Severe hospital-acquired pneumonia

Introduction to acquired pneumonia in severe hospitals Hospital acquired pneumonia (HAP), also known as nosocomial pneumonia (NP), does not exist at the time of admission and is not in an incubation period. It occurs in hospitals 48 hours after admission, and is caused by bacteria, fungi, mycoplasma, and viruses. Pulmonary parenchymal inflammation caused by protozoa, etc., also includes pneumonia that is infected after hospitalization and is discharged after hospital discharge. It occurs in elderly, infirm, chronically and severely ill patients with various underlying diseases, and patients with long-term use of glucocorticoids or other immunosuppressive agents. basic knowledge The proportion of sickness: 0.01% Susceptible people: no specific population Mode of infection: iatrogenic infection Complications: pleural effusion

Causes of acquired pneumonia in severe hospitals

(1) Causes of the disease

Hospital-acquired pneumonia can be caused by a variety of pathogenic microorganisms, of which more than 90% of bacterial infections. Understanding the epidemiological data of pathogens is of great value for the empirical selection of antibacterial drugs in the early stage of treatment. 678 hospital pathogens in China (1987-1988) Survey statistics show that Gram-negative bacilli infection accounted for 57%, Gram-positive cocci accounted for 29%, anaerobic bacteria 4%, fungi 7%, not 3%, Shanghai Ruijin Hospital pulmonary ventilator pneumonia bronchoalveolar lavage fluid The detection rate of (BALF) pathogen was 84.2%, Gram-negative bacilli accounted for 66.5% (Pseudomonas aeruginosa accounted for 20.9%), Gram-positive cocci accounted for 33.5%, single-species infection accounted for 63.3%, mixed bacteria infection 36.7. %, the microbiological data of HAP reported by Barlett are shown in Table 1.

1. Gram-negative gram-negative bacilli are the most common pathogens (50%-70%), mainly Pseudomonas aeruginosa, mostly in intensive care units and patients receiving mechanical ventilation, and have immune function inhibition. Or those with underlying diseases such as chronic obstructive pulmonary disease, those with antibiotics and glucocorticoids in advance, such as Klebsiella, Enterobacter, Proteus, Citrobacter, and Serratia are also common. Other non-fermenting bacteria, such as Pseudomonas aeruginosa / Pseudomonas cepacii, Pseudomonas putida, Acinetobacter, and Xanthomonas maltophilia are also found in hospital-acquired pneumonia in immunosuppressed individuals.

2. Staphylococcus aureus is the most common Gram-positive cocci infection (15% to 30%), especially in coma, trauma and wound infection, especially recent influenza virus infection, diabetes and renal failure, in recent years Reports of methicillin-resistant Staphylococcus aureus (MRSA) infection are increasing.

3. Anaerobic bacteria Due to problems in specimen collection and culture techniques, the incidence of anaerobic infections is reported differently, and may be the actual response rate. Common bacteria include Peptococcus, Streptococcus mutans, and Clostridium. , Bacteroides, etc., and is commonly found in mixed infections of Gram-negative bacilli.

4. Legionella can be found in the environment of the hospital (air, water supply) and medical equipment pollution, also seen in those who have used corticosteroids, there have been reports of local local epidemics.

5. The virus is more common in children, respiratory syncytial virus is more common, immunosuppressive and transplant recipients are common cytomegalovirus, and occasionally herpes simplex virus.

6. Fungi are more common in the long-term, extensive use of immunosuppressive agents, patients treated with glucocorticoids and antibiotics, such as burn patients, bone marrow transplants or other organ transplants, common pathogens are Candida, Aspergillus and Mucor, more Mixed with bacterial infections.

7. Mycobacterium tuberculosis and non-tuberculous mycobacteria are more common in patients with HIV infection and AIDS, and are also seen in other immunosuppressed patients. Although the incidence rate is <1%, it is still necessary to pay attention to differential diagnosis so as not to spread in the ward. .

