2.  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. Dual Control Concept

4. Decreased Compliance Maintained VT Higher Pressure

5. Decreased Compliance Lower VT Same Pressure

7. PRESSURE CONTROL VENTILATION PRVC

8. The Concept

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

10.  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.  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.  Set  Minimum respiratory rate  Target tidal volume

13. Measure V T Compare to set V T Same inspiratory pressure  inspiratory pressure  inspiratory pressure Test breath Less Equal More

14.  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. ControlTriggerLimitTargetCycle VolumePatient or Time PressureLowest pressure for set volume Time Pressure-limited Time-cycled Ventilation

16. PRVC. (1), Test breath (5 cm H 2 O); (2) pressure is increased to deliver set volume; (3), maximum available pressure; (4), breath delivered at preset E, at preset f, and during preset T I ; (5), when V T 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 1 2 3 4 5 6 Upper Pressure Limit 5 cm H 2 O Pressure Floe Time

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

18. The Mode on Different Ventilators

19. Pressure Flow Volume

20. Pressure Flow Volume Upper Pressure limit 5 cm H 2 O

24. Indications, Advantages and Disadvantages

25.  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.  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. DISADVANTAGES AND RISKS  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 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