Severe out-of-hospital pneumonia

Community-acquired pneumonia is the most common infectious disease in humans. The incidence of community-acquired pneumonia in Europe ranges from 2 to 15 per 1,000 people per year, in Russia up to 10-15 per 1,000 people per year. This figure is significantly higher in elderly patients 25-44 per 1,000 people per year in patients over 70 years old and up to 68-114 per 1,000 people per year in elderly patients in nursing homes and care homes. In the United States, 5-6 million cases of community-acquired pneumonia are registered annually, with 20% of those infected requiring hospitalization. According to rough estimates, for every 100 cases of community-acquired pneumonia (community-acquired pneumonia complicated by acute respiratory failure, community-acquired pneumonia complicated by severe sepsis or septic shock), about 20 patients require inpatient treatment, of which about 10% - in intensive care units.

ICD-10 code

• J13 Pneumonia due to Streptococcus pneumoniae
• J14 Pneumonia due to Haemophilus influenzae
• J15 Bacterial pneumonia, not elsewhere classified
  • J15.0 Pneumonia due to Klebsiella pneumoniae
  • J15.1 Pneumonia due to Pseudomonas spp.
  • J15.2 Pneumonia due to Staphylococcus spp.
  • J15.6 Pneumonia due to other aerobic gram-negative bacteria
  • J15.7 Pneumonia due to Mycoplasma pneumoniae
  • J15.8 Other bacterial pneumonias
  • J15.9 Bacterial pneumonia of unspecified etiology
• J16.0 Pneumonia due to Chlamydia spp.
• J16.8 Pneumonia due to other specified pathogens
• A48.1 Legionnaires' disease

Assessment of the severity and risk of death in community-acquired pneumonia

An objective assessment of the severity of the patient's condition is a necessary tool for determining the tactics of patient management, resolving issues of patient transportation, the optimal place for patient therapy (specialized department, intensive care unit, etc.), for comparing disease outcomes depending on the methods of therapy and the quality of care provided.

The use of pneumonia severity scales, as well as the recommendations of consensus conferences of respiratory societies, can significantly reduce treatment costs and significantly reduce treatment failure.

One of the most common scales for assessing the severity and prognosis of community-acquired pneumonia is the PSI (Pneumonia Severity Index) scale, proposed by Fine in 1997. Using this algorithm, it is possible to classify patients according to existing risk factors. According to this scale, the main criteria for the severity of pneumonia are age, concomitant pathology, and changes in vital parameters. However, calculating the PSI requires additional laboratory tests, blood gas analysis, and chest X-ray. The higher the score, the more likely the prognosis for the disease is poor. Patients in the fifth class usually have severe pneumonia and require intensive care.

Pneumonia Seventy Index scale for assessing the severity of patients with community-acquired pneumonia

Characteristics of patients	Points	Characteristics of patients	Points
Age of men	Age in years	Respiratory rate >30 per minute	+20
Age of women	Age in years minus 10	BP <90 mmHg	+20
Staying in a nursing home	+10	Body temperature <36 C or >40 'C	+15
Malignant tumors	+30	Hematocrit <30%	+30
Liver diseases	+20	PH <7.35	+30
Congestive heart failure	+10	Urea >11 mmol/l	+20
Cerebrovascular diseases	+10	Serum sodium <130 mEq/L	+20
Kidney diseases	+10	Hematocrit <30%	+10
General cerebral symptoms	+30	PaO2 <60 mm Hg	+10
Pulse rate >125 beats per minute	+10	Pleural effusion	+10

Mortality of patients with community-acquired pneumonia depending on the assessment of patients on the Pneumonia Severity Index scale

Risk classes	Score	Mortality, %	Place of treatment
I	Patients over 50 years of age, without concomitant diseases and changes in vital signs	0,1	Outpatient
II	<70	0.6	Outpatient
III	71-90	0.9	Stationary
IV	91-130	9.3	Stationary
V	>130	27.0	Stationary

