Characteristics of tracheostomy phonation valves.

Phonation valves are commonly used devices that allow the restoration of speech in tracheostomised patients. However, their use should not compromise the physiological benefit of tracheostomy. Six commercialised phonation valves were studied in a dynamic set-up simulating a respiratory frequency of 20 breaths.min(-1), a tidal volume of 0.5 L and a peak flow rate of 0.5 L.s(-1). Resistance and additional work of breathing (WOB) were calculated. In 10 tracheostomised patients, evaluations using no phonation valve (baseline), and the most and one of the least resistive valves were carried out. Respiratory patterns and gas exchanges were recorded. Inspiratory difficulty was evaluated using the modified Borg scale. Valves displayed a wide array of resistance ranging 1.3-5.9 cmH2O.L(-1).s(-1). Additional WOB varied with a ratio of 4.4 between the best and the worst valve. While the different clinical conditions did not modify respiratory patterns and gas exchanges, a significant effect on the Borg scale rating was observed using ANOVA and post hoc analysis of baseline versus worst valve and one of the best valves versus worst valve. In conclusion, the variety of aerodynamic characteristics of phonation valves should be considered when choosing the device, according to the underlying condition of the patients benefiting from their use.