Key Point:

A new tracheostomy tube that enables patients to speak during mechanical ventilation has been developed and tested.

TOKYO—Japanese physician Hiroaki Nomori, MD, PhD, has designed a novel device, the voice tracheostomy tube (VTT), that enables most mechanically ventilated patients to talk. Speech is possible with the VTT because it has a cuff that expands on inspiration and deflates on expiration, allowing some expired air to exit around the deflated cuff and through the upper airway.

Dr. Nomori recently tested the VTT in a group of 16 mechanically ventilated patients who had initially been given a conventional tracheostomy tube.[1] After being switched to the VTT, all but one of the patients were able to speak effectively, said Dr. Nomori, who is Chief of the Department of Thoracic Surgery at Saiseikai Central Hospital in Tokyo.

Use of the VTT was not associated with complications or damage to the tracheal mucosa. Furthermore, the device did not compromise the effectiveness of the mechanical ventilator, even in patients with low lung compliance.

FIRST, A NONCLINICAL TEST

Before starting studies in humans, the VTT was tested on a model lung and trachea adjusted to simulate respiratory failure with low lung compliance. In this experiment, which assessed the device’s ability to maintain a patent airway, the VTT was comparable to a conventional tracheostomy tube that had the same internal and external diameters and a continuously expanded cuff.

NEXT STEP, HUMAN TRIALS

The VTT was then tested in 16 mechanically ventilated patients, all of whom had respiratory failure because of tuberculosis, pneumonia, chronic obstructive pulmonary disease, amyotrophic lateral sclerosis, or spinal cord injury. The VTT devices used in the human trials had the same diameter as did the conventional tracheostomy tubes they were replacing. No changes were made to the patients’ ventilator modes or settings when the devices were switched.

In the initial nonclinical test of the VTT, a small amount of air leakage was noted during inspiration; however, no such leakage occurred when the device was used in vivo. The 15 patients who could speak effectively with the VTT did so during expiration as air passed through the vocal fold.

Of these patients, 13 could speak loudly enough to be heard by someone more than two meters away. The two patients with weak voices were further helped by an in-line, one-way speaking valve (ie, a Passy-Muir valve) between the VTT and the end of the ventilator circuit. According to Dr. Nomori, the addition of the Passy-Muir valve enabled these two patients to speak as loudly as a healthy person could; furthermore, the valve could be used for more than one hour with no changes in arterial oxygen tension (Pao2) or arterial carbon dioxide tension (Paco2).

The one patient who could not speak with the VTT had an anatomic abnormality (the trachea was bent at about a 100° angle due to longstanding tuberculosis), reported Dr. Nomori. As a result, the gap between the VTT and this patient’s trachea was occluded and less air could pass during expiration.

NO EFFECT ON VENTILATION

Although lung compliance in the patients was low, averaging about 23 mL/cm H2O, use of the VTT did not impede the mechanical ventilator’s function. Indeed, no significant differences were observed in mean Pao2 or Paco2 before and seven days after the patients were switched from a conventional tracheostomy tube to a VTT.

Furthermore, the VTT was used in nine patients for periods ranging from 25 to 386 days. In six patients, weaning from the ventilator occurred in seven to 50 days after the start of VTT use. The patient who could not speak effectively with the VTT was switched back to a conventional tracheostomy tube, noted Dr. Nomori.

NO RESIDUAL DAMAGE

After two weeks of VTT use, the patients underwent bronchoscopy, which revealed no damage to the tracheal mucosa at the point where the cuff of the VTT expanded. In fact, the tracheal mucosa of one patient returned to its normal pink color following the switch to the VTT; it had developed a whitish tone when the conventional tracheostomy tube had been in place.

There were no complications with the VTT. The 12 patients who could eat before they received a VTT continued to do so afterwards with no more difficulty swallowing than they had experienced with a conventional tracheostomy tube.

When will the VTT be available for use in the United States? “I am currently negotiating with a few companies interested in producing the VTT for worldwide use,” Dr. Nomori said.

—Timothy Begany

Reference
1. Nomori H. Tracheostomy tube enabling speech during mechanical ventilation. Chest. 2004;125:1046-1051.

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