Ventilator Acquired Pneumonia - Essay Example

? Ventilator Acquired Pneumonia Though medical interventions aim at restoration of patient’s well-being, some medical procedures may pose as demerits by acting as source infections. Ventilator acquired pneumonia (VAP) is one of those infections (Chastre and Fagon, 2008). Ventilator acquired pneumonia (VAP) is pneumonia that occurs in patients on endotracheal intubation or tracheostomy tube after 48 hours or more which was not originally present before the ventilation. It is the most common ICU infection and the most fatal of all. The length of ICU stay is increased by 28% with VAP and, each VAP incidence is estimated to produce a significant amount of cost increment. In addition, morbidity and mortality rates are also increased with this nosocomial infection. The NICE has collaborated with NPSA to investigate four technical solutions in patient safety for VAP prevention. Reduction or elimination of unnecessary antibiotic use is the most fundamental goal towards reducing nosocomial infections that are antibiotic-resistant. This article will tackle the literature on risk factors, diagnosis, prevention and treatment of VAP. Introduction The risk of death for patients in the intensive care unit (ICU) is not only increased by their critical illness but also from other secondary additions such nosocomial infections. Pneumonia affects about 27% of patients in the ICU, making it the second commonest nosocomial infection. Mechanical ventilation causes about 80% of the nosocomial pneumonias, referred to as ventilator-associated pneumonia (VAP). Only in the United States, about 250,000-300,000 cases of VAP occur annually, which makes an incidence rate of 5-10 cases 1,000 cases of hospital admissions with a mortality rate of 0-50% (Mirsaeidi, 2009). The organisms attributed to high VAP mortality include, Stenotrophomonas maltophilia, Acinetobacter spp., and Pseudomonas aeruginosa. In addition to high mortality rate, VAP has a negative effect on the patients’ economy due to long periods of stay in ICU and increased cost estimated to be about $5,000- $20,000 per each diagnosis. Diagnosis of VAP requires a combination of high clinical suspicion, bedside examination, microbiology examination of throat secretion and radiographic examination. Antibiotics should be used judiciously to prevent resistance. Other preventive measures like respiratory therapy and basic nursing intervention should also be adopted to reduce the risk of VAP (Chastre and Fagon, 2008). Ventilator associated pneumonia is limited only to those patients receiving mechanical ventilation. The general understanding of VAP has significantly grown over the past year in terms of risk factors, pathogenesis, diagnostic testing, therapies and prevention. This article assists the clinicians to understand VAP in a better way especially in terms of diagnosis, treatment and prevention. Diagnosis Diagnosis of VAP has remained a challenge despite its high incidence since the clinical signs mimic those found in other conditions like ARDS, cardiac failure, sepsis, and lung atelectasis, which are also common to patients in ICU. Among the patients diagnosed with VAP, 50% are false positives while one third remains undiagnosed. Diagnosis of VAP is often made when a patient is diagnosed of pneumonia after the initiation of mechanical ventilation. VAP is assumed when the patient on mechanical ventilation is found to have elevated leukocytes, and a chest x-ray suggestive of pneumonia. The causative micro-organisms are usually isolated on the blood culture. However, VAP does not have an obviously accepted gold standard way of diagnosing. Clinical diagnosis Patients on mechanical ventilation are usually sedated and unable to speak. Hence, the care providers often miss the typical symptoms of pneumonia. The most significant clinical signs include low body temperature, fever, hypoxia and new purulent secretions. An individual may develop new or progressive chest infiltrate seen on the radiograph and leukocytosis. However, the clinical criteria have a narrow diagnostic value in establishing VAP presence. Fabregas et al carried out a postmortem study for diagnosing VAP. His histological findings and culture of samples obtained from the lungs immediately after death; a new and progressive chest radiograph infiltrate for more than 48 hours; in addition to two or more of (i) leukocytosis (ii) fever >38.3°C (iii) purulent secretion from tracheobronchial tree, had a specificity of 75% and sensitivity of 69%. The sensitivity declined to 23% when the diagnosis was based on all the three clinical variables while using a single variable reduced the specificity to 33% (Zack, 2002). This was related to the fact that these symptoms were nonspecific and, they could be caused by any of other condition. The presence of ARDS lowers the sensitivity of the clinical criteria even further since new radiographic infiltrates are hard to detect. However, in the setting of ARDS, the suspicion of VAP should be high. Minor clinical symptoms include new or worsening dyspnoea, tachypnea or cough, worsening gas exchange, bronchial breath sounds or rales, purulent sputum or increased respiratory secretions. Nosocomial tracheobronchitis in patients with mechanical ventilation has led to longer time on ventilation and ICU stay without mortality increase. In a randomized trial of mechanically ventilated patients with nosocomial tracheobronchitis, there was a decrease in the incidence of pneumonia and mortality due to antibiotic therapy. However, antibiotic treatment of the nosocomial tracheobronchitis cannot take place unless a randomized trial has been done, which can increase the incidence VAP. Furthermore, the difference between pneumonia and tracheobronchitis is based on radiographic findings, of which in ICU the radiographs are portable and possibly of poor quality. Radiologic diagnosis Portable chest radiographs are vital components in the diagnosis of VAP in ICU patients on ventilation, although it too has problems with specificity and sensitivity. The accuracy of the chest x-rays is further compromised with poor-quality films. The radiological signs include at least one of; consolidation, cavitations, and new or progressive and persistent chest infiltrate in more than two serial chest x-rays. Although VAP is unlikely when the chest radiograph is normal, in one study carried out on surgical patients, computed tomography (CT) detected 26% of opacities which were not detected by a portable chest X-ray. Moreover, asymmetric pulmonary infiltrate common in VAP can be as a result of other non-infectious disorders such as chemical pneumonitis, atelectasis, pulmonary embolism, pulmonary edema, pulmonary hemorrhage, drug reaction, pulmonary contusion and drug reaction, among others. The general specificity of pneumonia in a radiograph showing pulmonary opacity is only 27%-37%. Based on Wunderink et al, some of the useful radiographic findings suggesting VAP include: air bronchogram (96% specificity); an airspace process adjoining a fissure (96% specificity) and rapid progressive pulmonary infiltrate cavitations. Unfortunately, it is rare to find such abnormalities on radiographs. Microbiology diagnosis This is based on culture of blood and pleural effusion. The spread of VAP to the pleural space or blood is less than 10%, but if the cultures are positive for organisms causing VAP, treatment is mandatory. Various clinicians recommend two different blood cultures and a culture of pleural fluid. However, it is imperative to note that the sensitivity of diagnosing VAP using blood cultures is Read More