EMS providers need to understand a few critical, potentially life-threatening GI presentations that require rapid identification and early management.
Multiple organ systems lie within or pass through the abdomen, but the majority of abdominal cavity is filled with the organs of digestion, absorption and excretion. Because there are so many organs and structures involved, there are a large number of GI conditions. By understanding the anatomy and physiology, as well as specific knowledge about potentially critical conditions, EMS providers can differentiate serious medical emergencies from minor belly pain complaints.
Anatomy and physiology
Beginning with mouth and ending with the anus, the GI tract is responsible for the intake of nutrients, water and other raw materials the body needs to grow and maintain itself. Teeth and the muscles of the oral cavity begin the mastication process, using teeth to mechanically break apart the food we eat. Saliva contains several enzymes that begin to break down complex carbohydrates such as starch. The tongue then maneuvers the food bolus posteriorly past the glottis opening, where it enters the esophagus, a muscular tube that rhythmically contracts to push the bolus toward the stomach. Chemical and mechanical breakdown of the food continues there, where hydrochloric acid begins the destruction of proteins and other compounds.
The resulting slurry of chyme is released into the small intestine, passing through the pyloric sphincter and into the first section called the duodenum. Additional enzymes are secreted from the pancreas and liver via the gall bladder to further extract key nutrients from the chyme. Most of the water is absorbed through the intestinal walls and back into the bloodstream; microvilli buried inside the intestinal tract absorb nutrients. Over a period of eight to 12 hours, the slurry becomes increasingly more solid, collecting in the large intestines. Most of the remaining water is absorbed and eventually the anal sphincter releases the feces from the GI tract.
The large and small intestines receive their blood supply through the mesentery, a membrane that begins at the posterior abdominal wall and attaches to the intestinal tract. The major GI organs have their own blood supply.
Due to the large number of structures involved, numerous medical conditions can arise from the GI system. Most of them are not life-threatening; however there are several presentations that warrant an immediate medical evaluation and possible intervention to reduce poor outcomes.
GI bleeding
There are several causes for bleeding in the GI tract, including peptic ulcers (local erosion of the mucosal lining), gastritis (inflammation of the inner stomach lining), esophageal varices (swelling of the esophageal veins secondary to liver disease) and cancer.
An especially dangerous condition is a Mallory-Weiss tear that occurs in the esophagus or stomach. These can occur after severe vomiting, forced coughing or seizures and is associated with excessive alcohol use [1]. Depending upon the size and location of the tear, bleeding can be minor or massive requiring immediate surgery. Blood, if vomited by the patient can become a significant airway obstruction, especially if the worsening hypovolemia causes a reduction in level of consciousness.
Occult blood from a slow bleed in the gastrointestinal tract cannot be seen by the eye in the patient's feces and can go undetected for some time. A fecal occult blood test is used to determine if there is blood in feces. Obvious or frank blood in either feces or emesis indicates more rapid bleeding is taking place. Blood that is very loose or bright red in color indicates bleeding happening closer to either end of the GI tract. Hemorrhoids are an example of bright red bleeding from the veins surrounding the anus and lower rectum.
Blood that has been sitting in the GI tract long enough to be partially digested by the various GI enzymes and acids is darker in color (dark red to black) and can take on a tar-like appearance in feces or coffee-ground texture in emesis. There is a unique odor with digested GI blood resembling a mixture of metal and rotten eggs.
If GI bleeding is significant, the patient can initially appear in compensated shock and may require fluid resuscitation. A patient may have orthostatic or postural vital signs variation. When a patient is moved from a supine to standing position, there is a change in blood pressure or pulse consisting of one or more of the following [2]:
- A decrease of systolic blood pressure 20 mm Hg or more
- A decrease in diastolic blood pressure of 10 mm Hg or more
- An increase in heart rate of 20 beats per minute or more
However, there is evidence to show that performing orthostatic vital signs may not detect volume depletion of 1000 mL or less [3].
Field treatment for GI bleeding is supportive. Maintain airway patency for patients who may be vomiting large amounts of blood through positioning and suctioning.
An advanced airway may be needed to minimize aspiration if basic procedures fail. Patients who present in shock may need rapid fluid resuscitation in large amounts to maintain perfusion [4]. Large bore, short length catheters should be used to deliver volume quickly. Crystalloids such as normal saline or lactated ringers should be administered at a 3:1 ratio, i.e. replacing each mL of blood loss with 3 mL of fluid.
