Author Question: Which of the following terms describes gas characterized by a parabolic gas profile during one phase ... (Read 32 times)

washai · **on:** Jul 16, 2018

Which of the following terms describes gas characterized by a parabolic gas profile during one phase of the ventilatory cycle and a square profile during the other phase?

A. Taylor dispersion
B. coaxial flow
C. molecular diffusion
D. Pendelluft

Question 2

What is a possible reason for being able to safely use higher mean airway pressures during HFV than during conventional ventilation?

A. because Taylor dispersion occurs during HFV and not during conventional ventilation
B. because the airway pressure swings are smaller during HFV
C. because of intraunit gas flow impedance differences occurring during HFV and lacking during conventional ventilation
D. because coaxial flow prevails during HFV and is absent during conventional ventilation

Moriaki · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Coaxial flow results if the gas-flow profile during one phase of the ventilatory cycle is parabolic and during the other phase is square, a net flow of gas can occur in one direction through the center of the airway and in the other direction via the periphery.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Observational trials with HFV often describe how high mean airway pressures are safely used, especially in comparison to those used for conventional ventilation. Sometimes mean airway pressures achieved during HFV are higher (>30 cm H2O) than the safe maximum pressure used during conventional ventilation. The safe use of these high pressures may be attributable to the small tidal pressure swings developing during HFV, and because the application of higher mean airway pressure with HFV may be a gradual process.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.