Classification of pneumonia

In the past, there were several successful clinical classifications of pneumonia, which provided for their division depending on the etiology, clinical and morphological variant of pneumonia, localization and extent of the lesion, severity of the clinical course, presence of respiratory failure and other complications.

For a long time, the division of pneumonias mainly by the clinical and morphological principle into lobar (lobar) and focal pneumonia (bronchopneumonia) prevailed in domestic medical practice, significantly differing in morphological changes in the lung parenchyma, pathogenesis, clinical manifestations and prognosis. However, in recent years, new data have been obtained indicating that such a division does not reflect the entire diversity of clinical variants of pneumonia and, most importantly, is uninformative from the point of view of choosing the optimal etiotropic therapy.

Thus, significant features of the clinical course and outcomes of the disease caused by intracellular pathogens of pneumonia (Legionella, mycoplasma, chlamydia, etc.), gram-negative microflora, anaerobic bacteria, etc. were demonstrated. Significant features of aspiration pneumonia, as well as pneumonia developing against the background of immunodeficiency states and other concomitant diseases were described. Thus, the decisive significance of the etiologic factor was demonstrated.

According to modern concepts, the basis for the classification of pneumonia is the etiological principle, which provides for the identification of the causative agent of pneumonia. This principle was implemented to the greatest extent in the International Statistical Classification of Diseases, 10th revision, 1992 (ICD-X).

However, it should be recognized that at present, in real clinical practice, not only in our country but also abroad, the etiological decoding of pneumonia at the first contact with the patient is practically impossible. Moreover, reliable identification of the causative agent of pneumonia in the next 4-7 days from the onset of the disease, even in a well-equipped specialized hospital, usually does not exceed 60-70%, and in outpatient settings - 10%. Nevertheless, adequate and, if possible, individually selected etiotropic therapy should be prescribed to the patient immediately, immediately after clinical or clinical-radiological confirmation of the diagnosis of pneumonia.

Therefore, in the last 10 years, the classification of pneumonia proposed by the European Society of Pulmonologists and the American Thoracic Society and approved by the V National Congress on Respiratory Diseases (Moscow, 1995) has received general recognition. According to this classification, 4 main forms of pneumonia are distinguished, each of which is distinguished by a very specific spectrum of the most likely pathogens of pneumonia.

1. Community acquired pneumonia develops outside a hospital, in a “home” setting and is the most common form of pneumonia.
2. Hospital-acquired (hospital, nosocomial) pneumonia, developing no earlier than 48-72 hours after the patient is admitted to hospital. The proportion of these forms of pneumonia is 10-15% of all cases of the disease, but the mortality rate reaches 30-50% and more in some cases due to the special virulence and resistance to antibacterial therapy of gram-negative microflora, which is the main cause of this form of pneumonia.
3. “Atypical” pneumonias are pneumonias caused by intracellular (“atypical”) pathogens (Legionella, mycoplasma, chlamydia, etc.).
4. Pneumonia in patients with immunodeficiency states.

Despite all the conventionality and internal inconsistency of this classification, its use in clinical practice is currently fully justified, since the division of pneumonia into community-acquired and hospital (nosocomial) in most cases allows the practicing physician to more reasonably approach the choice of optimal antibacterial treatment, and immediately after collecting the anamnesis and clinical examination of the patient.

At the same time, many researchers, not without reason, dispute the legitimacy of singling out so-called "atypical" pneumonias as a separate group, since the latter, caused primarily by intracellular pathogens, can develop both in "home" (outside the hospital) and hospital conditions. Therefore, in the current guidelines of the American and British Thoracic Societies (2001), it is recommended to avoid using the term "atypical" pneumonias altogether.

On the other hand, the advisability of identifying other types of pneumonia, the occurrence of which is associated with a particular clinical situation: aspiration of gastric contents, the use of artificial ventilation, operations, injuries, etc., is being increasingly discussed.