8. Some other community-acquired pneumonia pathogens, such as Streptococcus pneumoniae, Haemophilus influenzae, occasionally in patients with hospital acquired pneumonia, once used in the gastrointestinal tract for the treatment of selective digestive tract decontamination (SDD) Intestinal infections have occurred, and infections such as Pneumocystis carinii and Toxoplasma gondii have also attracted attention.

Hospital acquired lung pathogen changes are noteworthy, Miller et al. pointed out that since the 1980s, the incidence of certain pathogens has increased, such as Pseudomonas aeruginosa increased from 12% to 17%, Staphylococcus aureus 13% increased to 17%, Enterobacteriaceae increased from 9% to 11%, coagulase-negative Staphylococcus aureus increased from 1% to 2%, Candida albicans increased from 3% to 5%, and various bacteria used antibiotics The incidence of drug resistance has also increased rapidly. In addition, the incidence of certain pathogens has decreased. For example, E. coli has decreased from 9% to 6%, Klebsiella has decreased from 11% to 8%, and Proteus has been reduced. 7% to 3%, the epidemiological investigation of pathogens has important reference value for the research and application strategies of macro-control antibiotics.

(two) pathogenesis

The high incidence of hospital-acquired pneumonia may be related to two factors, namely, impaired systemic and respiratory local immune defense functions and the existence of a variety of environments and pathways that facilitate the invasion of pathogens into the lungs, including inhalation and dissemination. Risk factors affecting the incidence of hospital-acquired pneumonia include: old age, chronic lung disease or other underlying diseases, malignant tumors, immune damage, coma, inhalation, recent respiratory infections, etc., as well as long-term hospitalization, especially long-term ICU, artificial airway and Mechanical ventilation therapy, long-term nasal indwelling of gastric tube, chest and abdomen surgery, long-term antibiotic treatment, glucocorticoids, cytotoxic drugs and immunosuppressive agents, H2 receptor blockers and antacid applications, etc., these factors interact.

Inhalation of oropharyngeal secretions through the respiratory tract is an important cause of hospital-acquired pneumonia. The ability to defend the lower respiratory tract depends on the local respiratory and tract defense functions of the nasopharynx, trachea-bronchus, etc. The oropharyngeal secretions often occur in healthy people during sleep. Microinhalation, but the secretion contains a small number of bacteria, mainly Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and anaerobic bacteria, and the systemic and respiratory immune defense function is complete, so the bacteria can be effectively removed, The lower respiratory tract remains sterile, but many inpatients have a large increase in oropharyngeal colonization, which is easy to cause inhalation, and immune defense dysfunction. As a result, there are often a large number of bacteria inhaled, which exceeds systemic and local immune clearance, resulting in pneumonia.

Bacterial adhesion may be an important mechanism for the proliferation of colonization of upper respiratory tract. Old age, smoking, malnutrition, endotracheal intubation and other bronchial epithelial damage, local IgA production, macrophage reduction and chemotaxis are weak, etc., neutral granules The role of cellular elastase in clearing surface fibronectin, promoting cell adhesion and colonization, especially colonization of Gram-negative bacilli (EGNB), such as Pseudomonas aeruginosa direct contact with oropharyngeal epithelial cell binding site Adhesion and colonization, disturbance of consciousness, and intubation (intubation, stomach tube), swallowing and cough reflex are more conducive to the inhalation of secretions such as mouth and throat, such as the incidence of ventilator pneumonia in patients receiving mechanical ventilation. Higher than general hospital acquired pneumonia, because respiratory channels such as nasal cannula or endotracheal intubation bypass the nasopharyngeal defense, and the lower respiratory tract defense mechanism is impaired by cough reflex and mucociliary clearance, and respiratory secretions are under Respiratory tract, especially the retention of contaminated secretions around the intubation balloon, facilitates bacterial reproduction if the ward environment and Suction treatment equipment disinfection is not strict, especially tracheostomy care operations are not strict aseptic operation, resulting in more implanted pathogens.

