Nosocomial pneumonia

In accordance with the currently accepted criteria, to nosocomial pneumonia (synonyms: hospital pneumonia, ventilator-associated pneumonia)) only refer to cases of infectious lung disease that developed no earlier than 48 hours after admission of the patient to a medical institution. Nosocomial pneumonia (NP) associated with ventilator failure is an inflammatory lung disease that developed no earlier than 48 hours after the intubation and the beginning of the ventilator, in the absence of signs of pulmonary infection at the time of intubation. However, in many cases, the manifestation of nosocomial pneumonia in surgical patients is possible at an earlier time.

[1], [2]

Epidemiology of Nosocomial Pneumonia

Nosocomial pneumonia ranks second in the structure of all hospital infectious complications and is 15-18%. The frequency of development of non-surgical patients in surgical patients after planned operations is 6%, after emergency abdominal operations (inflammatory and destructive diseases), 15% of the NP is the most frequent infectious complication in the ICU. NPIVL constitutes 36% of all cases of postoperative pneumonia. The frequency of development of NRIVV is 22-55% in planned surgery with mechanical ventilation for more than 2 days, in emergency abdominal surgery - 34.5%, in ARDS - 55%. The incidence of nosocomial pneumonia in surgical ICU patients who are not ventilated does not exceed 15%. The lethality with NP is 19-45% (depends on the severity of the underlying disease and the volume of the operation). Mortality in PNIVL in purulent-septic abdominal surgery reaches 50-70%, depending on the underlying disease, causative agent and the adequacy of treatment tactics. Attributive lethality with NPIVL is 23% or more. The prevalence of NRIVs in a specific ICU for a certain period of time is calculated by the formula:

The frequency of development of NPIVL x 1000 / Total number of IVL-days

Lethality in the course of NRIV depends on the pathogen detected in the department.

Lethality in nosocomial pneumonia associated with artificial ventilation, depending on the pathogen

Pathogens	Mortality,%
Ps. Aeruginosa	70-80
Gram-positive bacteria	5-20
Aerobic Gram-negative bacteria	20-50

[3], [4], [5], [6], [7]

The etiological structure of nosocomial pneumonia

The spectrum of NP pathogens depends on the "microbiological landscape" of a particular medical institution and the ICU. In addition, the etiological structure of nosocomial pneumonia is affected by concomitant diseases (especially COPD) and the nature of the underlying pathological process requiring the use of mechanical ventilation (traumatic shock with aspiration, severe sepsis, surgical interventions in high-risk patients). In general, with NPIVL, Gram-negative microorganisms predominate in surgical patients, Pseudomonas aeruginosa, Acinetobacter, representatives of the Enterobactriaceae family, and H. Influenzae are detected much less frequently. Among Gram-positive cocci in the development of nosocomial pneumonia, a special place is occupied by Staphylococcus aureus, an etiological role significantly superior to S. Pneumoniae. In a number of cases (4-6%), fungi of the genus Candida play a role in maintaining pneumonia.

Pathogenesis of Nosocomial Pneumonia Associated with Artificial Ventilation of the Lungs

There are two sources of infection of the patient with ICU:

• exogenous,
• endogenous.

Exogenous sources of lung infection include environmental objects that directly or indirectly come into contact with the airway of the patient air, inhaled medical gases, equipment for ventilation (endotracheal and tracheostomy tubes, respirators, respiratory circuits, tracheobronchial tree cannula, bronchoscopes), and microflora of other patients and medical personnel.

Endogenous source of infection of the lungs is the microflora of the oropharynx, gastrointestinal tract, skin, urinary tract, accessory sinuses of the nose, nasopharynx, and pathogens from alternative foci of infection.

The highly contaminated secret of the oropharynx penetrates the tracheobronchial tree through microaspiration. The risk of aspiration of the secretion of the oropharynx is increased in patients undergoing ventilation because of the presence of an intubation tube that damages the mucous membrane of the swallow and trachea, which disrupts the function of the ciliary epithelium and prevents both spontaneous sputum examination and the swallowing act. Bacterial colonization of the oropharynx increases the risk of developing NPIVL because of the possibility of migration of bacteria near the cuff of the intubation tube.

