Development of a model to mimic pleural space mechanics.

BACKGROUND: A simulator of the respiratory system which includes the pleural space is currently lacking. However, such mechanical models are essential to develop and test new medical devices regulating the pressure in the pleural space.

OBJECTIVE: It was the aim of this study to develop a model which mimics the pleural space. The device should be able to represent biomechanical functions of the respiratory system and it is intended for applications in research and development to study pleural space mechanics. The system should allow adjusting parameters to simulate different kinds of breathing. Output parameters such as the pressure in pleural cavity or the breathing volume should be measured.

METHODS: A mechanical lung simulator was developed. The chest wall is represented by an elastic shell in which silicone balloons were implemented to mimic the lung tissue. These two components establish a pleural cavity. Pressure sensors were installed to measure pressure in the pleural space and an aeroplethysmograph was positioned above the two lungs to measure flow. The system was assembled and tested under various conditions.

RESULTS: Different tests demonstrated that the device is currently capable of simulating breathing volumes up to approx. 1700 ml. Different breathing characteristics including coughing can be simulated. Higher negative pressures especially during deep breathing were observed at the top of the lung because of higher balloon wall (lung) thickness in this area. It was possible to demonstrate the effect of certain changes of the lung tissue such as fibrosis with corresponding pressure recordings confirming known effects of such pathologies.

CONCLUSIONS: The device allows simulating pressures in the pleural space during breathing at an advanced level and will be of use to develop and validate medical devices under laboratory conditions that control and regulate the pleural space. This represents a significant benefit to improve the development process for devices in this area.