Corrective Measures for Compromised Oxygen Delivery During Endotracheal Tube Cuff Deflation With High-Frequency Percussive Ventilation

OBJECTIVE: To determine the effect of endotracheal-tube cuff deflation on airflow and F_IO2 during high-frequency percussive ventilation (HFPV), and explore methods of correcting the cuff-deflation-associated decrease in mean airway pressure and F_IO2 at the carina.

METHODS: Using a mechanical lung model in our respiratory research laboratory, we measured circuit pressure near the connection to the endotracheal tube (P_vent), mean airway pressure (P̄_aw), pulsatile tidal volume (V_T), and F_IO2 at the artificial carina. During cuff deflation we manipulated the pulsatile frequency, pulsatile flow, and the HFPV integral nebulizer. We then assessed 4 methods of correcting the decreased F_IO2 and airway pressure during cuff deflation: (1) oxygen delivery at the inspiratory fail-safe valve, (2) oxygen delivery at the T-piece between the HFPV and the endotracheal tube, (3) continuous activation of the HFPV's integral nebulizer, and (4) oxygen insufflation into the suction channel of the endotracheal tube.

RESULTS: Cuff deflation reduced P_vent, P̄_aw, pulsatile V_T, and F_IO2. Increasing the pulsatile flow and decreasing the pulsatile frequency further reduced F_IO2 during cuff deflation. Injecting supplemental oxygen at the inspiratory fail-safe valve provided the best F_IO2 increase. Injecting oxygen at the T-piece provided the second best F_IO2 increase. Continuous activation of the integral nebulizer provided the third best F_IO2 increase. Oxygen insufflation to the suction channel was least effective in correcting the F_IO2 decrease caused by cuff deflation.

CONCLUSION: Cuff-deflation-associated F_IO2, P̄_aw, and pulsatile V_T compromise can be partially corrected by any of the 4 methods we studied. Injecting supplemental oxygen at the inspiratory fail-safe valve is the most effective method.