Resp Care
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Between 15% and 35% of mechanically ventilated patients fail an initial spontaneous breathing trial. For these patients, 40% of total time on mechanical ventilation is consumed by the weaning process (60% for patients with chronic obstructive pulmonary disease). Longer duration of mechanical ventilation is associated with higher risk of complications and probably with higher mortality. ⋯ Randomized controlled trials have indicated that, in selected patients with chronic obstructive pulmonary disease and acute-on-chronic respiratory failure, NIV can facilitate weaning, reduce the duration of invasive mechanical ventilation, decrease complications, and reduce mortality, compared to weaning on continued invasive ventilation. However, extubation failure resulting in re-intubation is associated with higher mortality, and this mortality risk increases with delay of re-intubation and may not be prevented by application of NIV. Patients extubated to NIV must have careful monitoring by skilled clinicians able to provide timely re-intubation if the patient shows signs of intolerance or worsening respiratory failure.
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In patients with acute respiratory distress syndrome (ARDS), inhaled vasodilator can result in important physiologic benefits (eg, improved hypoxemia, lower pulmonary arterial pressure, and improved right-ventricular function and cardiac output) without systemic hemodynamic effects. Inhaled nitric oxide (INO) and aerosolized prostacyclins are currently the most frequently used inhaled vasodilators. Inhaled prostacyclins are as effective physiologically as INO and cost less. ⋯ No outcome studies have been reported on the use of prostacyclin in patients with ARDS. There is no role for the routine use of inhaled vasodilators in patients with ARDS. Inhaled vasodilator as a rescue therapy for severe refractory hypoxemia in patients with ARDS may be reasonable, but is controversial.
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Mechanically, breath design is usually either flow/volume-targeted or pressure-targeted. Both approaches can effectively provide lung-protective ventilation, but they prioritize different ventilation parameters, so their responses to changing respiratory-system mechanics and patient effort are different. These different response behaviors have advantages and disadvantages that can be important in specific circumstances. ⋯ In contrast, pressure targeting, with its variable flow, may be easier to synchronize and will limit inspiratory pressure, but it provides no control over delivered volume. Skilled clinicians can maximize benefits and minimize problems with either flow/volume targeting or pressure targeting. Indeed, as is often the case in managing complex life-support devices, it is operator expertise rather than the device design features that most impacts patient outcomes.
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Low-tidal-volume ventilation strategies are clearly beneficial in patients with acute lung injury and acute respiratory distress syndrome, but the optimal level of applied positive end-expiratory pressure (PEEP) is uncertain. In patients with high pleural pressure on conventional ventilator settings, under-inflation may lead to atelectasis, hypoxemia, and exacerbation of lung injury through "atelectrauma." In such patients, raising PEEP to maintain a positive transpulmonary pressure might improve aeration and oxygenation without causing over-distention. ⋯ Recently the use of esophageal manometry to identify the optimal ventilator settings, avoiding both under-inflation and over-inflation, was proposed. This method shows promise but awaits larger clinical trials to assess its impact on clinical outcomes.
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Ventilator-associated pneumonia (VAP) is a common and serious complication of mechanical ventilation via an artificial airway. As with all nosocomial infections, VAP increases costs, morbidity, and mortality in the intensive care unit (ICU). ⋯ Substantial evidence supports the use of endotracheal tubes (ETTs) that allow subglottic suctioning; silver-coated and antiseptic-impregnated ETTs; ETTs with thin-walled polyurethane cuffs; and HMEs, but these devices also can have adverse effects. Controversy still exists regarding the evidence, cost-effectiveness, and disadvantages and risks of these devices.