ACUTE PANCREATITS
Definition
This is acute inflammation of the pancreas which range from very mild and self limiting to fulminant and fatal
The incidence appears to have increased over the last 40 years in the UK the condition is a common cause of acute abdomen requiring hospital admission . the overall mortality has remained unchanged at 10%, in approximately 75%of patients complete recovery occurs after a few days of bed rest and alimentary rest however in the remainder the attack is severe with mortality of 25-3-%
Definition
This is acute inflammation of the pancreas which range from very mild and self limiting to fulminant and fatal
The incidence appears to have increased over the last 40 years in the UK the condition is a common cause of acute abdomen requiring hospital admission . the overall mortality has remained unchanged at 10%, in approximately 75%of patients complete recovery occurs after a few days of bed rest and alimentary rest however in the remainder the attack is severe with mortality of 25-3-%
Epidemiology
. Clinical series under report the incidence as cases diagnosed at post mortem are omitted. the incidence varies in relation to alcohol consumption which is the main cause in the young and the prevalence of gall stones which is the predominant cause in the elderly in many cases no cause is evident and these idiopathic cases are often referred to as the third most common cause of acute pancreatitis
. Clinical series under report the incidence as cases diagnosed at post mortem are omitted. the incidence varies in relation to alcohol consumption which is the main cause in the young and the prevalence of gall stones which is the predominant cause in the elderly in many cases no cause is evident and these idiopathic cases are often referred to as the third most common cause of acute pancreatitis
Aetiology of acute pancreatitis
the common predisposing conditions are gall stones and alcohol consumption but there are other causes as .trauma blunt penetrating iatrogenic post ERCP . obstruction of the pancreatic duct as by neoplasm pancreas divisum . hypercalcaemia . hypertriglyceridaemia . hypothermia . drugs like thiazides steroids oestrogen . renal failure . post operative (cardio-pulmonary bypass) . viral infections as mumps and coxsakie
the common predisposing conditions are gall stones and alcohol consumption but there are other causes as .trauma blunt penetrating iatrogenic post ERCP . obstruction of the pancreatic duct as by neoplasm pancreas divisum . hypercalcaemia . hypertriglyceridaemia . hypothermia . drugs like thiazides steroids oestrogen . renal failure . post operative (cardio-pulmonary bypass) . viral infections as mumps and coxsakie
Pathophysiology
The precise mechanisms by which the above factors can induce acinar rupture with release of activated enzymes within the gland parenchyma with autolysis of the gland are still not well understood . however a severe systemic inflammatory response occurs characterized by multiple inflammatory mediators like interleukin - 6 and -8 and tumour necrosis factor - alpha and activation of the cytokine cascade . fluid sequestration hypoalbuminia intra peritoneal fat necrosis and hypocalcaemia are all characteristic findings . the gland may become
haemofrrhagic
Diagnosis
Typically the patient complains of sudden onset severe upper abdominal pain radiating into the back . repeated vomiting is very characteristic . sitting up right may ease the pain abdominal findings range from mild epigastric tenderness to generalized peritonism . intradermal staining by extravasated blood in the flank (Gery Turner,s sign) or at the umbilicus (Cullen,s sign) heralds an attack of severe haemorrhagic pancreatitis whicj carries a high mortality . the dignosis is usually confirmed by an elevated serum amylase . urinary amylase can also be estimated rapidly by reagent strips . it is essential to exclude hyperamylasaemia in every acute abdomen . false positive test results (non pancreatitis hyperamylasaemia ) are common and may be caused by . perforated peptic ulcer . biliary disease particularly gall stone related . afferent loop obstruction following gastrectomy . mesenteric infarction ruptured ectopic pregnancy and salivary hyperamylasaemia the amylase level is often above the recognized upper limit of normal . false negative can occur if presentation is very early within the first 3-4 hours or late in the episode . in chronic alcohol dependency . previous destruction of the gland parenchyma accounts for very slowly rising levels
Typically the patient complains of sudden onset severe upper abdominal pain radiating into the back . repeated vomiting is very characteristic . sitting up right may ease the pain abdominal findings range from mild epigastric tenderness to generalized peritonism . intradermal staining by extravasated blood in the flank (Gery Turner,s sign) or at the umbilicus (Cullen,s sign) heralds an attack of severe haemorrhagic pancreatitis whicj carries a high mortality . the dignosis is usually confirmed by an elevated serum amylase . urinary amylase can also be estimated rapidly by reagent strips . it is essential to exclude hyperamylasaemia in every acute abdomen . false positive test results (non pancreatitis hyperamylasaemia ) are common and may be caused by . perforated peptic ulcer . biliary disease particularly gall stone related . afferent loop obstruction following gastrectomy . mesenteric infarction ruptured ectopic pregnancy and salivary hyperamylasaemia the amylase level is often above the recognized upper limit of normal . false negative can occur if presentation is very early within the first 3-4 hours or late in the episode . in chronic alcohol dependency . previous destruction of the gland parenchyma accounts for very slowly rising levels
