Volume controlled intermittent mandatory ventilation


Volume controlled intermittent mandatory ventilation

Volume Controlled Intermittent Mandatory Ventilation (VC-IMV) refers to any mode of mechanical ventilation with preset tidal volume (VT) and inspiratory flow. Spontaneous breaths (i.e., inspiration is patient triggered and patient cycled) can exist between mandatory breaths. For intermittent mandatory ventilation utilizing pressure regulation, the term pressure controlled intermittent mandatory ventilation is used.

Contents

Intermittent Mechanical Ventilation

IMV — IMV is similar to AC in two ways: the minute ventilation is determined (by setting the respiratory rate and tidal volume); and the patient is able to increase the minute ventilation. However, IMV differs from AC in the way that the minute ventilation is increased. Specifically, patients increase the minute ventilation by spontaneous breathing, rather than patient-initiated ventilator breaths.

Syncronized Intermittent Mechanical Ventilation

SIMV — SIMV is a variation of IMV, in which the ventilator breaths are synchronized with patient inspiratory effort.[1][2] SIMV with pressure support is the most efficient and effective mode of mechanical ventilation.[3]

Mandatory Minute Ventilation

MMV — Mandatory minute ventilation is a mode which requires the operator to determine what the appropriate minute ventilation for the patient should be, and the ventilator then monitors the patient's ability to generate this volume every 7.5 seconds. If the calculation suggests the volume target will not be met, SIMV breaths are delivered at the targeted volume to achieve the desired minute ventilation[4]. Allows spontaneous breathing with automatic adjustments of mandatory ventilation to the meet the patient’s preset minimum minute volume requirement. If the patient maintains the minute volume settings for VT x f, no mandatory breaths are delivered. If the patient's minute volume is insufficient, mandatory delivery of the preset tidal volume will occur until the minute volume is achieved. The method for monitoring whether or not the patient is meeting the required minute ventilation (VE) is different per ventilator brand and model, but generally there is a window of time being monitored and a smaller window being checked against that larger window (i.e., in the Dräger Evita® line of mechanical ventilators there is a moving 20-second window and every 7 seconds the current tidal volume and rate are measured against to make a decision for if a mechanical breath is needed to maintain the minute ventilation). MMV is the most optimal mode for weaning in neonatal and pediatric populations and has been shown to reduce long term complications related to mechanical ventilation.[5]

See also

References

  1. ^ Sassoon CS, Del Rosario N, Fei R, et al. Influence of pressure- and flow-triggered synchronous intermittent mandatory ventilation on inspiratory muscle work. Crit Care Med 1994; 22:1933.
  2. ^ Christopher KL, Neff TA, Bowman JL, et al. Demand and continuous flow intermittent mandatory ventilation systems. Chest 1985; 87:625.
  3. ^ D. C. Shelledy, J. L. Rau & L. Thomas-Goodfellow (January–February 1995). "A comparison of the effects of assist-control, SIMV, and SIMV with pressure support on ventilation, oxygen consumption, and ventilatory equivalent". Heart & lung : the journal of critical care 24 (1): 67–75. PMID 7706102. 
  4. ^ Scott O. Guthrie, Chris Lynn, Bonnie J. Lafleur, Steven M. Donn & William F. Walsh (October 2005). "A crossover analysis of mandatory minute ventilation compared to synchronized intermittent mandatory ventilation in neonates". Journal of perinatology : official journal of the California Perinatal Association 25 (10): 643–646. doi:10.1038/sj.jp.7211371. PMID 16079905. 
  5. ^ Scott O. Guthrie, Chris Lynn, Bonnie J. Lafleur, Steven M. Donn & William F. Walsh (October 2005). "A crossover analysis of mandatory minute ventilation compared to synchronized intermittent mandatory ventilation in neonates". Journal of perinatology : official journal of the California Perinatal Association 25 (10): 643–646. doi:10.1038/sj.jp.7211371. PMID 16079905.