Current Problems in Surgery 51 (2014) 370–372
Contents lists available at ScienceDirect
Current Problems in Surgery journal homepage: www.elsevier.com/locate/cpsurg
In brief
Severe acute pancreatitis attacks are associated with significant morbidity and mortality. Approximately 20% of severe pancreatitis attacks take place in the face of a necrotizing process. Gallstones and alcohol are the 2 most common causes for pancreatitis. The pathophysiology of acute pancreatitis is not well understood. Since the beginning of the last century, many hypotheses have emerged to explain the mechanism of gallstone pancreatitis. The first hypothesis published in 1901 of pancreatic ductal hypertension remains to be the most valid. The relationship between alcohol and pancreatitis is multifactorial, with genetic and environmental factors playing a major role. Alcohol, when related to pancreatitis, has been identified as a risk factor for developing necrosis. Pancreatitis attacks after endoscopic retrograde cholangiopancreatography (ERCP) are attributed to pancreatic ductal hypertension or direct toxicity from injected contrast materials or both. As a result of the initial insult to the pancreas and cellular stress, buildup of reactive oxygen radicals leads to impaired transport of zymogen across cellular membrane. Fusion of intracellular zymogen with lysosomes results in activation of trypsinogen leading to autocellular digestion and inflammation. A release of high mobility group box protein 1 is linked to pancreatic cellular damage. High mobility group box protein 1 initiates a sequence of inflammatory cascade through activation of toll-like receptor r and caspase 1 and mediated by interleukins (IL), IL-1 and IL-18. This cascade results in further cellular damage and necrosis. Tissue necrosis factor-alpha has been heavily investigated along with other cytokines to determine their role in the inflammatory cascade. In 2012, the original Atlanta classification for pancreatitis was revised by a group of practitioners from all disciplines. Two types of acute pancreatitis were identified: interstitial and necrotizing. Pancreatic necrosis itself has been categorized into parenchymal necrosis, peripancreatic necrosis, or both. The terminology for peripancreatic fluid collections was also addressed in the 2012 revised classification. Acute peripancreatic fluid collection is characterized by the lack of a well-defined wall and is confined by the normal fascial planes of the retroperitoneum and occurs in the early stage of interstitial acute pancreatitis. When acute peripancreatic fluid collections persist beyond 4 weeks, a well-defined wall develops and the term pancreatic pseudocyst is applied. Acute necrotic collections (ANCs) manifest within the first 4 weeks of the disease and contain variable amounts of fluid and necrotic solid materials. ANC is associated with necrotizing pancreatitis. http://dx.doi.org/10.1067/j.cpsurg.2014.07.002 0011-3840/& 2014 Elsevier Inc. All rights reserved.
D. Rohan Jeyarajah et al. / Current Problems in Surgery 51 (2014) 370–372
371
Walled-off pancreatic necrosis (WOPN) is used when ANC persists beyond 4 weeks and becomes encapsulated. Acute pancreatitis is diagnosed when 2 of 3 criteria are present: upper abdominal pain, amylase or lipase serum level greater than 3 times the upper normal limit, or computed tomography (CT) scan consistent with the finding of acute pancreatitis. The CT scan is usually not required on presentation unless needed to rule out other diagnoses. When acute pancreatitis is diagnosed, efforts should be made to identify the etiology. Right upper quadrant ultrasound is the modality of choice to assess the presence of gallbladder stones. A serum alanine aminotransferase level greater than 60 U/L is associated with biliary pancreatitis as well. The triglyceride and calcium levels may need to be obtained with each allergies acute pancreatitis is in doubt. It is important to assess the severity of acute pancreatitis because mild acute attacks carry a risk of mortality less than 1% whereas severe pancreatitis carries a mortality rate of 10%-30%. Three degrees of severity have been recognized in the 2012 revised Atlanta classification. Mild acute pancreatitis is defined by light organ failure, local or systemic complications. Moderately severe acute pancreatitis is defined by the presence of transient organ failure or the presence of local or systemic complications or both. Severe acute pancreatitis is characterized by the presence of persistent organ failure involving single or multiple organs. Transient organ failure was defined as organ failure that resolved within 48 hours whereas persistent organ failure was defined to last more than 48 hours. Persistent organ failure was found to be significantly associated with involvement of infected necrosis and increased mortality. The presence of infected necrosis is established based