Resp Care
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We saw a patient who presented with carbon dioxide narcosis and acute respiratory failure due to an exacerbation of chronic obstructive pulmonary disease. We intubated and 12 hours later he had recovered consciousness and could cooperate with noninvasive ventilation, at which point we extubated and used a helmet to provide noninvasive positive-pressure ventilation in assist/control mode, and then during the ventilator-weaning process, pressure support, and finally continuous positive airway pressure. The patient had no complications from the helmet, and he was discharged from intensive care 48 hours after helmet ventilation was initiated. Helmet noninvasive ventilation is a potentially valuable ventilator-weaning method for certain patients.
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Review Comparative Study
Alveolar mechanics in the acutely injured lung: role of alveolar instability in the pathogenesis of ventilator-induced lung injury.
With patients who have acute lung injury, respiratory function is routinely evaluated and the treatment may entail choices from various ventilatory strategies. The ventilatory strategies that have been used over the years are being replaced by newer protocols that represent improvements in patient treatment. However, the rationales for the various ventilatory strategies are largely empirical, because the physiology and mechanics of lung inflation are poorly understood. ⋯ We have researched alveolar histophysiology with animal experiments that combined a conventional histological approach with in vivo microscopy to assess alveolar dynamics during normal and disease-state ventilation. Our video and computer analyses document real-time changes of alveolar size and function, often in the same animal and in adjacent areas of the same lung. Our research indicates that, instead of supporting one theory of alveolar mechanics or another, the various behaviors reportedly exhibited by alveoli may be consistent and represent a continuum between normal alveolar function and the alveolar mechanics of acute lung injury.
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Comparative Study
Prognostic value of the pulmonary dead-space fraction during the first 6 days of acute respiratory distress syndrome.
The ratio of pulmonary dead space to tidal volume (VD/VT) in acute respiratory distress syndrome (ARDS) is reported to be between 0.35 and 0.55. However, VD/VT has seldom been measured with consideration to the evolving pathophysiology of ARDS. ⋯ In ARDS a sustained VD/VT elevation is characteristic of nonsurvivors, so dead-space measurements made beyond the first 24 hours may have prognostic value.