has been shown to enhance villi growth and increase bowel length in mice. Citrulline has been shown to be produced by the enterocytes. It can be used as a biomarker for an increase in small intestinal cells in patients with short bowel. In the present study, the timing and mechanism of adaptation of the short bowel is investigated. The study shows an increase in serum levels of P-YY over time when bowel continuity is restored. This may indicate that functional adaptation of the small bowel occurs after restoring bowel continuity. Functional adaptation starts within a month of restoring bowel continuity. While the serum levels of GLP-2 reduced over time, an increase in citrulline level was noticed. This may indicate that structural adaptation occurs after restoring bowel continuity and GLP-2 may not be responsible for this change. The delivery of home parenteral nutrition is expensive. In this study, the cost of restoring bowel continuity reduces the cost associated with long term parenteral nutrition with improvement in the quality adjusted life years (QALYS) over time. In summary, the studies presented in this thesis contribute to our clinical knowledge of patients with a short bowel and provide an understanding of the adaptation in the short bowel and following restoration of bowel continuity.