on 1 of 3 criteria: (1) ongoing signs of sepsis; (2) the combination of clinical signs and the CT finding of extraluminal gas within areas of necrosis; or (3) percutaneous, image-guided fine-needle aspiration when bacteria or fungi or both are seen on Gram stain and the culture is positive, or a secondary event after instrumentation. The indications for using fine needle aspiration to diagnose infection are not well defined, and its use is left up to the discretion of the managing clinician. Multiple scoring systems have been developed to assess the severity of pancreatitis attack and identify those with an increased risk of morbidity and mortality and hence the need for treatment in critical care setting for transfer to a higher level care. Some scoring systems have adopted logical features of the gland, whereas others used clinical parameters as the base of the scoring system. The Balthazar scoring system, the radiologic scoring system, was developed in 1985 using nonenhanced CT. Enhanced CT was later introduced along with CT severity index. Along with the modified CT severity index, the radiologic scoring systems were proven to be of benefit in detecting local complications but did not correlate well with the clinically based scoring system. The first clinically based scoring system was developed by Ranson utilizing 2 sets of clinical parameters on admission and 48 hours later. In addition to sensitivity and positive predicted value plus the 80%, to 48-hour delay was a limiting factor in adopting this scoring system. The acute Physiology and Chronic Health Evaluation II is another clinically based scoring system with more flexibility than Ranson's and has the ability for recalculation. Organ failure–related scoring systems have also been developed and applied but yet to be validated in larger studies. Some of the commonly used organ failure scoring systems are Sequential Organ Failure Assessment and Marshall. Single parameter scoring systems have been investigated as well. The hematocrit, blood urea nitrogen or creatinine level, C-reactive protein level, and procalcitonin level have all been studied with variable success. Contrast-enhanced CT is the primary tool for assessing the imaging-based criteria because of its wide availability for these severely ill patients and has a high degree of accuracy. However, contrast-enhanced CT should also be performed in patients with severe acute pancreatitis or complications related to it. The ideal time for assessing these complications using CT is after 72 hours from the onset of symptoms. Magnetic resonance imaging is reserved for the detection of choledocholithiasis not visualized on contrast-enhanced CT images and to further characterize collections for the presence of nonliquefied material and to delineate pancreatic ductal anatomy.
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D. Rohan Jeyarajah et al. / Current Problems in Surgery 51 (2014) 370–372
Endoscopic ultrasound has been reported to be valuable in patients with pancreatitis. Its therapeutic role is well established, but it is yet to be widely practiced, despite its promising diagnostic value. When the diagnosis of acute pancreatitis is made, assessment of severity and acuity should be determined and used to aid with allocation of the care for these patients. The management of acute pancreatitis cannot be divided into 3 phases: acute, subacute, and delayed. The acute phase takes place within the first 48 hours in the course of the pancreatitis attack. The use of aggressive fluid resuscitation is the key factor in this phase. The use of lactated Ringer's solution in this phase is supported by multiple reports. Improvements in the systemic inflammatory response syndrome picture have been documented with fairly aggressive fluid resuscitation. Urine output measurement should be used as the main tool to gauge the adequacy of fluid resuscitation. The role of antibiotics has been long debated. In the absence of acute cholangitis, the data speak against the use of antibiotics during this phase. The use of ERCP is reserved to decompress the biliary tree in patients with cholangitis. Octreotide has been investigated as an agent with potential benefit in patients with acute pancreatitis, but its role has yet to be defined. The benefit of early introduction of nutrition is well established. The data favor the enteral route over total parenteral nutrition. Transgastric vs transjejunal feeding has been investigated as well and is likely to be equivalent. The development of abdominal compartment syndrome is a bothersome situation in patients with acute pancreatitis. This situation can usually be managed medically without the need for decompressive laparotomy, which has a poor outcome. The subacute phase takes place in the second and third week of the attack, and necrosis is more evident on CT images. Systemic inflammatory response syndrome and multiorgan