![]() The advantage is that minute ventilation is guaranteed. The more compliant the lung is, the less pressure is required to achieve the set tidal volume. Pressure (IP and PIP) becomes the dependent variable and thus depends on the patient's compliance and airway resistance. ![]() Volume Control (VC): You set the tidal volume and the ventilator delivers that volume. The major advantage of PC is that it utilizes a decelerating flow pattern which generally is more comfortable, achieves the same volume at lower peak airway pressures, and is preferred for non compliant lungs. Conversely, lungs that have improving compliance will have increasingly larger tidal volumes in pressure control mode. Hence, if a patient has lungs that are getting worse and stiff (reduced compliance), their tidal volumes will decrease. Tidal volume becomes the dependent variable and thus depends on the patient's compliance and airway resistance. Pressure Control (PC): You set the pressures (IP and PEEP). ![]() STEP 2: A second classification can then be made by what variable is controlled or set: Patients generally find controlling the duration of their own breaths (ie PS breaths) more comfortable than ventilator controlled duration (ie AC or IMV breaths). However, the difference is that pressure supported breaths are generally terminated (cycled) when the flow reaches a certain point (ie 30% of maximal) whereas a normal pressure control breath is terminated (cycled) by the set inspiratory time. SIMV Pressure Control with a pressure support that is equal to the IP is nearly assist control (all breaths, whether strictly mechanical or patient triggered spontaneous breaths, receive the same pressure). Hence, this is sometimes considered a weaning mode but is routinely used for the majority of patients in the PICU. Any spontaneous patient triggered breaths above this set rate receive the set pressure support only. Synchronized Intermittent Mandatory Ventilation (SIMV): The ventilator delivers the set number of breaths with the preset PIP or V t, and I t. Every breath, whether mechanical or spontaneous (patient triggered) results in a fully supported breath (still synchronized) STEP 1: Can be divided into the a mount of support the ventilator provides for the patientĪssist Control (AC): More support and control.
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