• Patrick F Allan and Gregory Naworol.
• Department of Respiratory Therapy, Wilford Hall Medical Center, 759th MCCP, 2200 Bergquist Drive, Lackland Air Force Base, TX 78236, USA. patrick.allan@lackland.af.mil
• Resp Care. 2007 Mar 1;52(3):271-7.

ObjectiveTo 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.MethodsUsing 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 (P(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.ResultsCuff deflation reduced P(vent), P(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.ConclusionCuff-deflation-associated F(IO2), P(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.

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