加湿设备对机械通气机潮气量测量的影响。

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

作者信息

Fujita Yasuki, Imanaka Hideaki, Fujino Yuji, Takeuchi Muneyuki, Tomita Toshiji, Mashimo Takashi, Nishimura Masaji

机构信息

Intensive Care Unit, Osaka University Hospital, 2-15 Yamadaoka, Suita, 565-0871, Japan.

出版信息

J Anesth. 2006;20(3):166-72. doi: 10.1007/s00540-006-0390-0.

DOI:10.1007/s00540-006-0390-0

PMID:16897234

Abstract

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, applying two humidifying systems (a heat-moisture exchanger and a heated humidifier) and two tidal volumes (12 and 6 ml x 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.

摘要

目的

我们推测呼气潮气量被低估了，因为热湿交换器会截留呼出的水汽。因此，我们设计了患者研究和实验台研究来调查潮气量监测的准确性。

方法

在一项患者研究中，使用Servo 300呼吸机，应用两种加湿系统（热湿交换器和加热湿化器）以及两种潮气量（12和6 ml×kg⁻¹），我们记录了显示的呼气潮气量和通过呼吸感应体积描记法测量的胸廓容积位移。在气道开口处和呼气支路末端测量温度、相对湿度和绝对湿度。我们还使用模拟肺测试了三种不同的呼吸机（伟康7200ae、Evita 4和Servo 300），以研究热湿交换器和加热湿化器对监测潮气量的影响是否因呼吸机品牌而异。

结果

使用热湿交换器时，显示的呼气潮气量比使用加热湿化器时显著小12% - 14%，尽管两种系统中的胸廓容积位移相同。热湿交换器使呼气支路末端的温度和绝对湿度显著低于加热湿化器。在模拟肺研究中，我们研究了不同品牌呼吸机对呼气潮气量的影响。无论呼吸机品牌如何，使用热湿交换器时都观察到了类似程度（8% - 14%）的潮气量低估。