Resp Care
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Over the last 2 decades, it has become clear that mechanical ventilation itself can cause lung injury and affect outcome. The development of ventilator-induced lung injury is strongly associated with overdistension of lung parenchyma, and limiting lung stretch saves lives in patients with acute lung injury. The debate in this paper is whether all patients on mechanical ventilation should be managed with a tidal volume (V(T)) of 6 mL/kg predicted body weight. ⋯ Plateau pressure may be a better target for assessing and preventing alveolar over-distension. As the data evolve, it is conceivable that the actual V(T) used should be based on the individual patient's lung mechanics rather than assuming that one V(T) will suit all patients. Consensus at this time is not possible, and this paper presents the arguments on both sides of the controversy.
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High-frequency ventilation is the application of mechanical ventilation with a respiratory rate > 100 breaths/min. High-frequency oscillatory ventilation (HFOV) is the form of high-frequency ventilation most widely used in adult critical care. The principles of lung-protective ventilation have matured in parallel with the technology for HFOV. ⋯ Available evidence does not support that pulmonary inflammation is reduced with HFOV in adult acute respiratory distress syndrome. Heavy sedation and often paralysis are necessary. The promise of HFOV as a lung-protective ventilation strategy remains attractive, but additional clinical trials are needed to determine whether this approach is superior to lung-protective ventilation with conventional mechanical ventilation.
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Ventilator weaning protocols have the potential to expedite the weaning process and have been shown to reduce weaning time and the duration of mechanical ventilation in several studies. However, other studies have found no benefits from weaning protocols, and they may be particularly superfluous in highly staffed and structured intensive care units. Furthermore, for a protocol to improve outcomes, the clinicians must have a high rate of adherence to the protocol. Weaning protocols might improve patient care and outcomes, but their implementation should be based on local clinical characteristics and needs, and accompanied by an intensive education effort and measurement of adherence and outcomes.
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Lung recruitment maneuvers are being used in the management of acute lung injury and acute respiratory distress syndrome, but recruitment maneuvers are controversial. The proponents argue that when properly applied to appropriately selected patients, they are effective and can be safely applied. The expectation is that the recruitment maneuver will change the course of ARDS and improve outcomes. ⋯ Outcome data are clearly needed before recruitment maneuvers can be fully incorporated into clinical practice. If a recruitment maneuver is conducted, a decremental positive end-expiratory pressure (PEEP) trial must be done to determine the minimum PEEP that sustains the benefits of the recruitment maneuver. We explore both sides of the lung recruitment controversy.
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Noninvasive positive-pressure ventilation (NPPV) has been a major advance in the management of acute respiratory failure. Over the past decade alone, NPPV has been the subject of over 1,500 scientific papers, including 14 meta-analyses. NPPV's utility in many clinical settings has been well established, with demonstration in randomized trials of lower intubation rate, mortality, hospital stay, and advantages in other important clinical outcomes. ⋯ While there probably are situations in which NPPV is commonly under-utilized, there are other situations in which it is unlikely to be of benefit or likely to inflict harm. This paper debates the data for and against the more widespread application of NPPV. It will assist the clinician to identify both good and poor candidates for NPPV and thereby devote respiratory care resources where they will be most effective, and optimize patient outcomes.