1. Ventilation Modes and Current Trends
Denny Gish, BSRT, RRT
Clinical Specialist, Adult Respiratory Care
Legacy Emanuel Hospital and Health Center

2. Objectives Review current ventilator modes
Mode descriptions
Review trends in Respiratory Care
ARDS Network recommendations
Best PEEP
Recruitment Maneuvers
Identify various methods of High Frequency Ventilation

4. Modes of Ventilation
The Critical Question...
How do you choose ?

6. What Starts the Breath ? Controlled or timed breaths
Controller is really an interval timer
Assisted breaths are triggered by patient inspiratory effort in addition to Controlled breaths
Spontaneous breaths allowed in some modes

7. What Ends the Breath ? Preset pressure reached
Preset volume is delivered
Preset time has elapsed

8. All ordered by MD or by unit protocol
Ventilator Settings
Mode: Volume control, Pressure control, Spontaneous, etc (how the breath goes in)
Vt:Tidal Volume (size of breath 8-10 cc/kg, 4-6cc/kg for ARDS)
“Volutrauma” can be as damaging as “Barotrauma”
f : Frequency (rate # breaths per minute bpm)
PEEP: Positive End Expiratory Pressure (>/= 5 cmH20)
IP: Inspiratory Pressure (ideally < 30 cmH20)
FIO2: Fraction of Inspired Oxygen
All ordered by MD or by unit protocol
Ti or V: Inspiratory time or Flowrate (how long it takes the breath to go in - generally per RT discretion based on pt comfort & condition)

9. Ventilator Measurements
Vt = tidal volume - cc’s or ml’s
f = frequency, # breaths per minute - bpm
Ve = minute ventilation ( Vt * f) liters per minute
I:E Ratio= insp time to exp time (norm is 1:2)
PIP (or PAP) = Peak Inspiratory Pressure – cmH20
MAP = Mean Airway Pressure – cmH20
PEEP = Positive End Expiratory Pressure – cmH20
Pplat = Plateau or Static Pressure (true lung inflation pressure (eliminates airway & tubing resistance) – cmH20
Cstatic = Static Compliance (normal ml/cmH2O)
Learn to read measurements off vent screen

10. Some Basic Modes Volume Control: set Vt & f, pt may assist
Pressure Control: set IP & f, pt may assist
Synchronized Intermittent Mandatory Ventilation: set Vt & f, pt may take unassisted spontaneous breaths as well
Mandatory Minute Volume Ventilation – MMV: mandatory breaths are only provided if spontaneous breathing is not sufficient and below the prescribed minimum ventilation.
Pressure Support: pt’s own Vt & f, supported by insp boost to augment pt’s insp efforts. Pt may breathe deep or shallow, fast or slow w/o intervention from vent.

11. Name that Mode of Ventilation
Evita XL – Ventilation Modes
• CMV– Continuous Mandatory Ventilation
*AKA- Assist/Control
• MMV– Mandatory Minute Ventilation
*AKA-Smart SIMV
• PCV–Pressure Controlled Ventilation
*used when PIP is >35
• APRV– Airway Pressure Release Ventilation
*Low compliance disorders
• CPAP-Continuous Positive Airway Pressure – with or without PS

12. Draeger V 500 Ventilation mode
VC-CMV - Draeger XL has CMV, but it is NOT the same!
VC-AC–Works like CMV on the Draeger XL
VC-MMV-Draeger XL has MMV and it performs exactly like the VC-MMV on the V500
PC-AC – Draeger XL has PCV
PC-APRV with AutoRelease - Draeger XL does not have an autorelease function
SPN-CPAP/PS/VS-Draeger XL has CPAP mode that has Pressure Support capabilities, but no Volume Support

13. Now…Puritan Bennet 840

14. Viasys Avea

15. Servo I buy

16. More Advanced Modes
Volume Support: pt’s own f w/PS for goal Vt. Vent guarantees Vt by adjusting the PS based on lung compliance and/or resistance to ensure a preset tidal volume.
Pressure Regulated Volume Support: set f and goal Vt, pt may assist. Ventilator automatically adjusts pressure up or down, from breath to breath, as patient's airway resistance and lung compliance changes, in order to deliver the goal tidal volume.
Volume Control Plus: same as PRVC
Airway Pressure Release Ventilation: High and low pressures set w/minimal timed releases to facilitate gas exchange, high MAP w/very Inverse I:E ratio. Pt may breathe spontaneously during high pressure holds.

17. ARDS Current Definition
The 1994 North American-European Consensus Conference (NAECC) Criteria:
Onset - Acute and persistent
Radiographic - Bilateral pulmonary infiltrates
Oxygenation - regardless of the PEEP, with a Pao2/Fio2 ratio  300 for ALI and  200 for ARDS
Exclusion criteria - Clinical evidence of Left Atrial Hypertension or a PAOP of  18 mm Hg.
Bernard GR et al., Am J Respir Crit Care Med 1994

18. Tidal Volume Strategies in ARDS
Traditional Approach
High priority to traditional goals of acid-base balance and patient comfort
Lower priority to lung protection
Low Stretch Approach
High priority to lung
protection
Lower priority to traditional goals of acid-base balance
and comfort

19. Physiologic Benefits vs Patient- Important Outcomes
PaO2 improvement vs Survival Benefit
For ARDS, inhaled nitric oxide improves PaO2, but not mortality
(Taylor et al, JAMA 2004;291:1603)
High tidal volumes in patients with ARDS improves
PaO2, but mortality is lower for small tidal volumes
(ARDSnet, N Engl J Med 2000; 342:1301)
For ARDS, prone position improves PaO2, but not
mortality
(Gattinoni, N Engl J Med 2001;345:568)

20. ARDS Network Low VT Trial
Patients with ALI/ARDS of < 36 hours
Ventilator procedures
Volume-assist-control mode
6 vs. 12 ml/kg of predicted body weight Vt
(PBW/Measured body weight = 0.83)
Plateau pressure  30 vs.  50 cmH2O
Ventilator rate 6-35 to achieve a pH goal
of 7.3 to 7.45
Oxygenation goal: PaO mmHg,
SpO % )
ARDS Network. N Engl J Med

21. a highly controversial issue!
Lung Recruitment
First and foremost performed to provide an arterial oxygen saturation of 90% or greater at an FiO2 of less than 60%
Recruitment of nonaerated lung units (open-lung concept) but risk of regional lung overinflation :
a highly controversial issue!

