Marks J D, Schapera A, Kraemer R W, Katz J A
Department of Anesthesia, University of California, San Francisco.
Anesthesiology. 1989 Sep;71(3):403-8. doi: 10.1097/00000542-198909000-00016.
The effect of increasing airway pressure on the mean inspiratory flow and maximum minute ventilation (VE) capabilities of five anesthesia ventilators (Ohio Anesthesia, Airshields Ventimeter, Ohmeda 7000, Draeger AV-E and Siemens 900D) was compared to identify mechanical factor(s) limiting intraoperative ventilation of the lungs of patients with acute respiratory failure. The effect of increasing airway pressure on mean inspiratory flow was determined by cycling each ventilator through increasing restrictors. Maximum VE was measured under three study conditions using a test lung: 1) low compliance (10-30 ml/cmH2O) and minimal airflow resistance; 2) positive end-expiratory pressure (PEEP) of 0, 10, and 20 cmH2O at a compliance of 20 ml/cmH2O with minimal airflow resistance; and 3) increased resistance (19 +/- 11 cmH2O.1(-1).s-1) and compliance of 30 ml/cmH2O. As airway pressure increased from 0 to 80 cmH2O, mean inspiratory flow decreased markedly for all ventilators except the Siemens. The Siemens ventilator delivered the greatest VE under all three conditions and maintained VE when airway pressure increased due to decreased compliance or the application of PEEP; all other ventilators markedly decreased VE under these conditions. The addition of airway resistance reduced maximal VE for all ventilators by limiting the maximal inspiratory duty cycle (T1/TTOT). Thus, mean inspiratory flow of conventional anesthesia ventilators decreases with increasing airway pressure. The decreased inspiratory flow limits maximum VE when airway pressure is elevated because of decreased lung-thorax compliance and/or increased airway resistance, such as that characterizing patients with acute respiratory failure. Significant airway resistance further limits maximum VE by limiting the maximal T1/TTOT that can be used without increasing end-expiratory lung pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
比较了增加气道压力对五台麻醉呼吸机（俄亥俄麻醉机、Airshields Ventimeter、Ohmeda 7000、德尔格AV - E和西门子900D）的平均吸气流量和最大分钟通气量（VE）能力的影响，以确定限制急性呼吸衰竭患者术中肺通气的机械因素。通过使每台呼吸机通过增加的限流器循环来确定增加气道压力对平均吸气流量的影响。使用测试肺在三种研究条件下测量最大VE：1）低顺应性（10 - 30 ml/cmH₂O）和最小气流阻力；2）在顺应性为20 ml/cmH₂O且气流阻力最小时，呼气末正压（PEEP）分别为0、10和20 cmH₂O；3）增加阻力（19 ± 11 cmH₂O·L⁻¹·s⁻¹）且顺应性为30 ml/cmH₂O。随着气道压力从0增加到80 cmH₂O，除西门子呼吸机外，所有呼吸机的平均吸气流量均显著下降。西门子呼吸机在所有三种条件下提供的VE最大，并且当由于顺应性降低或应用PEEP导致气道压力增加时，能维持VE；在这些条件下，所有其他呼吸机的VE均显著下降。增加气道阻力通过限制最大吸气占空比（T₁/TTOT）降低了所有呼吸机的最大VE。因此，传统麻醉呼吸机的平均吸气流量随气道压力增加而降低。当气道压力因肺胸顺应性降低和/或气道阻力增加（如急性呼吸衰竭患者的特征）而升高时，吸气流量降低会限制最大VE。显著的气道阻力通过限制在不增加呼气末肺压力的情况下可使用的最大T₁/TTOT进一步限制最大VE。（摘要截短于第250个单词）