Gastrointestinal colonization can be an important source of oropharyngeal colonization by reverse colonization. The gastric juice of healthy people is acidic (pH 1.0), the sterility in the stomach cavity, the elderly, malnutrition, alcoholics, especially application As an acid-preventing agent and an H2 receptor antagonist, as a preventive stress ulcer, the pH of the gastrointestinal tract is increased, resulting in the proliferation of gastric colonization bacteria and refluxing through the gastroesophageal tract into the pharynx. If the patient has pharyngeal reflex disorder, the disturbance of consciousness And the use of gastric tube and tracheal intubation can cause a large amount of inhalation of esophageal/gastric contents. In addition, it is also believed that bacteria in the gastrointestinal tract can reach the lungs through translocation, various causes such as inflammation, shock, and chemotherapy cause intestinal wall to occur. Ischemic injury, impaired mucosal integrity, intestinal bypass in the intestine reaches regional lymph nodes, entering the portal system and reaching the lungs.

In addition, various respiratory treatment devices such as nebulizers, humidifiers, endotracheal tubes and suction tubes, as well as ventilator breathing circuit tubes and fiberoptic bronchoscopes, can cause large numbers of bacteria to enter the lungs directly, while long-term indwelling veins Catheters, urinary catheters, and other catheters can be spread through the bloodstream to the lungs.

Intensive hospital acquired pneumonia prevention

Hospital-acquired pneumonia has a poor prognosis and high mortality. In addition to early detection and active treatment, preventive measures should be taken actively to reduce the incidence of the disease, which has attracted widespread attention. There are many studies, and the pathogenesis of hospital-acquired pneumonia is exogenous and Two types of endogenous, the former is related to the hospital, the environmental factors of the hospital, various invasive and non-invasive treatment operations, and the latter is related to the body's own factors, such as respiratory and gastrointestinal colonies, the basis Diseases and immune status, etc., so these links should be prevented.

1. Prevention of exogenous infections Strict disinfection and isolation system and the effective implementation of aseptic technique are the key points. Education and management should be paid attention to. Medical personnel should wash their hands before touching patients and various operations. Disinfecting gloves should be used for invasive operations. , masks and gowns, for pneumonia patients with multi-drug resistant bacteria infection, should be properly isolated to avoid cross-infection, pay attention to the air (laminar flow chamber) and medical equipment disinfection, especially the strictness of various respiratory treatment equipment Disinfection, such as aerosol inhalation devices, suction devices, oxygen therapy devices, etc.

The incidence of ventilator pneumonia is extremely high, actively treating the primary disease, and trying to get rid of the machine as soon as possible, in order to shorten the artificial airway indwelling time and mechanical ventilation time as much as possible, can significantly reduce the incidence rate, and during the ventilator treatment, pay special attention to the respiratory tract. The aseptic operation keeps the airway open and the ventilator (suspension device) may reduce the amount of bacteria inhaled and avoid exhaled air polluting the environment.

2. Reducing endogenous infections The inhalation of oropharynx and gastrointestinal colonization is an important way of endogenous infection. Good nursing measures can reduce the occurrence of oropharyngeal secretions and aspiration of gastric contents, such as frequent changes. Position, high mouth feeding, chest physiotherapy, oral care, correct tracheal intubation care and gastrointestinal drainage technology. For long-term bed rest, you can use a rocking bed to rotate your body position to promote the discharge of respiratory secretions. For possible stress ulcers The critically ill patients use antacids to prevent gastrointestinal bleeding. It may be because the pH of the gastric juice is increased, resulting in the proliferation of colonization bacteria in the stomach, increasing the chance of attracting hospital-acquired pneumonia. Therefore, it is recommended to use gastric mucosal protective agents. For example, sucralfate has three sets of meta-analyses comparing the use of sucralfate, H2 blockers (cimetidine) and antacids, and the lowest incidence of acquired pneumonia in the sucralfate group. The antacid group was the highest, although the cimetidine group was higher than the sucralfate group, but did not increase the incidence of hospital-acquired pneumonia compared with the placebo group, probably because of cimetidine pH values increased, without increasing the volume of gastric juice, so reflux fewer opportunities and aspiration occurs, in addition to use as a jejunostomy parenteral nutrition therapy, without placing nasogastric catheter, the less opportunity to cause reflux.

