THE INFLUENCE OF FRESH-GAS DECOUPLING ON THE PERFORMANCE OF THE DRAEGER SULLA 808V ANESTHESIA VENTILATOR

In order to perform accurate low-flow anaesthesia ventilation,it is de sirable to avoid the influence of fresh gas flow (FGF) and inspiration duration (ID) on the resulting minute Volume (MV). The Sulla 808V ana esthesia ventilator (Draeger, Luebeck, Germany) is originally not equi pped with a fresh-gas decoupling (FGD) device. Therefore, changes of F GF and ID settings applied during controlled Ventilation may lead to a lterations of the resulting MV. Recently, a low-cost FGD device (Carba med, Bern-Liebefeld, Switzerland) has been developed,which can be inse rted into the circle system. We investigated the effect of this device on MV in the Sulla 808V anaesthesia apparatus. Methods: The performan ce of a Sulla 808V anaesthesia ventilator was tested with and without a FGD device. During ventilation of a test lung, stepwise changes of t idal volume (400-1000 ml), FGF (0.5-10 l/min), and ID (0.25-0.5) setti ngs were consecutively applied, and the resulting MV was recorded. Cor relation and mean prediction error between ventilation parameter setti ngs and MV were calculated. Results: In the presence of a FGD device, the administered MV was not affected by the magnitude of FGF and ID. A mean prediction error (bias) of -3.6 l/min of the resulting MV was ob served. Without FGD the bias was only -1.8 l/min, while FGF and ID rev ealed a pronounced influence on MV. These effects were statistically s ignificant when using FGF exceeding 4 l/min. Conclusions:The tested FG D device can easily be integrated into the circle system of convention al anaesthesia machines such as the Draeger Sulla 808V, and is availab le al a reasonable cost. It allows constant ventilation parameters to be maintained that remain unaffected by wide FGF and ID variations. Wi th this FGD the performance of the ventilator can be improved consider ably, and low-flow anaesthesia can be used more extensively.