In addition to verification of the etiologic factor, great importance in the modern clinical classification of pneumonia is attached to the diagnosis of the severity of pneumonia, localization and extent of lung damage, diagnosis of complications of pneumonia, which allows for a more objective assessment of the disease prognosis, selection of a rational program of complex treatment and identification of a group of patients requiring intensive care. There is no doubt that all these headings, along with empirical or objectively confirmed information about the most likely causative agent of the disease, should be presented in the modern classification of pneumonia.

The most complete diagnosis of pneumonia should include the following headings:

• form of pneumonia (community-acquired, hospital-acquired, pneumonia against the background of immunodeficiency states, etc.);
• the presence of additional clinical and epidemiological conditions for the occurrence of pneumonia;
• etiology of pneumonia (verified or suspected infectious agent);
• localization and extent;
• clinical and morphological variant of the course of pneumonia;
• severity of pneumonia;
• degree of respiratory failure;
• presence of complications.

From the point of view of correct interpretation of clinical and radiological signs, it is also important to pay attention to the clinical and morphological substrate of the disease - focal or lobar pneumonia, which differ in their clinical manifestations and some features of etiology and pathogenesis. It should be borne in mind that the terms "lobar" and "lobar" pneumonia are not synonyms in the strict sense of the word, since damage to an entire lobe of the lung (pleuropneumonia) in some cases can be the result of the formation of focal confluent bronchopneumonia with damage to several segments. On the other hand, there are cases when lobar pneumonia acquires an abortive course and ends with the corresponding damage to only several segments of the lung lobe.

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Working classification of pneumonia

By form

• Out-of-hospital (home)
• Intrahospital (hospital, nosocomial)
• Pneumonia in immunocompromised patients

By etiology (verified or suspected pathogen)

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis
• Mycoplasma spp.
• Chlamydophila (Chlamydia pneumoniae)
• Legionella spp.
• Staphylococcus aureus
• Klebsiella pneumoniae
• Eschenchiae coli
• Proteus vulgans
• Pseudomonas aeruginosa
• Anaerobic bacteria (Fusobacterium spp., Bacteroides spp., Peptostreptococcus spp., etc.)
• Viruses
• Mushrooms
• Other pathogens

According to clinical and epidemiological conditions of occurrence

• Aspiration
• Early VAP
• Late VAP
• Postoperative
• Post-traumatic
• Against the background of COPD
• Against the background of alcoholism
• Against the background of malignant neoplasms
• Against the background of immunodeficiency states
• In persons under 25 years of age
• In persons over 60 years of age
• Other options

According to clinical and morphological features

• Focal (bronchopneumonia)
• Confluent focal
• Lobar (lobar)
• Bilateral (indicating localization and extent)

By localization and extent

• Total
• Share (with indication of share)
• Segmental (indicating the segment number)

By severity of the course

• Severe course
• Moderate severity
• Mild flow

Complications

• Respiratory failure (acute or chronic) with indication of degree
• Pleural effusion
• Abscess formation
• Infectious toxic shock
• Sepsis
• Acute respiratory distress syndrome
• Other complications

* - So-called "atypical" pneumonias are excluded, the validity of which is currently being disputed

Below are some examples of formulating a diagnosis of pneumonia, taking into account all the headings presented in the working classification.

Examples of diagnosis

• Community-acquired pneumococcal bronchopneumonia with damage to segments IX and X of the right lung, moderate severity, complicated by grade II respiratory failure.
• Hospital (nosocomial) ventilation-aspiration pneumonia (causative agent - Pseudomonas aeruginosa) with damage to the VIII-X segments of the right lung, severe course, complicated by exudative pleurisy, infectious toxic shock and stage III respiratory failure.
• Community-acquired legionella pneumonia localized in the lower lobe of the right lung (lobar), severe course, complicated by parapneumonic effusion pleurisy, infectious toxic shock and stage III respiratory failure.
• Community-acquired lobar (croupous) pleuropneumonia of unknown etiology, localized in the lower lobe of the right lung, moderate severity, complicated by stage II respiratory failure.

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