Chapter 26 ICU Infections

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SECTION II • Medical and Surgical Crises

(particularly for visualizing the sphenoid sinus), CT of the head with attention directed to the sinuses is the preferred method of diagnosis. The best treatment for nosocomial sinusitis is prevention. Raising the head of the bed to a more physiological position may promote sinus drainage. Whenever possible, insertion of ostia-obstructing tubes into the nose should be avoided. For orally intubated patients, a standard orogastric tube can be placed easily for aspiration of the stomach, medication delivery, or feeding. Surprisingly, the incidence of acute sinus infection may be simi- lar for nasotracheal and orotracheal intubations. Once infection is established, however, nasal tubes and catheters impede ostial drainage and should be extracted or exchanged for one that is orally inserted. Orogastric passage does not increase the level of patient discomfort and avoids the problems of ostial obstruction. When feeding tubes must be inserted through the nose, small-bore, flexible cath- eters are preferable. Most cases of sinusitis respond to tube removal, decongestants, and antibiotics. Specific bacteriologic diagnosis can be established by endoscopic sampling of fluid from the middle meatus, a procedure that is generally better tolerated than direct puncture of the sinus cavity. Because important pathogens include pseudomonas, acineto- bacter, and staphylococci, empiric antibiotic selec- tion should include an antistaphylococcal penicillin and an agent appropriate to those gram negatives. For community-acquired sinusitis, H. influenzae is a common etiologic organism that often requires therapy with a β -lactamase–resistant drug, such as a third-generation cephalosporin. Adjunctive treat- ments may include decongestants, corticosteroids, and irrigation, but their efficacy in resolving a serious bacterial infection is not well established. Surgical intervention may be necessary for patients with sup- purative complications of sinusitis (e.g., retro-orbital cellulitis, osteomyelitis, and brain abscess).

often progress rapidly, but most patients with bac- terial meningitis are ill for days beforehand. The presentation often is subtle in the ICU, where intu- bation and sedation limit communication. Fever, leukocytosis, and an otherwise unexplained change in mental status may be the only clues. When men- ingitis results from malignancy, tuberculosis, or fun- gal infection, the clinical picture is even subtler and more likely to include focal neurologic deficits and perhaps seizures. Although focal deficits are possi- ble with uncomplicated meningitis, the presence of focal lesions should raise the possibility of an under- lying or complicating brain abscess, subdural empy- ema, or epidural abscess. Bacterial meningitis may be mimicked by several noninfectious conditions, including: drug reactions to trimethoprim–sulfa- methoxazole, ibuprofen, and OKT3; carcinomatous meningitis; subarachnoid hemorrhage; systemic lupus; and sarcoidosis. Organisms The microbiologic etiology varies with the site of acquisition (community vs. hospital) and patient age. The Pneumococcus remains the most common organism in community-acquired adult meningi- tis. Sinusitis, otitis, pneumonia, and endocarditis coexist frequently. Neisseria meningitidis is the sec- ond most frequent cause of sporadic meningitis. Nontypeable strains of H. influenzae represent the third. Although unusual in any setting, Listeria and enteric Gram-negative rods are especially rare when meningitis is acquired outside the hospital; how- ever, in hospital-acquired meningitis, S. aureus or S. epidermidis and enteric Gram-negative rods are the leading etiologies, particularly following brain surgery. Diagnostic Techniques Examination and culture of spinal fluid offer the only conclusive method of diagnosing meningitis. In the absence of papilledema or focal neurologic defi- cits suggestive of a mass lesion, lumbar puncture (LP) may be performed safely without CT scanning. (Full-dose anticoagulation, uncontrolled coagulopa- thy, and significant thrombocytopenia constitute other relative contraindications to LP.) An LP may be impossible technically because of poor patient cooperation or lumbar disease. In such patients, LP under fluoroscopy or cisternal puncture may secure a specimen of spinal fluid.

Meningitis Diagnosis

Bacterial meningitis should be suspected in all patients with mental status changes, fever, and signs of meningeal irritation. Suspected bacterial menin- gitis is a genuine medical emergency that demands a precipitous workup and immediate broad-spectrum coverage. When neurologic symptoms begin, they