Respiratory care
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Recent literature suggests that optimization of tidal driving pressure (ΔP) would be a better variable to target for lung protection at the bedside than tidal volume (VT) or plateau pressure (Pplat), the traditional indicators of ventilator-induced lung injury. However, the usual range or variability of ΔP over time for any subject category have not been defined. This study sought to document the ΔP ranges observed in current practice among mechanically ventilated subjects receiving routine care for diverse acute conditions in a community hospital environment. ⋯ Suggested safety thresholds for ΔP are often violated by a strategy that focuses on only VT and Pplat. Our data suggest that ΔP is lower for passive versus triggered breathing cycles. Vigilance is especially important in the initial stages of mechanical ventilator support, and attention should be paid to triggering efforts when interpreting and comparing machine-determined numerical values for ΔP.
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In 2013, the United States Centers for Disease Control and Prevention redefined surveillance for quality of care in ventilated patients by shifting from ventilator-associated pneumonia (VAP) definitions to ventilator-associated event (VAE) definitions. VAE definitions were designed to overcome many of the limitations of VAP definitions, including their complexity, subjectivity, limited correlation with outcomes, and incomplete capture of many important and morbid complications of mechanical ventilation. VAE definitions broadened the focus of surveillance from pneumonia alone to the syndrome of nosocomial complications in ventilated patients, as marked by sustained increases in ventilator settings after a period of stable or decreasing ventilator settings. ⋯ Risk factors for VAEs include sedation with benzodiazepines or propofol, volume overload, high tidal-volume ventilation, high inspiratory driving pressures, oral care with chlorhexidine, blood transfusions, stress ulcer prophylaxis, and patient transport. Potential strategies to prevent VAEs include minimizing sedation, paired daily spontaneous awakening and breathing trials, early mobility, conservative fluid management, conservative transfusion thresholds, and low tidal-volume ventilation. A limited number of studies that have tested subsets of these interventions have reported substantial decreases in VAEs; no group, however, has thus far assessed the impact of a fully optimized VAE prevention bundle that includes all of these interventions upon VAE rates and other outcomes.
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Editorial Comment
Spontaneous Inspiratory Effort During Lung-Protective Ventilation.
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Implementation of ventilator bundles is associated with reductions in ventilator-associated pneumonia (VAP). However, the new surveillance model of ventilator-associated events (VAEs) has shifted the focus from VAP to objective, generalized signs of pulmonary decompensation not specific to VAP. This raises the question of whether the ventilator bundle also is effective in reducing VAE. ⋯ The largest study found significant reductions in duration of intubation with weaning, sedation, and head of bed elevation, as well as reduced mortality risk with weaning and sedation bundle elements. Nonetheless, these studies should be useful in designing future prospective controlled studies to determine what elements of a future prevention bundle might be effective in reducing VAEs. At this juncture, and based on the limited evidence to date, it appears that incorporating daily sedation interruptions and spontaneous breathing trials are the factors most likely to reduce VAEs.
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There have been many innovations to the standard endotracheal tube over the years, many of which were intended to reduce the incidence of ventilator-associated pneumonia (VAP). Ventilator-associated events are associated with the objective outcomes of increased duration of mechanical ventilation, length of ICU and hospital stay, and increased risk of mortality. Many specialty tubes have been associated with a reduction in the clinical diagnosis of VAP, but studies have failed to show differences in objective outcomes. This article reviews the evidence related to specialty tubes and discusses their role in improving objective outcomes associated with ventilator-associated events.