A major role in the pathogenesis of nosocomial pneumonia is played by the translocation of opportunistic bacteria from the digestive tract. In the gastrointestinal tract of a healthy person, there are a lot of microbes - both anaerobes and aerobes. They support adequate motor, secretory and metabolic functions of the gastrointestinal tract. It is the anaerobic part of the intestinal microflora that provides colonization resistance and suppresses the growth of a potentially pathogenic aerobic bacterial microflora. However, under the influence of injuries, violations of hemodynamics and metabolism, or in other pathological conditions, ischemia of the intestinal wall develops and motor, secretory and barrier functions of the intestine are disrupted. There is a retrograde colonization of the intestinal microflora of the upper gastrointestinal tract, as well as, due to violation of the barrier function of the enterocytes, the translocation of bacteria and their toxins into the portal and systemic bloodstream. Polysystemic multifactorial bacteriological analysis in patients with ICU confirmed that the dynamics of contamination of the abdominal cavity, gastrointestinal tract, blood channel, and pulmonary tissue depend on the morphofunctional insufficiency of the intestine.

The development of the infectious process in the lungs can be considered as a result of a violation of the balance between aggression factors that contribute to the ingress of a large number of highly virulent microorganisms into the respiratory tract and factors of anti-infective protection. Only in conditions of a critical weakening of the protective factors, pathogens are able to manifest their pathogenicity and cause the development of an infectious process.

Features of Nosocomial Pneumonia in Surgery

• Early development (in the first 3-5 days of the postoperative period - 60-70% of all nosocomial pneumonia)
• Multifactorial infection.
• Difficulties of nosological and differential diagnosis.
• The complexity of prescribing empirical therapy.
• The incidence of IVPVL in patients with purulent-inflammatory foci in the abdominal cavity is 64%.

Causes of high incidence of NT in patients with abdominal sepsis:

• prolonged ventilation,
• repeated operations and anesthesia,
• application of "invasive" medical and diagnostic procedures,
• a pronounced syndrome of intestinal insufficiency, predisposing to the translocation of pathogenic microorganisms and their toxins from the digestive tract,
• the possibility of hematogenous and lymphogenic infection from the septic foci in the abdominal cavity,
• syndrome of acute lung damage associated with abdominal sepsis - "fertile" soil for the development of nosocomial pneumonia.

Factors contributing to the early development of nosocomial pneumonia:

• severity of the condition (high score according to APACHE II),
• abdominal sepsis,
• massive aspiration,
• age over 60 years,
• associated COPD,
• impaired consciousness,
• emergency intubation,
• carrying out a long (more than 72 hours) ventilation,
• use of invasive medical and diagnostic techniques, which increases the risk of exogenous infection,
• development of acute respiratory distress syndrome as a nonspecific response of the lungs,
• inadequacy of previous antibiotic therapy,
• repeated hospitalization for 6 months,
• thoracic or abdominal operations,
• nasotracheal and nasogastric intubation,
• position on the back with the head of the bed lowered (angle less than 30 °).

[8], [9], [10], [11], [12]

Diagnosis of Nosocomial Pneumonia

Health. A. Science policy committee of the american college of chest physians, 2000.

Suspicion of nosocomial pneumonia in the conduct of ventilation should occur if there are two or more of the following symptoms:

• purulent sputum character,
• fever> 38 ° C or hypothermia <36 ° C,
• leukocytosis> 11x10 ⁹ / ml or leukopenia <4x10 ⁹ / ml, shifting the leukocyte formula to the left (> 20% of stab or any number of young forms),
• paO ₂ / FiO ₂ (respiratory index) <300.

In the absence of the above symptoms, there is no need for further examination, it is advisable to carry out surveillance (level II evidence).

In the presence of two or more of the above symptoms, an X-ray examination is necessary. With a normal radiograph - it is necessary to look for alternative causes of symptoms (level III evidence).

In the presence of infiltrates on the roentgenogram, two tactical options are possible (evidence of level III).

In the presence of infiltrates on the roentgenogram, microbiological examination (quantitative methods of endobronchial aspirate, BAL, protected brushes, bronchoscopic methods) and empiric antibiotic therapy (ABT) should be performed. Adequate empirical ABT in patients with suspected pneumonia increases survival (level II evidence). In the absence of bacteriological confirmation in the stable state of the patient, ABT can be stopped.