The CURB-65 index consists of five parameters (four clinical and one laboratory), which have been shown to have high prognostic potential in pneumonia in hospitalized patients. These parameters reflect age, ARF, and signs of severe sepsis or septic shock. Patients with a score of 0-1 are considered to be at minimal risk (mortality rate of about 1.5%), while those with a score of 2 or 3-5 points have a mortality risk of 9 and 22%, respectively. Patients with a score of 4-5 points should be treated in an intensive care unit. A simplified CRB-65 index (without urea as an assessment criterion) is also well validated and has high prognostic value. The CURB-65 and CRB-65 indices have advantages over the PSI index in that they are based on the severity of CAP rather than on comorbidities, which avoids underestimation of the severity of pneumonia in young patients or possible errors due to undetected comorbidities, and they are easier to calculate.

A new scale PS-CURXO-80 based on eight indicators has been proposed relatively recently. According to preliminary data, this scale is a more reliable tool for determining indications for hospitalization of patients in the ICU than the PSI and CURB-65 scales.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ]

Classification and definition

Modern classifications divide pneumonia into several groups depending on the conditions under which the disease occurs:

• community-acquired pneumonia (acquired outside of medical institutions),
• nosocomial (hospital) pneumonia (acquired in medical institutions),
• aspiration pneumonia,
• pneumonia in individuals with immunodeficiency states.

This classification is based on various causal factors of pneumonia and different approaches to the choice of antibacterial therapy.

All community-acquired pneumonias can be conditionally divided into three groups according to severity:

• pneumonia, which does not require hospitalization (patients with mild pneumonia can receive therapy on an outpatient basis, the mortality rate does not exceed 1-5%),
• pneumonia, which require hospitalization of patients (patients with underlying chronic diseases and pronounced clinical symptoms, the mortality risk of hospitalized patients reaches 12%),
• pneumonia, which requires hospitalization of patients in intensive care (patients with severe community-acquired pneumonia, the mortality rate is about 40%).

Thus, severe community-acquired pneumonia is pneumonia characterized by a high risk of death and requiring management of patients in an intensive care unit.

The main signs of severe community-acquired pneumonia that determine the decision to send the patient to the intensive care unit:

• respiratory failure,
• severe sepsis or septic shock,
• Prevalence of pulmonary infiltrates based on chest radiography.

The American Thoracic Society has proposed criteria for severe community-acquired pneumonia, a new modification of the criteria is given below (GOBA/ATS, 2007)

The presence of at least three minor or one major criterion confirms severe community-acquired pneumonia, i.e. pneumonia that requires hospitalization of the patient in the intensive care unit.

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Criteria for severe community-acquired pneumonia

Minor criteria assessed during hospitalization:

• respiratory rate >30 per minute,
• RaO ₂ /FiO ₂ <250 mm. Hg st,
• multilobar infiltrates (according to chest X-ray data),
• confusion or disorientation,
• uremia (blood urea nitrogen >20 mg/dL),
• leukopenia (blood leukocytes <4000 in 1 mm3 ⁾ as a result of infection,
• thrombocytopenia (blood platelets <100/mm3 ⁾,
• hypothermia (body temperature <36 °C),
• hypotension (systolic BP <90 mmHg or diastolic BP <60 mmHg), if the administration of solutions is necessary.

Major criteria assessed during hospitalization or throughout the illness:

• need for mechanical ventilation,
• septic shock requiring vasopressors.

Other potential criteria include hypoglycemia (in patients without diabetes), alcoholism, hyponatremia, metabolic acidosis or elevated lactate levels, cirrhosis, and asplenia.

[ 10 ], [ 11 ], [ 12 ], [ 13 ]

How is severe pneumonia recognized?

The most common symptoms of community-acquired pneumonia are:

• cough,
• sputum production,
• fever,
• dyspnea,
• chest pain,
• chills,
• hemoptysis.

