Viral pneumonia is an infection of the upper respiratory tract by a virus that spreads downward causing inflammation of the lung tissue. The disease occurs mostly in winter and spring and can be outbreaks or epidemics. Common viruses that cause the disease in adults include influenza A and B viruses, adenovirus, parainfluenza virus, respiratory syncytial virus, coronavirus, SARS coronavirus, and highly pathogenic avian influenza virus. Viral pneumonia can occur in immunocompetent or suppressed children and adults, but bone marrow transplant or organ transplant recipients are susceptible to herpes virus and cytomegalovirus pneumonia.
I. Epidemiology In the past, viral pneumonia was thought to account for about 8% of hospitalized CAP, and epidemiological investigations in recent years have shown an increasing trend in the development of viral pneumonia, with about 13-50 being the cause of CAP, of which about 8-27% are mixed viral bacterial infections. Influenza viruses are the most important pathogens causing viral CAP in adults, and influenza A H1N1 and A H3N2 subtypes are important influenza viruses currently spreading on earth, with 3-5 million severe cases and 250,000-500,000 deaths per year. Influenza viruses can cause a worldwide pandemic, strengthening the prevention and control of influenza at the national level is an important strategy to deal with influenza pandemic.
Clinical manifestations and laboratory tests 1. Clinical manifestations of viral pneumonia are common in the epidemic season, often with acute onset, fever, headache, generalized aches and pains, myalgia and malaise are generally prominent, and may be accompanied by respiratory symptoms and/or gastrointestinal symptoms, and the elderly and children are prone to severe viral pneumonia and even acute respiratory failure and multi-organ failure.
2, laboratory tests total white blood cells are normal, or slightly high or reduced, often with lymphocytopenia. Some cases may have thrombocytopenia. Viral infection is often accompanied by enzymatic abnormalities, such as human infection with highly pathogenic avian influenza is often accompanied by significant enzymatic abnormalities, such as CK, LDH, AST, ALT, etc. are significantly increased.
3, chest X-ray examination of viral pneumonia chest X-ray examination can be seen in the form of lamellar interstitial or/and alveolar infiltrative shadow, which may involve bilateral lung fields or multiple lobes; other manifestations may include peribronchial thickening, pulmonary solidity, pleural fluid, etc.
Although viral culture is the gold standard for pathogenic diagnosis, it takes a long time to obtain results and has limited value for rapid diagnosis; the sensitivity and specificity of using immunofluorescence or enzyme-linked immunoassay methods to detect viral anti-causes in respiratory secretions are low, which limits the wide application of this detection method; nucleic acid amplification technology has the characteristics of rapid, high sensitivity and high specificity, and is gradually becoming the standard method for respiratory Nucleic acid amplification technique is becoming the standard method for respiratory virus detection, but the vulnerability to contamination is the shortcoming of this method; serological examination of 4-fold or more increase of virus-specific antibodies in the acute and remission phases is important for etiological diagnosis, but its significance is only retrospective. Therefore, further research is needed on how to obtain a rapid and accurate pathogenetic basis.
(C) Treatment 1. Close monitoring, rest, antipyretic, oxygen therapy, and nutritional support are the basic treatments for viral pneumonia. Oxygen therapy and mechanical ventilation are important means of life support. Those who need mechanical ventilation should follow the principles of treatment for acute respiratory distress syndrome (ARDS), and may adopt a lung-protective ventilation strategy of low tidal volume (6 mL/kg), pressure limitation and addition of appropriate positive end-expiratory pressure (PEEP). At the same time, airway management should be strengthened to prevent comorbidities related to mechanical ventilation.
2. Antiviral therapy for each type of viral pneumonia has very limited etiologic treatment value, and even with effective targeted therapeutic agents the best time for treatment is lost due to the difficulty in obtaining early diagnosis. During the influenza epidemic season, Tamiflu treatment can be given to high-risk groups such as the elderly, obese, and those with underlying diseases or pregnancy when they have influenza-like symptoms such as fever without waiting for the pathogenic diagnosis, which may be beneficial to reduce the occurrence of severe cases.
3, antimicrobial therapy theoretically viral pneumonia does not require antimicrobial therapy, but viral pneumonia is often combined with bacterial infection and it is difficult to distinguish viral pneumonia from bacterial pneumonia, so you can refer to CAP guidelines to select anti-infective drugs.