A System to Reproduce Human Breathing Patterns: Its Development and Validation

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Abstract
Studies of aerosol deposition in models of the human respiratory tract play a significant role in developing our understanding of drug delivery by inhalation and particle retention in the lungs during exposure to polluted environments. To use replica casts of human airways and compare the results with in vivo data, a device is required to simulate human breathing. The objective of this study was to simulate human breathing for nasal casts. Breathing through the nose is normally limited to about 50 L/min. Therefore, a system was built to simulate human breathing patterns as well as artificial ones up to this flow rate. The system consists of a reciprocating piston in a cylinder, which is displaced by a synchronous motor via a linear actuator. The desired signal to drive the motor is given in real time by purpose-written software. The rotation and position of the motor are controlled by an electronic position control unit. The validation of the system shows that it simulates breathing up to 50 L/min closely even for complex waveforms. At breathing rates above 50 L/min, a slight difference is apparent between the desired breathing pattern and the simulated one. The breathing simulator has been shown to be a reliable tool for reproducing a wide variety of breathing patterns.