TOC | ID | AIDS
Lung Disease in Patients with AIDS - Written by: Lois J. Geist, M.D.
A 27 year old Hispanic man with a history of asthma during childhood presents to the pulmonary clinic at the University of Iowa Hospitals and Clinics with a two week history of dyspnea on exertion that has not been relieved by an inhaled bronchodilator.
He was in his usual state of health until the gradual onset of dyspnea two weeks prior to presentation. He reports recurrent lowgrade fevers, chills and a 10 to 15 pound weight loss despite having a good appetite. He denies cough, hemoptysis or sputum production. His past medical history is remarkable for mild asthma as a child. He has never used corticosteroids, required hospitalization, or been intubated because of an asthma exacerbation. His only current medication is the inhaled bronchodilator that was prescribed two weeks before this presentation. He is a student who is a native of Puerto Rico and has lived in Iowa for five months. He has a 15 pack-year smoking history. He has had multiple male and female sexual partners. He denies intravenous drug use.
An alert, pleasant Hispanic male in mild respiratory distress, not using accessory muscles of respiration.
VS: Pulse 104, regular Respirations 24 BP 110/70 Temperature 37.8, oral
Skin: No lesions noted
Lymph: Small mobile nodes in the anterior cervical chain; small bilateral axillary nodes, nontender and freely mobile
HEENT: Eye grounds clear without exudates or hemorrhages; no oral lesions noted
Neck: Supple; adenopathy as noted
Lungs: Scattered crackles at the bases; no wheezes, rhonchi or consolidation
Cor: Tachycardia without murmurs, rubs or gallops
Abd: Normal bowel sounds; flat; nontender; no hepatosplenomegaly
Ext: No cyanosis, clubbing or edema
Neuro: Normal mental status; cranial nerves II-XII intact; normal strength, reflexes, sensation, and cerebellar exam
Labs: WBC: 10.5 x 103/mm3; no left shift,lymphocyte count normal, CD4: 20, General screen remarkable for: AST increased, ALT increased
CXR: Diffuse pulmonary infiltrates
ABG on room air: pH: 7.48, pCO2 34, pO2 65
Because of concern that the patient was immunocompromised with a pneumonia, he underwent bronchalveolar lavage (BAL). Silver stain demonstrated Pneumocystis carinii organisms.
Pulmonary disease is common in patients with AIDS, and it is frequently the initial infectious manifestation. The differential diagnosis in these patients is large. Our patient is clearly immunocompromised as evidenced by the low CD4 count, despite a normal lymphocyte count. He therefore meets diagnostic criteria for AIDS. In addition, with his pulmonary infiltrates, he likely has an AIDS-defining illness.
In patients who have HIV, the most common cause for chest disease is actually the encapsulated organisms, such as Strep. pneumoniae and Hemophilus influenza. The most frequent opportunistic infection in these patients is Pneumocystis carinii. Other important pulmonary infections include mycobacterial disease (typical and atypical), viral infections (e.g., cytomegalovirus), and fungal infections such as Histoplasmosis.
Most patients with AIDS will develop infection with Pneumocystis unless they receive prophylaxis. P. carinii is exclusively a pulmonary pathogen, with no known environmental reservoir. There are rare reports of dissemination. The infection tends to be intra-alveolar, with the development of a frothy proteinaceous exudate without a significant inflammatory component. A monocytic infiltrate develops in the lung interstitium. It appears that P. carinii pneumonia (PCP) results from reactivation of a latent infection as the immune system function declines. The infection appears to result primarily from a cell mediated defect. The infection does not occur in immunocompetent patients. The majority of infections in HIV infected individuals occur when the CD4 count is <100/mm3. Patients will frequently present with fever, nonproductive cough and dyspnea. Pleurisy is unusual. The illness usually progresses gradually, and patients will often present after an extended illness. However, some patients present with a fulminant clinical course that rapidly progresses to respiratory failure.
