Answer
This mode is basically the combination of the 2 modes described above. If the patient has no spontaneous breaths, the ventilator is set up in the PRVC mode. However, when the patient takes 2 consecutive breaths, the mode is switched to VSV. If the patient becomes apneic for 12 seconds, the ventilator switches back to PRVC mode.
Automode and variable support or variable-pressure control was designed for automatic weaning from pressure control to pressure support depending on the patient's effort. This ventilatory mode can also be used in conventional volume control and volume support. Again, the mode depends on the patient's effort. To the authors' knowledge, no randomized trials have been conducted to evaluate this automode, and no evidence suggests that this type of weaning is more effective than conventional weaning.
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An example of the Drinker and Shaw negative-pressure ventilator (iron lung).
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The pressure, volume, and flow to time waveforms for assist-control ventilation.
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The pressure, volume, and flow to time waveforms for controlled ventilation.
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The components of mechanical ventilation inflation pressures. Paw is airway pressure, PIP is peak airway pressure, Pplat is plateau pressure.
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The effects of decreased respiratory system compliance (A) and increased airway resistance (B) on the pressure-time waveform.
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Determination of the lower inflection point to estimate the best (optimal) positive end-expiratory pressure (PEEP) from the pressure-volume hysteresis curve.
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The effect of positive end-expiratory pressure (PEEP) on the pressure-time inflation curve.
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The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV).
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The pressure, volume, and flow to time waveforms for synchronized intermittent mandatory ventilation (SIMV) with pressure-support ventilation.
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The flow to time waveform demonstrating auto–positive end-expiratory pressure (auto-PEEP).
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The pressure, volume, and flow to time waveforms for pressure-regulated volume-controlled ventilation.
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The pressure, volume, and flow to time waveforms for proportional-assist ventilation.
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The pressure, volume, and flow to time waveforms for airway pressure–release ventilation.