APRV and ATC Flashcards
What is APRV?
Airway pressure release ventilation; has inverse I:E ratio
What are other names for APRV?
BiLevel, BiVent, BiPAP, DuoPAP
How does APRV work?
2 levels of CPAP as it switches from one pressure level to another. There is a set time for each pressure level which are called Phigh and Plow where Phigh is longer than Plow (lungs stay inflated more than deflated)
How long is Phigh held in APRV?
5-7 seconds
Why is Phigh held so long in APRV?
It allows for full distribution of pressure and volume throughout the lung, not all alveolar units fill at equal speeds so this allows them to fill, it may open atelectatic alveoli by sustained pressure, and it allows for better gas mixing in the alveoli.
How long is Plow held in APRV?
About 0.5-1.0 seconds
What does limiting exhalation time in APRV do?
It creates autopeep and prevents full exhalation
What are some advantages of APRV?
- Recruits collapsed lung units and opens lungs further
- Increases alveolar surface area
- There is more time for gas exchange and pressure equalization, oxygenation, and ventilation may improve
- High mean airway pressure while controlling PIP
What are some disadvantages of APRV?
- It can be uncomfortable for the patient and sedation might be required
- High MAP can impact cardiac function
- Difficult to use if you are unfamiliar with the mode
- May not work in patients requiring high MV
What is ATC ventilation?
Automatic tube compensation; ventilates to tracheal rather than circuit pressure because an artificial airway causes a fixed amount of resistance and imposes work of breathing on our patient.
How does an artificial airway change work of breathing?
The resistance of the artificial airway causes there to be a higher pressure in the circuit than the carina on inspiration.
How does ATC combat the resistance of artificial airways?
Constantly measures flow and adjusts pressure throughout the breath to maintain a carinal pressure which is calculated rather than a measured circuit pressure.
What extra settings do we need to consider when ventilating with ATC?
Tube size and type, and the level of compensation for the resistance in the tube.