Less common symptoms:

• headache,
• weakness,
• myalgia,
• arthralgia,
• syncope,
• diarrhea,
• nausea,
• vomit.

Physical examination reveals fever, tachypnea, cyanosis, wheezing, dullness to percussion, increased vocal fremitus and bronchophony, and signs of pleural effusion.

Classic signs of pneumococcal pneumonia:

• sudden onset (24-48 h),
• high fever,
• chills,
• pleural pain,
• separation of "rusty" sputum,
• During examination, labial herpes, signs of pulmonary consolidation and crepitus are often detected.

The clinical picture of pneumonia in elderly patients may differ significantly from that in younger patients. In patients over 75 years of age, fever and cough are absent in 15% and 40%, respectively. Sometimes the only signs of pneumonia in elderly patients are tachypnea, tachycardia, and confusion (50-75% of patients).

Chest X-ray is the "gold standard" for diagnosing pneumonia. Lobar consolidation syndrome (dense homogeneous infiltrates) with air bronchograms is typical for pneumonia caused by "typical" bacteria. Bilateral basal interstitial or reticulonodular infiltrates are more common in pneumonia caused by atypical microorganisms. However, the X-ray picture, like clinical data, does not allow for a reliable determination of the etiology of pneumonia.

Regardless of the type of pathogen, the inflammatory process most often affects the lower lobes of the lungs. In pneumococcal pneumonia complicated by bacteremia, involvement of several lobes of the lungs and the presence of pleural effusion are most often observed. Characteristic radiographic findings in staphylococcal pneumonia are multilobar lesions, abscess formation, pneumatocele, spontaneous pneumothorax. For pneumonia caused by K. pneumoniae, involvement of the upper lobes (usually on the right) and destruction of the lung parenchyma with the formation of abscesses are more typical. The formation of abscesses is also observed in pneumonias caused by anaerobes, fungi, mycobacteria, and is practically not encountered in pneumonias caused by S. pneumoniae, M. pneumoniae, C. pneumoniae.

It is quite rare for chest X-rays to produce false negative results in patients with pneumonia:

• in case of dehydration of patients,
• in case of neutropenia,
• in pneumocystis pneumonia,
• in the early stages of the disease (up to 24 hours from the development of the disease).

In complex cases, a chest CT scan may be performed, as this method is more sensitive.

Laboratory research methods

Laboratory tests in the ICU should include arterial blood gas analysis and basic blood parameters. A complete blood count is a routine diagnostic test in patients with pneumonia. A white blood cell count of more than 15x10 ⁹ /l is a strong argument in favor of a bacterial origin of pneumonia (usually pneumococcal), although lower values do not exclude a bacterial origin. Some biochemical tests (urea, glucose, electrolytes, liver function markers) are usually performed to assess the severity of the disease and identify concomitant pathology (renal or liver failure).

C-reactive protein cannot be used in differential diagnostics of bacterial and nonbacterial pneumonia. Its level weakly correlates with its severity. But the clinical course of pneumonia corresponds well to changes in the concentration of C-reactive protein. C-reactive protein, IL-6 and procalcitonin have independent prognostic value.

Microbiological research

Microbiological studies can help guide treatment decisions, especially in the most severely ill patients. The following microbiological studies are recommended for all patients with severe pneumonia admitted to the ICU:

• blood test,
• Gram stain and culture of sputum or lower respiratory tract material,
• pleural fluid analysis (if available),
• study of Legionella spp and S. pneumoniae antigens in urine,
• study of material from the lower respiratory tract using the direct immunofluorescence method to detect influenza virus and RS virus in the winter period,
• testing of lower respiratory tract material by PCR or culture to detect Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella spp. if reliable tests are available,
• serological studies for Legionella spp. and atypical pathogens initially and dynamically in the absence of PCR diagnostics.

