An oxygen-consuming model lung for evaluation of anaesthetic circuits.

We have constructed an oxygen-consuming model lung based on pure combustion of hydrogen. Besides consuming oxygen the model produces water vapour, and carbon dioxide is delivered to the lung, thus mimicking carbon dioxide production. Oxygen consumption and carbon dioxide production can be set at desired values. The model lung can be used for investigations on and evaluation of all types of anaesthesia circuits. Results in a circle system with carbon dioxide absorption show that FIO2 is related to the fresh gas flow. The end tidal CO2 level is correlated to the alveolar ventilation and cannot be used for predicting FIO2.