failure in this stage should be managed with aggressive supportive care and nutritional support. Surgical intervention should be avoided in these patients unless absolutely necessary. Percutaneous drainage catheters can be used if there is a concern regarding infected pancreatic necrosis. Surgical necrosectomy should be avoided if at all possible. Local complications and multiorgan failure owing to sepsis characterize this phase. Local complications are evaluated using CT, magnetic resonance imaging, or endoscopic ultrasound. The step-up approach has gained popularity in managing infected pancreatic necrosis and symptomatic WOPN in this phase. The step-up approach employs the use of percutaneous drainage approach and serial up-sizing of the drain as needed. When feasible, the drain should be placed through a retroperitoneal approach to form a track that can be used in video-guided retroperitoneal drainage. In addition to the percutaneous approach, local complications during this phase can be addressed through endoscopy or combination of dual endoscopic and percutaneous techniques. Percutaneous procedures alone with aggressive up-sizing of the drains can be successful in up to 40% of patients with infected pancreatic necrosis. This is a paradigm change as prior dictum was that these patients needed open surgical debridement. Some patients who fail the aforementioned approach may benefit from open surgical necrosectomy. Multiorgan failure in this phase is mainly due to sepsis, which should be managed by addressing the sepsis source, administering antibiotics, and giving supportive care. Nutritional support remains paramount in this phase as well. Patients who are symptomatic secondary to large pancreatic pseudocyst, WOPN, or disconnected pancreatic duct late in the process can be managed with cystogastrostomy or distal pancreatectomy. These patients are typically well beyond the acute phase and usually present in an outpatient setting.
Contents lists available at ScienceDirect
Current Problems in Surgery journal homepage: www.elsevier.com/locate/cpsurg
In brief
Severe acute pancreatitis attacks are associated with significant morbidity and mortality. Approximately 20% of severe pancreatitis attacks take place in the face of a necrotizing process. Gallstones and alcohol are the 2 most common causes for pancreatitis. The pathophysiology of acute pancreatitis is not well understood. Since the beginning of the last century, many hypotheses have emerged to explain the mechanism of gallstone pancreatitis. The first hypothesis published in 1901 of pancreatic ductal hypertension remains to be the most valid. The relationship between alcohol and pancreatitis is multifactorial, with genetic and environmental factors playing a major role. Alcohol, when related to pancreatitis, has been identified as a risk factor for developing necrosis. Pancreatitis attacks after endoscopic retrograde cholangiopancreatography (ERCP) are attributed to pancreatic ductal hypertension or direct toxicity from injected contrast materials or both. As a result of the initial insult to the pancreas and cellular stress, buildup of reactive oxygen radicals leads to impaired transport of zymogen across cellular membrane. Fusion of intracellular zymogen with lysosomes results in activation of trypsinogen leading to autocellular digestion and inflammation. A release of high mobility group box protein 1 is linked to pancreatic cellular damage. High mobility group box protein 1 initiates a sequence of inflammatory cascade through activation of toll-like receptor r and caspase 1 and mediated by interleukins (IL), IL-1 and IL-18. This cascade results in further cellular damage and necrosis. Tissue necrosis factor-alpha has been heavily investigated along with other cytokines to determine their role in the inflammatory cascade. In 2012, the original Atlanta classification for pancreatitis was revised by a group of practitioners from all disciplines. Two types of acute pancreatitis were identified: interstitial and necrotizing. Pancreatic necrosis itself has been categorized into parenchymal necrosis, peripancreatic necrosis, or both. The terminology for peripancreatic fluid collections was also addressed in the 2012 revised classification. Acute peripancreatic fluid collection is characterized by the lack of a well-defined wall and is confined by the normal fascial planes of the retroperitoneum and occurs in the early stage of interstitial acute pancreatitis. When acute peripancreatic fluid collections persist beyond 4 weeks, a well-defined wall develops and the term pancreatic pseudocyst is applied. Acute necrotic collections (ANCs) manifest within the first 4 weeks of the disease and contain variable amounts of fluid and necrotic solid materials. ANC is associated with necrotizing pancreatitis. http://dx.doi.org/10.1067/j.cpsurg.2014.07.002 0011-3840/& 2014 Elsevier Inc. All rights reserved.
