THORACIC AND RESPIRATORYDISORDERSCOMPLICATIONS
Endocarditis or hepatitis
Pneumocystis Pneumonia
CAUSES
PCP results from reactivation of a previously acquired Pneumocystis jiroveci
(formerly carinii) infection in an immunocompromised host (eg, HIV,
transplant). It is the most common AIDS-defining illness in HIV+patients
with a CD4 count < 200.
SYMPTOMS/EXAM
■ Symptom progression over a 2- to 3-week period
■ Dyspnea, dry cough
■ Low-grade fever
■ Hypoxic, tachypneic, tachycardic
■ The patient may have normal lung sounds or rales.
DIAGNOSIS
■ CXR:May be normal if early in the disease process or may have a classical
bilateral interstitial infiltrate that projects out from the perihilar region
■ Chest CT:More sensitive than CXR in early disease.
■ Ambulatory pulse oximetry:If CXR is normal but diagnosis is suspected.
■ O 2 desaturation to <90% with ambulation is enough to initiate treatment.
■ An LDH >450 is common, and the degree of elevation is prognostic.
■ Immunofluorescent stainingof sputum or BAL sample (gold standard) is
confirmative.
TREATMENT
■ TMP-SMXis the preferred agent.
■ High-dose oral therapy (two DS tabs TID) may be used for patients
with mild or early disease.
■ IV therapy should be given to all admitted patients.
■ Second-line agents include pentamidine or dapsone.
■ Steroidsare also considered first-line adjuvant therapy in patients with PO 2
<70 mmHg and/or an A–a gradient >35.
Tuberculosis
Approximately one-third of the world’s population is infected with TB; how-
ever, only about 10% of infected hosts develop active disease.
CAUSES
■ Mycobacterium tuberculosis, a slow-growing aerobic rod
■ Transmitted human-to-human via respiratory droplets
■ Humans are the only natural reservoir and usually must be in confined
environments over extended periods of time to transmit the disease.
■ See Table 10.12 for TB risk factors.
PATHOPHYSIOLOGY
■ Primary infectionin immunocompetent host →small number of organisms
contained in gramulomas or spread through the body →latent (dormant)
infectionand+PPD.