To objectify the evaluation of clinical, laboratory and radiographic data in patients with suspected NIVIL, it is advisable to use the CPIS (Clinical Pulmonary Infection Score)

• Temperature, ° C
  • 36,5-38,4 - 0 points,
  • > 38.5 or <38.9 - 1 point,
  • > 39 or <36 - 2 points
• Leukocytes, x10 ⁹
  • 4-11 - 0 points,
  • <4 or> 11 - 1 point + 1 point, in the presence of young forms
• Bronchial secretion
  • the need to sanitize LDP <14 times a day - 0 points,
  • the necessity of sanitizing TBD> 14 = 1 point + 1 point, if the secretions are purulent
• paO2 / FiO2 mmHg
  • > 240 or PLA / ARDS - 0 points,
  • <240 in the absence of PAL / ARDS - 1 point
• Radiography of the lungs
  • absence of infiltrates - 0 points,
  • diffuse infiltrates - 1 point,
  • localized infiltration - 2 points.
• Microbiological analysis of tracheal aspirate (semiquantitative method 0, +, ++ or +++)
  • no growth or 0 - + - 0 points.
  • ++ - +++ - 1 point + 1 point, when the same microorganism is allocated (Gram staining).

The diagnosis of NIVIL is considered confirmed at 7 or more points on the CPIS scale.

Considering that CPIS is inconvenient in routine practice, its modified version became more acceptable - the Doppler (scale of diagnosis and evaluation of pneumonia severity), which is presented in the table.

Sensitivity of the scale is 92%, specificity is 88%. The score of 6-7 points corresponds to the moderate severity of pneumonia, 8-9 - severe, 10 and more - extremely severe pneumonia. The diagnostic value of the Doppler is proved. Its use is useful for dynamic monitoring of patients, as well as for evaluating the effectiveness of the therapy

Scale of diagnosis and evaluation of the severity of pneumonia

Index	Value	Points
Body temperature, С	36.0-37.9 38.0-39.0 <36 0 or> 39.0	0 1 2
Number of leukocytes, x10 9	4.9-10.9 11 0-17 0 or > 20 sticks > 17.0 or the presence of any number of young forms	0 1 2
Respiratory index of pO2 / FiO2	> 300 300-226 225-151 <150	0 1 2 3
Bronchial secretion	+/-	0
	+++	2
Infiltrates in the lungs (based on the results of radiography)	Absence of	0
	Local	1
	Drainage, bilateral, with abscessing	2

Among patients with suspicion of NPIVL, three diagnostic groups

• I group - diagnosis of pneumonia is reliable in the presence of clinical, x-ray and microbiological criteria. As clinical experience shows, a full range of diagnostic signs can be detected in 31% of patients.
• II group is a probable diagnosis of pneumonia, in the presence of only clinical and laboratory or clinical and radiological, or laboratory and roentgenological criteria. This "diagnostic set" can be detected in 47% of patients.
• III group - a dubious diagnosis of pneumonia - there are only clinical, or only laboratory, or only radiologic signs of pneumonia. This diagnostic group is 22% among all patients with suspicion of NPIVL.

Antimicrobial therapy is mandatory for patients with I and II diagnostic groups. With a dubious diagnosis of nosocomial pneumonia, further dynamic monitoring is advisable.

[13], [14]

Features of microbiological diagnosis of nosocomial pneumonia

The sampling of the material for microbiological examination must be made before the initiation (or replacement) of antibacterial therapy.

For the collection and microbiological examination of the material from the tracheobronchial tree, the following methods are most commonly used.

[15], [16], [17], [18]

Diagnostic bronchoscopy and bromo-valvular lavage

The study is preceded by pre-oxygenation with FiO ₂ = 1.0 for 10-15 min. The procedure is performed under conditions of total intravenous anesthesia, since the use of local anesthetics is limited, given their possible bactericidal effect. Sampling is carried out from the zone of greatest damage, determined from the data of the radiograph and visually. In the case of diffuse pulmonary infiltration, samples of the material are taken from the middle lobe of the right lung or from the ligament segment of the left lung. The detachable (lavage fluid) of the lower respiratory tract from the internal catheter is placed in a sterile tube and immediately delivered to a microbiological laboratory.

