1. Background
Pneumonia occurring after more than 48 h of mechanical ventilation, the most common nosocomial acquired infection in ICU (6-52 cases/100 ICU patients), the risk of patients developing VAP per day after intubation is 1-3%, and almost 60% of patients develop VAP after 2 weeks of mechanical ventilation, VAP prolongs the length of stay and increases morbidity and mortality.
2. Risk factors
Patient side: >60 years, blood AB <2,2g/d, ARDS, COPD, coma, sinusitis.
Medical aspects: mechanical ventilation for more than 48h, tracheotomy, acid suppressants, inotropes, excessive sedation, nasogastric tube, supine position, reintubation.
3.Diagnosis
Traditional clinical diagnostic criteria: new invasive shadow on chest radiograph, fever, elevated neutrophils, aspiration of purulent secretions from the tracheal intubation. The biggest problem with this diagnostic criterion is its high sensitivity and low specificity, which can lead to overdiagnosis.
The reason is that bacterial colonization of the lower airway after tracheal intubation is very common, and colonized bacteria are not necessarily the causative agent of VAP; many other pulmonary lesions in ICU/MICU patients may also present as invasive shadows, such as pulmonary edema, pulmonary atelectasis, and ARDS, which cannot be distinguished from VAP on imaging.
The consequences of overdiagnosis are unnecessary antibiotic therapy, increased medical costs and bacterial resistance.
Transtracheal aspiration: high sensitivity (90%) and poor specificity (50%), so if culture of transtracheal aspirate is negative, VAP is highly unlikely.
New diagnostic method: bronchoalveolar micro lavage (micro BA) lavage of the lower airways using a protective catheter requires a well-trained physician to perform this procedure.
Quantitative analysis: microbiological cultures >104 are considered positive.
4. Treatment
If the diagnosis of VAP is clear but pathogenic information is not yet available, broad-spectrum antibiotic therapy should be started as soon as possible according to the hospital’s drug sensitivity (consult the bacteriology laboratory).
Switch to narrow-spectrum antibiotics as soon as possible after the culture results are clear and perform micro BA to guide treatment.
Course of treatment.
An 8-day regimen is as effective as a 15-day regimen for most pathogenic bacteria, and with less antibiotic use.
If the pathogen of VAP is a non-fermenting Gram-negative bacillus (including Pseudomonas aeruginosa, Acinetobacter baumannii and Maltophilus narrow-feeding monospora), an 8-day course is as effective as a 15-day course, but the former has a higher recurrence rate, so the course should be extended appropriately in such patients.
5.Prevention
Develop offline program as early as possible and offline as soon as possible
Minimize the use of broad-spectrum antibiotics
Prevent stress ulcers in low-risk patients with aluminum thioglycollate rather than acid suppressants
Isolation of patients already infected with multidrug-resistant, high-risk pathogens
Semi-recumbent position (elevate head of bed more than 30 degrees)
Avoid excessive sedation
Since the causative agent of VAP is mainly from oropharyngeal secretions, consider continuous subacoustic suctioning when available
Medical staff must wash their hands frequently!