Dries David J
From the *Surgical Care, HealthPartners Medical Group, Minneapolis, Minnesota; and †Department of Surgery and Anesthesiology, John F. Perry, Jr., Chair of Trauma Surgery, University of Minnesota, Minneapolis.
J Burn Care Res. 2016 Mar-Apr;37(2):75-85. doi: 10.1097/BCR.0000000000000231.
Controlled Mechanical Ventilation may be essential in the setting of severe respiratory failure but consequences to the patient including increased use of sedation and neuromuscular blockade may contribute to delirium, atelectasis, and diaphragm dysfunction. Assisted ventilation allows spontaneous breathing activity to restore physiological displacement of the diaphragm and recruit better perfused lung regions. Pressure Support Ventilation is the most frequently used mode of assisted mechanical ventilation. However, this mode continues to provide a monotonous pattern of support for respiration which is normally a dynamic process. Noisy Pressure Support Ventilation where tidal volume is varied randomly by the ventilator may improve ventilation and perfusion matching but the degree of support is still determined by the ventilator. Two more recent modes of ventilation, Proportional Assist Ventilation and Neurally Adjusted Ventilatory Assist (NAVA), allow patient determination of the pattern and depth of ventilation. Proposed advantages of Proportional Assist Ventilation and NAVA include decrease in patient ventilator asynchrony and improved adaptation of ventilator support to changing patient demand. Work of breathing can be normalized with these modes as well. To date, however, a clear pattern of clinical benefit has not been demonstrated. Existing challenges for both of the newer assist modes include monitoring patients with dynamic hyperinflation (auto-positive end expiratory pressure), obstructive lung disease, and air leaks in the ventilator system. NAVA is dependent on consistent transduction of diaphragm activity by an electrode system placed in the esophagus. Longevity of effective support with this technique is unclear.
在严重呼吸衰竭的情况下，控制机械通气可能至关重要，但对患者的影响包括镇静和神经肌肉阻滞的使用增加，这可能会导致谵妄、肺不张和膈肌功能障碍。辅助通气可使自主呼吸活动恢复膈肌的生理移位，并使灌注较好的肺区域复张。压力支持通气是最常用的辅助机械通气模式。然而，这种模式仍为呼吸提供单调的支持模式，而呼吸通常是一个动态过程。由呼吸机随机改变潮气量的噪声压力支持通气可能会改善通气与灌注的匹配，但支持程度仍由呼吸机决定。另外两种较新的通气模式，比例辅助通气和神经调节通气辅助（NAVA），可让患者决定通气的模式和深度。比例辅助通气和NAVA的潜在优势包括减少患者与呼吸机的不同步，并使呼吸机支持更好地适应患者不断变化的需求。使用这些模式也可使呼吸功正常化。然而，迄今为止，尚未证明有明确的临床获益模式。这两种较新的辅助模式目前面临的挑战包括监测有动态肺过度充气（内源性呼气末正压）、阻塞性肺疾病的患者以及呼吸机系统中的漏气情况。NAVA依赖于置于食管的电极系统对膈肌活动的持续传导。这种技术有效支持的持续时间尚不清楚。
