Effects of gastric distension on intraabdominal pressures in horses

Abstract

To determine the effect of gastric distension on intraabdominal pressures (IAP) measured directly from the intraperitoneal space. Prospective, experimental study. A university-based equine research facility. Ten healthy adult horses, 5 males and 5 females. Intraabdominal pressures were measured through an intraperitoneal cannula zeroed at a height midway between the height of the tuber ishii and point of the shoulder at 6 time points: at rest, after placement of a nasogastric tube, and after instillation of each 5 L increment up to a total of 20 L of water. Simultaneously, mean arterial pressures (MAP) were obtained using a tail cuff, and abdominal perfusion pressures (APP) were calculated using the measured IAP minus the measured MAP. Baseline direct IAP measurements were subatmospheric (-4.5 ± 3.0 cm H2 O). IAPs were not significantly affected by placement of a nasogastric tube (-2.69, 95% CI [-3.24, -2.14], P = 0.4195), but were significantly increased after placement of 5 L (-1.73, 95% CI [-2.28, -1.18], P = 0.0015), 10 L (-0.54, 95% CI [-1.09,0.01], P = 0.0001), 15 L (0.89, 95% CI [0.34, 1.44], P = 0.0001), or 20 L (3.08, 95% CI [2.53, 3.63], P = 0.0001) of water into the stomach. APPs were not significantly different for any volume of fluid infused into the stomach (P = 0.05 for all comparisons). IAPs were significantly increased when > 5 L of water was infused into the stomach. These results indicate the need for further research in clinical cases to determine the relationship between gastric pressures and the development of intraabdominal hypertension in horses.