Microbiological testing of blood (blood is collected from two sites) should be performed before any antibacterial therapy and as early as possible. Overall, positive blood cultures are found in 4-18% of cases, with S. pneumoniae being the main pathogen.

A sputum sample obtained by deep coughing is considered suitable for analysis. In patients on mechanical ventilation, tracheobronchial aspirate is used for bacteriological examination. Negative culture results using these methods are obtained in 30-65% of all cases. Certain problems are associated with the fact that 10-30% of patients with pneumonia do not have sputum, and up to 15-30% of patients have already received antibiotics before collecting sputum for analysis.

Express methods of microbiological diagnostics use methods for detecting microorganism antigens in urine. Currently, tests are available for detecting S. pneumoniae and Legionella pneumophila serogroup 1 antigens (responsible for 80% of all cases of legionella infection), the sensitivity of the methods is 50-84%, and the specificity is more than 90%.

PCR can be used as a rapid method to isolate some microorganisms (Chlamydophila, Mycoplasma, and Legionella) from sputum and aspirate. However, this method is poorly standardized and interpretation of results can be difficult.

Serologic tests are of no help in the initial evaluation of the etiologic agent of pneumonia and are not generally recommended for routine use. They may be of great value for retrospective analysis. Serologic tests are usually performed to detect atypical bacteria and include assessment of IgG antibody levels in paired sera (2-4 weeks apart). An increase in the cold hemagglutinin titer of more than 1:64 is observed in 30-60% of cases in patients with M. pneumoniae infection. However, this test becomes positive only after a week from the onset of the disease. About a week is also required to achieve a diagnostic IgM titer to M pneumoniae, and about three weeks are required to achieve a diagnostic IgM titer to C. pneumoniae. Detection of a single IgG titer to Legionella spp. more than 1:256 is considered sufficient to detect acute Legionella infection, but the sensitivity of the method is only 15%.

The disadvantage of sputum and aspirate analysis is contamination of the sample with oropharyngeal microflora. Such methods as transtracheal aspiration, transthoracic fine-needle aspiration, and bronchoscopy with protected brush biopsy and BAL can overcome this disadvantage. The first two methods are almost never used in practice, as they are quite traumatic and are accompanied by the development of side effects. Bronchoscopic methods are used mainly in patients with hospital-acquired pneumonia, and in community-acquired pneumonia they are used only in severely ill patients. When performing a protected brush biopsy, the diagnostically significant bacterial titer for diagnosing pneumonia is considered to be the number of colony-forming units in 1 ml greater than 10 ³, and when performing BAL - greater than 10 ⁴.

Microbiology of community-acquired pneumonia

Microbiological identification of the pathogen is possible only in 40-60% of all pneumonia cases. The structure of pathogens of CAP, based on the results of prospective studies conducted in Europe, is presented below.

Etiology of community-acquired pneumonia

Pneumonias that do not require hospitalization	Pneumonia requiring hospitalization	Pneumonia requiring hospitalization in intensive care
Streptococcus pneumoniae	Streptococcus pneumoniae	Streptococcus pneumoniae
Mycoplasma pneumoniae	Mycoplasma pneumoniae	Staphylococcus aureus
Haemophilus influenzae	Chlamydophila pneumoniae	Legionella spp
Chlamydophila pneumoniae	Haemophilus influenzae	Gram-negative bacteria
Viruses (a)	Legionella spp
	Anazrobes (for aspiration)
	Viruses (a)

Note a - influenza viruses A and B, adenoviruses, respiratory syncytial virus, parainfluenza virus.

