Page 119 - Clinical Application of Mechanical Ventilation

Operating Modes of Mechanical Ventilation 85

Table 4-1 Overview of Mechanical Breath Terminology

1. Mechanical Breath Variables

Control variable Mechanism to deliver a breath (e.g., pressure-controlled
or volume-controlled)
Trigger variable Mechanism to start inspiration (e.g., pressure or flow
trigger by patient, time trigger by ventilator)
Cycle variable Mechanism to end inspiration (e.g., volume-cycled,
pressure-cycled, flow-cycled, time-cycled)

2. Breath Sequence
Continuous mandatory All breaths are controlled by the ventilator. No
spontaneous breaths are allowed (e.g., CMV)

Intermittent mandatory Set number of mandatory breaths are provided by the
ventilator. Spontaneous breaths are allowed between
mandatory breaths (e.g., SIMV).
Continuous spontaneous All breaths are spontaneous with assistance (e.g.,
pressure support ventilation or PSV) or without
assistance (e.g., continuous positive airway pressure
or CPAP).

3. Type of Control or Target Scheme

Set point How the ventilator reaches its targeted goal (e.g., set
point for pressure-controlled ventilation is pressure)
Servo How the ventilator adjusts its output to suit the
patient’s variable (e.g., proportional assist ventilation
adjusts its pressure to generate an appropriate flow
to meet the patient’s flow demand)

Adaptive How the ventilator adjusts a set point to reach a
different targeted set point (e.g., pressure-regulated
volume control adjusts the pressure (by altering the
flow and I-time) to reach a targeted volume.
Optimal How the ventilator uses a mathematical model to alter
the set points to achieve a target goal (e.g., adaptive
support ventilation alters the frequency, tidal volume,
and pressure to achieve a target minute ventilation.
© Cengage Learning 2014

7. Intermittent mandatory ventilation (IMV)
8. Synchronized intermittent mandatory ventilation (SIMV)

9. Mandatory minute ventilation (MMV)
10. Pressure support ventilation (PSV)

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.