Follow-up paracentesis is recommended after 48 hours of antibiotic therapy to assess
response: a fall>25% in the number of ascites PMN cells is considered a success (32).
However, antimicrobials are not the only means of management: because renal impairment
secondary to decreased intravascular volume is a major cause of mortality in SBP, further
management may be aimed at preventing this fluid shift. The addition of albumin to an
antibiotic regimen has been shown to decrease in-hospital mortality almost two-thirds from
28% to 10%. It is considered especially beneficial for patients with already impaired renal
function and a creatinine>91 mmol/L, or advanced liver disease as evidenced by serum
bilirubin>68 mmol/L (33). Nevertheless, the future outlook for patients with SBP is bleak:
of those that survive the initial episode 30% to 50% will survive one year further, and only
25% to 30% will live a second year. Given these odds, patients with a history of SBP should
be considered for liver transplantation, as well as long-term antibiotic prophylaxis in the
interim (33).
Prophylaxis
On weighing the cost of antimicrobials and the threat of inducing antibiotic resistance against
the gravity of SBP, prophylaxis is indicated only for patients with the highest risk, namely,
those with a previous episode of SBP, ongoing gastrointestinal bleeding, or an ascitic fluid
protein <10 g/L. Fluoroquinolones, such as norfloxacin and ciprofloxacin, are the
antimicrobials recommended for prophylactic purposes (33). In cirrhotic patients with ascites
lacking these risk factors, the one- and three-year incidences of SBP are 0% and 3%
respectively, and do not justify regular long-term prophylaxis (32).
INFECTIOUS COMPLICATIONS OF PANCREATITIS
Pancreatitis is a serious but generally self-limited disorder that spontaneously resolves in 48 to
72 hours for the great majority of patients; however, 20% will develop severe acute pancreatitis
as defined by the presence of three or more Ranson criteria (38). Among this subset, infected
pancreatic necrosis is the leading cause of death (39).
Presentation and Diagnosis
In addition to the typical signs and symptoms of pancreatitis, such as moderate epigastric pain
radiating to the back, vomiting, tachycardia, fever, leukocytosis, and elevated amylase and
lipase, patients with severe acute pancreatitis present with relatively greater abdominal
tenderness, distension, and even symptoms of accompanying multiorgan failure (38). In these
patients, the intensivist must maintain a high level of clinical suspicion for necrosis and
possibly infection as well. CT scan with intravenous contrast is 80% to 90% sensitive for the
detection of necrotic areas as a focal lack of enhancement (40). Infection is estimated to develop
in 30% to 70% of patients with necrotic pancreatitis (40). However, necrosis both with and
without infection often manifest with similar clinical presentations because necrosis alone
causes a systemic inflammatory response, and additional diagnostic data is generally needed
to differentiate these (41). Although CT only rarely shows gas bubbles as evidence of necrotic
infection, CT-guided percutaneous aspiration of necrotic areas is 90% sensitive in yielding a
diagnosis of this complication, and by sampling multiple necrotic areas in a diffusely necrotic
pancreas, detection may be higher still (40).
Enterococcus species are the organisms most frequently isolated, although many different
pathogens includingCandidaspp. andPseudomonas aeruginosaare frequently seen (38,42).
Treatment and Prophylaxis
The distinction between sterile and infected necrotic pancreatitis is crucial, as the former may
be handled medically when necrosis affects less than 30% of the organ, whereas the latter often
demands surgical debridement (38). Patients with infected necrotic pancreatitis will return to
the operating room for an average of two to three operations as determined necessary by
recurrence of clinical signs and symptoms combined with evidence from follow-up
postoperative CT scans (41). Recently, several studies have explored the potential of
laparoscopy for infectious pancreatic necrosis, but this approach is rarely feasible in instances
of extensive necrosis, and data is not yet sufficient to compare the safety and efficacy of
Intra-abdominal Surgical Infections and Their Mimics in Critical Care 267