Determination of severity the degree of hyperamylasaemia does not correlate with the severity of the disease . early identification of the 25%of patients with a severe life threatening attack is desirable as this will allow early intensive monitoring of these patients clinical assessment is unreliable in the crucial first 48 hours of an attack though certain signs (shock , abdominal mass and tetany )are informative
A number of scoring system using multiple laboratory criteria
have been proposed of which Imrie,s is widely accepted as follow 1- age more than 55 years 2- WBC more than 15,000|l 3- glucose less than 10 mmol|l 4- albumin less than 32 g|l 5- urea more than 16 mmol|l 6- PaO2less than 8 k Pa (60 mmHg)7- LDH more than 600 i u|l 8- AST more than 200 I U |l the presence of the above three or more of the above criteria within the first 48 hours indicateds a severe attack we notice that Ranson,s criteria as the same as above but without the age criterion . a quiker assessment of severity can be made by abdominal paracentesis and examination of the fluid . a severe attack may be indicated by aspiration of more than 20 ml of free fluid irrespective of colour , dark free fluid or a dark lavage retrun . the combination of clinical assessment multiple laboratory criteria and abdominal paracentesis will be accurate in identifying 75%of severe attack
Complications of acute pancreatitis
Systemic complications
the systemic response can vary from mild fever to multi organ failure in fulminant pancraetitis . the pathophysiological basis of this response is probably due to the release of cytokines and other inflammatory mediators that cause endothelial damage and capillary leakage in many organ systems this can lead to refractory shock where maintenance of the circulating volume can only be achieved by measurement of left atrial pressure (pulmonary capillary wedge pressures ) to allow appropriate fluid replacement and inotrope administration the lungs are commonly affected and respiratory failure occurs because capillary leak results in interstitial oedema . this is exacerbated by the presence of pain or an abdominal mass both of which will promote suptum retention ,atelectasis and pneumonia . metabolic problems include hyperglycaemia and hypocalcaemia .hypocalcaemialargely reflects the hypo albuminaemia but calcium may be sequestered within intra abdominal soaps . calcium administration is only necessary if tetany occurs
Local complications
as 1- pancreatic pseudocyst :peripancreatic effusions occur in up to 20%of cases but the majority of these resolve within 4-6 weeks. pseudocysts are enzyme - rich fluid collections which arise in the region of the lesser sac from disruption of the pancreatic parenchyma . they have no epithelial lining but are surrounded bt granulation tissue and may develop quite well - defined capsules . they are generally detected by ultrasound or CT scanning but may present as an abdominal mass . they may be locally symptomatic , though the majority are not . pseudocysts are more common in alcoholic pancreatitis than in gall stone pancreatitis . complications of pseudocyst can be severe and include infection major erosion into splenic artery and obstruction of the duodenum , the gastro - oesophageal junction or rarely the common bile duct if the far recesses of the lesser sac are involved . haemorrhage and sepsis occur more frequently in gall stone - associated cysts and the incidence of these complications increases with the passage of time . large un resolving or symptomstic pseudocyst should be drained either percutaneously or internally by cyst - gastrostomy
Pancreatic mass abscess and necrosis
A pancreatic phlegmon is a clinical diagnosis confirmed on CT referring to a non infected inflammatory pancreatic mass the pancreas may become necrotic in part or wholly and if infection supervenes a pancreatic abscess may form . infected necrosis becomes apparent early during the course of the attack within two week and produce a dramatic clinical picture with fever , deteriorating respiratory and renal function , painful abdominal mass and a leucocytosis . a necrotic pancreas may require extensive debridement whilst the formation of pancreatic phlegmon usually resolves .an abscess require percutaneous or formal open drainage . all of these conditions are readily diagnosed by CT , particularly pancreatic necrosis which will not enhance following the injection of intravenous contrast unlike normal or recovering pancreatic tissue
Colonic infarction