[19], [20], [21], [22], [23]

The technique of using a "blind" protected catheter

After a five-minute pre-oxygenation with FiO ₂ = 1.0, the catheter is most distally injected through the endotracheal or tracheostomy tube. After this, put forward the internal catheter (with the destruction of the film, which protects the internal catheter from road contamination). Aspiration is performed using 20 ml of a sterile syringe attached to the proximal end of the internal catheter. The device is then removed from the endotracheal tube, and the detachable lower respiratory tract from the internal catheter is placed in a sterile tube and immediately delivered to a microbiological laboratory.

The diagnostic significance of quantitative cultures of endotracheal aspirates depends on the degree of bacterial contamination and the previous use of antibiotics.

Sensitivity and specificity of quantitative methods of diagnosis of nosocomial pneumonia associated with artificial lung ventilation

Methodology	Diagnostic value, cfu / ml	Sensitivity,%	Specificity,%
Quantitative endotracheal aspiration	10 5 -10 6	67-91	59-92
"Protected" brush-biopsy	> 10 3	64-100	60-95
BALL	> 10 4	72-100	69-100
"Protected" BAL	> 10 4	82-92	VZ-97
"Protected blind" catheter	> 10 4	100	82.2

Bronchoscopic (invasive) methods require the use of special equipment, the attraction of additional personnel and have low reproducibility. "Invasive" diagnosis of NPIVL does not lead to a significant improvement in long-term treatment outcomes.

Criteria for severe course of nosocomial pneumonia

• Severe respiratory failure (BH> 30 per minute).
• Development of cardiovascular failure (SBP <100 mmHg, DBP <60 mmHg).
• Body temperature> 39 ° C or <36 ° C.
• Violation of consciousness.
• Multiblobal or bilateral damage.
• Clinical signs of organ dysfunction.
• Hyperleukocytosis (> 30x10 ⁹ / L) or leukopenia (<4x10 ⁹ / l).
• Hypoxemia (RAO ₂ <60 mm Hg)

Antibiotic therapy of nosocomial pneumonia in surgical patients

To assign adequate empirical therapy, the following fundamental factors should be taken into account:

• influence on the alleged etiology of the disease duration of the patient's stay in the ICU and the duration of the ventilation,
• Specific features of the specific composition of NPIVD pathogens and their sensitivity to antimicrobial drugs in a particular medical institution,
• the effect of antimicrobial therapy on the etiologic spectrum of NPIVL and on the sensitivity of pathogens to antimicrobial agents.

Schemes of empirical antibiotic therapy of nosocomial pneumonia in surgical patients

Clinical situation	Mode of antibiotic therapy
Nosocomial pneumonia in patients with surgical department	Cephalosporins of the second generation (cefuroxime), cephalosporins of the third generation, which do not possess antipseudomonas activity (ceftriaxone, cefotaxime), fluoroquinolones (ciprofloxacin, pefloxacin, levofloxacin), amoxicillin / clavulanate
Nosocomial pneumonia in patients with ICU without ventilator	Third-generation cephalosporins with antipseudomonas activity (ceftazidime cefoperazone), 4th generation cephalosporins, fluoroquinolones Cefoperazone + sulbactam
Nosocomial pneumonia and without SPON (APACHE II is less than 15)	Third-generation cephalosporins with antipseudomonas activity (ceftazidime, cefoperazone) + amikacin Cephalosporins of the fourth generation (cefepime) Cefoperazone + sulbactam Fluoroquinolones (ciprofloxacin)
NP ilv + SPON (APACHE II more than 15)	Imipenem + cilastatin Meropenem Cephalosporins IV generation (cefepime) ± amikacin Cefoperazone + sulbactam

Notes

• With a reasonable suspicion of MRSA, any of the regimens can be supplemented with vancomycin or linezolid.
• At a high risk of aspiration or its verification by clinical diagnostic methods, antibacterial drugs that do not have activity against anaerobic pathogens should be combined with metronidazole or clindamycin.

