INTRODUCTIONGastrointestinal (GI) bleeding is a serious and potentially life-threatening condition that causes approximately one million hospitalizations per year in the United States alone. GI bleeding covers bleeding originating from any part of the gastrointestinal tract and may extend from the mouth to the anus. 1 It is divided into two categories: upper and lower GI bleeding.Upper GI bleeding is defined as bleeding in any area from the mouth to the ligament of Treitz. 2 Patients with upper GI bleeding usually present to emergency services with hematemesis or melena, while patients who are hemodynamically unstable and have a large amount of bleeding may also present with hematochezia. 3 Upper GI bleeding is estimated to occur in 80-150 out of every 100,000 people per year. The estimated mortality rates are between 2% and 15%. 4 The most common risk factors are a history of upper GI bleeding, use of anticoagulants, use of high doses of non-steroidal anti-inflammatory drugs (NSAIDs) and advanced age. 2,5 GI bleeding is the most common cause of non-traumatic hemorrhagic shock. Shock is generally accompanied by hypotension. However, not every hypotensive patient is in shock.In order to clarify the diagnosis, the "shock index", which is higher in patients with left ventricular dysfunction and fluid loss, has been proposed. It is obtained by dividing the heart rate by the systolic blood pressure, and its normal range is considered to be 0.5-0.7. The shock index increases in cases of trauma and bleeding, in which the left ventricular stroke volume decreases. [6][7][8] It presents great potential for determining possible short-term negative outcomes among patients with upper GI bleeding. Additionally, it may be used in emergencies to ascertain changes to the clinical picture and is as effective as other risk-scoring systems that have been suggested in the literature. 9