Resp Care
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Randomized Controlled Trial Comparative Study
Volume-targeted versus pressure-targeted noninvasive ventilation in patients with chest-wall deformity: a pilot study.
Long-term noninvasive ventilation (NIV) is an effective treatment for patients with chronic respiratory failure due to chest-wall deformity, but it is unknown if the time required for the patient to adjust to long-term NIV depends on whether the NIV is volume-targeted or pressure-targeted. ⋯ There was no significant difference in days needed to successfully establish volume NIV versus pressure NIV in patients with chest-wall deformity. However, two patients switched successfully from volume NIV to pressure NIV, which suggests that they preferred pressure NIV.
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To minimize ventilator-induced lung injury, attention should be directed toward avoidance of alveolar over-distention and cyclical opening and closure of alveoli. The most impressive study of mechanical ventilation to date is the Acute Respiratory Distress Syndrome (ARDS) Network study of higher versus lower tidal volume (V(T)), which reported a reduction in mortality from 39.8% to 31.0% with 6 mL/kg ideal body weight rather than 12 mL/kg ideal body weight (number-needed-to-treat of 12 patients). To achieve optimal lung protection, the lowest plateau pressure and V(T) possible should be selected. ⋯ PEEP should be set to maximize alveolar recruitment while avoiding over-distention. Many approaches for setting PEEP have been described, but evidence is lacking that any one approach is superior to any other. In most, if not all, cases of ALI/ARDS, conventional ventilation strategies can be used effectively to provide lung-protective ventilation strategies.
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It has been known for decades that shock and sepsis can cause a syndrome of acute respiratory failure with characteristics of non-cardiogenic pulmonary edema. Over the years, this syndrome has been given a number of names, including congestive atelectasis, traumatic wet lung, and shock lung. In 1967 the modern counterpart to this syndrome was described and subsequently called the "acute respiratory distress syndrome" (ARDS). ⋯ Although in 1994 a new standard ARDS definition was accepted, that definition failed to standardize the measurement of the oxygenation defect and does not recognize different severities of pulmonary dysfunction. Based on current evidence there is a need for a better definition and classification system that could help us to identify ARDS patients who would be most responsive to supportive therapies and those unlikely to benefit because of the severity of their disease process. This paper examines our current understanding of ARDS and discusses why the current definition may not be the most appropriate for research and clinical practice.
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Review
Noninvasive ventilation for patients with acute lung injury or acute respiratory distress syndrome.
Few studies have been performed on noninvasive ventilation (NIV) to treat hypoxic acute respiratory failure in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). The outcomes of these patients, for whom endotracheal intubation is not mandatory, depend on the degree of hypoxia, the presence of comorbidities and complications, and their illness severity. ⋯ The use of NIV in patients with severe acute respiratory syndrome and other airborne diseases has generated debate, despite encouraging clinical results, mainly because of safety issues. Overall, the high rate of NIV failure suggests a cautious approach to NIV use in patients with ALI/ARDS, including early initiation, intensive monitoring, and prompt intubation if signs of NIV failure emerge.
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A simple method for effective bronchodilator aerosol delivery while administering continuing continuous positive airway pressure (CPAP) would be useful in patients with severe bronchial obstruction. ⋯ CPAP bronchodilator delivery decreases the work of breathing as effectively as does standard nebulization, but produces a greater oxygenation improvement in patients with airway obstruction. To optimize airway humidification, a heat-and-moisture exchanger could be used with the Boussignac CPAP system, without modifying aerosol delivery.