Campbell Robert S, Davis Bradley R
Department of Surgery, Division of Trauma/Critical Care, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA.
Respir Care. 2002 Apr;47(4):416-24; discussion 424-6.
Volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) are not different ventilatory modes, but are different control variables within a mode. Just as the debate over the optimal ventilatory mode continues, so too does the debate over the optimal control variable. VCV offers the safety of a pre-set tidal volume and minute ventilation but requires the clinician to appropriately set the inspiratory flow, flow waveform, and inspiratory time. During VCV, airway pressure increases in response to reduced compliance, increased resistance, or active exhalation and may increase the risk of ventilator-induced lung injury. PCV, by design, limits the maximum airway pressure delivered to the lung, but may result in variable tidal and minute volume. During PCV the clinician should titrate the inspiratory pressure to the measured tidal volume, but the inspiratory flow and flow waveform are determined by the ventilator as it attempts to maintain a square inspiratory pressure profile. Most studies comparing the effects of VCV and PCV were not well controlled or designed and offer little to our understanding of when and how to use each control variable. Any benefit associated with PCV with respect to ventilatory variables and gas exchange probably results from the associated decelerating-flow waveform available during VCV on many ventilators. Further, the beneficial characteristics of both VCV and PCV may be combined in so-called dual-control modes, which are volume-targeted, pressure-limited, and time-cycled. PCV offers no advantage over VCV in patients who are not breathing spontaneously, especially when decelerating flow is available during VCV. PCV may offer lower work of breathing and improved comfort for patients with increased and variable respiratory demand.
容量控制通气（VCV）和压力控制通气（PCV）并非不同的通气模式，而是一种模式内不同的控制变量。正如关于最佳通气模式的争论仍在继续一样，关于最佳控制变量的争论也在持续。VCV提供了预设潮气量和分钟通气量的安全性，但要求临床医生适当地设置吸气流量、流量波形和吸气时间。在VCV期间，气道压力会因顺应性降低、阻力增加或主动呼气而升高，这可能会增加呼吸机相关性肺损伤的风险。PCV在设计上限制了输送到肺部的最大气道压力，但可能导致潮气量和分钟通气量变化。在PCV期间，临床医生应根据测得的潮气量调整吸气压力，但吸气流量和流量波形由呼吸机决定，因为它试图维持方形吸气压力曲线。大多数比较VCV和PCV效果的研究控制不佳或设计不当，对我们理解何时以及如何使用每个控制变量帮助不大。PCV在通气变量和气体交换方面的任何益处可能源于许多呼吸机上VCV期间可用的相关减速流量波形。此外，VCV和PCV的有益特性可在所谓的双控模式中结合，这种模式以容量为目标、压力受限且时间切换。对于非自主呼吸的患者，PCV相对于VCV没有优势，尤其是当VCV期间有减速流量时。对于呼吸需求增加且变化的患者，PCV可能会降低呼吸功并提高舒适度。
