Relatively high flow rates are necessary to achieve adequate voice production. Problems with this system include plugging of the air outflow site in the throat by secretions, drying of the mouth and nose by the relatively high airflow rates required, the necessity for a compressor or other external air source, and the fact that plugging of a valve is necessary for speech production, which makes this inappropriate for the severely neurologically-impaired patient. The best alternative for communication for most patients using mechanical ventilation via tracheostomy is with the cuff down or absent. As noted above, the tracheostomy tube must be cuffless or have the cuff deflated, and the tracheostomy tube must be of the appropriate size for the individual's trachea in order to allow adequate egress of air during exhalation. Occasionally this may require direct inspection of the interior of the windpipe for adequate sizing.
Most patients can produce adequate speech in the absence of any additional valves.
However, because the air for speech production enters during inhalation, the affected individual must learn to produce speech during inhalation, which is counter-intuitive for many, but essentially all patients master this. Because speech occurs during inhalation, sentence structure tends to be somewhat choppy. With experience, many patients learn to develop relatively natural patterns of speech geared to their ventilatory cycle. This device, manufactured by Passy-Muir, Inc., allows air to enter the lungs through the tracheostomy tube, but it must leave by way of the mouth and throat. As a result, speech patterns can be more normal, with speech occurring appropriately during expiration, allowing for variation in phrase length.