Streptococcus pneumoniae is the main causative agent of severe community-acquired pneumonia (about 22%), accounting for up to two-thirds of all causes of pneumonia with bacteremia. Staphylococcus aureus, Legionella pneumophila and gram-negative bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, etc.) also play a significant role in the genesis of severe community-acquired pneumonia. Legionella spp infections are found mainly in regions with a warm climate (Mediterranean countries) and quite rarely in Northern European countries. The role of anaerobic microorganisms in the genesis of community-acquired pneumonia is small, but increases significantly in aspiration pneumonia - up to 50% of all causes. Viral infections cause about 5% of all severe community-acquired pneumonia. The influenza virus is of primary importance, while parainfluenza viruses, adenoviruses, and respiratory syncytial virus are of lesser importance. Viral pneumonias are characterized by seasonality of occurrence, mainly in the autumn and winter.

Knowledge of epidemiological factors and the geographic situation can help in suggesting the etiologic factor of community-acquired pneumonia.

Risk factors for the development of community-acquired pneumonia of known etiology

Risk factors	Pathogens
COPD and/or bronchitis	Haemophilus influenzae, gram-negative enterobacteria, Pseudomonas aeruginosa
Recent hospitalization	Gram-negative enterobacteria, Pseudomonas aeruginosa
Recent antibiotic treatment	Gram-negative enterobacteria, Pseudomonas aeruginosa
Minor aspiration	Mixed infection, anasrobes
Massive aspiration	Gram-negative enterobacteria, Pseudomonas aeruginosa, anaerobes
Flu	Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae
Contact with cattle	Coxiella burnetii
Contact with birds	Chlamydia psittaci
Intravenous drug use	Staphylococcus aureus (methicillin-sensitive or methicillin-resistant)
Recent trips to the Mediterranean coast	Legionella spp
Recent travel to the Middle East or Southern US	Histoplasma cAPSulatum
Long-term treatment with glucocorticoids	Pseudomonas aeruginosa, Aspergillus spp

The proportion of S. pneumoniae strains resistant to penicillin exceeds 60% in some countries. According to Russian studies, the frequency of pneumococcal strains resistant to penicillin does not exceed 10%. Pneumococcal resistance to macrolides in Russia is also low (6-9%), but at the same time resistance to tetracyclines and co-trimoxazole is very high (30 and 41%, respectively).

Risk factors for the development of pneumococcal resistance to antibiotics:

• the age of patients is over 65 years,
• stay in nursing homes,
• therapy with ß-lactam antibiotics within the last 3 months,
• alcoholism,
• multiple comorbidities.

The level of resistance of Haemophilus influenzae to aminopenicillins in our country is also low and does not exceed 5%, however, about 30% of all strains of H. influenzae are insensitive to co-trimoxazole.

Treatment of severe community-acquired pneumonia

Treatment goals

Eradication of the pathogen, resolution of the clinical picture of community-acquired pneumonia, ensuring adequate gas exchange, therapy and prevention of complications.

Antibacterial therapy

Initial therapy should be empirical. Rapid initiation of adequate antibacterial therapy is the most important guarantee of successful treatment. Treatment should be initiated within the first 2-4 hours after admission to the hospital and within an hour of admission to the intensive care unit.

The initial choice of antimicrobial drug is made empirically (i.e. before receiving the results of microbiological testing), since:

• in at least half of the cases, the responsible microorganism cannot be identified even using the latest modern research methods, and existing microbiological methods are rather non-specific and insensitive,
• any delay in etiotropic therapy of pneumonia is accompanied by an increased risk of complications and mortality from pneumonia, whereas timely, correctly selected empirical therapy can improve the outcome of the disease,
• An assessment of the clinical picture, radiological changes, concomitant diseases, risk factors and severity of pneumonia in most cases allows one to make the right decision on the choice of adequate therapy.

Adequacy of initial antibacterial therapy is a must because adverse outcomes are often associated with inappropriate antibiotic use. Initial empirical antibacterial therapy should take into account:

• the most likely spectrum of pathogens depending on the severity of pneumonia and additional risk factors,
• local features of antibacterial resistance,
• tolerability and toxicity of antibiotics for a specific patient.

