Pressure-regulated Volume Controlled SIMV (SIMV with PRVC)

SIMV with PRVC

  • Volume Controlled
  • Time-Triggered – and the pressure support breaths are flow-triggered
  • Pressure-limited, or rather “Pressure Regulated”
  •  ….Flow-limited (but doesn’t have to be flow-limited)
  • Time-Cycled AND Flow-Cycled

 

This is essentially just a slightly smarter form of pressure-controlled SIMV. The key feature is, THE LOWEST POSSIBLE PRESSURE IS USED.

 The first breath tests for compliance; it’s a low-volume low-pressure calibration breath.   A compliance is calculated, and from this value, a pressure is calculated which would be required to deliver the controlled target volume.

The next breath is delivered at this calculated pressure. If the controlled target volume is exceeded, the ventilator adjusts the flow rate, so that with the next breath the pressure is slightly lower.

The subsequent breaths are delivered at the decreased pressure.

References

Most of this information comes from only two textbooks. With "Basic Assessment and Support in Intensive Care" by Gomersall et al (as well as whatever I picked up during the BASIC course) as a foundation, I built using the humongous and canonical "Principles and Practice of Mechanical Ventilation" by Tobins et al – the 1442 page 2nd edition.

Jonson B, Beydon L, Brauer K et al. Mechanics of respiratory system in healthy anesthetized humans with emphasis on viscoelastic properties. J Appl Physiol 1993; 75 : 132–40.

Zavala, Elizabeth et al.Effect of Inverse I: E Ratio Ventilation on Pulmonary Gas Exchange in Acute Respiratory Distress Syndrome Anesthesiology: January 1998 - Volume 88 - Issue 1 - p 35–42