Human Immunodeficiency Virus in the Intensive Care Unit
Aruna Sree
Raul Davaro
I. GENERAL PRINCIPLES
A. In the era of combined antiretroviral therapy (ART), the spectrum of patients with human immunodeficiency virus (HIV) infection admitted to the intensive care unit (ICU) falls into three general categories.
1. Acquired immunodeficiency syndrome (AIDS)-related opportunistic infections.
2. Complications related to ART.
3. Medical problems unrelated to HIV infection.
B. Respiratory failure has been the most common cause of ICU admission, both in the AIDS epidemic and in the ART era. The other causes include sepsis, neurologic disorders, and end-stage liver disease.
1. Bacterial pneumonias and acute respiratory distress syndrome (ARDS) are the most common cause of respiratory failure. Patients with AIDS may have more than one opportunistic infection simultaneously.
2. Pneumocystis jirovecii pneumonia (PCP) incidence has been declining since the introduction of ART, and obstructive airway disease is increasing.
3. Tuberculosis (TB), fungal infection, and noninfectious HIV-associated pulmonary disorders are other common complications in patients with HIV infection admitted to the ICU.
C. There is increased incidence of sepsis and sepsis-related mortality in the ART era.
D. HIV patients coinfected with hepatitis B or hepatitis C have more severe liver disease. End-stage liver disease is a leading cause of mortality in the coinfected patients, despite of their better immunovirologic status.
II. PNEUMOCYSTIS PNEUMONIA
A. Etiology.
1. Caused by soil-based fungus, P. jirovecii.
2. Distribution: worldwide.
B. Pathogenesis.
1. PCP almost always occurs in patients with absolute CD4 counts <200.
C. Diagnosis.
1. Patients with PCP complain of progressive dyspnea, nonproductive cough, and low-grade fever.
2. The physical examination often reveals tachypnea, crackles, and trending hypoxemia. Although unusual, PCP can sometimes rapidly lead to acute respiratory failure.
3. The classic radiologic pattern in patients with PCP is diffuse alveolar or interstitial pulmonary infiltrates; however, almost every conceivable radiographic pattern has been reported.
4. Definitive diagnosis is by identification of organisms in pulmonary secretions or lung tissue. Sputum induction has a sensitivity of 55% to 94%. If sputum is negative, then bronchoscopy with bronchoalveolar lavage (BAL) should be performed. BAL has a sensitivity of 89% to 98%.
5. The sensitivity of PCR for bronchoalveolar lavage appears to be high although the ability to distinguish colonization from disease is less clear.
6. 1,3ß-D-glucan (a component of fungal cell walls) may be elevated in patients with PCP, but the assay’s sensitivity and specificity for establishing a PCP diagnosis are problematic because other fungal diseases can produce elevation.
TABLE 68-1 Treatment of Moderate to Severe PCP | ||||||||||||
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D. Treatment (Table 68-1).
1. Trimethoprim-sulfamethoxazole (TMP-SMX) is the treatment of choice for moderate to severe PCP. TMP-SMX is dosed at 15 to 20 mg/kg/d of TMP in three or four divided doses for 21 days.
2. In patients with life-threatening reactions to TMP-SMX (Table 68-1), pentamidine isethionate is the preferred alternative therapy. Pentamidine is administered as a single daily dose of 4 mg/kg intravenously.
3. In patients with arterial oxygen pressure <70 mm Hg, or A-a gradient >35 mm, adjunctive therapy with steroids reduces mortality—give prednisone 40 mg PO bid on days 1 to 5, 40 mg PO daily on days 6 to 10, and 20 mg PO daily on days 11 to 20.
III. TUBERCULOSIS
A. General principles.
1. HIV increases the risk of developing active TB.
2. Drug-resistant TB is more common in patients with HIV.
B. Etiology.
1. Caused by infection with Mycobacterium tuberculosis.
C. Pathogenesis.
1. In patients with HIV infection, TB can occur as a reactivation of latent disease or from newly acquired infection.
2. HIV-positive patients with latent TB infection have a 7% to 10% annual risk for developing active disease.
D. Diagnosis.
1. Clinical features.
a. Patients with high CD4 cell counts (>400/mm3) tend to have similar presentations to those without HIV (upper lobe disease, low risk of extrapulmonary dissemination).
b. Patients with AIDS tend to have disseminated disease with prominent constitutional symptoms.
c. Sometimes patients may present with ARDS or sepsis syndrome with multisystem organ failure.