In severe pneumonia, a combination of third-generation cephalosporins (or amoxicillin in combination with clavulanic acid) and macrolides is prescribed as initial therapy. According to several retrospective studies, such a therapy regimen may be accompanied by a decrease in mortality, which is explained not only by the activity of the drug combination against typical and atypical microorganisms, but also by the ability of macrolides to reduce the proinflammatory effect of bacterial products. An alternative regimen is a combination of third-generation cephalosporins and respiratory fluoroquinolones. If Legionella spp. infection is suspected, parenteral rifampicin is added to these drugs.

In patients with severe community-acquired pneumonia, identification of risk factors for Gram-negative enterobacteriaceae and/or P. aeruginosa is essential because it dictates different initial empirical antimicrobial therapy. In one study, the presence of three of four risk factors (COPD/bronchiectasis, recent hospitalization, recent antimicrobial therapy, and suspected aspiration) translated into a 50% risk of acquiring Gram-negative enterobacteriaceae or P. aeruginosa. P. aeruginosa infection should be considered in patients receiving chronic glucocorticoid therapy (>10 mg prednisolone daily) and in any patient with rapidly progressing pneumonia who smokes.

Empirical antimicrobial therapy for patients with community-acquired pneumonia at high risk of P. aeruginosa should include third-generation cephalosporins with antipseudomonal activity (ceftazidime, cefepime) or carbapenems (imipenem, meropenem) in combination with ciprofloxacin or aminoglycosides.

Recommended treatment regimens for patients with severe community-acquired pneumonia

There are no risk factors for P. Aeruginosa infection.	IV cefotaxime or IV ceftriaxone or IV amoxicillin with clavulanic acid and an IV macrolide (azithromycin or clarithromycin) IV cefotaxime or IV ceftriaxone or IV amoxicillin with clavulanic acid and an IV respiratory fluoroquinolone (moxifloxacin or levofloxacin)
Risk factors for P Aeruginosa infection	Antipseudomonal beta-lactam IV (ceftazidime or cefepime or piperacillin/tazobactam or imipenem or meropenem) and fluoroquinolone IV (ciprofloxacin or levofloxacin) Antipseudomonal beta-lactam IV (see above) and aminoglycoside IV with azithromycin Antipseudomonal beta-lactam IV (see above) and aminoglycoside IV with respiratory fluoroquinolone IV (moxifloxacin or levofloxacin)

If aspiration genesis of severe community-acquired pneumonia is suspected, amoxicillin with clavulanic acid, cefoperazone with sulbactam, ticarcillin with clavulanic acid, piperacillin/tazobactam, carbapenems (meropenem, imipenem) are prescribed. Combinations of different pathogens can be found in 5-38% of patients, but their effect on the outcome of the disease has not yet been established.

At the same time, in patients with severe community-acquired pneumonia, it is necessary to seek to clarify the etiological diagnosis, since such an approach can affect the outcome of the disease. The advantages of "targeted" therapy are a reduction in the number of prescribed drugs, a reduction in the cost of treatment, a reduction in the number of side effects of therapy and a reduction in the potential for the selection of resistant strains of microorganisms. When specific pathogens are isolated, appropriate treatment is carried out.

