modes of mechanical ventilation.pptx

modes of ventilation

1. Volume-Controlled Ventilation (VCV): Trigger : VCV uses a hybrid trigger, which means it can be initiated by both the patient's effort and a pre-set ventilator rate. The patient can trigger a breath based on either a certain level of airway pressure or flow. Target : VCV focuses on maintaining a consistent flow of air during each breath. You can set both the flow rate and the pattern of flow (like constant or decelerating) on the ventilator. Cycle : In VCV, the cycle variable is volume. The ventilator delivers a specific volume of air during each breath, and this volume determines the inspiratory time. Patient effort or changes in respiratory system conditions don't affect the inspiratory time. Summary of VCV : VCV is a mode in which the ventilator controls the airflow by targeting a set volume of air per breath. It uses a hybrid trigger, and the inspiratory time is fixed .

2. Pressure-Controlled Ventilation (PCV): Trigger : PCV, like VCV, uses the same hybrid trigger system where both patient effort and a pre-set rate can initiate a breath. Target : PCV primarily targets maintaining a specific airway pressure. The ventilator adjusts the flow of air to achieve and sustain this pressure. Cycle : In PCV, the cycle variable is time. You set the inspiratory time on the ventilator, and the breath ends once that time is reached, regardless of patient effort or respiratory system changes. Summary of PCV : PCV is a mode where the ventilator maintains a set airway pressure for a predefined time. It uses the same trigger system as VCV, and the inspiratory time is fixed .

3. Pressure Support Ventilation (PSV): Trigger : PSV relies entirely on the patient's effort to initiate a breath. There are no pre-set, time-triggered breaths. Target : Similar to PCV, PSV targets maintaining a specific airway pressure. The ventilator adjusts the flow of air to achieve and maintain this pressure. Cycle : In PSV, the cycle variable is flow. The breath ends when the flow of air decreases to a specified percentage of the peak inspiratory flow. This allows for flexibility in inspiratory time, which patients can control by adjusting their respiratory effort. Summary of PSV : PSV is a mode in which the ventilator assists the patient in maintaining a set airway pressure. Patients can control their breathing effort, resulting in variable inspiratory times for greater comfort and synchronization with the ventilator.

4. Figure 3.2 Flow and Pressure Waveforms in Pressure-Controlled Ventilation (PCV) into easy-to-understand points: Target Variable in PCV : In PCV, the main thing we're aiming for is to control the airway pressure. That means we want to keep the pressure inside the patient's airway at a certain level. Cycle Variable in PCV : The way PCV operates is based on time. The clinician sets a specific amount of time for each breath. When this time is up, the breath ends, regardless of what the patient is doing. Setting Proximal Airway Pressure : The clinician can decide the desired airway pressure, and the ventilator works to reach and maintain this pressure during inspiration. Inspiratory Time (TI) : The inspiratory time is also set by the clinician. It determines how long each breath will last. Flow Waveform Result : The interaction between these set variables (pressure target and time cycle) and the patient's respiratory system leads to a specific flow pattern. In PCV, this pattern is typically a "decelerating ramp." This means that the flow of air starts high at the beginning of the breath and gradually decreases as the breath continues. PCV is all about controlling and maintaining a specific airway pressure and inspiratory time. The way the flow of air changes during a breath is like a ramp, starting fast and slowing down. This helps ensure that the patient receives the right amount of air at the right pressure for the set time, as determined by the clinician.

5. figure3.3 Flow and Pressure Waveforms in Pressure Support Ventilation (PSV): Target Variable in PSV : In PSV, the primary goal is to control the airway pressure. This means maintaining a specific pressure level in the patient's airway. Cycle Variable in PSV : PSV operates based on flow. Unlike PCV, which uses time as the cycle variable, PSV uses the flow of air as its cycle parameter. Setting Proximal Airway Pressure : Clinicians can set the desired airway pressure that they want to achieve and maintain during the patient's breathing. Percentage of Peak Inspiratory Flow for Cycling : Clinicians also set a specific percentage of the peak flow (in this case, 25%) as the threshold for ending the breath. Once the flow decreases to this level, the breath terminates. Flow Waveform Result : The way air flows during a PSV breath is similar to PCV; it's a "decelerating ramp." This means that at the start of the breath, the flow is high and gradually decreases as the breath continues.