1. CPAP/PSV

2. Objectives Understand the difference between CPAP, PEEP and PSV
Know the breath types with PSV: supported breaths
Know the phase variables of the PSV: trigger, limit and cycle
Understand the ETS cycling mechanisms: flow and time
Setting the Level of Pressure Support
Adjustment of pressure support
Using PSV with different modes: SIMV
Using PSV for weaning
Advantages and disadvantages of PSV

3. CPAP

4. Continuous Positive Airway Pressure: CPAP
Ventilators can provide CPAP for spontaneously breathing patients
Helpful for improving oxygenation in patients with refractory hypoxemia and a low FRC
CPAP setting is adjusted to provide the best oxygenation with the lowest positive pressure and the lowest FiO2

5. Spontaneous Breath

6. Spontaneous Breathing
Pressure
(cm H2O)
Flow
(L/m)
Volume
(mL)
Time (sec)

7. Continuous Positive Airway Pressure (CPAP)
(cm H2O)
CPAP Level
Flow
(L/m)
Volume
(mL)
Time (sec)

8. CPAP

9. CPAP

10. CPAP

11. CPAP

12. PEEP

13. PEEP: Positive End Expiratory Pressure
The term PEEP is defined as positive pressure at the end of exhalation during either spontaneous breathing or mechanical ventilation. However, use of the term commonly implies that the patient is also receiving mandatory breaths from a ventilator.
PEEP becomes the baseline variable during mechanical ventilation

14. PEEP
Helps prevent early airway closure and alveolar collapse and the end of expiration by increasing (and normalizing) the functional residual capacity (FRC) of the lungs
Facilitates better oxygenation
NOTE: PEEP is intended to improve oxygenation, not to provide ventilation, which is the movement of air into the lungs followed by exhalation

15. Pressure Support Ventilation
Phase Variables, Breath Type and Sequence

16. Pressure Support Ventilation: PSV
Patient triggered, pressure targeted, flow cycled mode of ventilation
Requires a patient with a consistent spontaneous respiratory pattern
The ventilator provides a constant pressure during inspiration once it senses that the patient has made an inspiratory effort

17. Patient Trigger

18. Pressure Limit

19. Flow Cycled

20. Flow Cycling During PSV
Flow cycling occurs when the ventilator detects a decreasing flow, which represents the end of inspiration
This point is a percentage of peak flow measured during inspiration
PB 7200 – 5 L/min
Bear 1000 – 25% of peak flow
Servo 300 – 5% of peak flow
No single flow-cycle percent is right for all patients

21. Flow Cycling During PSV
Effect of changes in termination flow
A: Low percentage (17%)
B: High percentage (57%)
Newer ventilators have an adjustable flow cycle criterion, which can range from 1% - 80%, depending on the ventilator

22. PSV: Time Cycling
NOTE: During pressure support ventilation (PSV), inspiration ends if the inspiratory time (TI) exceeds a certain value. This most often occurs with a leak in the circuit. For example, a deflated cuff causes a large leak. The flow through the circuit might never drop to the flow cycle criterion required by the ventilator. Therefore, inspiratory flow, if not stopped would continue indefinitely. For this reason, all ventilators that provide pressure support also have a maximum inspiratory time.

23. Supported Breaths

24. Pressure Support Ventilation
The Mode

25. Triggered Modes of Ventilation Pressure Support Ventilation
Control
Trigger
Limit
Target
Cycle
Pressure
Patient
Flow
Patient Triggered, Pressure Limited, Flow Cycled Ventilation

26. PSV

27. PSV

28. Pressure Support Ventilation (PSV)
Longer Inspiration
Set PS
Level
Pressure
(cm H2O)
Better Efforts
Flow
Cycling
Flow
(L/m)
Volume
(mL)
Time (sec)
Patient Triggered, Flow Cycled, Pressure limited Mode

29. CPAP+PSV Pressure (cm H2O) Flow (L/m) Volume (mL) Time (sec)
Set PS
Level
Pressure
(cm H2O)
CPAP Level
Flow
Cycling
Flow
(L/m)
Volume
(mL)
Time (sec)
Patient Triggered, Flow Cycled, Pressure limited Mode

30. Pressure Support Ventilation
Settings and Adjustment

31. Setting the Level of Pressure Support
Goal: To provide ventilatory support
Spontaneous tidal volume is 10 – 12 mL/Kg of ideal body weight
Maintain spontaneous respiratory rate <25/min
Goal: To overcome system resistance (ET Tube, circuit, etc.) in the spontaneous or IMV/SIMV mode
Set pressure at (PIP – Pplateau) achieved in a volume breath or at 5 – 10 cm H2O

32. Setting the Level of Pressure Support
Exercise: Using the PIP and the PPlateau from the pressure waveform below, recommend a pressure support setting for this patient (patient is in VC-SIMV mode) 35 25
Answer: 10 cm H2O

33. The Results of Your Work
35 cm H2O
10 cm H2O

34. PS=6, VT= 350

35. PS=10, VT= 600

36. Pressure Support Ventilation
Indications, Advantages and Disadvantages

37. Pressure Support Ventilation: Indications
Spontaneously breathing patients who require additional ventilatory support to help overcome
WOB, CL, Raw
Respiratory muscle weakness
Weaning (either by itself or in combination with SIMV)

38. Pressure Support Ventilation: Advantages
Full to partial ventilatory support
Augments the patients spontaneous VT
Decreases the patient’s spontaneous respiratory rate
Decreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valves
Allows patient control of TI, I, f and VT

39. Pressure Or Volume-Targeted Ventilation
Advantages
Disadvantages
Full to partial ventilatory support
Augments the patients spontaneous VT
Decreases the patient’s spontaneous respiratory rate
Decreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valves
Allows patient control of TI, Vm , f and VT
Set peak pressure
Prevents respiratory muscle atrophy
Facilitates weaning
Improves patient comfort and reduces need for sedation
May be applied in any mode that allows spontaneous breathing, e.g., VC-SIMV, PC-SIMV
Requires consistent spontaneous ventilation
Patients in stand-alone mode should have back-up ventilation
VT variable and dependant on lung characteristics and synchrony
Low exhaled VE
Fatigue and tachypnea if PS level is set too low

40. PS with Other Modes
SIMV

41. VC-SIMV: +Efforts

42. VC-SIMV/PSupp

43. PCV+ PSupp

44. Thank You