22. Recruitment Maneuvers (RMs)
Effective in improving arterial oxygenation at low PEEP and small tidal volumes.
Recruitment maneuvers may be poorly effective or deleterious, inducing overinflation of the most compliant regions, hemodynamic instability, and an increase in pulmonary shunt resulting from the redistribution of pulmonary blood flow toward nonaerated lung regions.
The effect of recruitment may not be sustained unless adequate PEEP is applied to prevent derecruitment.
Many questions still need to be answered

23. PEEP in ARDS: How much is enough ?
PEEP, by avoiding repetitive opening and collapse of atelectatic lung units, could be protective against VILI
PEEP, has been shown to prevent surfactant loss in the airways and avoid surface film collapse.
The lung is kept open by using PEEP to avoid end- expiratory collapse.
High PEEP should make the mechanical ventilation less dangerous than low PEEP.
Levy MM. N Engl J Med
Rouby JJ, et al. Am J Respir Crit Care Med
Gattinoni L, et al. Curr Opin Crit Care

24. Optimizing PEEP Optimizing PEEP.
PEEP level is at low lung volume and below critical opening pressure.
PEEP increased to optimize compliance.

25. larson

26. ARDS Network Low VT Trial
Allowable combination of FiO2 and PEEP:
FiO
PEEP

27. APRV Mode First described 1987
Baseline airway pressure is the upper CPAP level, and the pressure is intermittently “released” to a lower level, thus eliminating waste gas
Time spent at low pressure (short expiratory time): prevents complete exhalation; maintains alveolar distension

28. APRV Evidence
Prospective, randomized intervention study (N=45); PC/PS vs. APRV; patients with ALI
Oxygenation was significantly better in APRV group
Sedation use and hemodynamics were similar
Puntsen, Am J Respir Crit Care Med,2001

29. APRV settings
Flow
Paw
Thigh
Tlow
Phigh
Plow
insp
exp

30. “If this...
why not this?”
- John B. Downs, MD

31. High Frequency Ventilation HFOV Oscillatory HFJV JET HFPV Percussive

32. High Frequency Percussive Ventilation HFPV
-High Frequency Percussive Ventilation (HFPV) is a hybrid form of high frequency ventilation.
-This concept of pneumatic diffusive / convective protocols is not related to high frequency vibration, jet insufflation or electronically controlled crank or magnetically servoed dynamic oscillators.

33. Rationale for HFV-Based Lung Protective Strategies
HFV uses very small tidal volumes
Avoids excessive end-inspiratory lung volumes
Allows for higher end-expiratory lung volumes to achieve better recruitment
HFV uses much higher respiratory rates
Allows for maintenance of normal PaCO2 even with very small tidal volumes

34. High-frequency Ventilation
HFOV may improve oxygenation when used as a rescue modality in adult patients with severe ARDS failing CV.
HFOV may be considered for patients with severe ARDS:
FiO2 > 0.60 and/or SpO2 < 88% on CV with PEEP > 15 cm H2O, or
Plateau pressures (Pplat) > 30 cmH2O, or
Mean airway pressure  24 cm H2O, or
Airway pressure release ventilation Phigh  35 cm H2O
HFOV for adults with ARDS is still in its infancy and requires further evaluations.
Higgins J et al., Crit Care Med 2005

35. High Frequency Percussive Ventilation HFPV
-High Frequency Percussive Ventilation (HFPV) is a hybrid form of high frequency ventilation.
It is a combination of convective style ventilation and percussive high frequency linked together.

36. Inverse Ratio Ventilation
Technique used prior to latest generation of vents
Used in refractory hypoxemia
Another way to increase FRC
Expiratory time is longer than inspiratory time.
Heavy sedation/paralytics required
Fluids, pressors usually needed as well due to decrease in venous return to thorax
Sometimes occurs inadvertently by erroneous vent changes or pt agitation & high RR. Must be corrected!

37. Other Advanced Interventions
Require separate or additional machines
Inhaled Nitric Oxide selective pulmonary artery vasodilator. Used for pulm htn, lg saddle PE’s, to reduce intrapulmonary shunting & improve V/Q matching. Prohibitively expensive, may cause methemoglobin buildup
High Frequency Ventilation high frequency (>200 breathes per min)
HFOV, HFJV, HFPV
Extracorporeal Membrane Oxygenation (ECMO) similar to bypass pump used in cardiac surgery

38. Adjuncts Recruitment Maneuver
PEEP - does not recruit alveoli, but can help maintain alveolar stability
Prone positioning – has not changed morbidity or mortality outcomes in ARDS, but has been shown to help improve oxygenation

39. A man suffered from insomnia and dyslexia. He was also an agnostic
A man suffered from insomnia and dyslexia. He was also an agnostic. What did he do?
He stayed up all night wondering if there was a DOG.