14
Intra-abdominal Surgical Infections and Their
Mimics in Critical Care
Samuel E. Wilson
Department of Surgery, University of California, Irvine School of Medicine, Orange, California, U.S.A.INTRODUCTION
Postsurgical patients in the intensive care unit (ICU) often confront a myriad of medical and
new surgical complications. Among these, intra-abdominal infections remain the most
formidable adversary, affecting an estimated 6% of all critically ill surgical patients. Organ
dysfunction continues to be a major manifestation of these infections, resulting in a high
mortality of 23% (1). Yet, the literature is relatively sparse in recommendations for diagnosis in
management. In updating this chapter, a search of PUBMED for “Intraabdominal infection and
ICU” disclosed only 37 articles published between 1989 and 2008, many of which were
tangential or simply not relevant. Also, we have not included management of the “open
abdomen” in our discussion, focusing instead on specific diseases.
Intra-abdominal infection in the surgical ICU (SICU) patient may occur as a complication
of a previous condition or arise de novo. In either event, it is evident that the critically ill
patient is predisposed to a different set of disease states and pathogens than the clinician might
routinely encounter. Moreover, given the complex background of concomitant illnesses in
these individuals, physicians must be prepared to interpret a variety of atypical presentations.
The burden of the diagnostician in the care of the ICU patient, however, remains not only of
sensitivity but also of specificity; accordingly, the physician must be alert to a variety of clinical
pictures that may masquerade as abdominal infection in the SICU patient. In this chapter, we
review the unique characteristics of intra-abdominal infections in critically ill patients, as well
as the challenges faced in their diagnosis and treatment.
TERTIARY PERITONITIS
With a startling mortality of 20% to 50%, the diagnosis and treatment of tertiary peritonitis has
remained a source of intense research for two decades (2). Tertiary peritonitis, or intra-
abdominal infection persisting beyond a failed surgical attempt to eradicate secondary
peritonitis, represents a blurring of the clinical continuum, often characterized by the lack of
typically presenting signs and symptoms. Nevertheless, prompt diagnosis is essential for cure,
and given the grim propensity of this complication to strike already critically ill patients—
rapidly devolving into multi-organ system failure—the intensivist should be equipped with
the necessary knowledge to suspect, confirm, and treat this serious illness.
Early Recognition
The gradual postoperative transitional period between a diagnosis of secondary and tertiary
peritonitis causes the clinical presentation of tertiary peritonitis to be quite subtle. Moreover,
because patients are frequently sedated, intubated, or otherwise incapacitated, history and
physical exam in the early stages of disease are often an insensitive means to a diagnosis.
Therefore, the physician must pay particular attention to those secondary peritonitis patients
whose conditions place them at risk, including malnutrition and the several variables detailed
under the acute physiological and chronic health evaluation score (APACHE) II scoring system
such as age, chronic health conditions, and certain physiologic abnormalities while in the
ICU (3). In these individuals, fever, elevated C reactive protein (CRP), and leukocytosis—
although admittedly nonspecific in the postsurgical patient—should be addressed quickly and
assertively, even when lacking other evidence of infection such as abdominal tenderness and
absent bowel sounds (3). As one might reasonably predict, clinical evidence of tertiary
peritonitis becomes increasingly more obvious the farther the disease has progressed,