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Original Research |
1 Division of Abdominal Imaging and Intervention, Department of Radiology,
Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston,
MA 02115.
2 Department of Surgery, Brigham and Women's Hospital, Harvard Medical School,
Boston, MA.
3 Division of Gastroenterology, Department of Medicine, Brigham and Women's
Hospital, Harvard Medical School, Boston, MA.
Received April 24, 2008;
accepted after revision July 29, 2008.
S. G. Silverman is a consultant to Siemens Medical Solutions.
Abstract
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MATERIALS AND METHODS. We reviewed clinical, radiologic, and bacteriologic data on 35 patients (23 men, 12 women; mean age, 50 years; range, 21-83 years) with acute necrotizing pancreatitis refractory to standard medical care who underwent CT-guided percutaneous catheter drainage with 12- to 22-French catheters. Experiences with two subgroups were compared. One group consisted of 22 patients, 10 with multisystem organ failure, who presented with sterile necrosis (median Atlanta score, 1.3; range, 0-3). The other group consisted of 13 patients, one with multisystem organ failure, who presented with infected necrosis (median Atlanta score, 0.4; range, 0-3). Differences between the group with sterile and the group with infected necrosis were analyzed with the Fisher-Holton exact and Mann-Whitney U tests.
RESULTS. Among 35 patients, 17 (49%) were treated successfully with CT-guided percutaneous catheter drainage alone. The effectiveness of CT-guided percutaneous catheter drainage in patients with sterile necrosis (11/22, 50%) was not significantly different from that of drainage in patients with infected necrosis (6/13, 46%). Among 11 patients with multisystem organ failure (10 with sterile necrosis, one with infected necrosis), only four (36%) were treated successfully with CT-guided percutaneous catheter drainage alone; five patients (45%) died. Among 24 patients without multisystem organ failure, 13 (54%) were treated successfully with CT-guided percutaneous catheter drainage alone; one patient died.
CONCLUSION. In our experience, primary CT-guided percutaneous catheter drainage was successful for approximately one half of the patients with acute necrotizing pancreatitis. The presence of multisystem organ failure appears to be a more important indicator of outcome than does the presence of infection.
Keywords: organ failure • pancreatic necrosis • pancreatitis • percutaneous catheter drainage
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Despite the availability of several clinical (Ranson criteria, Acute Physiology and Chronic Health Evaluation II score) and radiologic (Balthazar scoring system, modified CT severity index) grading systems, accurate prediction of outcome and best treatment of patients with acute necrotizing pancreatitis remains difficult [5-7]. In particular, these grading systems cannot be used to predict whether patients with severe acute pancreatitis, whose condition is refractory to standard medical care, are treated best with primary percutaneous catheter drainage, surgical débridement, or continuation of conservative medical care.
Limited studies [8-11] have evaluated the role of CT-guided percutaneous catheter drainage in the care of patients with infected pancreatic necrosis. Moreover, to the best of our knowledge, in only one previous study [12] has the clinical utility of CT-guided percutaneous catheter drainage in the care of patients with sterile pancreatic necrosis been evaluated. In addition, to our knowledge, no studies have been conducted to compare clinical experience with primary CT-guided percutaneous catheter drainage in patients with sterile necrosis with the same procedure in patients with infected necrosis. Nor has the effect of clinical comorbid conditions, such as multisystem organ failure, on the outcome of primary CT-guided percutaneous catheter drainage been assessed. This study was conducted to evaluate our clinical experience and observations using primary CT-guided percutaneous catheter drainage of acute necrotizing pancreatitis and to compare the utility of the procedure in the care of patients with sterile and those with infected necrosis.
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The study group consisted of 35 patients (23 men, 12 women; mean age, 50 years; range, 21-83 years). Causes of acute pancreatitis included cholelithiasis in 12 cases (34%); alcohol in eight (23%); ERCP in six (17%); idiopathic factors in four (11%); and hypertriglyceridemia, autoimmune disorder, systemic lupus erythematosus, bone marrow transplantation, and trauma in one case (3%) each.
Patients were categorized according to whether they presented with sterile or infected necrosis. The group of patients with sterile necrosis consisted of 22 patients (63%) (14 men, eight women; mean age, 51.4 years; range, 27-83 years) in whom no microorganisms were identified with either Gram stain or culture of fluid specimens obtained by needle aspiration of the necrotic pancreas at the initial percutaneous CT-guided catheter drainage procedure. The group of patients with infected necrosis included 13 patients (37%) (10 men, three women; mean age, 48.5 years; range, 21-64 years) who had documented positive results of Gram stain or culture of fluid specimens obtained by needle aspiration of the necrotic pancreas before or at the initial percutaneous CT-guided catheter drainage procedure.