The use of antibiotics to reduce potential pathogenic bacteria in the oropharynx and gastrointestinal tract is controversial. Many studies suggest that selective decontamination of the digestive tract (SDD), regardless of the application of local antibiotics in the respiratory tract. Systemic application of antibiotics may not reduce the incidence of pneumonia, and may lead to the emergence of drug-resistant strains, increase treatment difficulties, should be cautious, have used intratracheal instillation or inhalation of gentamicin or polymyxin B, etc., although The colonization of Gram-negative bacilli in the oropharynx was reduced, but the incidence and treatment rate of hospital-acquired pneumonia were not improved, which may be related to the emergence of drug-resistant bacteria. In recent years, there have been many reports on selective digestive tract decontamination (SDD). Compared with the control group, the incidence of SDD was lower, but most of them were non-double-blind randomized controls. More oral polymyxin, tobramycin and gentamicin were used in the gastrointestinal tract. Absorbed while maintaining a high drug concentration, for Gram-negative bacilli such as Proteus, Moganellla, Serratia and Pseudomonas aeruginosa, other alternative drugs include fluoroquinolones Vancomycin, but not universally accepted, there may be selectively applied to surgical cases, it is quite worth exploring methods.

3. Immune prevention uses comprehensive measures, such as nutritional support, to correct the imbalance of the body environment, in order to reduce the incidence of hospital acquired pneumonia, malnutrition will increase the incidence of pneumonia, nutritional support treatment has an important position, through intestinal nutrition has Stimulate the intestinal mucosa to prevent bacterial translocation, but should pay attention to methods, such as nasal feeding method, if the amount of infusion is too large, causing reflux of gastric contents, especially in the supine position, long-term indwelling nasal feeding catheter may also cause rhinitis. Jejunal ostomy for enteral nutrition support may avoid reflux.

Pneumococcal vaccines and influenza virus vaccines can be selectively applied to certain high-risk patients. Pseudomonas aeruginosa immunoglobulins, anti-endotoxin serum and immunoglobulins have limited preventive effects, and some immunomodulatory organisms are being studied. Formulations, such as IL-1 receptor antagonists, tumor necrosis factor (TNF) antibodies, broad-spectrum anti-lipopolysaccharide antibodies, cyclooxygenase inhibitors, and the like.

Severe in-hospital acquired pneumonia complications Complications pleural effusion

Clinically complicated by pleural effusion.

Symptoms of acquired pneumonia in severe hospitals Common symptoms Fever with cough, slightly... Pneumothorax after lung activity

The general symptoms are the same as community-acquired pneumonia, that is, fever, cough, cough, shortness of breath and chest pain. Chest physical examination can find signs and voices in the lesions, but they all appear after hospitalization or are in the original respiratory infection. Symptoms on the basis of symptoms increase, and purulent sputum, but sometimes covered by the performance of the original underlying disease and not easy to find early, so be alert to high-risk groups, once the suspicious clinical manifestations, promptly for further examination.

Examination of acquired pneumonia in severe hospitals

1. The blood routine white blood cell count is increased (>10×10 ⁹ /L), the number of neutrophils is increased, or the left nucleus is shifted. If the white blood cell count is >20×109/L or <4×10 ⁹ /L, Neutrophil count <1×10 ⁹ /L indicates severe disease; lymphopenia, absolute count <1000/dl, CD4<200/dl suggests HIV infection, and decreased platelet count should be alert to diffuse intravascular coagulation. For further examination, anemia suggests a possible combination of chronic disease or mycoplasma infection.

2. Blood gas analysis helps to determine the severity of the disease, the patient's arterial oxygen partial pressure (PaO2) <60mmHg, with or without PaCO2>50mmHg, or PaO2/FiO2<300 under breathing air conditions.

3. Blood electrolytes, liver and kidney function tests, etc., comprehensively assess the condition, timely discover the occurrence of environmental disorders in the body and the occurrence of multiple organ dysfunction, and timely take corresponding rescue measures is of great significance.

