Design and characterization of a volume-cycled small animal mechanical ventilator coupled with a respiratory system model

Abstract

Small animals such as mice are generally used in experiments that study the behavior of the respiratory system under the influence of drugs, and accurate gas flow measurements are necessary due to the small volumes involved. Based on this need, a mechanical ventilator for small animals was developed using a linear actuator coupled with a 3ml precision glass syringe controlled by a driver. A mechanical load representing a mouse's respiratory system consisting of a rigid plastic cylinder with internal volume of 78ml was ventilated by the machine, and its measured resistance and elastance parameters were compared to values obtained with theoretical mathematical models. A 12.7% maximum deviation was found in the model's elastance in comparison with the predicted value, and the measured resistance did not assume the expected behavior of a linear system, decreasing sharply with the increase of frequency.