2. Airway Pressure Release Ventilation
APRV review and indications in paediatrics

3. APRV Terminology How it works Indications Advantages/disadvantages
Review of paediatric studies
Set-up (paed specific)
Weaning
Discussion

4. APRV
Continuous positive airway pressure with regular, brief releases in airway pressure to facilitate alveolar ventilation and CO2 removal
Time triggered, pressure limited, time cycled mode
Allowing unrestricted spon. Breathing throughout the ventilatory cycle

5. Terminology P high = the baseline airway pressure level,
P low = airway pressure resulting from airway release (PEEP)
Time high = the length of time that P high is maintained
Time PEEP = time spent in airway release at P low

6. How does it work?
The constant airway pressure at P high facilitates alveolar recruitment and therefore enhances gas diffusion
The long time at P high allows alveolar units with slow time constants to open
The timed releases in pressure T PEEP allows alveolar gas to be expelled via natural lung recoil not with repetitious opening of alveoli

7. APRV waveform

8. Indications Recruitable low compliance lung disorders
Lung dysfunction secondary to thoracic restriction i.e.. obesity, acites
Inadequate oxygenation with FiO2 > .60
PIP> 35 cmH2O and /or PEEP>10 cmH2O
Lung protective strategies (high PEEP, low Vt) are failing
Can be used with other interventions i.e.. INO therapy, prone positioning

9. Advantages
Significantly lower peak Paw and improved oxygenation when compared to conventional ventilation
Requires lower min. vol. suggesting decreased dead space ventilation
Avoids low volume lung injury by avoiding repetitious opening of alveoli

10. Advantages
Allows for spontaneous breathing at all points in the respiratory cycle
Spon. breathing tends to improve V/Q matching
Decreased need for sedation and near eliminating need for neuromuscular blockade

11. Disadvantages
Volumes affected by changes in compliance and resistance and therefore close monitoring required
Integrating new technology
Limited research and clinical experience

12. Paediatric Studies
Studies in the paediatric population are few and small
Several are ongoing
3 published
Most evidence is extrapolated from the adult studies

13. Airway pressure release ventilation in paediatrics Schultz T, et al
Airway pressure release ventilation in paediatrics Schultz T, et al. Pediatric Crit Care Med jul;2(3):24 3-6
Airway pressure release ventilation in paediatrics Schultz T, et al. Pediatric Crit Care Med jul;2(3):24 3-6
a prospective, randomized, cross-over trial of 15 PICU pt. >8kg
Randomized to either VCV (9) or APRV (6)
APRV had lower PIP and Pplat than VCV in all patients
No sig. differences in physiologic variables e.g.. EtCO2

14. Airway Pressure Release in a Paediatric Population Jones R, Roberts T, Christensen D. St.Luke’s Reginal Medical Center, Boise, ID AARC open Forum 2004
A case series of 7 paediatric patients aged 3 to 13 with ALI
All failing conventional PPV with severe hypoxemia
2 failed HFOV with severe hypoxemia
6/7 lower PIP, all had higher MAP, all had improved oxygenation, all had lower FiO2 requirements

15. Airway Pressure Release Ventilation: A Pediatric Case Series Krishnan,J. ,Morrison, M.: University of Maryland, Pediatric Pulmonology 42:
retrospective review of 7 pediatric cases
Approved by the University of Maryland institutional review board
All pt.s failed on conventional ventilation
Implemented similar starting parameters as to be described later

16. Case 1 9 y.o. leukemia with septic shock, ARDS and MSOF
SIMV PC , FiO2 = 1.0, PIP/PEEP= 38/14 cmH2O, PaO2= 91 mmHg
Failed HFOV secondary to hypotension
APRV – Phigh 37 cmH20, Plow 0cmH2O with Pmean of 32 cmH2O
PaO2 improved over 84 hrs and required no NMB
Weaned and d/ced home

17. Case 2 5 y.o. 60% body area burns with development of sepsis and ARDS
Failed convention ventilation (39/19) and was placed on HFOV with intractable hypercarbia (PaCO2= 121mmHg)
APRV of 40/0 PaCO2 improved to 78mmHg
MSOF worsened and pt. made limited resuscitation

18. Case 3 8 y.o. CF with development of ARDS
Pt. required heavy sedation with CV with 30/13 and FiO2 = .50
APRV settings 28/0 and sedation was decreased and pt. was extubated to NIV
No NMB was required

19. Case 4
4 y.o. with fever, jaundice, hepatomegaly, pancytopenia and hypofibrinogenemia
Requiring CRRT for MSOF and ARDS
CV with 40/10 cmH20 and FiO2 = 1.0
APRV 34/0 and O2 weaned to .6 and NMB was lifted
Weaned to CPAP and septic shock resolved but pt suffered an intracranial haemorrhage which led to his death
Autopsy revealed hemophagocytic lymphohistiocytosis

20. Case 5
1 y.o. leukemia post bone marrow transplant with sepsis and neutropenia and graft vs host disease and tracheotomy
Difficult to ventilate with PaCO2 of 64mmHg and tachypnea and distress
APRV 30/0 cmH20 and was rapidly weaned with noted increase in comfort
Weaned to FiO2 to .45 and PaCO2 = 39mmHg
Later exacerbation of leukemia resulted in renal failure

21. Hints for set-up P high = same as plateau or 125% of mean Paw
PEEP = 0 cmH2O
T PEEP = long enough to get returned Vt but not long enough to derecruit – titrate to end at % of the PEF
T high = manipulated to achieve RR
PS = set to avoid flow hunger with spon. resps.

23. Set-up Set-up Be patient
The change to APRV may not provide instant improvement in oxygenation
The effects may take hours to be realized
Has been shown that the maximum benefit occurred at approx. 8 hours after implementation

24. Weaning Decrease FiO2 first and then P high is small increments
As compliance improves the TCs lengthen and T PEEP may need adjustment to allow for adequate Vt
When P high is weaned to a low level consider extubation
Lengthen T high and therefore decreasing the # of pressure releases per minute

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