Causes of ineffectiveness of antibiotic therapy of nosocomial pneumonia:

• unsanitary focus of surgical infection,
• severity of the patient's condition (APACHE II> 25),
• high antibiotic resistance of pathogens NPIVL,
• persistence of problem pathogens (MRSA, P. Aeruginosa, Acinetobacter spp, S. Maltophilia),
• microorganisms "outside the spectrum" of the action of empirical therapy (Candida spp., Aspergillus spp, Legionella spp., P. Carinnii),
• development of superinfection (Enterobacter spp., Pseudomonas spp., fungi, Clostridium difficile),
• inadequate choice of drugs,
• late onset of adequate antibiotic therapy, 
• non-observance of the dosing regimen of drugs (the route of administration, single dose, interval between administrations),
• low doses and the concentration of antibiotic in plasma and tissues.

[24], [25], [26], [27]

Prevention of Nosocomial Pneumonia

Prevention of NIPIV can be effective only if it is carried out within the framework of a common infection control system covering all elements of the treatment and diagnostic process and aimed at preventing various types of nosocomial infections. Here are just some of the activities most directly aimed at the prevention of just nosocomial pneumonia. Such measures as, for example, isolation of patients with infectious complications, the introduction of the principle "one sister - one patient", reduction of the preoperative period, timely detection and adequate surgical sanitation of alternative foci of infection certainly play an important role in preventing nosocomial pneumonia, as well as in others forms of nosocomial infections, but have a more universal character and are not considered in this document.

All the requirements stated in this subsection are based on the results of scientific research and practical experience, take into account the requirements of the legislation of the Russian Federation and international practice data. Here, the following ranking system is used for the extent of their validity.

Requirements that are mandatory for execution and are convincingly substantiated by data from methodologically advanced experimental, clinical or epidemiological studies (meta-analyzes, systematic reviews of randomized controlled trials (RCTs), and well-organized RCTs). In the text they are marked - 1A.

Requirements that are mandatory for performance and are based on a number of noteworthy experimental, clinical or epidemiological studies with a low probability of systematic error and a high probability of causation (cohort studies without randomization, case-control studies, etc.) and having a convincing theoretical justification. In the text they are marked - 1B.

Requirements that must be enforced by applicable federal or local legislation. In the text they are marked - 1B.

The requirements recommended for execution, which are based on the presumptive data of clinical or epidemiological studies and have a certain theoretical basis (rely on the opinion of a number of authoritative experts). In the text they are indicated by the number 2.

The requirements traditionally recommended for execution, however, there is no conclusive evidence either "for" or "against" their implementation, and experts' opinions differ. In the text they are indicated by the number 3.

The above ranking system does not imply an evaluation of the effectiveness of the activities and reflects only the quality and quantity of the studies, the data of which formed the basis for the development of the proposed activities.

Fighting endogenous infection

[28], [29], [30], [31], [32], [33],

Prophylaxis of aspiration

• It is necessary to remove invasive devices, such as endotracheal, tracheostomy and (or) enteral (naso-, orogastral, -intestinal) tubes, immediately to eliminate clinical indications for their use (1B).
• With septic acute lung injury (APL) or acute respiratory distress syndrome (ARDS), non-invasive mechanical ventilation is ineffective and life threatening.
• As far as possible, avoid repeated endotracheal intubation in patients on mechanical ventilation (1B).
• The risk of developing NPVIL with nasotracheal intubation is higher than with orotracheal (1B).
• A permanent aspiration of the secret from the supramangular space is desirable (1B).
• Before extubation of the trachea (cuff deflation), it is necessary to make sure that the secret is removed from the supramangular space (1B).
• In patients with a high risk of aspiration pneumonia (located on the IVL, with nasogastric, naso-intestinal tube), the head end of the bed should be raised by 30-45 ° (1B).
• For the prevention of oropharyngeal colonization, an adequate toilet of the oropharynx should be performed - aspiration of the mucus by a special catheter, as well as treatment with antiseptic solutions (eg, 0.12% chlorhexidine bigluconate solution) in patients after cardiac surgery (2) and other patients at high risk for pneumonia (3) .

Fighting exogenous infection

[34], [35]

Hygiene of the hands of medical personnel

• Hand hygiene is a general term for a range of activities, including hand washing, hand antiseptic and cosmetic care for the skin of the hands of medical personnel.
• In case of contamination, wash hands with water and soap. In other cases, hygienic hand antiseptic with alcoholic antiseptic (1A) should be used. Hygienic hand antiseptic is an antiseptic of the hands of medical personnel, whose goal is to remove or destroy transient microflora.
• It should be hygienic antiseptic hands, even if the hands are visually unclean (1A)

Hygienic hand antiseptic should be carried out:

• before direct contact with the patient,
• before putting on sterile gloves when staging a central intravascular catheter,
• before the placement of urinary catheters, peripheral vascular catheters or other invasive devices, if these manipulations do not require surgical intervention,
• after contact with the intact skin of the patient (for example, when measuring the pulse or blood pressure, shifting the patient, etc.),
• after removing the gloves (1B).

