Resp Care
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Review Comparative Study
Noninvasive positive-pressure ventilation and ventilator-associated pneumonia.
There is much interest in the use of noninvasive positive-pressure ventilation (NPPV) to prevent intubation and afford a survival benefit for patients. The risk of pneumonia in patients receiving NPPV has been reported in 12 studies. Compared to patients receiving invasive mechanical ventilation (4 studies), the pneumonia rate is lower with the use of NPPV (relative risk [RR] 0.15, 95% confidence interval [CI] 0.04 to 0.58, p = 0.006). ⋯ One randomized controlled trial of continuous positive airway pressure compared with standard treatment in patients who developed acute hypoxemia after elective major abdominal surgery reported a lower rate of pneumonia with continuous positive airway pressure (2% vs 10%, RR 0.19, 95% CI 0.04 to 0.88, p = 0.02). In patients who are appropriate candidates for NPPV or continuous positive airway pressure, the available evidence suggests a benefit in terms of a lower risk of pneumonia. Perhaps "endotracheal-tube-associated pneumonia" is a better term than "ventilator-associated pneumonia."
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The gastrointestinal tract is believed to play an important role in ventilator-associated pneumonia (VAP), because during critical illness the stomach often is colonized with enteric Gram-negative bacteria. These are the same bacteria that frequently are isolated from the sputum of patients with VAP. Interventions such as selective decontamination of the digestive tract (SDD), use of sucralfate for stress ulcer prophylaxis, and enteral feeding strategies that preserve gastric pH, or lessen the likelihood of pulmonary aspiration, are used to decrease the incidence of VAP. ⋯ Rather, therapy should be focused on strategies other than antibiotic prophylaxis. Second, in patients who are at risk for clinically important gastrointestinal bleeding, a histamine-2 receptor antagonist should be used for stress ulcer prophylaxis, rather than sucralfate, because histamine-2 receptor antagonist provides substantially better protection without substantially increasing the risk of VAP. Third, post-pyloric enteral feeding may reduce the incidence of VAP.
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Rotational beds, prone position, and semi-recumbent position have been proposed as procedures to prevent ventilator-associated pneumonia (VAP). Rotational therapy uses a special bed designed to turn continuously, or nearly continuously, the patient from side to side; specific designs include kinetic therapy and continuous lateral rotation therapy. A meta-analysis of studies evaluating the effect of rotational bed therapy shows a decrease in the risk of pneumonia but no effect on mortality. ⋯ One study reported a lower rate of VAP in patients randomized to semi-recumbent compared to supine position. Although each of the techniques discussed in this paper has been shown to reduce the risk of VAP, none has been shown to affect mortality. The available evidence suggests that semi-recumbent position should be used routinely, rotational therapy should be considered in selected patients, and prone position should not be used as a technique to reduce the risk of VAP.
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Ventilator-associated pneumonia (VAP), which is usually defined as an infection occurring greater than 48 hours after hospital admission in a patient requiring mechanical ventilation, is an entity that should be viewed as a subcategory of health-care-associated pneumonia, which includes any patient who was hospitalized in an acute care hospital for 2 or more days within 90 days of the infection; resided in a nursing home or long-term care facility; received recent antibiotic therapy, chemotherapy, or wound care within the past 30 days of the current infection; or attended a hospital or hemodialysis clinic. VAP is the most frequent intensive-care-unit (ICU)-acquired infection among patients receiving mechanical ventilation. In contrast to infections of other frequently involved organs (eg, urinary tract and skin), for which mortality is low, the mortality rate for VAP ranges from 20% to 50% and can reach 70% in some specific settings or when lung infection is caused by high-risk pathogens and/or when initial antibiotic therapy is inappropriate. ⋯ Antimicrobial therapy of patients with VAP should follow a 2-stage process. The first stage involves administering broad-spectrum antibiotics to avoid inappropriate treatment in patients with true bacterial pneumonia. The second stage focuses on trying to achieve this objective without over-using and abusing antibiotics, combining a number of different steps, such as stopping therapy in patients with a low probability of the disease, streamlining treatment once the etiologic agent is known, switching to monotherapy after days 3-5, and shortening duration of therapy to 7-8 days, as dictated by the patient's clinical response to therapy and information about the bacteriology of the infection.
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Pooling of contaminated secretions above the cuff of the endotracheal tube predisposes patients to ventilator-associated pneumonia (VAP). Subglottic secretion drainage requires a special endotracheal tube that has a separate lumen that opens in the subglottic region above the tracheal tube. A recent meta-analysis of the 5 randomized clinical trials that evaluated the efficacy of removing these secretions found that this technique significantly reduces the incidence of VAP. ⋯ While silver-coated endotracheal tubes reduce pseudomonas pneumonia in intubated dogs and delay airway colonization in intubated patients, evaluation of studies with a variety of case mixes is warranted to identify subsets likely to benefit from the technique before it is implemented on a large scale. A patient who has a colonized airway and who undergoes percutaneous tracheotomy has an increased risk of VAP, particularly due to Pseudomonas aeruginosa, in the week following the procedure. As many studies suggest that incidence of VAP is highly dependent on the strategies of airway management, health care workers should be alerted to issues related to the artificial airway.