Vent settings

[andi.w]

Hello, all. I've been looking for a good resource that explains the different vent modes/settings. Does anyone have any favorites? Thanks!

[andi.w]

Good resources! Thank you all!

One thing that I think I may be confused about is CMV vs. SIMV. It's my understanding that in CMV, the ventilator gives a fixed number of breaths with a fixed Vt and ignores any spontaneous breaths from the patient. Whereas in SIMV, the ventilator will support spontaneous breaths and ensure that they achieve the set Vt. Is this correct? Also, would this mean that in CMV a patient may be taking more breaths than the set rate, just not necessarily with the same Vt? And lastly, can you give pressure support in CMV mode?

Thanks again!

[TraumaSurfer]

CMV? What ventilator are you using? Again as stated before, many different ventilators use similar terminology but to represent totally different modes. Many ventilators do not use the term CMV at all.

There are no longer ICU ventilators which deliver only a fixed number of breaths and nothing else used today in countries with advanced medical care. What you are describing is from the 1970s and earlier. The exception might be some of the very simple ventilators used by Paramedics. This is why you need to be careful about the sources you use as a reference. Outdated material is misleading.

CMV can be an Assist mode. It can deliver a set tidal volume and have a set rate. Both of these parameters can be exceeded by the patient.

SIMV can be more like what you where describing for a fixed rate and volume (or pressure) if not used correctly. Pressure support should be set at an adequate level for the spontaneous breaths. Some set it too low or fail to set it at all which makes the patient to struggle over the resistance of the tube.