Page 107 - Clinical Application of Mechanical Ventilation

Classification of Mechanical Ventilators 73

Pressure (cm H 2 O) 50 50
40
30
20
40
10
30
20
1 2 3 4
Flow (L/min) 1 2 3 4
Time (sec) 10

1.0 10 Time (sec)
20
Volume (L) 30

40
50
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1 2 3 4
Time (sec)
Figure 3-19 Sinusoidal pressure waveform illustrated with the corresponding volume and
flow waveforms. This type of pattern is typical of a rotary-driven piston drive mechanism.

piston drive mechanism (Figure 3-19). Ventilators using this drive mechanism
include the Emerson 3-MV, Respironics PLV-100, Bear 33, and Puritan-Bennett
LP-10 and LP-20.

Volume Waveforms

Volume waveforms can be classified into two types, ascending ramp and sinusoi-
dal (Figure 3-20). The ascending ramp waveform is produced by a constant (i.e.,

A B

1.0 1.0
Volume (L) Volume (L)

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1 2 3 4 1 2 3 4
Time (sec) Time (sec)
Figure 3-20 Two types of volume waveforms: (A) ascending ramp; and (B) sinusoidal.

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