The physical exam may be normal or the lung exam may reveal fine rales or wheezes. The CXR can be normal in up to 10 percent of patients. The remaining 90 percent most often have:
Less commonly, patients can present with pneumothorax. Even with a normal CXR, hypoxemia with an increased A-a gradient is very common.
Diagnosis of Pneumocystic carinii
The diagnosis of PCP can be made in a number of ways.:
Once obtained, the sample is stained with Gomori's methenamine silver stain. The cyst form takes up the stain, and the organism is identified as black rings. P. carinii organisms are of varying sizes, often with indentations leading to the designation of a "helmet shape". The organism is differentiated from Histoplasma capsulatum by its larger size. Cytology preparation of the lavage may also show the amorphous pink material from the alveoli with the appearance of negative images where the organisms are located.
Treatment of PCP
Primary Therapy :
Trimethoprim/sulfamethoxasole (TMP-sulfa, Bactrim, Septra) is the first line drug.
Unfortunately, many patients (as many as 50 percent) with HIV infection have idiosyncratic responses to sulfonamide therapy that results in drug withdrawal and necessitates the use of another agent. These adverse reactions include fever, rash neutropenia, and hepatitis. The reactions are usually delayed (seven to 14 days) after the initiation of therapy. This adverse reaction rate is much higher than that seen in other immunocompromised patients.
Pentamidine given intravenously or intramuscularly is the second line therapy for patients who do not tolerate sulfonamide. Unfortunately, this drug can result in life threatening complications, including hypoglycemia, hypocalcemia, cardiac arrhythmias, thrombocytopenia and neutropenia.
Because the immune defect does not resolve, those patients who survive PCP require suppressive therapy once the acute course of treatment is completed. In patients with HIV who develop respiratory compromise with hypoxemia secondary to P. carinii infection, the use of corticosteroids early in the course increases survival and improves exercise tolerance. It is not entirely known how steroids benefit patients, although it is thought that the anti-inflammatory effects of steroids play a role in improving lung function.
Once the CD4 counts fall below 200/mm3 or after treatment of a primary infection, prophylactic aerosolized pentamidine is started. Pentamidine is used rather than sulfonamides because of the high incidence of adverse effects to oral Bactrim. These patients can be treated with weekly to monthly pentamidine to prevent the development of PCP.
1. Murray, J. F. and J. Mills. 1990. Pulmonary infectious complications of human immunodeficiency virus infection. Am. Rev. Respir. Dis. 141:1356-1372 (part 1) and 141:1582-1589 (part 2).
This review provides an excellent overview of the wide range of pulmonary infections which can occur in this patient population. It also provides a handy reference for therapeutic approaches to the various infections. It does not contain an update of the newer drugs being used for prophylaxis of the infection itself.
2. Masur, H. 1992. Prevention and treatment of pneumocystis pneumonia. N. Engl. J. Med. 327:1853-1860.
A good review of the current therapeutic approaches for both prophylaxis and treatment with a broader discussion of other drug options than in the case history.
3. Zaman, M.K., O.J. Wooton, B. Suprahmanya, W. Ankobiah, P.J.P. Finch, and S.L. Kamholz. 1988. Rapid noninvasive diagnosis of Pneumocystis carinii from induced liquefied sputum. Ann. Int. Med 109:7-10.
Gives a nice perspective for the use of induced sputum in the diagnosis of pneumocystis. Also describes the induced sputum technique.
4. Kovacs, J.A. et. al. 1984. Pneumocystis carinii pneumonia: a comparison between patients with the acquired immunodeficiency syndrome and patients with other immunodeficiencies. Ann. Int. Med. 100:663-671.
Provides some insight into the salient differences in presentation and outcome of different patient population. An early study which continues to have clinical relevance.
5. Mottin, D., M. Denis, and H. Dombret, et al. Role for steroids in treatment of Pneumocystis carinii pneumonia in AIDS. Lancet 2:519, 1987.
Prospective study using steroids in AIDS patients with respiratory failure from PCP.
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