Nine of 50 combat casualties studied prospectively developed severe gastric hemorrhage due to proved gastric ulcers. On the day of injury, gastric acid outputs were very low (30 ± 14 mEq/24 hr) in all patients, and increased thereafter. Urinary steroid excretion was always within the normal range. Total gastric juice sialic acid output was identical, whether bleeding occurred or not.
The actual total "leak" plasma protein output was significantly greater in those who developed gastric ulcers (8 gm for six days), than in those who did not have clinically significant bleeding (5 gm for six days). Initial decreased acid output, accompanied by plasma protein "leakage" into the gastric lumen, is consistent with back diffusion of H+ ions soon after trauma.
Stremple JF, Molot MD, McNamara JJ, Mori H, Glass GBJ. Posttraumatic Gastric BleedingProspective Gastric Secretion Composition. Arch Surg. 1972;105(2):177-185. doi:10.1001/archsurg.1972.04180080031006