Assessment of the patient's clinical condition at initial percutaneous CT-guided catheter drainage was based on criteria set forth by the International Symposium on Acute Pancreatitis in Atlanta in 1992 [13]. Using the Atlanta classification, we calculated the organ failure score for each patient. One point each was assigned for the presence of renal failure (serum creatinine concentration > 2.0 mg/dL), respiratory failure (PaO2 < 60 mm Hg or necessitating intubation), and cardiovascular failure (systolic arterial pressure < 90 mm Hg or hemodynamic instability necessitating the use of vasopressor or inotropic agents). In our study population, the mean cumulative organ failure score among the 35 patients was 0.92 (range, 0-3) (Table 1). Among the patients with sterile necrosis (n = 22), the mean organ failure score was 1.3 (range, 0-3). Nine patients had no organ failure, three patients had single organ failure, and 10 patients had multisystem organ failure. Among patients with infected necrosis (n = 13), the mean organ failure score was 0.4 (range, 0-3). Ten patients had no organ failure, two patients had single organ failure, and only one patient had multisystem organ failure.
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CT Analysis
After IV injection of 100 mL of iopromide (Ultravist 300, Bayer
HealthCare), each patient underwent contrast-enhanced CT with a 4-MDCT scanner
(Volume Zoom, Siemens Medical Solutions) (Figs.
1A,
1B,
1C,
1D,
2A,
2B,
2C,
3A,
3B,
3C, and
3D). The interval between
admission to our hospital and the initial CT examination averaged 3.4 days
(range, 0-15): 3.7 days (range, 0-15 days) for patients with sterile necrosis
and 2.8 days (range, 0-11 days) for patients with infected necrosis. Two
radiologists (14 years and 5 years of experience interpreting abdominal and
pancreatic CT scans) in consensus reviewed the initial diagnostic
contrast-enhanced CT scans of each patient. The initial CT findings showed the
35 patients had a mean modified CT severity index score of 9.4 (range, 8-10).
Central pancreatic necrosis, defined as necrosis of the full anteroposterior
width of the pancreas, was present in 23 patients (66%): eight patients (62%)
with infected necrosis and 15 patients (68%) with sterile necrosis. No
statistically significant difference was found between the mean modified CT
severity index score and prevalence of central pancreatic necrosis among
patients with infected necrosis and those among patients with sterile necrosis
(Table 1).
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When percutaneous CT-guided needle aspiration and catheter drainage were requested for patients with coagulation deficiencies, we attempted to normalize the coagulation status before the procedure (e.g., transfusion of platelets or fresh frozen plasma, vitamin K administration). We preferred that the platelet count be 50,000/µL or higher and strove for an international normalized ratio of 1.5 or less. We did not use these guidelines as absolute thresholds. The risk of performing the procedure, including the risk of bleeding, was evaluated in the context of the need for the procedure, and decisions were rendered on a patient-by-patient basis.
The mean number of CT-guided procedures per patient was three (range, 1-7). Of 95 interventions performed, 11 (12%) were needle aspiration alone, and 84 (88%) involved both needle aspiration and catheter drainage. A total of 117 catheters were placed in 35 patients for an average of 3.3 (range, 1-9) catheters per patient during 84 CT-guided interventional procedures (mean, 2.4 catheters per procedure; range, 1-6). Tandem trocar technique was used in 64 of the 84 procedures (76%); Seldinger technique was used in 20 (24%). The total volume of fluid drained during each procedure averaged 605 mL (range, 3-3,340 mL), or 178 mL/catheter (range, 1-800 mL). The mean catheter size was 12 French (range, 7-22 French). The largest catheter placed during the initial drainage procedure was 14 French. Catheters were placed for gravity drainage, and the nursing staff routinely irrigated the catheters with 10 mL of normal saline solution every 8 hours. Although a statistically significant difference with regard to the number of interventional procedures per patient (3.5 vs 2.4, p = 0.031) was observed between patients with infected and those with sterile necrosis, no statistically significant difference was found with regard to total number of catheters per patient, diameter of catheters, or volume of fluid drained per catheter (Table 1).
Surgical Débridement
At our institution, the indications for surgical treatment of patients with
acute necrotizing pancreatitis who have already undergone percutaneous
catheter drainage include persistent systemic or local manifestations of
infected pancreatic necrosis, deterioration of clinical condition, persistent
pain, and inability to tolerate oral intake after the systemic inflammatory
response syndrome has resolved. All surgical candidates who did not improve
with percutaneous drain age alone were offered an operation. In general,
surgery was performed at least 1 month after the onset of pancreatitis.
