1, ventilator-associated pneumonia
Ventilator-associated pneumonia refers to the original patients without lung infection, tracheotomy or tracheal intubation after 48h of mechanical ventilation treatment, or extraction of the tube within 48h of the occurrence of lung infection.
Ventilator-associated pneumonia is very common in the clinic, in the respiratory department of long-term patients on the machine, the incidence rate of 9% to 70%, the mortality rate of 15% to 70%, the patient, once it happens, it is easy to cause off the machine difficulties. This prolongs hospitalization time, increases hospitalization costs, and in severe cases even threatens the patient's life and leads to death.
2, ventilator-associated pneumonia causes
①The body's respiratory and systemic defense mechanism is impaired. Mechanically ventilated patients are in serious condition, and the body's defense mechanism of the whole body is impaired after suffering from severe disease states and trauma. Local airway defense function is affected, coupled with tracheal intubation directly damage the pharynx, so that the natural defense function of the airway is damaged, while tracheal intubation also weakened the ability of the ciliary system to remove bacteria, inhibit the cough reflex protection, which is very likely to lead to lower respiratory tract infections.
②Oropharyngeal colonization bacteria mistakenly inhaled into the lungs. In critically ill patients, germs colonize the oropharynx, and with mechanical ventilation, these germs accumulate around the catheter air sacs as secretions from the subglottic area to form a bacterial reservoir, which makes it possible for the otherwise sterile lungs to become infected due to factors such as misinhalation.
3) Reflux of gastric and duodenal colonizing bacteria and pulmonary aspiration. The vast majority of patients using a ventilator are in critical condition, in order to prevent the occurrence of stress ulcers, the routine clinical application of acid-suppressing drugs such as omeprazole, which can lead to a higher-than-normal pH value of the gastric juice, weakening the gastric juice for the killing effect of the bacteria into the stomach, which is conducive to the bacterial colonization of the stomach. At the same time, critically ill patients are very prone to reflux aspiration, both *** with the same role, making the lung infection aggravated.
④The formation of bacterial biofilm. PVC material made of tracheal tube, bacteria are easy to adhere to its surface proliferation, a large number of secretion of extracellular polysaccharide to form a bacterial biofilm, mechanical ventilation patients, the flow of gas and liquid tracheal tube, sputum suction tube mechanical collision may lead to the movement of bacteria, buildup or shedding, and shedding of bacterial debris into the lower respiratory tract is easy to lead to infection.
⑤Exogenous bacterial infection. The high concentration of pathogenic bacteria in the air of the ward, the laxity of aseptic technique of medical staff, the non-strict implementation of common infection control measures, and the incomplete disinfection of air in the ward may lead to exogenous bacterial infections, and in the clinical work, the cross-infection between many patients is often realized through the hands of medical staff and the air in the ward.
3, how to diagnose
The diagnosis of ventilator-associated pneumonia is the most important and controversial of the problems related to ventilator-associated pneumonia! To date, there is no real practical clinical gold standard for the diagnosis of ventilator-associated pneumonia.
Traditional diagnostic criteria are easy to observe: fever, leukocytosis, purulent airway secretions, etc., but have the disadvantage of high sensitivity and low specificity. At present, the international community usually adopts the comprehensive diagnostic criteria with high specificity: that is, the oxygen and index and sputum culture smear are considered on the basis of the traditional diagnostic criteria to find the pathogenic bacteria, and the diagnosis of ventilator-associated pneumonia can be confirmed when the lung infection score of CPIS6 is scored.
4, 12 comprehensive preventive measures
①Prevention of cross-infection wording. Strict hand washing, wearing gloves and masks, and strict aseptic operation are still recognized as one of the most effective measures to prevent cross-infection.
②Avoid tracheal intubation/transoral intubation. Unnecessary tracheal intubation and reintubation should be avoided at all times. Noninvasive positive-pressure ventilation via face mask or nasal mask can be the ventilation of choice for many patients with acute respiratory failure. Judge cautiously whether extubation is possible and avoid repeated insertion and removal of the tracheal tube.
