Airway Pressure Release Ventilation APRV review and indications
- Slides: 25
Airway Pressure Release Ventilation APRV review and indications in paediatrics
APRV l l l l Terminology How it works Indications Advantages/disadvantages Review of paediatric studies Set-up (paed specific) Weaning Discussion
APRV l l l Continuous positive airway pressure with regular, brief releases in airway pressure to facilitate alveolar ventilation and CO 2 removal Time triggered, pressure limited, time cycled mode Allowing unrestricted spon. Breathing throughout the ventilatory cycle
Terminology l l 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? l l l 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 l l l Recruitable low compliance lung disorders Lung dysfunction secondary to thoracic restriction i. e. . obesity, acites Inadequate oxygenation with Fi. O 2 >. 60 PIP> 35 cm. H 2 O and /or PEEP>10 cm. H 2 O Lung protective strategies (high PEEP, low Vt) are failing Can be used with other interventions i. e. . INO therapy, prone positioning
Advantages l l l 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 l l l 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 l l l Volumes affected by changes in compliance and resistance and therefore close monitoring required Integrating new technology Limited research and clinical experience
Paediatric Studies l l 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 in paediatrics Airway Schultz. T, T, et etal. Pediatric. Crit. Care. Med. 2001 jul; 2(3): 243 -6 Schultz l l a prospective, randomized, cross-over trial of 15 PICU pt. >8 kg 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. . Et. CO 2
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 l l 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 Fi. O 2 requirements
Airway Pressure Release Ventilation: A Pediatric Case Series Krishnan, J. , Morrison, M. : University of Maryland, Pediatric Pulmonology 42: 83 -88. 2007 l l 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 l l l 9 y. o. leukemia with septic shock, ARDS and MSOF SIMV PC , Fi. O 2 = 1. 0, PIP/PEEP= 38/14 cm. H 2 O, Pa. O 2= 91 mm. Hg Failed HFOV secondary to hypotension APRV – Phigh 37 cm. H 20, Plow 0 cm. H 2 O with Pmean of 32 cm. H 2 O Pa. O 2 improved over 84 hrs and required no NMB Weaned and d/ced home
Case 2 l l 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 (Pa. CO 2= 121 mm. Hg) APRV of 40/0 Pa. CO 2 improved to 78 mm. Hg MSOF worsened and pt. made limited resuscitation
Case 3 l l 8 y. o. CF with development of ARDS Pt. required heavy sedation with CV with 30/13 and Fi. O 2 =. 50 APRV settings 28/0 and sedation was decreased and pt. was extubated to NIV No NMB was required
Case 4 l l l 4 y. o. with fever, jaundice, hepatomegaly, pancytopenia and hypofibrinogenemia Requiring CRRT for MSOF and ARDS CV with 40/10 cm. H 20 and Fi. O 2 = 1. 0 APRV 34/0 and O 2 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 l l l 1 y. o. leukemia post bone marrow transplant with sepsis and neutropenia and graft vs host disease and tracheotomy Difficult to ventilate with Pa. CO 2 of 64 mm. Hg and tachypnea and distress APRV 30/0 cm. H 20 and was rapidly weaned with noted increase in comfort Weaned to Fi. O 2 to. 45 and Pa. CO 2 = 39 mm. Hg Later exacerbation of leukemia resulted in renal failure
Hints for set-up l l l P high = same as plateau or 125% of mean Paw PEEP = 0 cm. H 2 O 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 l l 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 l l Decrease Fi. O 2 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?
- Airway pressure release ventilation
- Positive pressure ventilation vs mechanical ventilation
- Epiglottic
- Indications for artificial airway
- Immediate release dosage form
- Ocusert definition
- Extended release vs sustained release
- Pressure support ventilation
- Peep in ventilator
- Indication for mechanical ventilation
- Drop and stretch aprv
- Mean airway pressure
- Mean airway pressure
- Mean airway pressure formula
- Ahi cpap
- Pressure and release model
- Pressure and release model
- Aprv
- Aprv modu
- Kompliyans
- Prvc mode in ventilator
- Tactical ventilation
- Ventilator pressure support
- Pressure support ventilation
- Psv mode in ventilator
- Pressure support ventilation