Proton Pump Inhibitors for Upper GI Bleed: Mechanism
During the bleed, there will be sympathetic mediated vasoconstriction and also hemostasis (platelet plug).
It has been demonstrated in an acidic environment (6.0 compared physiological pH 7.4), there is a 2-4 fold prolongation of prothrombin time, aPTT, and thrombin time.
Thus, in an acidic environment, the coagulation cascade and platelet aggregation are inhibited and disaggregation of stable platelet plugs occurs.
In addition, pepsinogen is converted to pepsin under acidic conditions. Pepsin can lyse the blood clots that plug vessels in the ulcer base and induce re-bleeding thereafter.
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