Patient Outcome
Patient outcome was categorized into three groups: successful treatment
with percutaneous catheter drainage alone, successful treatment with
percutaneous catheter drainage and subsequent surgical débridement, and
death with or without surgery. Total length of hospital stay was defined as
the number of days of hospitalization at our institution related to the
episode of acute necrotizing pancreatitis. In addition, we recorded the length
of hospital stay after the initial percutaneous catheter drainage procedure
and the number of days elapsed before surgical dé bridement. To
calculate how long percutaneous catheter drainage procedures temporized
surgery, we assumed that if they had not undergone percutaneous catheter
drainage, patients would have been treated with surgical débridement.
Thus the time to surgery was calculated as the number of days between the date
of the first percutaneous catheter drainage procedure and the date of surgery.
Cause of death and interval between interventional procedure or surgery and
patient death were recorded. Complications related to the percutaneous
CT-guided interventional procedures also were tabulated.
Statistical Analysis
Statistical comparisons between patients with infected and those with
sterile necrosis were made with the Fisher-Holton exact test for categoric
variables and the Mann-Whitney U test for continuous variables
(Table 1). A value of
p < 0.05 was considered statistically significant.
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The effectiveness of CT-guided percutaneous catheter drainage did not differ significantly between patients with sterile and those with infected necrosis. Among 22 patients with sterile necrosis, 11 (50%) were treated successfully with percutaneous catheter drainage alone. The mean hospital stay of patients with sterile necrosis was 52 days (range, 11-137 days). Six of the 22 patients (27%) underwent surgery and ultimately had no evidence of disease; surgery was performed a median of 55 days (mean, 107 days; range, 5-447 days) after admission and a median of 31 days (mean, 100.8 days; range, 4-445 days) after the first interventional procedure. Five patients (23%) with sterile necrosis, all with multisystem organ failure, died, four before and one after surgery.
Six of 13 patients (46%) with infected necrosis were treated successfully with CT-guided catheter drainage alone. The mean length of hospital stay of patients with infected necrosis was 33 days (range, 11-68 days). Seven of the 13 patients (54%) underwent surgery after initial treatment with catheter drainage. Surgery was performed a median of 41 days (mean, 54.3 days; range, 11-121 days) after hospital admission and a median of 24 days (mean, 41.6 days; range, 3-120 days) after the first interventional procedure. Among patients with infected necrosis, one patient (8%) died before surgery.
Among 11 patients with multisystem organ failure (10 with sterile necrosis, one with infected necrosis), four (36%) were treated successfully with percutaneous CT-guided catheter drainage alone. Two patients (18%) underwent surgery after initial catheter drainage. Surgery was performed 37 and 74 days after admission and 5 and 53 days after the first interventional procedure. Among 11 patients with multisystem organ failure, five (45%) died. In contrast, among 24 patients without multisystem organ failure, 13 patients (54%) were treated successfully with CT-guided catheter drainage alone. Eleven patients (46%) underwent surgery after initial catheter drainage. Surgery was performed a median of 41 days (mean, 82.8 days; range, 5-447 days) after admission and a median of 31 days (mean, 76.2 days; range, 4-445 days) after the first interventional procedure. Among 24 patients without multisystem organ failure, only one patient died.
Surgical débridement followed percutaneous catheter drainage in the care of 13 of 35 patients (37%): seven patients with infected necrosis and six patients with sterile necrosis. Among these 13 patients, the mean multisystem organ failure index at the first interventional procedure was 0.46; three of these patients had organ failure (two patients, multisystem organ failure; one patient, single organ failure). The first interventional procedure was performed a median of 7 days (mean, 10 days; range, 1-32 days) after hospital admission; surgery was performed a median of 41 days (mean, 79 days; range, 5-447 days) after admission. Therefore, for the assumption that patients would have undergone surgical débridement as initial therapy instead of being treated with percutaneous CT-guided catheter drainage, the mean estimated interval to surgery among these patients was 34 days. At surgery, the mean multisystem organ failure index was 0.3. Multisystem organ failure resolved in one patient. One patient had persistent multisystem organ failure, and one patient who had respiratory failure at percutaneous catheter drainage that resolved had renal failure at surgery.
Complications
Complications occurred after four of 95 CT-guided interventional procedures
(4%); one of the complications was major. In a patient with sterile necrosis,
arterial blood emanated from a 14-French drainage catheter immediately after
drainage of sterile necrosis in the left upper quadrant. CT showed acute
intraperitoneal hemorrhage. Subsequent subtraction angiography showed
irregularities of the wall of the splenic artery with active contrast
extravasation; transcatheter embolization was attempted but failed. Despite
emergency surgical intervention, the patient died 1 day later. Three patients
with infected pancreatic necrosis had minor complications after CT-guided
intervention. One of these patients had a small self-limited retroperitoneal
hemorrhage; another patient experienced severe abdominal pain that responded
to analgesic medication; and another patient had a small, self-limited,
spontaneously resolving pneumothorax.
