Ronald Estrada Seminario
Acute pancreatitis is an acute inflammatory process of the pancreas that is generally associated with severe pain in the upper abdomen. In most cases, blood levels of pancreatic enzymes, including amylase and lipase, are increased at least three times above the upper limit of normal. If the cause of the acute episode can be eliminated (such as by cholecystectomy in acute pancreatitis related to gallstones) no more acute episodes occur and the pancreas normalizes in terms of its morphology and function. However, if the acute episode is severe, there may be significant morphology and function alterations. For example, severe pancreatitis can cause a pancreatic ductal injury that results in a narrowing or a dustal obstruction, and causing chronic obstructive pancreatitis. In addition, after massive pancreatic necrosis the patient can develop steatorrhea and diabetes mellitus.
Acute pancreatitis is a clinical entity that responds to numerous causes and that can take from edematous to necrotizing forms. Hemorrhagic pancreatitis can complicate any of these pathologic forms.
Until recently it was believed that the pathophysiology of acute pancreatitis was fully explained by three processes. The first, as already indicated, is the activation of pancreatic enzymes and their release into the interstitium of the pancreas. The second is the self-digestion of the parenchyma by these activated enzymes. The third is the absorption of activated enzymes into the systemic circulation, which causes widespread systemic toxicity and damage to specific organs, including the lungs.
The initial injury occurs within the acinar cell.
The conversion of trypsinogen to trypsins and the subsequent activation of pancreatic proteases and phospholipase A2 are supposed to play an important role in the initiation of acinar cell inflammation. After acinar injury, pancreatic enzymes leak into the interstitium, causing edema and possibly also inflammation. Lipase and co-li-passes also filter from acinar cells located in the periphery, which causes peripancreatic fat necrosis. Injured fat cells can produce noxious agents that induce further damage to acinar cells in the periphery.
For this to occur, phospholipase A2 has to cause additional damage to the peripheral acinar cell membranes.
The first white blood cells to appear in areas of inflammation are neutrophils, followed by macrophages, monocytes, lymphocytes, and other cells.
There is evidence that free oxygen radicals derived from neutrophils play a key role in lung injury associated with severe acute pancreatitis.
This would result in the digestion of the pancreatic tissues. A chain reaction occurs with tissue damage and death, enzyme release, increased enzyme activation and release of bradykinins and vasoactive substances with increased vascular permeability and edema.
Acute pancreatitis can be caused by toxic (alcohol), mechanical (gallstones), traumatic, and metabolic causes (hypercalcemia, hypertroglyceridemia). Medications (thiazides), viral (urlian fever), etc.
Symptoms and signs
The picture is characterized by the presence of constant pain in the epigastrium, hypochondria and flanks, known as belt pain, which can vary from mild to very intense, and which leads the patient to remain still while flexing the trunk. It can be accompanied by diffuse abdominal pain, nausea, and vomiting. Physical examination reveals tenderness on deep palpation of the epigastrium, fever, hypotension, tachycardia, signs of left pleural effusion, abdominal wall rigidity, decompression pain, and absent bowel sounds. The presence of periumbilical bluish macules is known as Cullen's sign and is due to the existence of a hemoperitoneum.
The picture is defined by an increase in amylasemia and amylauria. There may be leukocytosis and hyperglycemia, and hypocalcemia is found in 25 cases.
Direct abdominal radiography may show a regional ileus. Ultrasound is primarily useful for diagnosing pseudocysts.
Abnormalities consistent with acute pancreatitis include enlargement of the pancreas and loss of normal internal echoes.
The computed tomography (CT) is useful in the care of patients with acute pancreatitis. There are three main indications for obtaining a CT scan in these cases. First, if other serious intra-abdominal diseases such as mesenteric infarction or perforated ulcer cannot be excluded, CT is very useful in establishing the appropriate diagnosis.
Second, CT is useful in staging the severity of acute pancreatitis.
Third, CT is useful in defining the presence of complications from pancreatitis, which includes involvement of the gastrointestinal tract, nearby blood vessels, and neighboring organs such as the liver, spleen, and kidney.