Design and control of a novel mechatronic tracheostomy tube-inserted suction catheter for automated tracheal suctioning

Mechanical ventilation is required to aid patients with breathing difficulty to breathe more comfortably. A tracheostomy tube is inserted through an opening in the patient neck into the trachea, below the vocal cords. This opening is either created surgically or using a percutaneous dilatational technique. The inserted tube sits in the trachea, above the carina, and before the airways branch into the left and right main bronchi. In mechanical ventilation, the tube is connected to a ventilator and air is moved in and out of the lungs via positive pressure. In this process, mucus will accumulate at the point of branching into the branchi. Currently, this mucus is manually removed half-hour by inserting a suction tube via the tracheostomy to reach the point of branching. Nurses spend millions of person-hours to perform this task yearly. To save significant person-hours, an automated system is needed. This system also allows the patient to recover at home, rather stay in hospital solely for nurses to remove mucus periodically. In this paper, we present a novel mechatronic device to perform automatic tracheal suctioning in conjunction with a tracheostomy tube. A new suctioning catheter is also developed. It is known that nonlinear friction and backlash between the suctioning catheter and its conduit as well as in the gear system of the actuator cause difficulties to accurately control the position of catheter tip. To enhance the system performances, a novel direct inverse of backlash-like hysteresis model-based feedforward is also developed. The designed device and proposed compensation scheme are experimentally validated. The results demonstrate a significant contribution and potential benefits to the mechanical ventilation works.