Respiratory care
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The unifying goal of lung-protective ventilation strategies in ARDS is to minimize the strain and stress applied by mechanical ventilation to the lung to reduce ventilator-induced lung injury (VILI). The relative contributions of the magnitude and frequency of mechanical stress and the end-expiratory pressure to the development of VILI is unknown. Consequently, it is uncertain whether the risk of VILI is best quantified in terms of tidal volume (VT), driving pressure (ΔP), or mechanical power. ⋯ In trials of lung-protective ventilation strategies, VT, ΔP, Powerelastic, Powerdynamic, and Powerdriving exhibited similar moderation of treatment effect on mortality. In this study, modified mechanical power did not add important information on the risk of death from VILI in comparison to VT or ΔP.
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The ventilatory ratio (VR) is a dead-space marker associated with mortality in mechanically ventilated adults with ARDS. The end-tidal alveolar dead space fraction (AVDSf) has been associated with mortality in children. However, AVDSf requires capnography measurements, whereas VR does not. We sought to examine the prognostic value of VR, in comparison to AVDSf, in children and young adults with acute hypoxemic respiratory failure. ⋯ VR should not be used for prognostic purposes in children and young adults. AVDSf added prognostic information to the severity of oxygenation defect and overall severity of illness in children and young adults, consistent with previous research.
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A spontaneous breathing trial (SBT) is commonly used to determine extubation readiness in patients receiving mechanical ventilation. However, the physiological impact of such a trial in preterm infants has not been well described. This study aimed to investigate the effects of a 3-min SBT on the cardiorespiratory stability of these infants. ⋯ In preterm infants receiving prolonged mechanical ventilation, the performance of a 3-min SBT was associated with increased respiratory instability while still leading to a 10% extubation failure rate. Therefore, the routine use of SBTs to assess extubation readiness in this population is not recommended until there are clear standards and definitions, as well as good accuracy to identify failures.