This document discusses newer modes of mechanical ventilation. It explains that ventilator modes simulate either pressure control or volume control through microprocessor control of solenoids and adjustments of pressure, flow, time and volume. The quality of control depends on how frequently measurements are made and adjustments implemented. During inhalation, different modes control and target either flow, pressure, time or volume, and make adjustments based on patients' breathing efforts. Exhalation control is discussed but details will be covered next year. The document aims to help understand how ventilator modes function and make adjustments.

1. Newer Modes of
Mechanical Ventilation
Timothy A. Morris, M.D.
Division of Pulmonary and Critical Care Medicine
Medical Director, Respiratory Care
University of California, San Diego

2. How to Assess Ventilator Modes
 Inhalation
» what is controlled during the breath
» what is targeted (how much is enough?)
» how does it adjust to changes

3. How to Assess Ventilator Modes
 Exhalation
» what is controlled
» when does it end
» how does it adjust

4. How to Assess Ventilator Modes
 Inhalation
» what is controlled
» what is targeted
» how does it adjust

5. Simple Pressure System
Pressure 20 cm H2O
Pressure
20 cm H2O

6. Time Constant
 time it takes to get 1/2 way to
equilibrium
 total resistance x total compliance

7. Increased Compliance
Pressure 20 cm H2O
Pressure
20 cm H2O

8. Increased Resistance
Pressure 20 cm H2O
Obstruction
Pressure
20 cm H2O

9. Simple Volume System
Volume 500 ml
Pressure 3500 cm H20
Volume 500 ml

10. Simple Volume System
Volume 2000 ml
Pressure 3500 cm H20
Pop!

11. Big Secret!
 Ventilator modes are simulations
» pressure control
» volume control
 Microprocessors control the simulation

12. Dadmobile

13. Minivan Tire

14. High Pressure Pump

15. Filling the Tire

16. Tire Pressure

17. Toy Balloon: deflated

18. Toy Balloon: inflated

19. Toy Balloon: popped

20. Flow Control

21. Control of Resistor

22. High Pressure System
Pressure 3500 cm H20
Pressure 35 cm H20
Tidal volume 500 ml

23. Volume Control
Deflated Volume Inflated Volume

24. Pressure Control
Deflated Pressure Inflated Pressure

25. What controls the adjustments?
Volume?
(flow control)
Pressure?

26. Microprocessor Control
solenoid
Pressure 3500 cm H20
Microprocessor
Tidal volume 500 ml
Pressure 35 cm H20

27. Quality of the control
 hardware:
» how frequently is the flow/pressure
measured
» how rapidly are adjustments made
» how are adjustments made
 software
» timing and patterns of control

28. How to Assess Ventilator Modes
 Inhalation
» what is controlled
» what is targeted
» how does it adjust

29. Targeting
 How much breath is enough?

30. Targeting
Control
 Flow
 Pressure
Target
 Time
 Pressure
 Volume
Volume
control

31. Targeting
Control
 Flow
 Pressure
Target
 Time
 Pressure
 Volume
Time-cycled
pressure
control

32. Targeting
Control
 Flow
 Pressure
Target
 Time
 Pressure
 Volume
Volume
targeted
pressure
control

33. How to Assess Ventilator Modes
 Inhalation
» what is controlled
» what is targeted
» how does it adjust

34. Patients generate pressures
 Negative pressure
» inhalation efforts
 Positive pressure
» “bucking”

35. Negative pressure: Adjustments
 No adjustment
 Increase in pressure/flow to match
demand
 Decrease in pressure/flow to foster
weaning

36. Positive pressure: Adjustments
 No adjustment
 End inhalation, open exhalatory
valve
 Adjust inspiratory and expiratory
valves to maintain control

37. How to Assess Ventilator Modes
 Exhalation
» next year

38. Coming up next...
Reality