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CT-guided percutaneous catheter drain age has been found to be an effective alternative to surgical débridement in the treatment of selected patients with infected pancreatic necrosis [9-11]. Freeny et al. [9] described a series of 34 patients with acute necrotizing pancreatitis in whom the infected necrosis was managed with percutaneous catheter drain age; in 47% of the patients, in effect, the disease re solved without surgery. As important, sepsis was controlled in 74% of patients, the treatment acting as a bridge to elective surgery. Similarly, in our study, six of 13 patients (46%) with infected pancreatic necrosis were treated successfully with percutaneous CT-guided catheter drainage alone; seven patients (54%) underwent bridge care to surgical débridement. The median time between hospital admission and surgery was 41 days; therefore, initial catheter drainage allowed these patients to avoid potentially complicated early surgical intervention.
It is unclear whether severely ill patients with sterile necrosis and systemic toxicity should undergo surgical débridement or any other form of invasive therapy. It is conceivable, however, that a patient with sterile necrosis whose condition continues to deteriorate despite aggressive supportive therapy may also benefit from percutaneous catheter drainage [12, 16, 17]. In our study, 11 of 22 patients (50%) with sterile necrosis were treated successfully with primary percutaneous catheter drainage alone; six (27%) were treated successfully with initial catheter drainage followed by surgical débridement after a median interval of 31 days; and five (23%) were treated with catheter drainage but died without surgery. Although these results seem reasonable, without a randomized comparison of severely ill patients with sterile necrosis treated with and those treated without percutaneous catheter drainage, it remains difficult to draw conclusions about the benefit of primary percutaneous catheter drainage in this specific group of patients.
The median mortality rate of necrotizing pancreatitis is estimated to be 17% [1]. Infected pancreatic necrosis generally confers a higher mortality than does sterile necrosis: a median of 30% (range, 14-62%) for infected necrosis versus a median of 12% (range, 2-44%) for sterile necrosis [1]. Despite these data, we found that the presence of sterile necrosis did not confer a more favorable patient outcome. Of the six patients who died, five had sterile necrosis and only one had infected necrosis. The patients with sterile necrosis most likely had a higher mortality rate because their condition was much worse than that of patients with infected necrosis, as evidenced by their statistically significantly higher median Atlanta score. This observation supports the hypothesis, substantiated by other investigators [16, 18, 19], that multisystem organ failure is a more reliable indicator of poor patient outcome and severity of severe pancreatitis than is the presence of infected necrosis.
The prevalence of organ failure in acute necrotizing pancreatitis has been reported to be 54% (range, 29-78%) [1]. Patients with no organ failure have a 0% mortality rate; those with single organ failure have a median mortality of 3% (range, 0-8%); and those with multisystem organ failure have a median mortality rate of 47% (range, 28-69%) [1]. In our study, among 11 patients with multisystem organ failure, five (45%) died. Therefore, although primary CT-guided percutaneous catheter drainage can be used successfully to treat approximately one half of patients with acute necrotizing pancreatitis and systemic toxicity, it does not appear to reduce mortality among patients with multisystem organ failure [1].
As suggested by our data, successful treatment of patients with acute necrotizing pancreatitis and systemic toxicity is labor intensive. These patients often need several procedures that can involve multiple catheter insertions during each procedure. Vigilant follow-up is warranted, including daily rounds by the interventional radiologist with assessment of the patient's vital signs, WBC count, and catheter drainage output. Each catheter should be irrigated with sterile saline solution at least three times a day. Abdominal CT should be performed periodically on the basis of clinical status and amount of drainage to check for residual and undrained fluid collections. The CT findings help determine whether drainage is adequate or additional catheters should be placed.
Our study had several limitations, including the relatively small sample size and retrospective nature. Nevertheless, to the best of our knowledge, this series is the largest reported to date, and the study is the only comparison of the clinical utility of CT-guided percutaneous catheter drainage in patients with sterile pancreatic necrosis and those with infected pancreatic necrosis. Furthermore, our study is the only evaluation, to our knowledge, of the effect of the presence of multisystem organ failure on the outcome of percutaneous catheter drainage in patients with acute necrotizing pancreatitis. Another potential limitation was the variability of experience among the interventional radiologists and surgeons involved in the treatment of these patients. Variation in experience is inherent to any retrospective study of the value of an interventional or surgical procedure. Nevertheless, at our institution, we try to minimize variability by adhering to general approaches that are reviewed periodically in consensus.
In our experience, CT-guided percutaneous catheter drainage is effective in the definitive treatment of approximately one half of patients with necrotizing pancreatitis. Further more, in our experience, the presence of multisystem organ failure appears to be a more important indicator of patient outcome in severe pancreatitis than is the presence of infection.
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