D. Rohan Jeyarajah et al. / Current Problems in Surgery 51 (2014) 370–372
371
Walled-off pancreatic necrosis (WOPN) is used when ANC persists beyond 4 weeks and becomes encapsulated. Acute pancreatitis is diagnosed when 2 of 3 criteria are present: upper abdominal pain, amylase or lipase serum level greater than 3 times the upper normal limit, or computed tomography (CT) scan consistent with the finding of acute pancreatitis. The CT scan is usually not required on presentation unless needed to rule out other diagnoses. When acute pancreatitis is diagnosed, efforts should be made to identify the etiology. Right upper quadrant ultrasound is the modality of choice to assess the presence of gallbladder stones. A serum alanine aminotransferase level greater than 60 U/L is associated with biliary pancreatitis as well. The triglyceride and calcium levels may need to be obtained with each allergies acute pancreatitis is in doubt. It is important to assess the severity of acute pancreatitis because mild acute attacks carry a risk of mortality less than 1% whereas severe pancreatitis carries a mortality rate of 10%-30%. Three degrees of severity have been recognized in the 2012 revised Atlanta classification. Mild acute pancreatitis is defined by light organ failure, local or systemic complications. Moderately severe acute pancreatitis is defined by the presence of transient organ failure or the presence of local or systemic complications or both. Severe acute pancreatitis is characterized by the presence of persistent organ failure involving single or multiple organs. Transient organ failure was defined as organ failure that resolved within 48 hours whereas persistent organ failure was defined to last more than 48 hours. Persistent organ failure was found to be significantly associated with involvement of infected necrosis and increased mortality. The presence of infected necrosis is established based on 1 of 3 criteria: (1) ongoing signs of sepsis; (2) the combination of clinical signs and the CT finding of extraluminal gas within areas of necrosis; or (3) percutaneous, image-guided fine-needle aspiration when bacteria or fungi or both are seen on Gram stain and the culture is positive, or a secondary event after instrumentation. The indications for using fine needle aspiration to diagnose infection are not well defined, and its use is left up to the discretion of the managing clinician. Multiple scoring systems have been developed to assess the severity of pancreatitis attack and identify those with an increased risk of morbidity and mortality and hence the need for treatment in critical care setting for transfer to a higher level care. Some scoring systems have adopted logical features of the gland, whereas others used clinical parameters as the base of the scoring system. The Balthazar scoring system, the radiologic scoring system, was developed in 1985 using nonenhanced CT. Enhanced CT was later introduced along with CT severity index. Along with the modified CT severity index, the radiologic scoring systems were proven to be of benefit in detecting local complications but did not correlate well with the clinically based scoring system. The first clinically based scoring system was developed by Ranson utilizing 2 sets of clinical parameters on admission and 48 hours later. In addition to sensitivity and positive predicted value plus the 80%, to 48-hour delay was a limiting factor in adopting this scoring system. The acute Physiology and Chronic Health Evaluation II is another clinically based scoring system with more flexibility than Ranson's and has the ability for recalculation. Organ failure–related scoring systems have also been developed and applied but yet to be validated in larger studies. Some of the commonly used organ failure scoring systems are Sequential Organ Failure Assessment and Marshall. Single parameter scoring systems have been investigated as well. The hematocrit, blood urea nitrogen or creatinine level, C-reactive protein level, and procalcitonin level have all been studied with variable success. Contrast-enhanced CT is the primary tool for assessing the imaging-based criteria because of its wide availability for these severely ill patients and has a high degree of accuracy. However, contrast-enhanced CT should also be performed in patients with severe acute pancreatitis or complications related to it. The ideal time for assessing these complications using CT is after 72 hours from the onset of symptoms. Magnetic resonance imaging is reserved for the detection of choledocholithiasis not visualized on contrast-enhanced CT images and to further characterize collections for the presence of nonliquefied material and to delineate pancreatic ductal anatomy.
