APRV Flashcards
At it simplest, what is APRV?
A mode of ventilatory support designed to provide 2 levels of CPAP
T/F: APRV does not allow for spontaneous breathing
False. APRV allows for spontaneous breathing at both levels
What are the general indications for APRV?
Acute lung injury
Diffuse pneumonia
Atelectasis requiring >50% FiO2
Tracheoesophageal fistula
What are the goals of APRV
Improve oxygenation
Reduce physiological dead space
Decrease PIP
What are the most common patients receiving APRV?
ARDS patients
What is APRV called on the Drager and Evita?
APRV
What is APRV called on the Hamilton?
APRV
DuoPAP
What is APRV called on the servo?
BiVent
What is APRV called on Covidien?
Bi-level
What are the initial settings for FiO2 on APRV?
FiO2 starts at 90%
What is the goal for SpO2 when using APRV?
Titrate O2 for an SpO2 of >88%
What does Phigh represent?
Inspiratory pressure
What does Plow represent?
PEEP
What does T high represent?
Inspiratory time
What is the function of Phihg?
Promotes alveolar stabilization and alveolar recruitment
What does Tlow represent?
Expiratory time
What is Phigh usually set to?
20-30 cmH2O at initiation
What is Thigh initially set to?
4.5-6 seconds
What is Plow set to?
0 cmH2O
What is Tlow initially set to?
0.5-0.8 seconds
What is the purpose of Plow?
Promotes CO2 removal
Lowers mean airway pressure
Reduces risk of cardiac compromise
How is Phigh set?
Set at Plateau pressure (volume control)
Set at 3 cmH2O above MAP
PIP (pressure control)
What should Phigh be kept below?
40 cm H2O
Why is autoPEEP built into APRV?
It maintains alveolar recruitment and prevents the collapse and re-expansion of the alveoli
A patient with compliance issues should have their expiration end when?
75% of PEFR
When should expiratory flow end when a patient is on APRV?
Should end 50-75% of PEFR
What determines tidal volume in APRV?
Pressure gradient between Phigh and Plow
Duration of T high
Patients pulmonary mechanics
How should the expiration change as the patient improves?
Can end closer to 25% of PEFR
What determines a patients alveolar ventilation and PaCO2 on APRV?
Tidal volume
Frequency of airway pressure release maneuver
Level of patients spontaneous breathing
What should you assess after initiating APRV?
SpO2
HR
Blood pressure
Minute ventilation
Expiratory flow curve
ABG
If APRV is successfully implemented, what should the WOB look like and what muscle group will be doing most of the WOB?
Decrease work of breathing
Focuses WOB on diaphragm and allows accessory muscles to rest
If you need to increase a patients SpO2, what are your options on APRV?
Increase FiO2
Increase Phigh in 2 cmH2O increments
Decrease Tlow to be closer to 75% of PEFR
What should be done intially if a patient on APRV begins to develop a respiratory acidosis?
Increase Phigh in 2 cmH2O increments
Increase Thigh in increments of 0.5 second increments
Increase T low to allow for more time for exhalation
What should be done if a patient on APRV has a persistent respiratory acidosis and initial interventions do not help?
Decrease Thigh
Increase Phigh to maintain MAP and maintain alveolar recruitment
If a patient on APRV develops a respiratory alkalosis, what adjustments should be made?
Decrease Phigh to lower delta P in 2 cm H2O increments
Increase Thigh to decrease cycles per minute
How should a patient on APRV be weaned?
FiO2 should be weaned first
What FiO2 should be targeted when weaning a patient on APRV?
Target 50% with SpO2 of 88%
How should Thigh be treated when weaning APRV?
Stretch Thigh by 0.5 seconds until Thigh is 12-15 seconds
How should Phigh be weaned for a patient on APRV?
Drop Phigh in 2 cmH2O increments until Phigh is below 10 cm H2O
What are the advantages of APRV?
Decrease PIP
Improve alveolar recruitment
Improve oxygenation
Improve gas exchange
Allows for spontaneous breathing = improvements in recruitment and gas exchange
Potential decrease in need for sedation and paralytics, time on vent, and length of ICU stay
What mode should you transfer a patient who is improving on APRV to?
When appropriate, you can shift a patient onto PSV 10/5
What are the disadvantages of APRV
Variable tidal volumes
Minimum minute ventilation not guaranteed
autoPEEP
High MAPs may reduce venous return in hemodynamic unstable patients
What patients have contraindications for the use of APRV?
Severe obstructive lung disease
What does Phigh to Plow allow?
allows lungs to deflate
Why should patients with severe obstructive lung disease not be put on APRV?
Significant chance of severe air trapping and barotrauma
How is tidal volume determined on APRV
patients pulmonary mechanics
duration of Thigh
pressure gradient between Phigh and Plow
What should Tlow be set to?
set to end expiratory flow at about 50-75% of PEF
When using the last conventional mode of ventilation as a reference, Phigh should be set to
At PIP
At the Pplat
At 3 cmH2O above the MAP
What does Plow to Phigh do?
inflates the lungs
The patients alveolar ventilation and PaCO2 are determined by __________ in APRV
frequency of airway release maneuver
Plow
the level of the patients spontaneous breathing
the tidal volume
What is a contraindication for APRV
congestive heart failure
what are indications for the use of APRV
acute lung injury
atelectasis requiring >50% FiO2
diffuse pneumonia
What are the goals of APRV
decreasing PIPs
improving oxygenation
reducing dead space
APRV could be best described as a:
mode of ventilatory support designed to provide two levels of CPAP
