Serum lactate and phosphate as biomarkers of intestinal ischaemia among patients with mechanical intestinal obstruction in Mulago Hospital.

Abstract

Background: Intestinal ischaemia is a common complication of intestinal obstruction and arises from impaired perfusion of the supplying mesenteric blood vessels or from direct constriction of the intestines. The resultant local and systemic inflammatory response and bacterial translocation comes with a proportionate degree of morbidity and mortality. This study investigated the accuracy of serum lactate and phosphate as biomarkers of intestinal ischaemia among patients with mechanical intestinal obstruction. Methods: A Cross-sectional analytical study, done at Mulago Hospital. The study population consisted of both male and female patients 1year of age and above. Convenience sampling technique was used. Upon enrolment of an eligible patient, under appropriate conditions, a blood sample was drawn upon which the two assays were performed. Determination of bowel ischaemia was done at laparotomy. Analysis was done using Mann Whitney-U and Fischer’s exact test, as well as Kruskal Wallis equality-of-populations rank test and modified Cox regression. Ethical approval was secured and all participants consented. Results: Serum lactate was associated with and was predictive of bowel ischaemia while phosphate was not. Of the 81 patients enrolled 70 had the outcome of interest and were analysed. (57.1%) 40 had ischaemic bowel while 42.9% (30) had normal bowel. Among those with ischaemic bowel 40% had reversible ischaemia and 17.1 % had irreversible ischaemia. Both serum lactate and phosphate levels had an increasing trend from normal towards reversible to irreversible ischaemia, p = 0.59 & 0.19 respectively. Lactate was predictive of bowel ischaemia in general (p = 0.011) [CI 95%], PPV = 14.3%, but more significantly predictive of irreversible ischaemia (p= 0.009) [CI 95%], PPV = 41.7%. NPV for lactate in both forms of ischaemia was 93.3%. Hernias (46.5%) 33 were the commonest cause of intestinal obstruction, followed by intestinal volvulus (22.5%) 16 and adhesions (16.9%) 12. Ileum (72.2%) and colon (37.5%) were the commonest parts of gut involved. Conclusion: Serum lactate assay has a sensitivity of 66% and specificity of 53% for bowel ischaemia in general and a higher sensitivity of 71% and specificity of 80% for irreversible bowel ischaemia. Serum phosphate has no association with bowel ischaemia. A combination of serum lactate and phosphate assays had no diagnostic value in bowel ischaemia.