acute pancreatitis

Severe acute pancreatitis has a mortality rate of

15% to 30%. More frequent in males than females, acute pancreatitis occurs over all age spans, and the risk of pancreatitis is two to three times higher among African Americans than Caucasians.

Causes of Acute Pancreatitis

Alcohol, Gallstones, Trauma, Medication reactions, Hypertriglyceridemia, Hypercalcemia, Bile duct abnormalities or obstruction (tumor), Surgery, Infectious organisms, Parasites, Spider bites, Scorpion stings, idiopathic (unidentified cause), Pancreas divisum (congenital anomaly where pancreatic duct is divided into two parts)

Table 60.2 Ranson's Criteria

At Admission At 48 Hours Age greater than 55 years Hematocrit decrease greater than 10% WBC greater than 16 103/mm3 BUN increase greater than 5 mg/dL after fluid resuscitation LDH greater than 350 IU/L Calcium less than 8 mg/dL AST greater than 250 IU/L PaO2 less than 60 mm Hg Glucose greater than 200 mg/dL Base deficit greater than 4 mg/dL Fluid sequestration greater than 6 LAST, Aspartate transaminase; BUN, blood urea nitrogen; LDH, lactate dehydrogenase; WBC, white blood cell count.

In acute pancreatitis

patients usually present with life-threatening conditions that require hospitalization, frequently in the intensive care unit (ICU). Acute pancreatitis is an inflammation of the pancreas that can be mild to severe and affect people of all ages. Patients with a mild case of pancreatitis have no end-organ dysfunction and have a low mortality rate (<1%). Mild pancreatitis is self-limiting, and 85% of patients fully recover. Patients with severe acute pancreatitis may develop SIRS and end-organ dysfunction.

Chronic pancreatitis is defined as

persistent inflammation that causes scarring and damage to the pancreas and surrounding tissue.

Pathophysiology

Acute pancreatitis is a reversible process involving inflammation of the pancreas secondary to the release of pancreatic enzymes that "autodigest" the pancreas, peripancreatic tissues, and adjacent areas. Autodigestion occurs when the pancreatic enzymes digest the pancreas and surrounding tissue- may occur as an isolated event, or it may be recurrent. The exact mechanism of the release of the pancreatic enzymes is not well known

FIGURE 60.2

FIGURE 60.2 Diagram of pancreatic and bile duct openings. Gallstones obstruct the bile duct or the area near where the bile duct and pancreatic duct empty into the duodenum. They both cause alteration in the flow of bile and pancreatic enzymes, thus leading to inflammation of the pancreas.

There are several scoring systems to determine the severity of pancreatitis.

Four such scoring mechanisms are the Ranson's criteria, the APACHE II score (Acute Physiology and Chronic Health Evaluation), the Balthazar CT severity index, and the Bedside Index Severity of Acute Pancreatitis (BISAP). Most commonly used is the Ranson's criteria, which are a means to measure the severity of illness and the likelihood of mortality in patients with pancreatitis (Table 60.2). The patient is evaluated upon admission and then again within the first 48 hours according to the scoring criteria. If at 48 hours the patient has a score of greater than or equal to 3, severe pancreatitis is likely, and with a score less than 3, severe pancreatitis is unlikely. The mortality rate associated with the score is found in Box 60.3. The higher the overall score, the higher the mortality rate.

Computed tomography with contrast is the standard for the diagnosis of pancreatic necrosis or fluid collections around the pancreas and is used for scoring the severity of pancreatitis.

The Balthazar index is calculated from the results of a CT scan and ranges from 0 to 10 on a point system given the extent of the inflammation of the pancreas and surrounding pancreatic tissue and the presence of pancreatic necrosis. The grading of the pancreas is given a letter grade of A through E, representing the range from normal pancreas to inflammatory changes to peripancreatic fluid collections. Necrosis of the pancreas is scored based on the percentage of the pancreas with necrosis with an overall higher percentage correlating with a higher severity of illness and poor outcome.

Physical examination reveals

a tender abdomen with localized guarding and rebound tenderness. The presence of Cullen's sign (periumbilical bruising) and Bulletblue Turner's sign (flank bruising) are infrequent findings and indicate retroperitoneal hemorrhage. Bulletblue Turner's and Cullen's signs usually take 24 to 48 hours to develop and can be a predictor of acute pancreatitis with pancreatic necrosis and retroperitoneal or intra-abdominal bleeding.

The APACHE II score

is an illness severity score calculated on the basis of the first 24 hours of ICU stay. The score is based on demographic factors (age, immunosuppression, chronic health status) and physiological factors (fever, mean arterial pressure, heart rate, oxygenation status, serum electrolytes [sodium, potassium, creatinine, hematocrit, and WBC count], and Glasgow Coma Scale score).

Elevated serum lipase

is the most specific test for pancreatitis because lipase is produced only by the pancreas.

Diagnostic imaging tests for pancreatitis include

abdominal CT scans, abdominal magnetic resonance imaging (MRI), and abdominal ultrasound. The purpose of these diagnostic tests is to evaluate for the presence of an inflamed pancreas, gallstones, and bile duct obstruction or distention.

The general clinical presentation of patients with pancreatitis includes

abdominal fullness from gas or bloating, hiccups, indigestion, fever, tachycardia, and hypotension.

Laboratory tests used in the diagnosis of pancreatitis include

metabolic panel, hematology studies, and specific tests of pancreatic enzymes such as serum amylase and serum lipase.

Elevated AST indicates

damage to liver cells, and elevated ALT is indicative of gallstone pancreatitis.

Patients with gallstone pancreatitis may have

elevated serum bilirubin, serum amylase, and serum liver enzymes—AST, ALT, ALP, and LDH—related to gallstones obstructing bile flow. Elevated WBC counts are an indicator of inflammation.

The most prevalent causes of acute pancreatitis are

gallstones and alcohol. Alcohol consumption accounts for approximately one-third of all cases of pancreatitis and is more commonly found in men because of the increased frequency of heavy alcohol consumption in males. Gallstone pancreatitis is due to the presence of gallstones obstructing the bile duct or located near the area where the bile duct and pancreatic duct empty into the duodenum (Fig. 60.2), both causing alteration in the flow of bile and pancreatic enzymes and leading to inflammation of the pancreas. Gallstone pancreatitis is more common in women than men, and the incidence increases with every decade of life. Cannabis has recently been identified as a possible risk factor due to toxin release in a small number of reports.

Elevated BUN indicates

impaired kidney function suggestive of hypovolemia or a hypercatabolic state. Monitoring elevations in BUN early in the course of the disease may provide an indicator of mortality from pancreatitis.

Pancreatitis

is a disease characterized by inflammation of the pancreas and is classified as acute or chronic.

Amylase

is an enzyme that aids in the digestion of carbohydrates, and lipase is an enzyme that aids in the digestion of fats. Patients can exhibit elevated BUN, AST, ALT, and WBC (Table 60.1).

Clinical Manifestations (pain)

sudden onset of epigastric pain that is felt in the upper left quadrant or mid-abdomen and can radiate to the back or shoulder blades. This pain is usually characterized as being deep and very sharp and becomes more intense within minutes of eating foods high in fat content. The pain can be constant and severe and last for several days, and some patients complain of severe pain when lying flat or bending forward. Pain can also be associated with nausea, vomiting, and anorexia. Patients with alcoholic pancreatitis may not have symptoms of pain for several hours or days after binge drinking.