Critical care - Acute gastrointestinal bleeding: Nursing

Acute gastrointestinal, or GI, bleeding occurs when there’s sudden loss of blood from the upper or lower GI tract. Upper GI bleeds occur in structures above a suspensory ligament called the ligament of Treitz, including the esophagus, stomach, and duodenum. On the other hand, lower GI bleeds occur in structures below this ligament, including the colon, rectum, and anus.

GI bleeds are caused by any condition that disrupts the integrity of the GI tract. Causes of upper GI bleeding include ulcers and varices, while causes of lower GI bleeds typically include cancer, hemorrhoids, and diverticulosis. As the nurse, you’ll provide patient-centered care for critically ill patients with acute GI bleeding.

Okay, so the GI tract consists of multiple layers. The mucosa is the innermost layer which helps absorb nutrients; provides protection from harmful bacteria and substances, like excess stomach acid; and produces mucus to lubricate food and prevent excoriation. The submucosa layer is under the mucosa and contains connective tissue, blood vessels, and nerves. Then there’s the muscular layer, where the muscles of the GI tract reside, and the serosa layer, which is the outermost layer that helps reduce friction and protects the inner structures.

Now, these mucosal layers can be disrupted, like when stomach acid auto-digests the layers or if a tumor within the GI tract, like colon cancer, directly invades the layers. Once the submucosal layer is disrupted, blood vessels can be damaged, leading to bleeding. Additionally, varices, which are dilated, fragile vessels commonly found in the esophagus, can easily rupture and bleed.

If bleeding is severe, hypovolemic shock can occur due to a reduced circulating blood volume. When this happens, the body compensates by vasoconstricting blood vessels and increasing heart rate, which can help maintain cardiac output and mean arterial pressure, or MAP. If left untreated, acute GI bleeding can progress to multiple organ dysfunction syndrome and death.

Clinical manifestations vary depending on the location of the bleeding. Upper GI bleeds can cause hematemesis, which is bloody vomitus that can either be bright red or look like coffee grounds. Bright red blood indicates fresh blood, whereas coffee grounds indicate older blood that has been oxidized by stomach acid, turning it a dark color. Blood may also move from the upper GI tract to the lower GI tract and present as melena, which is a shiny, black, tarry, foul-smelling stool. On the other hand, with lower GI bleeds, bright red or maroon blood, known as hematochezia, can occur; though, keep in mind that acute GI bleeding can also be occult, meaning not visible to the naked eye.

Hematocrit and hemoglobin can be normal early in the disease process but can decrease with continued bleeding, which can manifest as fatigue and lightheadedness. Platelets may initially increase in an attempt to stop the bleeding but may ultimately decrease as well.

Now, if blood loss is severe and circulating volume decreases, signs and symptoms of hypovolemic shock can be present, such as low blood pressure and tachycardia; cool and clammy skin as blood is shunted to major organs; and altered level of consciousness, if the brain doesn't receive enough oxygenated blood. Lastly, acid-base imbalances such as metabolic acidosis may occur when cells in hypoxic tissues switch to anaerobic metabolism.