The document discusses the essential aspects of mechanical ventilation, emphasizing safety, efficacy, and patient comfort. It outlines various mechanical ventilation modes, including pressure-cycled ventilation (PCV) and volume-cycled ventilation (VCV), along with their specific variables and characteristics. The importance of clinician skills in utilizing these ventilation strategies effectively is highlighted, along with a cautionary note that new ventilator modes must be assessed critically against traditional lung-protective strategies.

1. Modes of Mechanical Ventilation: The Essentials
Lluis Blanch MD, PhD
Senior Critical Care Department
Director Research and Innovation
Corporació Sanitaria Parc Tauli. Sabadell. Spain.
Universitat Autònoma de Barcelona. Spain.
22-23 January 2014 Cairo, Egypt

2. Objectives MV
• Safety
• Efficacy
– Oxygenation
– Ventilation
– Work of Breathing
• Comfort / Synchrony
– Surveillance of Flow & Pressure

3. Modes of Mechanical Ventilation:
Relationship between possible breath types and
inspiratory-phase variables
Phase variables that define inspiration:
trigger variable
limit variable: pressure, flow or volume
cycle variable that ends inspiration
Gas delivery:
pressure, volume, flow, time or dual control
Breath type:
mandatory or spontaneous

4. PCV & VCV Waveforms
PCV
Rectangular
Pressure
Waveform
VCV
VCV
VCV
Rectangular
Flow
Waveform
Ascending
Ramp Flow
Waveform
Descending
Ramp Flow
Waveform
VCV
Sinusoidal
Flow
Waveform

5. Pressure vs Volume Control
• Volume Control
• Pressure Control
- Set VT
- Set Pressure
- Set Flow waveform - Set Inspiratory Time
- Set Flow rate
- Variable VT
- Set Inspiratory Time - Variable Flow waveform
- Variable pressure
- Variable Flow rate
- Linear Rate/VE
- Non-linear Rate/VE

6. Daily Use of Modes of Mechanical Ventilation
1998
VCV
PCV
PSV
Esteban A et al. JAMA 2002;287:345-55

7. Daily Use of Modes of Mechanical Ventilation
2010
VCV
PSV
PCV
Esteban A et al. Am J Respir Crit Care MedJ 2013;188:220-30

8. VCV. Effects of an End-Inspiratory Occlusion
Time

9. Assist/Controlled Ventilation
Hess DR, Kacmarek RM. Essentials of Mechanical Ventilation. 2on Ed. McGraw Hill. 2002.

10. Variations in Crs in VCV (square flow)
High Crs
Intermediate Crs
Low Crs
Corretger E, Murias G,… Blanch L. Med Intensiva ((2011 Oct 17)

11. Variations in Rrs in VCV (square flow)
Low Rrs
Intermediate Rrs
High Rrs
Corretger E, Murias G,… Blanch L. Med Intensiva (2011)

12. AutoPEEP Generation: Lengthen Ti at equal Ttot
(Airflow decreased for a similar VT)
1.0
0.5
Airflow
(L/s)
AutoPEEP
0.0
-0.5
-1.0
0
1
2
3
4
Time (s)
Blanch L, Bernabe F, Lucangelo U. Respir Care 2005;50:110-123

13. Progressive increase of inspiratory pause during VCV
Lucangelo U, Bernabè F, and Blanch L. Resp Care 2005; 50 : 55-65

14. VCV with progressive increase of inspiratory
time, but with constant pause
Lucangelo U, Bernabè F, Blanch L. Resp Care 2005; 50 : 55-65

15. Patient WOB during Triggered Ventilation
Marini JJ et al. Am Rev Respir Dis 1988; 138:1169-79

16. VCV Increased Work of Breathing

17. Georgopoulos D et al Intensive Care Med 2006;32:34-47 (on line suppl)

18. Pressure Controlled Ventilation
Time

19. Variations in Crs in PCV
High Crs
Intermediate Crs
Low Crs
Corretger E, Murias G,… Blanch L. Med Intensiva (2011 Oct 17)

20. Variations in Rrs in PCV
Low Rrs
Intermediate Rrs
High Rrs
Corretger E, Murias G,… Blanch L. Med Intensiva ((2011 Oct 17)

21. PCV: Effect of AutoPEEP
Marini JJ & Amato MB. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

22. PCV: Effect of ↑Resistance
High Raw = Low VT
Marini JJ & Amato MB. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

23. PCV: Effect of ↓Compliance
Low Crs = Low VT
Marini JJ & Amato MB. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