Recommended treatment when specific pathogens are identified

Exciter	Recommended treatment
Moderately resistant Streptococcus pneumoniae <2 mg/dL	High doses of amoxicillin, third generation cephalosporins, respiratory fluoroquinolones
Highly resistant Streptococcus pneumoniae >2 mg/dL	Respiratory fluoroquinolones, vancomycin, linezolid
Methicillin-susceptible Staphylococcus aureus	Second generation cephalosporins, clindamycin, respiratory fluoroquinolones
Methicillin-resistant Staphylococcus aureus	Vancomycin, possibly rifampicin, linezolid
Ampicillin-resistant Haemophilus influenzae	Amoxicillin/clavulanate and amoxicillin/sulbactam, respiratory fluoroquinolones
Mycoplasma pneumoniae	Macrolides, respiratory fluoroquinolones, doxycycline
Chlamydia pneumoniae	Macrolides, respiratory fluoroquinolones, doxycycline
Legionella spp	Respiratory fluoroquinolones, macrolides, possibly rifampin, azithromycin
Coxiella burnetii	Macrolides, respiratory fluoroquinolones
Enterobactenaceae	Third generation cephalosporins, carbapenems (drugs of choice in case of extended spectrum beta-lactamase producers), inhibitor-protected beta-lactams, fluoroquinolones
Pseudomonas aeruginosa	Antipseudomonal beta-lactam and ciprofloxacin or lefofloxacin
Acmetobacter baumannu	Third generation cephalosporins and aminoglycosides
Burkholderia pseudomallei	Carbapenems, ceftazidime, fluoroquinolones, co-trimaxazole
Anaerobes (by aspiration)	Inhibitor-protected beta-lactams, clindamycin, carbapenems

The response to antimicrobial therapy depends on the immune reactivity of the body, the severity of the disease, the causative pathogen, and the extent of pneumonia according to the radiographic picture. The subjective response to antibiotic therapy is usually observed within 1-3 days from the start of therapy. The objective response includes an assessment of fever, clinical symptoms, laboratory parameters, and radiographic changes.

[ 14 ], [ 15 ], [ 16 ], [ 17 ], [ 18 ], [ 19 ]

Criteria for stabilization of a patient with community-acquired pneumonia

• body temperature <37.8 °C,
• pulse <100 per minute,
• Respiratory rate <24 per minute,
• systolic blood pressure >90 mm Hg,
• SaO ₂ >90% or pa02 >90 mm Hg,
• ability to take liquid and food per os,
• normal mental status

When the clinical condition stabilizes, it is possible to switch from intravenous to oral antimicrobials. This approach is defined as "step" therapy if the same antibiotic is used, or as "sequential" therapy if one intravenous antibiotic is replaced by another oral drug. The use of step or sequential therapy can significantly reduce treatment costs and shorten the length of hospital stay. The oral antibiotic in sequential therapy must have high bioavailability.

The duration of antimicrobial therapy for severe community-acquired pneumonia is usually at least 10 days. For pneumonia caused by intracellular pathogens, such as Legionella spp, treatment should be continued for at least 14 days. In addition, a longer duration of antimicrobial therapy (14-21 days) is recommended for patients with CAP caused by S aureus and gram-negative bacteria.

[ 20 ], [ 21 ], [ 22 ], [ 23 ], [ 24 ], [ 25 ], [ 26 ], [ 27 ]

Treatment of systemic disorders

Antibacterial drugs are the basis of therapy for patients with pneumonia, however, in the situation of managing patients with severe pneumonia, treatment aimed at preventing complications of pneumonia (respiratory failure, septic shock, etc.) is of great importance.

In case of moderate hypoxemia (S O ₂ 80-89%), provided that the patient has sufficient respiratory effort, consciousness is preserved, and the infectious process quickly reverses, hypoxemia can be corrected by inhaling oxygen using a simple nasal mask (FiO ₂ 45-50%) or a mask with a disposable bag (FIO 2 75-90%).

Indications and approaches to mechanical ventilation in severe community-acquired pneumonia without pronounced asymmetry between the lungs do not differ significantly from the tactics of managing patients with ARDS.

An alternative to traditional respiratory support is NIVL using face masks. According to one study, NIVL improves gas exchange in 75% of patients and avoids tracheal intubation in 60% of patients with community-acquired pneumonia. A good positive effect of NIVL is achieved in patients with COPD suffering from severe community-acquired pneumonia. The need to use NIVL in patients with other concomitant pathologies is controversial. The principles of using non-invasive ventilation are the same as in all other situations.

