SIMV mode and initiating a breath

  1. I have been reading up on this trying to find an answer. Maybe someone here can help.

    I have a question. If the vent is set on SIMV with no pressure support, would it be initiating too many breaths? Back to back or three in a row quickly.

    No distress
    lungs and trach clear
    sleeping soundly.

    I will be talking to my don about this later when she calls back, but I am just curious if anyone else has seen this before.

  2. Visit Magsulfate profile page

    About Magsulfate, BSN

    Joined: Oct '06; Posts: 1,262; Likes: 1,704
    RN; from US
    Specialty: 13 year(s) of experience in ICU


  3. by   turnforthenurse
    To my understanding, SIMV sets a TV, FiO2 and f. The patient will receieve the preset TV and FiO2 as well as the f but the patient can breathe ABOVE the rate. If the rate is set at 10, the patient will receive those breaths but when the patient breathes spontaneously, the vent does not deliver those extra breaths. Therefore, I don't see how it could initiate too many breaths (unless the f is set really high or something). PS is is supposed to help the patient to decrease work of breathing but PS can also be decreased so that the patient does more work to breathe.
  4. by   PageRespiratory!
    Synchronized...Intermittent...Mandatory...Ventilat ion...SIMV is a set rate (volume control or pressure control [either a set tidal volume or insp pressure]) and the Pt is able to breathe spontaneously (with or without pressure support) inbetween mandatory breaths. Pressure support is only activated during spontaneous breaths. In Assist Control (often called CMV or AC) the Pt may initiate a breath but it will be a set mandatory breath. There should be a trigger setting (pressure or flow) that determines how much effort is neccessary to initiate a breath. Often a vent will "autotrigger" if this is set to low, and/or, there is a lot of condensation (rainout) or some sort of partial occlusion or something in the circuit.
  5. by   Magsulfate
    Thank you everyone, I am still learning. I've talked to a friend and have a better understanding. Even after all those years of critical care nursing, we ALWAYS had a respiratory therapist or two to do most of this while we focused on other things like drips and vital signs and education and... keeping the family informed or calm or ... the list goes on and on. So when RT is there, we just let them have at it...

    I am really enjoying this new job. I know I will be learning so much more in the weeks to come..

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