Development of a Mechanical Test Lung for Respiratory Mechanics Research

Due to the high nonlinearity and variability of the respiratory system in the human body, the physiological response of patients to mechanical ventilation (MV) treatment is often unpredictable. Hence, there is a lack of proper guidelines for optimising MV settings in standard clinical protocols. By giving clinicians the opportunity to test multiple MV settings, a mechanical test lung could assist in determining the optimal settings that suit a particular patient. Therefore, this warrants the design and development of an active test lung with a spontaneous breathing system, reasonable tidal volume and ranges of lung mechanics. The finished prototype consists of three subsystems: the lung compartment, the airway, and the spontaneous breathing system. The performance of this test lung was evaluated through several experiments, and the results show that it can achieve continuous respiratory elastance that spans from 20 to 90 cmH2O/L, whereas the respiratory resistance ranges from 20 to 50 cmH2O·s/L. Moreover, it has a maximum tidal volume of 850 mL and can simulate spontaneous breathing with different frequencies, inspiratory, and expiratory times.