The SIMV mode provides a flexible combination of mandatory and spontaneous breaths, adapting to the patient’s breathing efforts while maintaining a consistent backup ventilation rate.
How SIMV Works:
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The ventilator delivers mandatory breaths at a fixed rate set by the user.
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Between these breaths, the patient is allowed to breathe spontaneously.
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If the patient initiates a breath before the next scheduled mandatory breath, the ventilator synchronizes and delivers a volume-controlled breath in coordination with the patient’s effort.
🔄 Trigger Sensitivity (Flow Trigger):
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Default value: 3 L/min
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Adjustable range: 1 to 15 L/min
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If the patient meets this trigger condition, the ventilator synchronizes the mandatory breath accordingly.
Pressure Support in SIMV Mode
During spontaneous breaths, the ventilator can provide Pressure Support Ventilation (PSV):
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PSV assists patients who can initiate breaths but need help maintaining adequate ventilation.
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Once the ventilator senses an inspiratory effort, it delivers a constant pressure to support the breath.
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This reduces the patient’s work of breathing while maintaining respiratory efficiency.
⚙️ Termination (also known as Timation):
Adjusts the flow percentage at which the inspiratory phase ends, allowing the ventilator to adapt to the patient’s breathing pattern.
Available Settings in SIMV Mode
SIMV mode includes many of the same adjustable parameters as ACV mode, such as:
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VT (Tidal Volume)
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Rate (Mandatory breaths per minute)
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MV (Minute Volume)
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I:E Ratio (Inspiratory to Expiratory time)
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DI (Inspiratory Time)
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PEEP (Positive End-Expiratory Pressure)
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Trigger Sensitivity
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FiO₂ (%) (Oxygen concentration)
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MV Max/Min (Minute volume alarms)
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P Max/Min (Pressure alarms)
SIMV is especially useful for weaning patients off mechanical ventilation, offering full support when needed while encouraging natural breathing between assisted breaths.
