tis) or primary CNS lymphoma. Painless visual loss occurs

with CMV retinitis.

Gastrointestinal complaints. Difficulty swallowing

occurs with candidal esophagitis, and failure to improve

with fluconazole (Ditlucan) suggests CMV or herpes

esophagitis. Acute diarrhea may be caused by bacteria ( eg,

Salmonella), whereas chronic diarrhea may represent a

parasitic ( eg, Giardia, Cryptosporidium) or viral ( eg, CMV)

cause. Pancreatitis and kidney stones most often occur as a

result of antiretroviral therapy.

� Physical Examination

A comprehensive physical examination may not only help

provide a general picture of the overall health of the

patient, it can also help identify the source for any acute

presenting complaint. Some key systems to examine

include:

Vital signs. History of fever at home requires a workup, even if the patient is afebrile in the ED. Tachypnea and

hypoxia suggest PCP.

General appearance. Assess for respiratory distress.

Wasting, dehydration, and parietal hair loss are common in

patients with advanced AIDS.

Head and neck. Assess visual acuity and perform

funduscopic examination for possible CMV retinitis ("ketchup

and mayo" retinal findings). Perform oral examination for

Figure 37·1. Photograph showi ng patient with oral

ca ndid iasis.

candidiasis (thrush) and oral hairy leukoplakia (Figure 37-1).

Assess the neck for lymphadenopathy or meningismus.

Pulmonary. Auscultate for rales, rhonchi, or wheezes;

however, many patients with PCP will have normal breath

sounds.

Cardiovascular. Listen for new murmurs, suggesting

endocarditis, especially in the N drug user.

Gastrointestinal. Examine for evidence of peritonitis,

pancreatitis, or hepatobiliary disease, which may occur secondary to acute infection or antiretroviral medications.

Neurologic. Assess mental status and any focal deficits

(present in up to 60o/o of patients with toxoplasmosis,

though absent in many cases of cryptococcal meningitis).

Skin. Examine for Kaposi sarcoma, cellulitis, abscesses,

evidence of disseminated infection (endocarditis, fungal

disease, dMAC), or drug reactions.

DIAGNOSTI C STUDIES

� Laboratory

Complete Blood Count. Use the absolute lymphocyte

count as a correlation for the CD4 count. If the CD4 count

is unknown, an absolute lymphocyte count (ALC) can be

used to predict the CD4 count. The ALC is equal to the total

white blood cell count multiplied by the percentage of lymphocytes. An ALC of< 1 ,000/!!L predicts a CD4 count <200/

!!L. An ALC of >2,000/!!L predicts a CD4 count >200/!!L.

CHAPTER 37

Chemistry. Useful in patients with prolonged diarrhea,

dehydration, or wasting to assess glucose level, electrolytes,

and renal function. Can be helpful in patients presenting

with abdominal pain to check for lactic acidosis.

Liver profile, lipase, lactate dehydrogenase. In patients

with abdominal pain and j aundice. Lactate dehydrogenase

(LDH) is also useful in patients with s uspected PCP. Elevation

> 220 IU /L in patients with shortness of breath suggests PCP

(94% sensitive), and a normal LDH level suggests an alternative diagnosis.

Blood cultures. In patients with a fever without a

source and for suspected serious bacterial (including

mycobacterial), viral, or fungal infections.

Urine. Obtain a urinalysis and urine culture in all

febrile patients without a source. Many AIDS patients have

urinary tract infections without localizing symptoms. The

urinary histoplasma antigen can be useful in detecting disseminated histoplasmosis.

StooL Check for leukocytes, bacterial culture, ova, and

parasites (including microsporidia, Cryptosporidium, Isospora,

and Cyclospora) in patients with diarrhea or bloody stools.

Some causes of diarrhea may require biopsy for diagnosis.

Blood gas. An arterial blood gas should be performed

for patients with pulmonary complaints. Patients with

PCP and an elevated A-a gradient (>35 mmHg) or low

Pa02 ( <70 mmHg on room air) are candidates for adjunctive steroid therapy.

Viral load. Rarely used emergently to establish risk of

opportunistic infection.

.... Imaging

Chest x-ray. All HN-positive patients with pulmonary

symptoms or fever without a source. PCP classically shows

diffuse bilateral interstitial infiltrates, but findings vary

widely and can be normal (39%) or indistinguishable from

bacterial pneumonia (Figure 37-2).

Head computed tomography ( CT) scan with contrast.

All patients with neurologic symptoms (Figure 37-3).

Brain magnetic resonance imaging (MRI) with contrast. Consider for patients with focal neurologic findings

but minimal or only subtle changes on head CT. Some

lesions of progressive multifocal leukoencephalopathy

(PML) or toxoplasmosis are seen only on MRI.

Abdominal CT scan and ultrasound. Immuno suppression masks normal inflammatory responses to serious

intra-abdominal pathology such as appendicitis and biliary

disease. Maintain a low threshold for imaging patients with

abdominal pain.