Overview of human immunodeficiency virus (HIV)
Human immunodeficiency virus (HIV), also known as HIV, is a rapidly spreading disease that destroys CD4+ T-cells, leading to impaired cellular immunity and severe opportunistic infections and tumors. The disease spreads rapidly, has a slow onset, and has an extremely high case fatality rate.HIV-associated pulmonary infections may present with fever, tachycardia, and cyanosis. Chest radiographs can provide clues to the diagnosis of HIV lung infection and inform the choice of diagnostic steps.
Etiology
The cause of the high incidence of pulmonary infections in people with HIV/AIDS is not fully understood. Recent studies have found that alveolar macrophages are also one of the target cells attacked by HIV, with no decrease in cell number but a decrease in cell function (antigen presentation, etc.); the ratio of T4H/TS in bronchoalveolar lavage fluid is decreased, and TS is elevated; there is a linear correlation between HIV viral load and CD4 cell depletion, and CD4 cells in the blood are an important indicator for predicting the likelihood of immunodeficiencies and opportunistic infections in the lungs, as well as the type of infection and its pathogen profile. pathogen spectrum are important indicators.
Symptoms
Respiratory symptoms are quite common in people with HIV/AIDS who have lung infections, the incidence of which increases with decreasing CD4+ counts, and the clinical presentation lacks diagnostic specificity because respiratory symptoms such as cough and dyspnea can occur in HIV-infected patients with other complications. However, certain clinical symptoms can be helpful in providing diagnostic clues, such as the nature of the cough, which is usually considered bacterial pneumonia, or a dry, sputumless cough, which is more common in Pneumocystis carinii pneumonia (PCP).
Tests
1. Blood tests
In HIV-infected patients with bacterial lung infections, the blood white blood cell count is elevated from basal values (because the basal white blood cell counts of HIV-infected patients are often lower than normal), and the nucleus is shifted to the left. the risk of bacterial and fungal (e.g., Aspergillus) infections of the lungs is markedly increased in HIV associated with agranulocytosis.
2. Serum lactate dehydrogenase (LDH)
Serum LDH is usually elevated in PCP, but can be elevated in other lung diseases (e.g., bacterial pneumonia and tuberculosis) or in non-pulmonary diseases, and therefore lacks specificity.LDH has a high sensitivity in patients with severe PCP, and is poorly sensitized in patients with less severe PCP.The LDH value correlates with the response to treatment for PCP and with prognosis.
3. Arterial blood gas
HIV-infected patients with concomitant pulmonary infections usually have arterial blood gas abnormalities, such as hypoxemia and increased alveolar-arterial oxygen partial pressure difference [PO2(A-a)]. Carbon dioxide alkalosis, but lacks diagnostic specificity. In the case of PCP, it is helpful in determining prognosis and deciding whether to admit to the hospital, or whether to use glucocorticoids.
4. Other auxiliary examinations
(1) Chest X-ray Chest X-ray can provide clues for the diagnosis of HIV combined with various infections in the lungs, and provide reference for the selection of diagnostic steps.
(2) Chest CT examination is helpful in the differential diagnosis of multiple lung lesions. As immunodeficiency can be combined with various opportunistic lung infections at different stages of the immunodeficiency, it can be any type of infection with various pathogen spectrums, which leads to many variations of lung lesions, including limited, diffuse, nodular, mass, cavity, interstitial and/or mixed lesions with pleural effusion and enlarged lymph nodes. If the majority of nodules are less than 1 cm in diameter and centrally distributed along the bronchioles, they are usually opportunistic lung infections; if they are accompanied by intrathoracic lymph node enlargement and the nodules are larger than 1 cm, then neoplastic organisms are considered. Kaposi’s sarcoma is often associated with peribronchial vascular widening in addition to intrapulmonary nodules.
Diagnosis
China has entered a period of rapid increase in the prevalence of HIV infection, and clinicians are relatively inexperienced in diagnosing HIV/AIDS. Therefore, clinicians should be alert to the possibility of HIV/AIDS whenever they encounter infections with special manifestations, and they should also be alert to the possibility of HIV/AIDS in high-risk individuals (homosexuals and heterosexuals who have multiple sexual partners, history of venereal narcotics, history of transfusion of imported blood products or blood that has not been tested for HIV, and history of other sexually transmitted diseases, history of sexually transmitted diseases in high-endemic countries or countries with high prevalence of HIV/AIDS, and history of HIV infection. Especially for high-risk individuals (homosexuals and heterosexuals with multiple sexual partners, history of imported blood products or blood transfusions without HIV testing, history of other sexually transmitted diseases, history of residence in countries or regions with high prevalence of the disease), serum specimens must be collected and sent to a specialized prevention and treatment facility for HIV screening and confirmation.
Treatment
HIV/AIDS lungs should be treated with anti-infective therapy, and its anti-microbial treatment is basically the same as that for general patients, but it should be noted that the incidence of toxic side effects in anti-infective chemotherapy for HIV/AIDS patients is high and serious, and should be closely observed and prevented. Anti-HIV treatment should be based on CD4+ and viral load. If CD4+ <500/μl and viral load >500 copies per milliliter, treatment is indicated; CD4+ >500/μl and viral load >500 copies per milliliter, there is no consensus on whether to treat or not, but if the patient is cooperative, then treatment is possible; CD4+ <200/μl and viral load is below the detectable level, no treatment, and regular review. The most common treatment options are two nucleotide reverse transcriptase inhibitors (NRTIs) and a protease inhibitor (PI).