Indications for non-invasive ventilation in severe community-acquired pneumonia:

• severe dyspnea at rest, respiratory rate >30 per minute,
• PaO2 /FiO2 _< 250 mmHg _,
• PaCO ₂ >50 mm Hg or pH <7.3.

The use of NIV in severe community-acquired pneumonia is justified in patients with underlying COPD, provided there is good drainage of the airways and in the early stages of ARF development.

The problem of providing ventilation assistance to patients with ARF against the background of unilateral (asymmetrical) lung damage is particularly difficult. Several approaches have been proposed to improve oxygenation in a patient with unilateral pneumonia:

• use of pharmacological drugs (almitrine, inhaled nitric oxide),
• periodically placing the patient on the healthy side,
• separate ventilation of the lungs taking into account the different compliance and different PEEP needs in the healthy and “sick” lungs.

Indications for independent (separate) ventilation of the lungs:

• hypoxemia refractory to high FiO ₂ and PEEP,
• PEEP-induced deterioration of oxygenation and increase in shunt flow fraction,
• hyperinflation of the unaffected lung and development of collapse of the affected lung,
• significant deterioration in hemodynamic status in response to PEEP administration.

This type of ventilation aid allows selective application of PEEP only in the affected lung, thus reducing the risk of barotrauma and hemodynamic disturbances. When performing independent ventilation of the lungs, intubation tubes with two channels and two inflatable cuffs are used.

In patients with severe sepsis and septic shock, solutions to replenish the volume of circulating fluid (usually colloids) are prescribed at the first stage of therapy. In some cases, the administration of solutions may be sufficient to correct circulatory disorders. If they are ineffective, vasopressors are prescribed. The effectiveness of glucocorticoids in severe community-acquired pneumonia has not yet been proven. In "refractory" septic shock, with suspected adrenal insufficiency (patients with previous glucocorticoid intake), low doses of glucocorticoids (hydrocortisone 100 mg 3 times a day for 5-10 days) can be used.

New recommendations for the treatment of severe patients with community-acquired pneumonia with septic shock include the use of activated protein C - drotrecogin alfa. The drug is recommended for patients with septic shock with a total score on the APACHE II scale of more than 25. The greatest reduction in mortality when using drotrecogin alfa is noted in patients with severe CAP caused by S. pneumoniae. In addition to the patient's severity according to APACHE II, an adequate indication for the administration of drotrecogin alfa in patients with severe community-acquired pneumonia and septic shock is the presence of failure of at least two organ systems.

Preventive therapy with low molecular weight heparins (enoxaparin sodium 40 mg/day or nadroparin calcium 0.4-0.6 ml/day) in patients with ARF reduces the incidence of thromboembolism from 15 to 5.5% and prevents thromboembolic complications

In case of community-acquired pneumonia, the use of drugs such as nystatin, NSAIDs, and antihistamines is not indicated.

What is the prognosis for severe community-acquired pneumonia?

Mortality in patients with severe community-acquired pneumonia hospitalized in the intensive care unit is high (22-54%). In prospective studies devoted to the prognosis of patients with severe community-acquired pneumonia, the main parameters associated with an unfavorable prognosis were:

• age over 70 years,
• conducting artificial ventilation,
• bilateral localization of pneumonia,
• bacteremia,
• sepsis,
• need for inotropic support,
• ineffectiveness of initial antibiotic therapy,
• P. aeruginosa infection.

Validated indices PSI, CURB-65 and CRB-65 have become a good tool for predicting the course of community-acquired pneumonia. In addition, some simple algorithms also allow identifying patients with severe community-acquired pneumonia who have an increased risk of death, for example, the presence of two of three indicators (HR> 90 per minute, _systolic blood pressure <80 mm Hg and LDH> 260 units / L) increases the risk of death of patients six times compared to patients without these signs.

The causal factor also influences the prognosis: the mortality rate of patients is significantly increased when such microorganisms as S. pneumoniae, Legionella spp., Klebsiella pneumoniae, P. aeruginosa are detected.