Page 356 - Clinical Application of Mechanical Ventilation

322 Chapter 11

TABLE 11-2 Calculations to Determine the Volume Delivered during Constant-Flow Ventilation (See Figure 11-8)

1. Computations necessary to find volume under the CFW:

Volume 5 Average Flow (L/sec) 3 (T sec) Volume 5 0.8333 L/sec 3 0.25 sec 5 0.2083 L
I
per 0.25 sec
V 5 (50 L/min 3 1 min/60sec) 3 1.0 sec Volume 5 0.2083 L 3 2 5 0.4166 L in 0.50 sec
T
V 5 0.833 L/sec 3 1.0 sec Volume 5 0.2083 L 3 3 5 0.6249 L in 0.75 sec
T
V 5 0.833 L Volume 5 0.2083 L 3 4 5 0.833 L in 1.00 sec
T
Or
Volume 5 0.8333 L/sec 3 0.25 sec 5 0.2083 L
Volume 5 0.8333 L/sec 3 0.50 sec 5 0.4166 L
50 Volume 5 0.8333 L/sec 3 0.75 sec 5 0.6249 L
V (L/min) V1 V2 V3 V4 Volume 5 0.8333 L/sec 3 1.00 sec 5 0.8333 L

V1 5 0.2083 L

0 0.25 0.5 0.75 1.0 © Cengage Learning 2014 V2 5 0.2083 L
V3 5 0.2083 L
Time (sec)
V4 5 0.2083 L
V 5 V1 1 V2 1 V3 1 V4 5 0.833 L
T
© Cengage Learning 2014

TABLE 11-3 Calculations to Determine the Inspiratory Volume Waveform that Develops during Constant-Flow
Ventilation (See Figure 11-8)

1. Computations necessary to plot the volume pattern during inspiration:

Volume 5 Average Flow (L/sec) 3 T (sec) Volume 5 0.8333 L/sec 3 0.25 sec 5 0.2083 L
I
V 5 (50 L/min 3 1 min/60sec) 3 1.0 sec Volume 5 0.8333 L/sec 3 0.50 sec 5 0.4166 L
T
V 5 0.833 L/sec 3 1.0 sec Volume 5 0.8333 L/sec 3 0.75 sec 5 0.6249 L
T
V 5 0.833 L Volume 5 0.8333 L/sec 3 1.00 sec 5 0.8333 L
T

0.833

0.625

V (L)
0.417

0.208
© Cengage Learning 2014

0 0.25 0.5 0.75 1.0
Time (sec)
© Cengage Learning 2014

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