Page 108 - Clinical Application of Mechanical Ventilation

74 Chapter 3

rectangular) inspiratory flow pattern. The shape is characterized by a linear rise to
the peak inspiratory pressure value. Sinusoidal volume waveforms are produced by
ventilators that have a rotary-driven piston drive mechanism. Ventilators using this
drive mechanism include the Emerson 3-MV, Respironics PLV-100, BEAR 33, and
Puritan-Bennett LP-10 and LP-20.

Flow Waveforms

The four types of flow waveforms are shown in Figure 3-21. The waveforms in-
clude rectangular (constant), ascending ramp, descending ramp, and sinusoidal.
The rectangular waveform is produced when volume is the control variable
and the output is an ascending ramp. The flow waveform (a derivative of the

A B

40 40
30 30
20 20
Flow (L/min) 10 1 2 3 4 Flow (L/min) 1 2 3 4
10
10

20
20 Time (sec) 10 Time (sec)
30 30
40 40

C D
40 40
30 30

20 20
Flow (L/min) 10 1 2 3 4 Flow (L/min) 10 1 2 3 4

10
20 Time (sec) 10 Time (sec)
20
30 30 © Cengage Learning 2014

40 40
Figure 3-21 Four types of flow waveforms: (A) rectangular (constant); (B) ascending ramp;
(C) descending ramp; and (D) sinusoidal.

Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.