372
D. Rohan Jeyarajah et al. / Current Problems in Surgery 51 (2014) 370–372
Endoscopic ultrasound has been reported to be valuable in patients with pancreatitis. Its therapeutic role is well established, but it is yet to be widely practiced, despite its promising diagnostic value. When the diagnosis of acute pancreatitis is made, assessment of severity and acuity should be determined and used to aid with allocation of the care for these patients. The management of acute pancreatitis cannot be divided into 3 phases: acute, subacute, and delayed. The acute phase takes place within the first 48 hours in the course of the pancreatitis attack. The use of aggressive fluid resuscitation is the key factor in this phase. The use of lactated Ringer's solution in this phase is supported by multiple reports. Improvements in the systemic inflammatory response syndrome picture have been documented with fairly aggressive fluid resuscitation. Urine output measurement should be used as the main tool to gauge the adequacy of fluid resuscitation. The role of antibiotics has been long debated. In the absence of acute cholangitis, the data speak against the use of antibiotics during this phase. The use of ERCP is reserved to decompress the biliary tree in patients with cholangitis. Octreotide has been investigated as an agent with potential benefit in patients with acute pancreatitis, but its role has yet to be defined. The benefit of early introduction of nutrition is well established. The data favor the enteral route over total parenteral nutrition. Transgastric vs transjejunal feeding has been investigated as well and is likely to be equivalent. The development of abdominal compartment syndrome is a bothersome situation in patients with acute pancreatitis. This situation can usually be managed medically without the need for decompressive laparotomy, which has a poor outcome. The subacute phase takes place in the second and third week of the attack, and necrosis is more evident on CT images. Systemic inflammatory response syndrome and multiorgan failure in this stage should be managed with aggressive supportive care and nutritional support. Surgical intervention should be avoided in these patients unless absolutely necessary. Percutaneous drainage catheters can be used if there is a concern regarding infected pancreatic necrosis. Surgical necrosectomy should be avoided if at all possible. Local complications and multiorgan failure owing to sepsis characterize this phase. Local complications are evaluated using CT, magnetic resonance imaging, or endoscopic ultrasound. The step-up approach has gained popularity in managing infected pancreatic necrosis and symptomatic WOPN in this phase. The step-up approach employs the use of percutaneous drainage approach and serial up-sizing of the drain as needed. When feasible, the drain should be placed through a retroperitoneal approach to form a track that can be used in video-guided retroperitoneal drainage. In addition to the percutaneous approach, local complications during this phase can be addressed through endoscopy or combination of dual endoscopic and percutaneous techniques. Percutaneous procedures alone with aggressive up-sizing of the drains can be successful in up to 40% of patients with infected pancreatic necrosis. This is a paradigm change as prior dictum was that these patients needed open surgical debridement. Some patients who fail the aforementioned approach may benefit from open surgical necrosectomy. Multiorgan failure in this phase is mainly due to sepsis, which should be managed by addressing the sepsis source, administering antibiotics, and giving supportive care. Nutritional support remains paramount in this phase as well. Patients who are symptomatic secondary to large pancreatic pseudocyst, WOPN, or disconnected pancreatic duct late in the process can be managed with cystogastrostomy or distal pancreatectomy. These patients are typically well beyond the acute phase and usually present in an outpatient setting.
