1. Special Thanks to: Nancy Hemmert, MPH, RRT
Fundamentals of APRV (Airway Pressure Release Ventilation) or ‘CPAP with release’
Special Thanks to:
Nancy Hemmert, MPH, RRT

2. APRV - Brief History of Mechanical Ventilation
ca. 400 BC Hippocrates describes cannulation of the trachea
ca Fire bellows used to assist ventilation; Vesalius and Reed
1786 First volume limiting device used with bellows system
Negative Pressure ventilators are developed and refined
1886 First “cuffed” endotracheal tube
1906 Intermittent positive pressure ventilation device
1967 PEEP with mechanical ventilation is introduced
1971 CPAP introduced for the treatment of IRDS
1973 IMV used as technique to facilitate spontaneous breathing
early 1980s Pressure Support introduced to augment Vt in spontaneously breathing patients
1986 APRV conference on by Stock and Downs
1990 First ventilator with APRV is introduced

3. Importance of PEEP for Alveolar Recruitment
PEEP vs ZEEP for Alveolar Recruitment

4. APRV Classic Definition:
APRV is a pressure-limited spontaneous breathing mode (CPAP) with time-cycled pressure releases designed to enhance CO2 elimination and prevent alveolar collapse.
…PC-CSV

5. APRV - waveforms

6. APRV – Indications for use
RDS/ALI
REFRACTORY HYPOXEMIA
(R>L Intrapulmonary Shunt)
SEVERE ATELECTASIS (Threshold Opening Pressure [TOP] and time)
RESTORE FRC (increase alveolar surface area) O2 O2

7. PERFUSION WITHOUT VENTILATION
RIGHT TO LEFT SHUNT
PERFUSION WITHOUT VENTILATION
Resulting in refractory hypoxemia
PaO2 IS Decreased !
Responds only to PEEP
Increases in FIO2 With Shunt Fractions >50% of Cardiac Output have little Effect on augmenting PaO2

8. RDS/ALI
Disturbed oxygenation due to poor V/Q matching (refractory hypoxemia)
Severe atelectasis w/high TOPs (threshold opening pressures)
Chest x-ray - “white out”
Non-homogenous lung disease (MRI)
Reduced compliance with poor lung mechanics and high WOB
Increased PCWP (pulmonary hypertension)
With the "Breathing Support Package" Dräger offers a complete new
philosopy in breathing support technique.

9. NORMAL V/Q RELATIONSHIP. . .
NORMAL V/Q RELATIONSHIP
4LPM VA /5LPM QT = 0.8 .

10. Alveolar Dead Space - Over-distention Ventilation without Perfusion
Leads to increase Vd/Vt ratio
ultimately with HYPERCAPNIA (CO2)
WOB INCREASES WITH A DEADSPACE QUOTIENT OF ~70%.
SPONT. BREATHING IS NO LONGER POSSIBLE

11. PRESSURE / VOLUME CURVE
FLAT LOWER PORTION
OF CURVE V>Q
MIDDLE STEEP PORTION
OF CURVE V/Q normal
FLAT UPPER PORTION
OF CURVE V<Q

12. APRV P-V CT SCAN

13. APRV - Impact of spontaneous breathing

14. APRV – Impact of spontaneous breathing

15. APRV EIT image

16. APRV controls Dräger XL

17. APRV initial set-up Neonates Newly intubated
Phigh—set at desired plateau pressure (typically 10–25 cm H2O)
Plow—0 cm H2O
Thigh—2–3 secs
Tlow—0.2–0.4
Transition from conventional ventilation
Phigh—plateau pressure in volume-cycled mode or peak airway pressure in pressure-cycled mode
Transition from HFOVb
Phigh—mPaw on HFOV plus 0–2 cm H2O
Note: Phigh 25 cm H2O may be necessary in patients with decreased thoracic/abdominal compliance With a Phigh25 cm H2O, use of noncompliant ventilator circuit is recommended to minimize circuit volume compression

18. APRV initial set-up Pediatrics Newly intubated
Phigh—set at desired plateau pressure (typically 20–30 cm H2O)
Plow—0 cm H2O
Thigh—3–5 secs
Tlow—0.2–0.8
Transition from conventional ventilation
Phigh—plateau pressure in volume-cycled mode or peak airway pressure in pressure-cycled mode
Transition from HFOVb
Phigh—mPaw on HFOV plus 2–4 cm H2O
Note: Phigh 30 cm H2O may be necessary in patients with decreased thoracic/abdominal compliance or morbid obesity (73, 74). With a Phigh 25 cm H2O, use of noncompliant ventilator circuit is recommended to minimize circuit volume compression.

19. APRV initial set-up ADULTS Newly intubated
Phigh—set at desired plateau pressure (typically 20–35 cm H2O)
Plow—0 cm H2O
Thigh—3–5 secs
Tlow—0.2–0.8 (RLD) —1.5 (OLD)
Transition from conventional ventilation
Phigh—plateau pressure in volume-cycled mode or peak airway pressure in pressure-cycled mode
Thigh—4–6 secs
Transition from HFOVb*** use a non compliant ventilator circuit***
Phigh—mPaw on HFOV plus 2–4 cm H2O
Note: Phigh 30 cm H2O may be necessary in patients with decreased thoracic/abdominal compliance or morbid obesity (73, 74). With a Phigh 25 cm H2O, use of noncompliant ventilator circuit is recommended to minimize circuit volume compression.

20. APRV MANIPULATION
Pressure release cycles improve CO2 elimination. Increasing the number of cycles (reducedThigh) lowers PaCO2.
Pdelta changes will affect the volume exhaled. Plow = 0
Mean airway pressure (Phigh) and FiO2 control oxygenation.
Exhalation waveform is adjusted by Tlow to insure PEEPi, preventing alveolar collapse (50-75% PEFR). . .

21. APRV pre & post

22. What it would lild look like on other Vents:

23. APRV - Weaning Always decrease FiO2 to a non-toxic level.
Phigh  in increments of 2cmH20 to maintain SpO2. Sudden abrupt changes could cause DE- RECRUITMENT and the patient could “CRASH” !
“Drop and stretch”
Phigh gradually Thigh gradually

24. APRV - Weaning

25. APRV – short and simple Benefits of APRV and spontaneous breathing:
Better distribution of Tidal Volume without regional over-distention
Improves V/Q matching – TOP and time required for lung units to open
Increases venous return/cardiac output
CO2 removal is enhanced by allowing a pressure release
The extremely short phase of the pressure release (Tlow) prevents alveolar collapse and de-recruitment
Avoidance of cyclic de-recruitment avoids shear force tearing
FRC is increased and V/Q mismatch is improved resulting in better oxygenation

26. APRV – Literature citations
Downs JB, Stock MC: Airway pressure release ventilation: a new concept in ventilatory support. Crit Care Med 1987; 15:459–461
Habashi N : Other approaches to open-lung ventilation: Airway Pressure Release Ventilation. Crit Care Med 2005; vol. 33, No 3 (suppl.) s228-s240
Putensen C, Wrigge H: Clinical review: BiPhasic positive airway pressure and airway pressure release ventilation. Critical Care 2004, 8:
Shultz T, et al: Airway pressure release ventilation in pediatrics. Pediatric Critical Care 2001; vol. 2, No. 3, pp

27. Fighting the Machine or Synchrony?