Measurement of Pulsatile Tidal Volume, Pressure Amplitude, and Gas Flow During High-Frequency Percussive Ventilation, With and Without Partial Cuff Deflation

Authors: Allan, Patrick F1; Thurlby, Jefferson R2; Naworol, Gregory A3

Source: Respiratory Care, Volume 52, Number 1, January 2007 , pp. 45-49(5)

Publisher: The Journal Respiratory Care Company

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Abstract:

OBJECTIVE: With a high-frequency percussive ventilator and a mechanical lung model, to measure tidal volume (VT), pulsatile pressure amplitude (difference between peak and nadir pulsatile pressure [ΔP]), and mean airway pressure (Paw) at various pulsatile frequencies, pulsatile inspiratory-expiratory ratios (I:Ep), and pressures (measured at the interface between the pulse-generator and the endotracheal tube [Pvent]). METHODS: With the endotracheal tube inside an artificial trachea, we manipulated the high-frequency percussive ventilation settings and adjuncts, including pulsatile frequency, I:Ep, and Pvent by manipulating pulsatile flow. We also studied the effects of partially deflating the endotracheal tube cuff. We measured Paw, pulsatile pressure amplitude at the carina (ΔPc), and pulsatile VT at the carina. With the cuff partly deflated, we measured the fraction of inspired oxygen (FIO2) in the gas efflux above and below the cuff. RESULTS: Increasing the pulsatile frequency from 300 cycles/min to 600 cycles/min and changing the I:Ep from 1:3 to 1:1 significantly reduced VT (p < 0.001). Paw and ΔPc were unaffected by the change in pulsatile frequency or I:Ep, except when we did not preserve the pulsatile flow. The measured VT range was from 19.1 mL (at 600 cycles/min) to 47.3 mL (at 300 cycles/min). Partial cuff deflation did not significantly reduce Paw or ΔPc, but it did significantly reduce VT and FIO2. CONCLUSION: During high-frequency percussive ventilation, the pulsatile frequency is inversely related to VT. Partial cuff deflation reduces the delivered FIO2.

Keywords: CUFF LEAK; HIGH-FREQUENCY PERCUSSIVE VENTILATION; HIGH-FREQUENCY VENTILATION; TRACHEAL TUBE; VOLUMETRIC DIFFUSIVE RESPIRATION; VOLUMETRIC DIFFUSIVE VENTILATION

Document Type: Research Article

Affiliations: 1: Pulmonary Medicine Flight, Wilford Hall Medical Center, 759th MSGS/MCCP, 2200 Bergquist Drive, Lackland Air Force Base TX 78236;, Email: patrick.allan@lackland.af.mil 2: Surgical Intensive Care Medicine Flight, Department of the Air Force, Wilford Hall Medical Center, Lackland Air Force Base, Texas 3: Pulmonary Medicine Flight, Department of the Air Force, Wilford Hall Medical Center, Lackland Air Force Base, Texas

Publication date: January 1, 2007

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