Intermittent mandatory ventilation
Intermittent Mandatory Ventilation (IMV) refers to any
To help illustrate the use of the different types of ventilation, it is helpful to think of a continuum of the common ventilator settings; assist control or continuous mechanical ventilation (AC/CMV), to SIMV, to pressure support (PS). The lungs require a certain amount of oxygen to fill them, the volume, and a certain amount of force to get the oxygen into the lungs, the pressure. In assist control, one of those two variables will be controlled by the ventilator, either pressure or volume. Typically, in AC/CMV, it is volume.
In AC/CMV, the ventilator will deliver a set volume whenever the patient triggers a breath. In contrast, pressure support delivers a set pressure for every triggered breath, rather than a set volume. SIMV works in between AC and PS; it will deliver a set volume, only when the patient reaches the breath threshold, instead of just triggering a breath. If the patient does not reach the threshold, then no volume will be delivered, and the patient will be responsible for whatever volume they get into their lungs.[1]
Synchronized intermittent mechanical ventilation (SIMV)
Synchronized Intermittent Mechanical Ventilation is a variation of IMV, in which the ventilator breaths are synchronized with patient inspiratory effort. have demonstrated potential detrimental effects of SIMV on respiratory muscles and respiratory drive.
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.[12] 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.[12]
Proportional assist ventilation (PAV)
Proportional assist ventilation is a mode in which the ventilator guarantees the percentage of work regardless of changes in
Adaptive support ventilation (ASV)
Adaptive Support Ventilation is a positive pressure
The invention of ASV is claimed by two competing groups,[16] published as scientific article by one group[17] and disclosed as one of the embodiments of US Patent No. 4986268.[18] In this invention, the control algorithm computes the optimal rate of respiration to minimize the work rate of breathing. The rationale is to make the patient's breathing pattern comfortable and natural within safe limits, and thereby stimulate spontaneous breathing and reduce the weaning time.
See also
References
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- ^ 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.
- ^ Christopher KL, Neff TA, Bowman JL, et al. Demand and continuous flow intermittent mandatory ventilation systems" Chest 1985; 87:625.
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- ^ Younes M. Proportional assist ventilation, a new approach to ventilatory support. Theory. Am Rev Respir Dis 1992; 145(1):114-120.
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- ^ Tehrani, Fleur T., "Method and Apparatus for Controlling an Artificial Respirator" US Patent No. 4986268, issued Jan. 22, 1991.