BUMC Basics.pdf - Anesthesia Home

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Invasive Mechanical Ventilation (MV) Modes
Pressure Support Ventilation (PSV): *NOTE: This mode is
only for patients with an intact respiratory drive*
• Patient initiates a breath, which is supported by vent at a
preset pressure
• Flow cycled NOT volume cycled like in SIMV/AC
• “Pressure Support” = inspiratory pressure selected to
achieve adequate TV and ventilatory support
• Can be combined w/ SIMV to partially assist
spontaneous breaths
• Could be considered to make patient more “comfortable”
on vent; also used for SBT at the appropriate level.
Synchronized Intermittent Mechanical Ventilation (SIMV):
• Patient receives vent support at a given tidal volume and
respiratory rate. If patient initiates additional breaths, the
vent provides no support to these breaths unless pressure
support is added.
• This mode has been proposed to prevent respiratory
alkalosis; however, it requires more respiratory muscle
work than AC.
• Used primarily in SICU
Assist-Controlled Mechanical Ventilation (AC): Can set volume
targeted or pressure targeted.
• When using volume targeted: Patient receives vent
support at a given tidal volume and respiratory rate. If
patient initiates additional breaths, the vent delivers the
pre-set tidal volume with each additional breath.
• If the patient is tachypnic, then hyperventilation can
occur
Other modes to minimize lung injury:
• High Frequency Jet Ventilation/Oscillation: Alveoli are
kept fully open as if the patient is kept at full inspiration
while gases are exchanged by oscillating the air at high
frequency
Indications for intubation
• Refractory hypoxemia
• Hypercapnea with respiratory acidosis (note that
patients w/ COPD often live w/ pCO2 b/t 50-70)