Flow-volume curves as measurement of respiratory mechanics during ventilatory support: the effect of the exhalation valve

作     者：Lourens, MS van den Berg, B Hoogsteden, HC Bogaard, JM 

作者机构：Erasmus Med Ctr Rotterdam Dept Pulm & Intens Care Med NL-3015 GD Rotterdam Netherlands 

出 版 物：《INTENSIVE CARE MEDICINE》 (抢救护理医学)

年 卷 期：1999年第25卷第8期

页      面：799-804页

核心收录：

学科分类：1002[医学-临床医学] 1011[医学-护理学（可授医学、理学学位）] 10[医学] 

基　　金：Dutch Asthma Founda Nederlands Astma Fonds 

主　　题：flow-volume curve mechanical ventilation exhalation valve intensive care 

摘      要：Objective: To assess the feasibility of expiratory flow-volume curves as a measurement of respiratory mechanics during ventilatory support: to what extent is the shape of the curve affected by the exhalation valve of the ventilator? Design: Prospective, comparative study. Setting: Medical intensive care unit of a university hospital. Patients: 28 consecutive patients with various conditions, mechanically ventilated with both the Siemens Servo 900C and 300 ventilators, were studied under sedation and paralysis. Interventions: The ventilator circuit was intermittently disconnected from the ventilator at end-inspiration in order to obtain flow-volume curves with and without the exhalation valve in place. Measurements and results: Peak flow (PEF) and the slope of the flow-volume curve during the last 50% of expired volume (SF50) were obtained both with and without the exhalation valve in place. The exhalation valve caused a significant reduction in peak flow of 0.3 l/s (from 1.27 to 0.97 l/s) with the Siemens Servo 900 C ventilator and of 0.42 l/s (from 1.36 to 0.94 l/s) with the Siemens Servo 300 ventilator (p 0.001). The SF50 was not affected. Conclusion: In mechanically ventilated patients, the exhalation valve causes a significant reduction in peak flow, but does not affect the SF50. This study further suggests that the second part of the expiratory flow-volume curve can be used to estimate patients respiratory mechanics during ventilatory support.