Effect of humidifying devices on the measurement of tidal volume by mechanical ventilators

被引：6

作者：

Fujita Y. ^{[1
]}

Imanaka H. ^{[2
]}

Fujino Y. ^{[1
]}

Takeuchi M. ^{[2
]}

Tomita T. ^{[1
]}

Mashimo T. ^{[3
]}

Nishimura M. ^{[4
]}

机构：

[1] Intensive Care Unit, Osaka University Hospital, Suita 565-0871

[2] Surgical Intensive Care Unit, National Cardiovascular Center, Osaka

[3] Department of Anesthesiology, Osaka University School of Medicine, Osaka

[4] Emergency and Critical Care Medicine, The University of Tokushima Graduate School, Tokushima

来源：

Journal of Anesthesia | 2006年 / 20卷 / 3期

关键词：

Absolute humidity; Heat-moisture exchanger; Heated humidifier; Temperature;

D O I：

10.1007/s00540-006-0390-0

中图分类号：

学科分类号：

摘要：

Purpose: We hypothesized that expiratory tidal volume was underestimated, because a heat-moisture exchanger traps the expired vapor. We, therefore, designed patient and bench studies to investigate the accuracy of tidal volume monitoring. Methods: In a patient study, a pplying two humidifying systems (a heat-moisture exchanger and a heated humidifier) and two tidal volumes (12 and 6ml·kg-1) with a Servo ventilator 300, we recorded the displayed expiratory tidal volume and thoracic volume displacement, measured by respiratory inductive plethysmography. Temperature, relative humidity, and absolute humidity were measured at the airway opening and at the end of the expiratory limb. Using a model lung, we also tested three different ventilators (Puritan-Bennett 7200ae, Evita 4, and Servo ventilator 300) to investigate whether the effects of the heat-moisture exchanger and the heated humidifier on monitored tidal volume varied according to the brand of ventilator. Results: With the use of the heat-moisture exchanger, the displayed expiratory tidal volume was significantly smaller, by 12%-14%, than that with the heated humidifier, although thoracic volume displacement was identical in the two systems. The temperature and absolute humidity at the end of the expiratory limb were significantly lower with the heat-moisture exchanger than with the heated humidifier. In the model lung study, we investigated the effects of different brands of ventilator on the expiratory tidal volume. A similar degree (8%-14%) of underestimation of tidal volume was observed with the heat-moisture exchanger, regardless of ventilator brand. Conclusion: Monitored expiratory tidal volume was underestimated by approximately 10%, when using a heat-moisture exchanger. © JSA 2006.

引用

页码：166 / 172

页数：6

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