Author Question: How many time constants are necessary for 95 of the tidal volume (VT) to be delivered from a ... (Read 29 times)

mp14 · **on:** Jul 16, 2018

How many time constants are necessary for 95 of the tidal volume (VT) to be delivered from a mechanical ventilator?

a. 1
b. 2
c. 3
d. 4

Question 2

Compute the inspiratory time necessary to ensure 100 of the volume is delivered to an intubat-ed patient with a Cs = 60 mL/cm H2O and the Raw = 6 cm H2O/(L/sec).

a. 0.36 second
b. 0.5 second
c. 1.4 second
d. 1.8 second

underwood14 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
One time constant allows 63 of the volume to be inhaled; 2 time constants allow about 86 of the volume to be inhaled; 3 time constants allow about 95 to be inhaled; 4 time constants allow about 98 to be inhaled; and 5 time constants allow 100 to be inhaled.

Answer to Question 2

ANS: D
Time constant (TC) = C (L/cm H2O) R (cm H2O/(L/sec)). 100 of the volume will be delivered in 5 time constants. Therefore, multiply 5 times the time constant.