this can occur if the blood supply is interrupted by extension of the extra pancreatic necrosis and may follow drainage of pancreatic abscess , this is rare but a functional obstruction at the level of the transverse colon is a familiar though rare ,complication or even presentation of acute pancreatitis
Pancreatic fistula
this result from external drainage of pancreatic abscess or pseudocyst . spontaneous closure usually occurs unless there is distal pancreatic duct obstruction . somatostatin or its synthetic analogues have been used with some success to reduce fistula output
A number of scoring system using multiple laboratory criteria
have been proposed of which Imrie,s is widely accepted as follow 1- age more than 55 years 2- WBC more than 15,000|l 3- glucose less than 10 mmol|l 4- albumin less than 32 g|l 5- urea more than 16 mmol|l 6- PaO2less than 8 k Pa (60 mmHg)7- LDH more than 600 i u|l 8- AST more than 200 I U |l the presence of the above three or more of the above criteria within the first 48 hours indicateds a severe attack we notice that Ranson,s criteria as the same as above but without the age criterion . a quiker assessment of severity can be made by abdominal paracentesis and examination of the fluid . a severe attack may be indicated by aspiration of more than 20 ml of free fluid irrespective of colour , dark free fluid or a dark lavage retrun . the combination of clinical assessment multiple laboratory criteria and abdominal paracentesis will be accurate in identifying 75%of severe attack
Complications of acute pancreatitis
Systemic complications
the systemic response can vary from mild fever to multi organ failure in fulminant pancraetitis . the pathophysiological basis of this response is probably due to the release of cytokines and other inflammatory mediators that cause endothelial damage and capillary leakage in many organ systems this can lead to refractory shock where maintenance of the circulating volume can only be achieved by measurement of left atrial pressure (pulmonary capillary wedge pressures ) to allow appropriate fluid replacement and inotrope administration the lungs are commonly affected and respiratory failure occurs because capillary leak results in interstitial oedema . this is exacerbated by the presence of pain or an abdominal mass both of which will promote suptum retention ,atelectasis and pneumonia . metabolic problems include hyperglycaemia and hypocalcaemia .hypocalcaemialargely reflects the hypo albuminaemia but calcium may be sequestered within intra abdominal soaps . calcium administration is only necessary if tetany occurs
Local complications
as 1- pancreatic pseudocyst :peripancreatic effusions occur in up to 20%of cases but the majority of these resolve within 4-6 weeks. pseudocysts are enzyme - rich fluid collections which arise in the region of the lesser sac from disruption of the pancreatic parenchyma . they have no epithelial lining but are surrounded bt granulation tissue and may develop quite well - defined capsules . they are generally detected by ultrasound or CT scanning but may present as an abdominal mass . they may be locally symptomatic , though the majority are not . pseudocysts are more common in alcoholic pancreatitis than in gall stone pancreatitis . complications of pseudocyst can be severe and include infection major erosion into splenic artery and obstruction of the duodenum , the gastro - oesophageal junction or rarely the common bile duct if the far recesses of the lesser sac are involved . haemorrhage and sepsis occur more frequently in gall stone - associated cysts and the incidence of these complications increases with the passage of time . large un resolving or symptomstic pseudocyst should be drained either percutaneously or internally by cyst - gastrostomy
Pancreatic mass abscess and necrosis
A pancreatic phlegmon is a clinical diagnosis confirmed on CT referring to a non infected inflammatory pancreatic mass the pancreas may become necrotic in part or wholly and if infection supervenes a pancreatic abscess may form . infected necrosis becomes apparent early during the course of the attack within two week and produce a dramatic clinical picture with fever , deteriorating respiratory and renal function , painful abdominal mass and a leucocytosis . a necrotic pancreas may require extensive debridement whilst the formation of pancreatic phlegmon usually resolves .an abscess require percutaneous or formal open drainage . all of these conditions are readily diagnosed by CT , particularly pancreatic necrosis which will not enhance following the injection of intravenous contrast unlike normal or recovering pancreatic tissue
Colonic infarction
this can occur if the blood supply is interrupted by extension of the extra pancreatic necrosis and may follow drainage of pancreatic abscess , this is rare but a functional obstruction at the level of the transverse colon is a familiar though rare ,complication or even presentation of acute pancreatitis
Pancreatic fistula
this result from external drainage of pancreatic abscess or pseudocyst . spontaneous closure usually occurs unless there is distal pancreatic duct obstruction . somatostatin or its synthetic analogues have been used with some success to reduce fistula output
tags:pancreatitis,acute
.jpg)
.jpg)
0 comment:
Post a Comment