4. Pathogen examination The pathogen examination provides an important basis for the diagnosis of hospital-acquired pneumonia. It plays a key guiding role in the rational use of antibiotics for treatment. Usually, sputum specimens are used for examination, but sputum specimens are contaminated by upper respiratory secretions. Therefore, the sensitivity and specificity of the diagnosis are not high. In recent years, many examination methods have been carried out to reduce the chance of contamination of specimens, such as tracheal aspirate (TA), bronchoalveolar lavage (BAL), protective bronchoalveolar Protected bronchoalveolar lavage (PBAL), protected specimen brush (PSB), transthoracic needle aspiration (TNA), transbronchial biopsy (ITB), thoracoscopic surgery Biopsy and open lung biopsy.

(1) sputum: taking sputum specimens for pathogen examination, the method is simple, non-invasive, and saves money, so the application is common, but sputum specimens are susceptible to contamination by upper respiratory secretions, so the reliability is not high, many studies It was found that the results of sputum culture were inconsistent with the results of protective brushing and open lung biopsy. In order to obtain satisfactory test results as much as possible, patients should be sputum sputum before collecting sputum specimens, then cough up deep sputum and respond The sputum specimens were stained with Gram stains, and microscopic examinations, such as microscopic examination, were squamous epithelial cells <10/low power field, polynuclear white blood cells>25/low power field, or both ratios <1:2.5, indicating The sputum is coughed from the deep part and is suitable for further culture examination. The sputum sample should be sent for prompt examination. In addition to routine culture, appropriate medium such as fungi, mycobacteria, virus, etc. should be selected according to clinical needs. Before the application of antibiotics, specimens were taken for pathogenic examination. Although the anti-pollution and screening methods were used, the diagnosis rate was only about 50%. Therefore, comprehensive analysis should be combined with clinical practice.

(2) Anti-pollution technology to collect lower respiratory secretions: At present, anti-pollution measures for bronchoalveolar lavage or protective specimens are generally carried out by fiberoptic bronchoscopy, and satisfactory sensitivity and specificity are obtained. The department used a protective specimen brush (PSB) to collect bacterial specimens for hospital-acquired pneumonia, and compared it with the bacteriological culture results of bronchoalveolar lavage (BAL) specimens and sputum specimens. 25% are pathogenic bacteria, 71% of BAL culture positive results are pathogenic bacteria, 81.2% of PSB culture results are pathogenic bacteria, and BAL and PSB methods take specimens to reduce the chance of specimens being contaminated by upper respiratory tract parasites. The diagnostic specificity of specimens taken with PSB is high, but the diagnostic sensitivity is low due to the small amount of specimens taken, while the BAL specimens involve a wide range and the specimens are taken more frequently, so the positive rate is higher, and quantitative culture is adopted. Method, with a colony count of 103 CFU / ml as a positive diagnostic criteria, can obtain a satisfactory diagnostic sensitivity and specificity, according to a group of 524 cases of ventilator pneumonia meta-analysis, using PSB to take specimens for quantitative culture, The number of bacteria >103 CFU/ml was positive, the diagnostic sensitivity rate was 90%, and the specificity was 94.5%. It was also reported that the protective (anti-pollution) bronchoalveolar lavage method was used to take the specimen, and the diagnostic sensitivity was 97%. 92% of the patients, for patients receiving mechanical ventilation, can be directly through the artificial airway (tracheal intubation) for protective bronchoalveolar lavage or transcatheter, such as the top of the bolt to prevent contamination of the curved catheter to attract specimens for bacteriology an examination.

The bronchoscopy or brushing of the specimen is an invasive examination, which may cause adverse effects on the body, such as causing arrhythmia, bronchospasm, hypoxemia, hemorrhage and fever. Therefore, the indications should be strictly controlled. Check operation, strict monitoring and observation, the relative contraindications for the examination are:

1 When severe hypoxemia is absorbed by pure oxygen (FIO21.0), the arterial partial pressure of oxygen (Pa02) is lower than 75 mmHg.

