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1. CONVENTIONAL & ADVANCED MODES OF
MECHANICAL VENTILATION:
Niall D. Ferguson, MD, FRCPC, MSc
Head of Critical Care Medicine
University Health Network & Sinai Health System
Professor, Departments of Medicine & Physiology,
Institute of Health Policy, Management and Evaluation
Interdepartmental Division of Critical Care Medicine
University of Toronto

2. Disclosure
Dr. Niall Ferguson
• Advisory Board – Xenios
• Advisory Board - Baxter
2

3. Outline
How basic modes work
How to set PEEP
How proportional modes work
Cases

4. Question 1
4
Which of the following statements is TRUE about pressure
support ventilation?
a. It is the most commonly used mode of ventilation
b. It is ok to paralyze patients on pressure support
c. It is volume limited for a given pressure
d. Flow cycle threshold can be adjusted

5. Question 1
5
Which of the following statements is TRUE about pressure
support ventilation?
a. It is the most commonly used mode of ventilation
b. It is ok to paralyze patients on pressure support
c. It is volume limited for a given pressure
d. Flow cycle threshold can be adjusted

6. 6

7. Ventilator modes have 3 key elements

8. 8
Ventilator modes have 3 key elements

9. 9
Ventilator modes have 3 key elements

10. 10
Ventilator modes have 3 key elements

11. Which is better – Volume or Pressure Control?

12. 12
Ventilator modes have 3 key elements

13. Ventilator modes have 3 key elements

14. Ventilator modes have 3 key elements

15. Question 2
15
All of the following are true about PEEP except:
a.Average set PEEP levels have risen modestly
over time
b.PEEP levels should be individualized
c.PEEP 5-10 cm H2O is most common in ARDS
d.Higher PEEP does not improve mortality in ARDS

16. Question 2
16
All of the following are true about PEEP except:
a.Average set PEEP levels have risen modestly
over time
b.PEEP levels should be individualized
c.PEEP 5-10 cm H2O is most common in ARDS
d.Higher PEEP does not improve mortality in ARDS

18. Set PEEP (cm of H2O) in ARDS – Means & %age

19. Set PEEP 8.4 7.4 8.3 10.1

20. Setting PEEP
Defined range
• Low PEEP arm of ExPress (5-9 cm H2O)
Plateau pressure limit
• High PEEP arm of ExPress (28-30 cm H2O)
PEEP-FiO2 Table
• Higher vs. Lower – ARMA, LOVS, ALVEOLI
Pressure/Volume measurements
Transpulmonary pressure limit
Decremental PEEP titration

21. ARDS Network
High Stretch
• VT: 11.8
• PPLAT: 32-34
• RR: 18
• VMIN: 13
• PEEP: 8
Mortality 40%
Low Stretch
• VT: 6.2 ml/kg
• PPLAT: 25 cm H2O
• RR: 29
• VMIN: 13 L/min
• PEEP: 9 cm H2O
Mortality 31%* *p=0.005

23. ICU Mortality: RR 0.85 (0.76-0.94)
Hosp Mortality: RR 0.90 (0.81-1.0)

26. Only PEEP by O2 gave
higher PEEP with
increasing severity &
recruitability

27. ARMA & ALVEOLI Trials
Latent Class Modeling

28. Question 3
28
Which of the following is FALSE:
a. Without dyssynchrony, PSV dictates a minimum VT
b. Dyssynchrony is unlikely to be harmful
c. Patients can choose high rate and low VT with
proportional modes
d. Proportional modes can reduce dyssynchrony

29. Question 3
29
Which of the following is FALSE:
a. Without dyssynchrony, PSV dictates a minimum VT
b. Dyssynchrony is unlikely to be harmful
c. Patients can choose high rate and low VT with
proportional modes
d. Proportional modes can reduce dyssynchrony

30. 25% of patients showed significant asynchrony

31. PAV: adds flow and pressure to effort

34. Higher vs. Lower Assist Levels in PSV and PAV

35. Real-time measurements of
Elastance and Resistance have
brought PAV to usual practice

36. PAV – Clinical Application
Performs as designed - gives comfortable support
• Am Rev Resp Dis 1992;145:114
• Thorax 2002:57:79
• J Appl Physiol 1996;81:429
• Am J Resp Crit Care Med 1996;153:1005
No good outcomes trials to date
Reasonable to use in pts with flow or cycle dys-synchrony
• Will still have PEEPi issues
• Will require monitors/alarms for low, unstable drive

38. Pressure Support NAVA

41. 41

42. Increasing NAVA
gain leads to a
plateau in VT

44. What mode behaves like this?
A. VACV
B. PACV
C. PSV
D. SIMV
E. PRVC
67 yo man with
pancreatitis and ARDS is
on a ventilator
A mucus plug develops
and graphics change

45. What mode behaves like this?
A. VACV
B. PACV
C. PSV
D. SIMV
E. PRVC
67 yo man with
pancreatitis and ARDS is
on a ventilator
A mucus plug develops
and graphics change

46. PRVC (aka APV, Automode)
Pressure targeted, time cycled mode
Has volume “guarantee” and machine adjusts pressure
target to assure the desired volume
Advantage:
• MaintainsVT in setting of worsening mechanics, drive
• Reduces pressure as mechanics improve
Disadvantage:
• May inappropriately reduce pressure in setting of dyspnea/increase
drive
• Large variations in volumes with intermittent efforts
• Higher pressures may be delivered depending on limits set

47. Spot the Mode
A patient is receiving the
pictured mode of MV.
What is this mode:
A. PSV
B. PAV
C. VS
D. VACV
E. CPAP

48. Spot the Mode
A patient is receiving the
pictured mode of MV.
What is this mode:
A. PSV
B. PAV
C. VS
D. VACV
E. CPAP

49. A patient recovering from ARDS is
receiving pressure assist control
ventilation and is triggering virtually
all of the ventilator breaths. An upper
endoscopy is required to evaluate
new upper GI bleeding and a
neuromuscular blocker (NMB) is
administered to facilitate this. The
ventilator graphics abruptly change.
What is the best explanation for this?
Case:

50. What has happened?
A. Loss of spontaneous effort
B. Idiosynchratic reaction to NMB
causing edema
C. Bronchospasm
D. Mucus plugging
E.Tension pneumo

51. What has happened?
A. Loss of spontaneous effort
B. Idiosynchratic reaction to NMB
causing edema
C. Bronchospasm
D. Mucus plugging
E.Tension pneumo

52. University of Toronto Critical Care Medicine International Fellowship Programme
n.ferguson@utoronto.ca www.criticalcaretoronto.com

53. n.ferguson@utoronto.ca
@nialldferguson December 5-8, 2021
Sheraton Centre Hotel, Toronto