Airway Pressure Release
Ventilation
APRV review and
indications in
paediatrics
APRV








Terminology
How it works
Indications
Advantages/disadvantages
Review of paediatric studies
Set-up (paed specific)
Weaning
Discussion
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
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
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
APRV waveform
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
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
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
Disadvantages



Volumes affected by changes in compliance
and resistance and therefore close
monitoring required
Integrating new technology
Limited research and clinical experience
Paediatric Studies




Studies in the paediatric population are few
and small
Several are ongoing
3 published
Most evidence is extrapolated from the adult
studies
Airway pressure release ventilation in paediatrics
Schultz T, et al. Pediatric Crit Care Med. 2001 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
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
Airway Pressure Release Ventilation: A Pediatric Case Series
Krishnan,J. ,Morrison, M.: University of Maryland, Pediatric Pulmonology 42:83-88. 2007




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
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
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
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
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
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
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 25 50% of the PEF
T high = manipulated to achieve RR
PS = set to avoid flow hunger with spon. resps.
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
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
Lets talk!
Any questions?