Relationship between altered small intestinal motility and absorption after abdominal aortic aneurysm repair

Small intestinal (SI) motor patterns are often disrupted after major non-gastrointestinal (non-GI) surgery, but the impact on luminal flow and nutrient absorption is unclear. This study examines interactions between SI motility, flow and absorption in the first 3 days after surgical repair of abdominal aortic aneurysm (AAA).

Concurrent assessments of SI motility (manometry), flow (impedancometry) and lipid (¹³C-triolein) and glucose [plasma 3-O-methyl-glucose (3-OMG)] absorption were performed in 13 patients (12 male; 77 ± 2 years) on days 1 and 3 post surgery during 3-h intra-duodenal nutrient infusion (Ensure® with 200 μl ¹³C-triolein, 3 g 3-OMG). Data, presented as mean ± standard error of mean (SEM), are compared with 10 healthy volunteers (9 male; 57 ± 4 years).

On day 1 post surgery, there were more motility bursts, fewer impedance events and reduced absorption of ¹³C-triolein [cumulative percent dose recovery (cPDR) 22.9 ± 2.4% versus 31.2 ± 4.2%; P < 0.001] and 3-OMG, compared with health. By day 3, total number of bursts and flow events were similar between groups, with fewer retrograde and more antegrade flow episodes. ¹³C-triolein absorption remained low in patients on day 3 (26.7 ± 2.2%, P < 0.05), correlating positively with total number of flow events (r = 0.49; P < 0.01), but negatively with prolonged events (r = -0.37; P = 0.03). In patients, 3-OMG absorption increased from day 1 to 3 to a level comparable to health.

Whilst disruption in SI motility and flow (impedance) events was associated with reduced absorption of both lipid and carbohydrate, lipid malabsorption was more prolonged. This may reflect inadequate mixing of chyme from altered motility, so varying the nutrient composition of enteral feed may improve absorption in these patients.