Diagnosis of pneumonia in children

Laboratory diagnostics of pneumonia

Peripheral blood analysis should be performed in all patients with suspected pneumonia. Leukocytosis of more than 10-12x10 ⁹ /l and a band shift of more than 10% indicate a high probability of bacterial pneumonia. If pneumonia is diagnosed, leukopenia of less than 3x10 ⁹ /l or leukocytosis of more than 25x10 ⁹ /l are considered unfavorable prognostic signs.

Biochemical blood analysis and acid-base balance of the blood are standard methods of examination of children and adolescents with severe pneumonia requiring hospitalization. They determine the activity of liver enzymes, the level of creatinine and urea, electrolytes.

Etiological diagnosis is established mainly in severe pneumonia. Blood culture is performed, which gives a positive result in 10-40% of cases. Microbiological examination of sputum in pediatrics is not widely used due to technical difficulties in collecting sputum in the first 7-10 years of life. But in cases of bronchoscopy, microbiological examination is used, the material for it is aspirates from the nasopharynx, tracheostomy and endotracheal tube. In addition, to identify the pathogen, a puncture of the pleural cavity and sowing of the punctate of the pleural contents are performed.

Serological methods of research are also used to determine the etiology of the disease. An increase in the titers of specific antibodies in paired sera taken in the acute period and the period of convalescence may indicate mycoplasmal or chlamydial etiology of pneumonia. Reliable methods also include detection of antigens by latex agglutination, counter immunoelectrophoresis, ELISA, PCR, etc. However, all these methods take time, do not affect the choice of treatment tactics, and have only epidemiological significance.

Instrumental methods of pneumonia diagnostics

The "gold standard" for diagnosing pneumonia in children is chest X-ray examination, which is considered a highly informative and specific diagnostic method (the specificity of the method is 92%). When analyzing X-ray images, the following indicators are assessed:

• the size of pulmonary infiltration and its prevalence;
• presence or absence of pleural effusion;
• the presence or absence of destruction of the lung parenchyma.

All these data help to determine the severity of the disease and choose the right antibacterial therapy. Subsequently, with a clear positive dynamics of clinical manifestations of community-acquired pneumonia, there is no need for control radiography (upon discharge from the hospital or when the child is treated at home). It is more advisable to conduct control radiography no earlier than 4-5 weeks from the onset of the disease.

Dynamic X-ray examination during the acute period of the disease is performed only in the presence of progression of symptoms of lung damage or the appearance of signs of destruction and/or involvement of the pleura in the inflammatory process. In cases of complicated pneumonia, mandatory X-ray control is performed before the patient is discharged from the hospital.

In hospital pneumonia, it is important to remember that if pneumonia develops 48 hours before death, then the X-ray examination may give a negative result. Such X-ray negative pneumonia (when X-ray examination performed 5-48 hours before the patient's death did not reveal pneumonic infiltration in the lungs) is observed in 15-30% of cases. The diagnosis is established only clinically based on severe respiratory failure, weakened breathing; there may often be a short-term rise in temperature.

Dynamic radiographic examination of hospital pneumonia in the acute period of the disease is performed when symptoms of lung damage progress or when signs of destruction and/or involvement of the pleura in the inflammatory process appear. With clear positive dynamics of clinical manifestations of pneumonia, control radiography is performed upon discharge from the hospital.

When assessing the condition of children previously hospitalized for any pathology and children with severe community-acquired pneumonia, special attention should be paid to the condition and effectiveness of the respiratory function, in particular pulse oximetry readings. In severe pneumonia and hospital pneumonia, especially VAP, it is also necessary to monitor such indicators as respiratory rate, pulse rate, blood pressure, acid-base balance, diuresis, and, in children in the first half of life, body weight.

Computed tomography (CT) is used when necessary for differential diagnostics, since CT has a 2-fold higher sensitivity compared to plain radiography in detecting foci of infiltration in the lower and upper lobes of the lungs.

Fibrobronchoscopy and other invasive techniques are used to obtain material for microbiological examination in patients with severe immune disorders and for differential diagnostics.

Differential diagnosis of pneumonia in a child

When conducting differential diagnostics, it is necessary to take into account the child’s age, since pathological processes in the lungs have their own characteristics at different age periods.

In infancy, the clinical picture of respiratory failure may be caused by conditions such as aspiration, foreign body in the bronchi, previously undiagnosed tracheoesophageal fistula, gastroesophageal reflux, malformations of the lungs (lobar emphysema), heart and large vessels, cystic fibrosis and alpha-antitrypsin deficiency. In children of the second to third year of life and at an older age (up to 6-7 years), Kartagener syndrome; pulmonary hemosiderosis; nonspecific alveolitis; selective IgA deficiency should be excluded.

Differential diagnosis at this age should be based on the use (in addition to chest radiography and peripheral blood analysis) of endoscopic examination of the trachea and bronchi, lung scintigraphy, angiography, sweat and other tests for cystic fibrosis, determination of the concentration of alpha-antitrypsin, study of the blood immunogram and other studies.

At any age, it is necessary to exclude pulmonary tuberculosis. In the absence of positive dynamics of the process within 3-5 days (maximum - 7 days) of therapy, protracted course of community-acquired pneumonia, its resistance to the therapy, it is necessary to expand the examination plan both to identify atypical pathogens (C. psittaci, Ps. aerugenozae, Leptospira, Coxiella burneti) and to diagnose other lung diseases.

In patients with severe immune deficiencies, when dyspnea and focal infiltrative changes appear on a chest X-ray, it is necessary to exclude the involvement of the lungs in the underlying pathological process (for example, in systemic connective tissue diseases), as well as lung damage as a consequence of the therapy (drug-induced lung damage, radiation pneumonitis, etc.).

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