24. Effect of Inspiratory Flow on Work of Breathing
Cinnella G. Am J Resp Crit Care 1996; 153:1025-33

25. Suggestion for settings
ACV
- VT about 6 - 8 mL/kg (AVOID Pplat > 28 and large VT)
- Inspiratory flow 60 L/min
- Ti /Ttot
PCV
- Inspiratory pressure (for a VT of 6-8 ml/kg) (AVOID Ppaw > 30)
- Ti / Ttot
Common for ACV & PCV
- FiO2 for Sat ≥ 90% and < 97%. Avoid FiO2 1 if possible.
- PEEP 5-10 cmH2O
- Back up Rate 12 - 15 x’
Then, titrate according to individual patient’s clinical condition (gas
exchange, mechanics, patient/ventilator interactions)

26. flow cycle
pressure limit
Spontaneous breath type
• patient triggered (no set rate)
• pressure limited
• usually flow cycled
patient trigger
Volume (mL)
Pressure (cm H2O)
Flow (L/min)
Pressure Support Ventilation
Hess D.
Respir Care 2005; 50:166-186
time

27. Pressure Support Ventilation
Hess DR, Kacmarek RM. Essentials of Mechanical Ventilation. 2on Ed. McGraw Hill. 2002.

28. PSV: Expiratory Trigger Setting

29. PS 20 cm H2O
Rise time (τ) 0.01 s
Neural inspiratory time 1.0 s
120
Peak flow 100 L/min
flow (L/min)
100
80
60
Flow termination
25% peak flow
40
20
R 10 cm H2O/L/s, C 0.02 L/cm H2O
0
0
0.2
0.4
0.6
0.8
1
time (s)
Peak flow 60 L/min
flow (L/min)
60
40
R 20 cm H2O/L/s, C 0.05 L/cm H2O
20
0
0
0.2
0.4
0.6
0.8
1
time (s)
Hess D. Respir Care 2005; 50:166-186

30. PSV: Autotriggering
Flow
(L/s)
Can occur when:
- too sensitive inspiratory
trigger
Paw
(cmH2O)
- end-expiratory leaks
Pes
(cmH2O)
Time (s)
Brochard L. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

31. PSV: Ineffective Efforts
Flow
(L/s)
Can occur when:
- too much PSV
Paw
- presence of autoPEEP
(cmH2O)
Pes
(cmH2O)
Time (s)
Brochard L. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

32. Adaptative Pressure Control Modes:
It is a pressure-controlled breath that utilized closed-loop control
of the pressure to maintain a minimum delivered tidal volume
Commercial Names for Adaptative Pressure Control Modes:
Branson RD & Chatburn RL. Respir Care 2007;52:478-488

33. Implementation of AutoFlow on the Drager Evita 4 Ventilator
Paw
(cmH2O)
Flow
(L/s)
VT
(mL)
PCV Breaths
VCV Breath
Adaptative PCV until
target VT is reached
Crs Increases and VT exceeds
the target, Paw is reduced until
VT reaches the target

34. Airway pressure delivered during the inspiratory phase in
relation to patient effort in different modes of ventilation

35. VCV
Normal
respiratory
effort
PSV
PCV
ASV PAV NAVA
SmartCare IntelVent
Paw
Ppl
Paw
Increase
respiratory
effort
Ppl
Murias G, Villagrá A, Blanch L. Minerva Anestesiol 2013;79:434-44

36. Adaptive Support Ventilation:
Negative Feedback Control
Target minute ventilation: 100 ml/min/kg (IBW)
% Min Volume: 20 – 200%
Rate based on Otis minimal work equation (1950)
All combinations of rate/VT calculated
Te = 3 RC (I:E ratio)
PRVC or VS depending upon whether or not the
patient is actively breathing
Available on Hamilton ventilator

37. Working principles of
Adaptive Support Ventilation
(ASV) to maintain the target
minute ventilation.

38. Arnal JM et al ICM 2012

39. Pressure Support Ventilation
Paw
Airflow
EADi

40. Level of pressure delivered with PSV & PACV and with NAVA &
PAV two cycles with different inspiratory efforts.

41. PAV: The bases

42. PAV % Patient Effort

43. Crit Care Med 2007;35:1048

44. Neuro Ventilatory Coupling
Ideal Technology
Central Nervous System
Phrenic Nerve
Diaphragm Excitation
New
Technology
Ventilator
Unit
Diaphragm Contraction
Chest Wall & Lung Expansion
Airway Pressure, Flow & Volume
Current Technology

45. NAVA (Neural Adjusted Ventilation Adaptation)

46. Neuro-muscular coupling
Health
µV
Disease
µV
µV
Edi
ml
VT
ml
ml

47. Neurally Adjusted Ventilatory Assistance
(NAVA): Positive Feedback Control
Sinderby, Nature Medicine 1999;5:1433

48. Running in NAVA mode

50. The Evidence for New Ventilator
Modes …
It’s not the ventilator mode that makes a difference …
… It’s the skills of the clinician that makes the difference.
Any ventilator mode has the potential to do harm!
High level evidence is lacking that any new ventilator
mode improves patient outcomes compared to existing
lung-protective ventilation strategies.
Dean Hess 2010