Hygienic hand antiseptics should be carried out during patient care manipulations when moving from contaminated areas of the patient's body to clean ones, and after contact with environmental objects (including medical equipment) in the immediate vicinity of the patient (2).

Do not apply to the antiseptic hand napkins / balls, impregnated with antiseptic (1B).

Measures to improve hand hygiene should be an integral part of the infection control program in a health care facility and have priority funding (1B).

Care for patients with tracheostomy

Tracheostomy should be performed under sterile conditions (1B).

The replacement of the tracheostomy tube should be performed under sterile conditions, the tracheostomy tubes should be sterilized or disinfected at a high level (1B).

[36], [37], [38], [39], [40]

Airway sanitation

When performing the sanation of the tracheobronchial tree (TBD), sterile or clean disposable gloves should be worn (3).

When using open systems for aspiration of the secretion of the respiratory tract, sterile single-use catheters (2) should be used.

[41], [42], [43]

Care of respiratory equipment

It should not be without special indications (obvious contamination, malfunctioning, etc.) to replace the breathing circuit when used in one patient based only on the duration of its use (1A).

Before using reusable breathing circuits, sterilize or disinfect them at a high level (1B-B).

It is necessary to remove any condensate in the circuit (1A) in a timely manner.

It is recommended to use bacterial filters when performing mechanical ventilation (2).

To fill the reservoirs of humidifiers, sterile or pasteurized distilled water (1B) should be used.

It is recommended to use heat and moisture filters (TBE) (2).

Closed aspirating systems (CAS) are designed for sanitation, lavage of the tracheobronchial tree and collection of the separated tracheobronchial tree (TBD) for microbiological analysis in closed mode, i.e. Under conditions completely separated from the environment. The purpose of creating such systems was to eliminate the contamination of the lower respiratory tract through the lumen of the endotracheal tube during the "traditional" sanation of the tuberculosis and to reduce the negative effect of the procedure of the sanitation of the trachea on the ventilation parameters under "aggressive" modes of ventilation. The closed aspiration system is built into the "patient-ventilator" a filter and an endotracheal tube. If during the ventilation is used active moistening with a stationary humidifier, the system is installed between the endotracheal tube and the V-shaped connector of the respiratory circuit.

Thus, a single closed sealed space is created "ventilator - breathing filter - closed aspiration system - intubation tube - patient". In the distal part of the system there is a vacuum control button and a connector to which a vacuum aspirator tube is connected and, if necessary, a device for taking a tracheo-bronchial aspirate for performing laboratory and microbiological studies. Since the closed aspiration system assumes the protection of the aspiration catheter from contact with the external environment, it is covered with a special protective sleeve, the presence of which excludes the contact of the personnel's hands with the surface of the catheter. At the same time, the air in the protective sleeve (potentially contaminated with the patient's flora), when the catheter is inserted into the intubation tube, is removed to the external environment, and the air coming from the external environment into the protective sleeve when the catheter is removed from the trachea may, in turn , is contaminated with a flora alien to the patient. Repeated unobstructed movement of air in both directions with repeated episodes of sanitation of the trachea becomes a source of mutual infection of the patient and the environment of separation. Obviously, ideally the air moving from the protective sleeve and back must undergo a microbiological "cleaning". From this point of view, it is preferable to use truly closed suction systems in the conditions of the ICU, which are equipped with a built-in antibacterial filter that excludes the possibility of mutual contamination of the ICU medium and the patient with a pathogenic microflora. The accumulated data on the application of AAS with a built-in filter indicate a significant reduction in the number of nosocomial tracheobronchitis and pneumonia associated with ventilation, a significant increase in the average time from the onset of mechanical ventilation until the appearance of a stump vmonii, which can be an effective means of preventing respiratory infections in patients with prolonged ventilation.

[44], [45], [46], [47], [48]