3) Avoid nonessential airway circuit manipulation and replacement. The airway circuit is an important site for bacterial colonization, and frequent tube changes can allow bacteria carried in the air or on the hands of healthcare workers to enter the airway circuit. These bacteria will use condensate and aerosols as carriers to enter and colonize the lower airway, and ventilator-associated pneumonia will occur.
4 Use of heat and moisture exchangers. The artificial airway has lost the function of heating and humidifying the upper respiratory tract. The heat and humidity exchanger can effectively utilize the temperature and humidity of the patient's exhaled gas to keep the exhalation tube dry and avoid bacterial breeding, and at the same time heat and humidify the inhalation gas; its bacterial and viral filters can filter and adsorb bacteria in the respiratory tube to achieve the function of replacing the upper respiratory tract, which may reduce the incidence of respiratory-associated pneumonitis.
⑤Positional management. Supine position is more prone to reflux aspiration as well as pneumonia than semirecumbent position, but semirecumbent position in practice patients have can not be maintained for a long period of time, but even if you can only maintain semirecumbent position for a certain period of time, the incidence of pneumonia is less than that of patients who have always been in the prone position.
6 subglottic secretion drainage. In patients with tracheal intubation, secretions from the upper airway accumulate above the catheter balloon, and with the patient's respiration, the secretions leak into the lower airway due to a transient drop in balloon pressure (pressure of 20 cm Hz0), changes in body position, and changes in the diameter of the airway tubing, which can lead to the occurrence of ventilator-associated pneumonitis. Therefore, subglottic secretion drainage is considered necessary and effective in preventing the occurrence of ventilator-associated pneumonia.
7 Avoid gastric hyperinflation and reduce gastroesophageal reflux. Enteral nutrition is superior to parenteral nutrition in reducing complications of central venous catheterization and preventing atrophy of intestinal mucosal villi and the resulting bacterial migration. However, gastric hyperinflation exacerbates ventilator-associated pneumonia, so avoiding gastric hyperinflation and reducing gastroesophageal reflux and thus aspiration can reduce the incidence of ventilator-associated pneumonia.
8 Strengthen the education and supervision of ward staff. Strengthen the standard operation of hand washing and disinfection of health care personnel, reduce the patient's family and patient contact time, while urging the patient's family to do a good job of aseptic protection to reduce cross-infection.
⑨Reduce bacterial colonization of the airway and digestive tract. Selective digestive tract decontamination (SDD) is one of the more advanced and debated issues in recent years. Most studies have shown that, on the one hand, SDD can reduce the colonization of gram-negative bacteria, reduce the incidence of ventilator-associated pneumonia, and reduce the average hospitalization in respiratory medicine; on the other hand, SDD can increase the resistance of pathogenic bacteria, which may lead to outbreaks of multidrug-resistant bacteria, thus increasing the pressure to select antimicrobial drugs against drug-resistant bacteria.
⑩Prevention of biofilm formation. The use of pipe surface-adherent antimicrobial agents to stop bacterial adhesion, oxidized slurry-treated polyvinyl chloride, and the use of aerosolized antimicrobial drugs can be effective in preventing biofilm formation.
Try to avoid blood transfusions. Stock concentrated red blood cells contain a large number of pro-inflammatory cytokines, and blood transfusion can promote the release of cytokines in the body and cause "cascade" amplification and other effects. In addition, residual leukocytes in the donor's concentrated red blood cells may act as epitopes, causing changes in immune function through alterations in T-cell function.
Enhancing immune function. For such patients, in addition to strengthening nutrition and other general supportive treatment, the patient's defense mechanism can be improved through active and passive immunity.
5, the clinical manifestations of severe pneumonia
1, the rapid onset of severe pneumonia, the condition is severe, 1-3 days will develop into a slow shock or in a state of shock at the time of consultation.
2, severe pneumonia patients will also have chills, fever, body temperature does not exceed 40 ℃, a small number of patients do not have elevated body temperature or only low fever.
3, severe pneumonia patients with shock symptoms, mainly manifested as pale, cold limbs, cold sweat, shortness of breath, lips and limbs cyanosis.
4, severe pneumonia may also appear blurred consciousness, restlessness, delirium, drowsiness and so on.