Ionic composition of gastric reflux and small intestinal fluid in horses: implications for fluid replacement.

Abstract

BACKGROUND: Small intestinal (SI) distension and gastric reflux (GR) are common in horses with mechanical and functional ileus. Removal of GR results in fluid/ion losses. AIMS/OBJECTIVES: 1) Determine the capacity of healthy SI; 2) measure ion concentrations in normal SI fluid, GR, or fluid from SI undergoing resection. The authors hypothesized that Naand Clconcentrations would be lower and higher, respectively, in GR as compared to SI fluid from healthy horses, while there would be little difference in Kconcentration. METHODS: Observational study: two to 15 meters of SI from 15 horses were distended with water to 6-7 cm in diameter. Volume drained was measured to determine capacity. Ion concentrations were measured in SI fluid from healthy horses (n=10), GR (n=11), and strangulated bowel (n=2). RESULTS: Normal SI had a fluid capacity of 2.8 &#xb1; 0.6 L/m. Na, K, and Clconcentrations were 100 &#xb1; 6, 22 &#xb1; 5, and 66 &#xb1; 30 mmol/L, respectively, in normal SI fluid; 77 &#xb1; 16, 16 &#xb1; 11, and 96 &#xb1; 25 mmol/L, respectively, in GR; and 116 &#xb1; 11, 12 &#xb1; 5, and 43 &#xb1; 27 mmol/L, respectively, in fluid from strangulated SI. Concentrations of Nawere lower (P<0.01) and Clgreater (P<0.03) in GR than in normal SI fluid or fluid from strangulated SI, while all fluid Kconcentrations were 3-5-fold greater than serum Kconcentration. CONCLUSION: These data can be used to estimate water and ion losses that occur with SI disorders to implement appropriate fluid therapy plans.