Peritonitis
The peritoneum is a membrane that lines the inner wall of the abdomen and covers most of the abdominal organs. This lining can become infected with bacteria or fungi, causing peritonitis. In turn this can cause life-threatening sepsis if untreated.
There are several causes for peritonitis. Liver disease can cause ascites, a build up of fluid in the abdominal cavity. This fluid can become infected.
Patients receiving peritoneal dialysis due to kidney failure can introduce infection into the abdominal cavity. Rupture of a GI organ such as an appendix, stomach or diverticulum (a weak spot or sac in the intestinal wall) can introduce acids, enzymes and bacteria. Other conditions include pelvic inflammatory disease, pancreatitis and Crohn's disease (chronic inflammation of the intestines).
Peritonitis generally starts with vague signs and symptoms, such as loss of appetite, nausea and a dull, aching feeling in the abdomen. The discomfort can rapidly turn into severe pain that is constant and changes with movement and palpation. Fever can develop, along with vomiting, chills and aches. Urinary frequency and amount diminish, as well as bowel movements.
In severe cases or peritonitis bacteremia, which is infection of the blood, develops and can cause sepsis, affecting the entire body. Septic shock can be fatal and requires rapid identification, fluid replacement and possibly the administration of a vasopressor such as dopamine to maintain perfusion to critical organs. Pain medication may be administered to provide comfort care and some EMS systems authorize their paramedics to initiate antibiotic administration in the field.
Acute mesenteric ischemia
Although rare, a drop in blood flow to the mesenteric arteries can result in ischemia, injury or infarct of the intestinal tract. This may result from a sudden blockage via a thrombus or embolus, a dissection of the superior mesenteric artery, or systemic hypotension. Patients will most likely feel a rapid onset of pain that becomes quite severe, as well as nausea, vomiting and diarrhea.
Depending on the location of the arterial block, large sections of the intestines may infarct and die, requiring surgical removal and resection of the bowel. If left untreated, gangrene (tissue decomposition) may occur, resulting in sepsis and septic shock.
Bowel obstruction
The intestines can become partially or completely blocked, causing its contents to back up and cause inflammation. The blockage may be the result of tumors, adhesions within the intestinal walls, foreign bodies or impacted stool, which is a large lump of feces that becomes stuck. This results in abdominal swelling, pain and cramping; the patient may experience severe constipation or diarrhea. Vomiting is likely. In severe cases of obstruction, patients may experience fecal vomiting.
Another cause of bowel obstruction is known as paralytic ileus, or a dramatic slowing of the normal peristaltic motions of the intestines. This can be caused by bacterial or fungal infections, mesenteric ischemia, appendicitis, kidney or lung disease, and certain medications such as narcotics.
Most cases of bowel obstruction are not life-threatening. However, necrosis of the intestines at the site of the blockage, or a perforation can develop, causing systemic infection, sepsis and possibly septic shock.
Pancreatitis
The pancreas is located posterior to the stomach, deep inside the abdominal cavity. As described earlier, the digestive function of the pancreas is to form digestive enzymes that break down carbohydrates, proteins and lipids in the intestinal chime and secrete them through the pancreatic duct into the intestines. It also has the function of forming the hormone insulin used in regulating glucose levels in the blood and cells.
Pancreatitis occurs when the pancreas becomes inflamed, usually caused by gallstones (clumps of cholesterol and pigments leaving the gall bladder and blocking the pancreatic duct) or heavy alcohol use. Other causes include infection, cancer, trauma, surgery and certain metabolic disorders such as hypercalcemia or hypertriglyceridemia.
Patients with acute pancreatitis will experience pain that is usually located in the upper abdominal quadrants, with radiation to the back. The abdomen may be tender to palpation and the patient may experience, nausea and vomiting. Some patients will report a close association of pain onset with food intake, especially food with a high fat content.
Pancreatitis is usually not immediately life-threatening. However it can become infected which can lead to sepsis. It can also cause pseudocysts (fluid-filled pouches) to form in the pancreas itself; these can burst can cause infection. Severe pancreatitis cases can result in Systemic Inflammatory Response Syndrome (SIRS), causing high fevers and systemic shock.
Summary
Most gastrointestinal disorders are not immediately life-threatening and require routine monitoring and transport of patients from the field to in hospital care. However, in a few cases, identifying significant GI problems and providing initial care may help improve the chances of recovery for patients who experience true GI emergencies.
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