Diseases of the pancreas- Acute pancreatitis
Acute pancreatitis is characterized by an acute episode of epigastric to central abdominal pain, usually of rapid onset. The pain often radiates into the middle of the back. In some instances the patient may complain of vomiting; however, this is not a constant feature. There may be a history of significant alcohol consumption (>40 g/day) or the presence of gallstones. Examination reveals a person in distress from the pain and varying signs of shock, dependent on these verity of the attack. Vital signs may range from totally normal to severe hypotension, tachycardia and tachypnoea. Abdominal examination will reveal tenderness in the epigastrium, and, depending on severity, there may be signs of peritonism. A tender mass may be palpable and abdominal distension evident due to a developing ileus. In severe cases, flank ecchymosis (Grey–Turner sign) or periumbilical ecchymosis (Cullen’s sign) may be seen.
The diagnosis of acute pancreatitis is made on the clinical features and demonstration of an abnormally elevated serum amylase. Amylase is one of the major enzymes of the pancreas. It is also present in salivary glands but has a different molecular size. Damage to the pancreas is associated with a release of amylase into the bloodstream, demonstrating a rapid rise in the serum level. The amylase is then rapidly cleared from the serum; therefore, the peak is only short-lived (i.e. 24 hours). For this reason, the rise in the amylase level does not correlate with the severity of pancreatitis because there is no way of predicting the timing of the sample to coincide with the peak amylase level. Other enzymes have also been used for the diagnosis of pancreatitis, including serum lipase and serum trypsinogen levels. These investigations are more difficult to perform and, therefore, in most institutions, reliance is placed on serum amylase estimation. As all of these enzymes are cleared from the serum by the kidneys and excreted in urine, estimation of urinary enzyme levels (i.e. urinary amylase or lipase) can be used to assist in the diagnosis in patients where there may be some doubt. The peak rise for the urinary levels occurs 24–48 hours later than the serum peaks and hence allows for subsequent estimation. The severity of pancreatitis is estimated by determining systemic criteria, which have been shown by carefully conducted studies to relate to outcome. The more of these positive systemic criteria, the greater is the severity of illness. These objective criteria are named after their originators and are known as Ranson or Imrie (Glasgow) scores. In addition, a more general. A contrast-enhanced CT scan in a patient with severe acute pancreatitis. It demonstrates an area of hypoperfusion that reflects necrosis of the pancreas score, which is also used for other severely debilitating conditions, is the APACHE II score, which may be used. If three or more of the Ranson/Imrie criteria or eight or more of the APACHE II criteria are abnormal, then pancreatitis is defined as severe. Criteria that are measured include systolic blood pressure, Pao2, creatinine, blood sugar level, urea, albumin, calcium, white cell count and level of liver transaminases. A positive score for each is registered when an abnormal value is detected within the initial 48 hours of the disease. Structural changes of the pancreas may be demonstrated using computed tomography (CT), and when this is combined with contrast to perform a contrastenhanced CT scan, areas of necrosis can be visualised, thus determining the degree of local complications.The optimal time for the CT is approximately 5 days after the onset of the disease. CT scan is also used to determine the presence or absence of fluid collections and pseudocysts. Ultrasound is used to determine any evidence of gallstones in the gall bladder.
The treatment of a patient with acute pancreatitis is directed four ways: general, local, complications and cause.
Depending on the severity of the fluid loss, patients with acute pancreatitis are treated for their fluid loss and given appropriate cardiovascular support. In the most common situation of mild pancreatitis, this consists of intravenous fluid replacement via a peripheral intravenous line. However, in severe pancreatitis, careful fluid replacement with central venous pressure measurements may be necessary. Oxygen is given via nasal mask or speculum as hypoxia is a common association of acute pancreatitis. In addition effective pain control needs to be ensured, and usually this means administration of parenteral opiate analgesics such as morphine.
There is no specific treatment for the pancreatic inflammation. Therefore, treatment is directed at minimizing the progression of the disease and preventing complications. Initially, the patient is fasted; however, enteral feeding has been shown to minimize the fasting associated breakdown of the gut mucosal barrier and hence prevent bacterial translocation. Furthermore, enteral nutrients have been shown to decrease the incidence of pancreatic abscess formation in patients with severe pancreatitis. Consequently once it has been determined that the pancreatitis is severe nasoenteric feeding is commenced. In some instances it may not be possible to deliver the total nutritional needs of the patient via the enteral route, because the ileus, which accompanies the inflation, limits the volume of the feed. In such circumstances parenteral nutrition is added to supplement the patient’s needs. Early studies in the management of acute pancreatitis have not shown a role for antibiotics. However, recent studies that have used antibiotics whose effects are concentrated in the pancreatic parenchyma (imipenen) have shown a decrease in complications. Consequently, prophylactic antibiotics that are taken up by the pancreatic parenchyma are used in patients demonstrating evidence of pancreatic necrosis on CT scan. Antibiotics are also used if there is clear evidence of infection.
Complications are treated as they arise and often require surgery via an endoscopic, percutaneous or open approach. Surgical intervention in pancreatitis is reserved for the treatment of complications and in gallstone pancreatitis for the treatment of the cause. In severe pancreatitis with infected necrosis, there is a need for operation to debride the pancreas of infected necrosed tissue. Infection may be diagnosed from either the presence of gas in the necrosed tissue as demonstrated by CT or the presence of organisms in tissue that has been aspirated from the pancreas following a percutaneous radiologically guided needle approach. Pancreatic abscesses may be drained via percutaneous techniques but usually require open surgical drainage. Pseudocysts are treated either by a combination of percutaneous and endoscopic techniques, or by open surgery. In severe acute pancreatitis of a biliary cause (i.e. gallstones), acute intervention by endoscopic retrograde cholangiopancreatography (ERCP) often demonstrates the cause (i.e. a stone), and treatment by endoscopic sphincterotomy results in a greatly improved outcome for these patients when compared to either a more conservative approach or intervention by open surgery.
In one third of patients with acute pancreatitis, the cause is gallstones that pass from the gall bladder into the duodenum. Following recovery from an acute attack of pancreatitis, the patients are treated by cholecystectomy, which in the majority is done via a laparoscopic approach. No further episodes of pancreatitis occur after cholecystectomy. In patients with the rare cause of sphincter of Oddi dysfunction, division of the sphincter of Oddi is also associated with cure. In patients where the cause is alcohol consumption, abstinence is accompanied with a decreased frequency and ultimately cure of pancreatitis. However, in many instances alcohol addiction is a major problem and patients require much community and social support before abstention is achieved. Thus acute pancreatitis is a debilitating acute abdominal disorder that, in the majority of patients, has a benign outcome when appropriately diagnosed and treated. In a small number of patients the disease may be severe and may be associated with complications that ultimately may lead to the patient’s death. The progression of the disease is unpredictable, hence all patients given the diagnosis of acute pancreatitis should be observed carefully in the initial period and a severity score determined. Once the severity of the disease is defined, appropriate treatment can be given.