Design and test of a new tracheostoma valve based on inhalation.

BACKGROUND Tracheostoma valves are used to make hand-free speaking possible for persons who have undergone a laryngectomy. OBJECTIVE To design and test a new tracheostoma valve to improve existing tracheostoma valves. METHODS The tracheostoma valve closes by means of strong inhalation so that all the air that is exhaled is available for phonation. The device automatically stays in the"speaking position" until the patient deliberately changes the device to the "breathing position" by a fast expiration. If all the air that has been exhaled has been consumed during phonation, the patient can inhale again, without changing the device, because a small valve automatically opens, thus allowing phonation without time limits. An experimental setup with a computer-based acquisition program was used to measure the pressure at which the valve opened and the flow at which the valve closed. The pressure and flow needed to open and close the magnetic adjustable valve were measured for different positions and contained in the computer through a data acquisition program. Also, the airflow resistance coefficients for inhaling and exhaling were measured. RESULTS The airflow necessary to close the tracheostoma valve ranges from 1.6 to 3.8 L/s. The opening pressure of the valve ranges from 1 to 7 kPa. The airflow resistance coefficient is 290 Pa x s2 x L(-2) for inhalation and 430 Pa x s(2) x L(-2) for exhalation. CONCLUSIONS The device appears to function well in physiological ranges and is optimally adjustable. The airflow resistance coefficient lies in the range of the entire airway resistance (120-470 Pa x s(2) x L(-2)) in quiet breathing.