2 severe bronchospasm.

3 acute myocardial ischemia (acute myocardial infarction, unstable angina).

4 severe hypotension, mean arterial pressure <65mmHg with booster.

5 increased intracranial pressure.

6 severe bleeding constitution.

Transcatheter puncture and aspiration (TTA) was once used in the 1970s and 1980s, but the false positive rate is high, the specificity is low, and the patient is uncomfortable. It is easy to cause complications such as hemorrhage and pneumothorax. It has been rarely used. Transthoracic biopsy is more commonly used in patients with pleural effusion, and the positive rate and specificity of thoracoscopic lung biopsy and open lung biopsy are high, but traumatic, suitable for severe immunosuppression, opportunistic infection In high-risk patients, lung tissue samples were taken for further examination, including Pneumocystis carinii, cytomegalovirus and Aspergillus infection, and used to identify non-infectious lung diseases.

Chest X-ray and chest CT scan are of great value for diagnosis. They can help to detect lung lesions, determine the location, determine the nature and severity, usually manifest as pulmonary flaky infiltration or interstitial changes, and possibly There are holes or pleural effusions. Chest X-ray findings may be affected by basic chest diseases or by photography techniques and conditions, which may affect the correct judgment. Especially in the early stage, chest CT scans may show the nature of lung lesions more clearly. Combined with pleural effusion, chest X-ray findings may also be caused by other non-infectious lung diseases, such as atelectasis, pulmonary hemorrhage, acute respiratory distress syndrome, pulmonary edema, pulmonary embolism, tumor, etc., so chest X-ray Abnormal performance is not a specific cause diagnosis, but should be comprehensively analyzed with various clinical and examination data.

Diagnosis and diagnosis of acquired pneumonia in severe hospital

diagnosis

1. Principle of diagnosis

Hospital-acquired pneumonia must be neither present nor in the incubation period at the time of admission, but rather a pulmonary infection that occurs during hospitalization. It should rely on detailed clinical, laboratory and other auxiliary diagnostic data, such as X-ray examination, to determine the comprehensive analysis. To diagnose and assess the severity of the disease, in order to guide clinical treatment, adapt to the needs of prevention and treatment, with special emphasis on pathogenic diagnosis (such as sputum bacteriological examination), if necessary, for invasive microbiological examination, such as fiberoptic bronchoscopy.

2. Diagnostic criteria

To standardize the clinical diagnosis of NP, the Centers for Disease Control (CDC) has developed a definition of intra-hospital pneumonia.

China has also developed the Diagnostic Criteria for Acquired Bronchial-Lung Infection in Hospitals and Diagnostic Criteria for Lower Respiratory Infections in Hospitals and the draft guidelines for the diagnosis and treatment of hospital acquired pneumonia (1999).

3. Evaluation of the severity of the disease

(1) mild, moderate: general condition is good, early onset disease ( admission 5 days, mechanical ventilation 4 days); no risk factors (such as advanced age, >65 years old, chronic obstructive pulmonary disease, diabetes, chronic heart Renal insufficiency, inhalation or inhalation factors, history of pneumonia hospitalization, mental status changes, chronic alcoholism or malnutrition, post-spleen resection, etc. in the past year, vital signs are stable, and organ function is not abnormal.

(2) severe illness: disturbance of consciousness, respiratory rate > 30 beats / min, respiratory failure PaO2 <60mmHg, PaO2 / FIO2 <300, need mechanical ventilation, blood pressure <90/60mmHg, oliguria, urine output <20ml / h, Or <80m1/4h, sepsis or extrapulmonary complications, or acute renal failure requiring dialysis treatment, chest radiograph showing bilateral multiple lung lobe involvement, or lesion expansion within 50% within 48 hours of admission, and late onset disease (admission >5 days) , mechanical ventilation > 4 days) and those with high risk factors, even if not fully meet the criteria for severe pneumonia, is considered serious.

Differential diagnosis

Should be differentiated from atelectasis, lung tumor, pulmonary embolism, acute respiratory distress syndrome.

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