Synchronized Intermittent Mandatory Ventilation: SIMV

1. Synchronized Intermittent Mandatory Ventilation: SIMV

2. Objectives • Understand the different breath types with SIMV • Know the Phase variables of the different breath types: trigger/limit/cycle • Know the breath sequence with SIMV • Controlled variables: PC-CMV vs VC-CMV • Understand the synchronization mechanism • Initial settings of SIMV • Adjustment of SIMV • Indications, advantages and disadvantages

3. Phase Variable SIMV

4. Patient or Time Triggered

5. Time Cycled

6. Breath Sequence and Mode SIMV

7. IMV and SIMV • Periodic volume or pressure targeted breaths occur at set interval (time triggering) • Between mandatory breaths, the patient breathes spontaneously at any desired baseline pressure without receiving a mandatory breath • Patient can breathe either from a continuous flow or gas or from a demand valve

8. SIMV/PS: Phase and Control Variables

9. SIMV+PS(Volume Targeted Ventilation) Set PS Level Tsupp Tsynch M Pressure (cm H2O) Flow-cycled Flow (L/m) Volume (mL) Time (sec)

10. SIMV(Volume Targeted Ventilation) Tsynch Tsynch Tsynch Pressure (cm H2O) Spontaneous Breaths Flow (L/m) Volume (mL) Time (sec)

11. SIMV + PS (Pressure-Targeted Ventilation) Tsynch Tsynch Tsupp Pressure (cm H2O) Set PC Level Set PS Level Time Cycled Flow-cycled Flow (L/m) Volume (mL) Time (sec)

12. VC-SIMV: +Efforts:

13. VC-SIMV/Psupp:

14. PC-SIMV: Spontaneous Efforts, 0 PSV

15. PC-SIMV+PSupp

16. SIMV: No Efforts

17. Synchronization SIMV

18. Synchronized IMV • Operates in the same way as IMV except that mandatory breaths are normally patient triggered rather than time triggered (operator set the volume or pressure target) • As in IMV, the patient can breathe spontaneously through the ventilator circuit between mandatory breaths

19. Synchronized IMV • At a predetermined interval (respiratory rate), which is set by the operator, the ventilator waits for the patient’s next inspiratory effort • When the ventilator senses the effort, the ventilator assists the patient by synchronously delivering a mandatory breath

20. Synchronized IMV • If the patient fails to initiate ventilation within a predetermined interval, the ventilator provides a mandatory breath at the end of the time period

21. Synchronization (SIMV+PSV) M Tsynch Tsynch Tsupp Tsupp M Pressure (cm H2O) Flow (L/m) Mandatory Cycle Time Cycles Time (sec) Triggered window for supported breaths Triggered window for synchronized breaths

22. Advantages and Disadvantages SIMV

23. Indications • Facilitate transition from full ventilatory support to partial support

24. SIMV Advantages Disadvantages When used for weaning, may be done too quickly and cause muscle fatigue Mechanical rate and spontaneous rate may asynchronous causing “stacking” May cause barotrauma or volutrauma • Maintains respiratory muscle strength by avoiding muscle atrophy • Decreases mean airway pressure • Facilitates ventilator discontinuation – “weaning”!

25. When used for weaning, may be done too quickly and cause muscle fatigue Mechanical rate and spontaneous rate may asynchronous causing “stacking” May cause barotrauma or volutrauma IMV: Stacking

26. Thank You