Chiumello D, Pelosi P, Calvi E, Bigatello L M, Gattinoni L
Istituto di Anestesia e Rianimazione, Universita' degli Studi di Milano, Ospedale Policlinico-IRCCS, Italy.
Eur Respir J. 2002 Oct;20(4):925-33. doi: 10.1183/09031936.02.01552001.
The aim of the present study was to verify that the patient/ventilator interaction is similar, regardless of the mode of assisted mechanical ventilation (i.e. pressure- or volume-limited) used, if tidal volume (VT) and peak inspiratory flow (PIF) are matched. Therefore, the authors compared the effects of three different modes of assisted ventilation on the work of breathing (WOB) and gas exchange in patients with acute respiratory failure. For Protocol 1, in seven patients, the authors compared pressure support, assist pressure control and assist control (with square and decelerating wave inspiratory flow pattern) set to deliver the same VT and PIF. For Protocol 2, in another 10 patients, the authors compared pressure support and assist control with high (0.8 L x s(-1)) and low (0.6 L x s(-1)) PIFs set to deliver the same VT. In Protocol 1, there was no difference in WOB and gas exchange between the three modes of assisted ventilation tested. In Protocol 2, the decrease of PIFs during assist control significantly increased WOB. In conclusion, different modes of assisted ventilation similarly reduce work of breathing and provide adequate gas exchange at fixed tidal volume and peak inspiratory flow only. During assist control, tidal volume and peak inspiratory flow (set by the physician) are the main determinants of the patient/ventilator interaction.
如果潮气量（VT）和吸气峰流速（PIF）匹配，无论使用何种辅助机械通气模式（即压力限制或容量限制模式），患者与呼吸机之间的相互作用都是相似的。因此，作者比较了三种不同辅助通气模式对急性呼吸衰竭患者呼吸功（WOB）和气体交换的影响。在方案1中，作者对7例患者进行了比较，将压力支持、辅助压力控制和辅助控制（采用方波和减速波吸气气流模式）设置为输送相同的VT和PIF。在方案2中，作者对另外10例患者进行了比较，将压力支持和辅助控制设置为输送相同的VT，但PIF分别设置为高（0.8L·s⁻¹）和低（0.6L·s⁻¹）。在方案1中，所测试的三种辅助通气模式之间的WOB和气体交换没有差异。在方案2中，辅助控制期间PIF的降低显著增加了WOB。总之，不同的辅助通气模式在仅固定潮气量和吸气峰流速时，同样能减少呼吸功并提供足够的气体交换。在辅助控制期间，潮气量和吸气峰流速（由医生设置）是患者与呼吸机相互作用的主要决定因素。
