- Patterns of presentation of the acute abdomen in the intensive care unit (ICU) may be unusual.
- Conjoint evaluation by intensivist, surgeon, and gastroenterologist is frequently needed.
- Prompt diagnosis is the key to successful management.
- Computed tomography (CT) or ultrasonography should be used liberally in the evaluation of intra-abdominal sepsis.
- Complications occur frequently in the postsurgical ICU patient; “stable vital signs" does not imply clinical stability.
- Postoperative residual or recurrent intra-abdominal sepsis may not be clinically obvious and may not be demonstrated by a CT scan; cardiorespiratory instability should prompt a high level of suspicion.
- The treatment of the febrile postsurgical patient is not simply the administration of further antibiotics.
- Acalculous cholecystitis is a treacherous disease which requires urgent treatment; definitive diagnosis is not always possible or necessary before treatment.
Patients with an “acute abdomen” present challenging problems for surgeons and intensivists. The term acute abdomen refers to a patient whose chief presenting symptom is the acute onset of abdominal pain. The vast majority of these patients present in the emergency department and do not require treatment in an ICU. However, the small percentage of patients who do require such treatment constitute a significant fraction of the surgical ICU patients in most general hospitals. Furthermore, the intensivist must be aware that an ICU patient may develop an acute abdomen while being treated for some other condition.
In this chapter, we will first discuss the approach to the ICU patient who develops abdominal pain while undergoing treatment for some other disorder. The bulk of the chapter, however, will be directed to the patient with known intra-abdominal sepsis (IAS) who requires intensive care. Emphasis will be placed on the early diagnosis of intra-abdominal septic complications.
The diagnosis of abdominal pain depends heavily on an accurate history and a complete physical examination.1 Both of these sources of data may be severely limited in the ICU patient. History may be unobtainable because of intubation or a decreased level of consciousness. Physical examination is made difficult by the many tubes emanating from the patient, and may be further compromised by medications such as corticosteroids. Indeed, abdominal pain itself may be masked by narcotics or other painful disease processes. Some physical signs, such as the absence of bowel sounds, which would be considered significant in an otherwise well patient, may not be significant in an ICU patient, in whom multiple extra-abdominal causes of ileus may be present. Hence, in the ICU setting, it is rare that an abdominal complaint comes to light because the patient complains of abdominal pain; rather, the physician usually must infer its presence on the basis of nonspecific findings such as unexplained sepsis, hypovolemia, and abdominal distention.
Table 89-1 provides an abbreviated summary of the many causes of acute abdominal pain. Rather than describing a complete algorithm for the diagnosis of these conditions in ICU patients, we will list some important principles.