APRV Flashcards by Hannah Taylor

What are the advantages of APRV?

uses lower peak and mean airway pressures
increases cardiac index
decreases central venous pressure

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What is the open lung approach?

high peep, low lung pressure

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What is the best mode to help limit lung damage?

low volume settings adjusted to maintain plateau pressures between 25-30 cmH2O simulating PCV

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What are some lung protective strategies?

ALI and ARDS
keep plateau pressures <30 cmH2O
low tidal volume ventilation (4-6 mL/kg)
peep to restore FRC

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What are the current strategies for ventilating between upper and lower inflection points?

increase MAP while limiting peak alveolar pressure
preventing alveolar collapse by ventilating above the lower inflection point
preventing over distention by ventilating below the upper inflection point

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What is BiLevel in comparison to APRV?

a form of pressure ventilation designed to embrace dual peep levels and inspiratory/expiratory times that allow traditional PC-like breath delivery to APRV-like breath delivery

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What are the four main settings in APRV?

P-high
P-low
T-high
T-low

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P-high and P-low are specific independent settings, therefore what happens to P-high when you raise P-low?

does not change

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If your P-low is set to 5 and you P-high is set to 15, what is your set PS?

15 cmH2O

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If your P-low is set to 5, your P-high is set to 15 and your PS is 15, what are all spontaneous breaths at P-high supported by??

5 cmH2O

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How does bilevel look similar to PCV-SIMV?

by setting P-high, T-high and frequency close to typical ventilation settings

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What are the clinical advantages to spontaneous breathing at 2 peep levels?

a potential decrease in sedation (sedation due to patient/ventilator dyssynchrony may be kept at a lower level)
less sedation could result in: less interaction with other organ function, patients can be mobilized easier, an active cough may improve secretion removal, inability to identify complications that can be masked by sedation

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How does spontaneous breathing ventilation differ from paralyzed patients?

it provides ventilation to dependent lung regions which get the best blood flow

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How does paralyzed ventilation differ from spontaneous breathing?

during PPV for paralyzed patients, the anterior diaphragm is displaced towards the abdomen with the non-dependent regions of the lung receiving the most ventilation where the perfusion is the least

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Is there mechanical breathing in APRV?

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What is APRV?

utilizes very short expiratory time. this short time at a low pressure allows for exchange of gas

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What is the critical setting in APRV?

T-low

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How is T-high used in APRV?

it varies with frequency changes and merely determines the interval that the lungs are held at P-high

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When should you consider APRV?

bilateral infiltrates
p/f ratio <300 and falling
plateau pressure

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What are the goals with APRV? (first five)

to prove LPV supported by the ARDSnet research
minimize alveolar over distension
avoid repeated alveolar collapse and reexpansion
restore FRC through recruitment and maintain FRC by creating intrinsic peep

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What are the goals with APRV? (last five)

lower FIO2
protect lungs
make patient comfortable
use less sedation
wean patient off the ventilator

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What are the three types of lung units in ARDS pattern?

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normal region (primarily non-dependent area)
consolidated, edematous, atelectatic region (dependent area)
region that is collapsed during exhalation and recruitable during inspiration

What are the clinical advantages to spontaneous breathing in ARDS during APRV?

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APRV with spontaneous breathing showed a decrease in V/Q mismatch that increased over time
spontaneous breaths in APRV as small as 70-150 mL in adults improved oxygenation and CO2 removal

What are the similarities of APRV to high frequency ventilation?

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both hold lungs at near constant lung MAP, limiting pressure swings
both shown to be effective in decreasing dead space, improving gas exchange, increasing cardiac output
APRV is accomplished with a conventional ventilator, a conventional circuit and is less technically challenging

What is high frequency ventilation?

breathing in and out at the same time. like filling a glass all the way and still put in water so it over flows

Who are poor candidates for APRV?

- patients with increase RAW - patients who are unable to empty their lungs in 2 seconds - asthma and COPD patients

What is a reliable indicator that tells if a patient is a poor candidate for APRV?

examine their expiratory flow pattern to determine increased resistance

What are the APRV clinical guidelines?

- APRV has been suggested for restrictive patients only (obstructive easily develop air trapping) - start early with CPAP and switch to APRV as CO2 clearance and/or decreased work of breathing is desired

How do you set up APRV?

- P-high: set so plat is not above 30 - P-low: 0 - T-high: start at 5 - T-low: start at 0.5

Initial settings of P-high

typically about 20-25, however in patients with play at or above 30, set at 30 (in desperation can go to 35)

What are the exceptions to setting really high P-high settings?

- morbid obesity | - decreased thoracic or abdominal compliance

What should you set P-low to and why?

zero because it creates the greatest pressure gradient and fast expiratory flows

What is T-high and how should you set it?

the inspiratory time that is set to a minimum of 5 seconds, and is progressively increased. do NOT use rate of over 15. its target is oxygenation

Establishing T-low

do not want to let exhalation go to complete emptying and regional auto-peep is desirable outcome

How would you set T-low?

set time low so that expiratory flow from patient ends at about 75-50% of peak expiratory flow OR one time constant (i.e, if peak expiratory flow is 80 L/min, then "dump" should end when flow is between 60-40 L/min

How would you improve oxygenation with APRV?

- reduce sedation - re-assess peep (move towards 75%) - decrease T-low - increase P-high, T-high, FIO2

What should you NOT do if a patient has a high CO2?

increase T-high

What should you do if your patient has PaO2 that is too low?

decrease T-low

What should be your goal for all oxygenation choices?

increase MAP

How could you improve CO2?

- reduce sedation - upper pressure is adjusted to maintain dec WOB or O2 delivery goals - increase T-low and PS of spontaneous breaths - decrease T-high

What are you doing when you increase P-high?

increasing the pressure gradient which increases flow

What should you do to decrease CO2?

- decrease T-high - increase P-high to increase change in pressure and volume exchange - check T-low and increase if possible

What should you do to increase CO2?

- increase T-high - decrease P-high to decrease change in pressure - it may be better to accept hypercapnia than to reduce P-high so much that oxygenation decreases

What are the disadvantages of APRV?

- potential for alveolar de-recruitment during the pressure release - APRV is affected by changes in lung compliance - if release phase is not synchronous with patient's effort, discomfort may result

What patients should you be cautious with using APRV?

- patients that have COPD, asthma or any other type of air trapping disease - barotrauma could be a side effect

What are the overall advantages?

- spontaneous breathing - maintains peak airway pressures at CPAP levels (over distention minizmed) - continuous lung recruitment maneuver

What should you accomplish before weaning from APRV?

- FIO2 40-50% - reduce P-high by 2 until it is below 20 - increase T-high to change vent set rate by 5 releases/time

What is DROP and DRAG?

DROP- drop P-high in increments of 1-3 (usually about 2) DRAG- increase T-high ^do the above until it looks just like CPAP

For a P/F ratio of greater than or equal to 300, what should your estimated MAP requirements be?

10-15 cmH2O

For a P/F ratio of greater than or equal to 250, what should your estimated MAP requirements be?

15-20 cmH2O

For a P/F ratio of greater than 200, what should your estimated MAP requirements be?

20-25 cmH2O

For a P/F ratio of greater than 150, what should your estimated MAP requirements be?

25-30 cmH2O

For a P/F ratio of greater than 100, what should your estimated MAP requirements be?

30-35 cmH2O

APRV Flashcards

(53 cards)