1. PRVC Mode Workshop

2. Objectives • Understand the dual control concept • Understand the pressure regulation mechanism in PRVC • Demonstration of PRVC • Settings and adjustment with Servo i and Dragger • Indications, advantages and disadvantages

3. Volume vs Pressure Control Dual Control Concept

4. Volume Control Higher Pressure Decreased Compliance Maintained VT

5. Pressure Control Same Pressure Decreased Compliance Lower VT

6. Dual Control

7. PRVC Automatically Adjusts To Compliance Changes Pressure control Ventilation PRVC

8. Pressure Regulation The Concept

9. PRVC • Assist-control ventilation • Pressure control titrated to a set tidal volume • Time cycled

10. Assist control • Breaths: • Ventilator initiated (control breaths) • Patient initiated (assist breaths) • Set minimum frequency • Characteristics of each inspiration are the same • Not affected by whether breath is control breath or an assist breath

11. Assist control • Set • Minimum respiratory rate • Patient’s spontaneous respiratory rate < set rate  ventilator gives additional control breaths to make up difference • Patient’s spontaneous rate > set rate  no control breaths

12. PRVC • Set • Minimum respiratory rate • Target tidal volume

13. PRVC Test breath Measure VT Compare to set VT More Less Equal  inspiratorypressure Same inspiratorypressure  inspiratorypressure

14. PRVC • Set • Minimum respiratory rate • Target tidal volume • Upper pressure limit: • Maximum delivered pressure = 5 cm H2O below pressure alarm limit • FIO2 • Inspiratory time or I:E ratio • Rise time • PEEP

15. Dual Control Breath-to-BreathPressure Regulated Volume Control Pressure-limited Time-cycled Ventilation

16. PRVC (Pressure Regulated Volume Control) Upper Pressure Limit Pressure 5 cm H2O Time 5 4 6 3 2 1 Floe Time PRVC. (1), Test breath (5 cm H2O); (2) pressure is increased to deliver set volume; (3), maximum available pressure; (4), breath delivered at preset E, at preset f, and during preset TI; (5), when VT corresponds to set value, pressure remains constant; (6), if preset volume increases, pressure decreases; the ventilator continually monitors and adapts to the patient’s needs

17. yes Volume from Ventilator= Set tidal volume no Calculate compliance Calculate new Pressure limit Time= set Inspiratory time yes Trigger Pressure limit Based on VT/C Cycle off no Control logic for pressure-regulated volume control and autoflow

18. PRVC The Mode on Different Ventilators

19. PRVC in Servo i Pressure Flow Volume

20. PRVC Upper Pressure limit 5 cm H2O Pressure Flow Volume

21. Pressure Regulation in Drager

22. Pressure Regulation in CMV

23. Pressure Limit in Autoflow

24. PRVC Indications, Advantages and Disadvantages

25. Advantages • Decelerating inspiratory flow pattern • Pressure automatically adjusted for changes in compliance and resistance within a set range • Tidal volume guaranteed • Limits volutrauma • Prevents hypoventilation

26. Disadvantages • Pressure delivered is dependent on tidal volume achieved on last breath • Intermittent patient effort  variable tidal volumes • Less suitable for patients with asthma or COPD

27. PRVC (Pressure Regulated Volume Control) Disadvantages and Risks Afvantages Maintains a minimum PIP Guaranteed VT Patient has very little WOB requirement Allows patient control of respiratory rate Decelerating flow waveform for improved gas distribution Breath by breath analysis • Varying mean airway pressure • May cause or worsen auto-PEEP • When patient demand is increased, pressure level may diminish when support is needed • May be tolerated poorly in awake non-sedated patients • A sudden increase in respiratory rate and demand may result in a decrease in ventilator support

28. Thank You