Monday, September 19, 2011

Decreasing Dyspnea during Mechanical Ventilation

Flow Mismatch Associated with VC-CMV

Utilizing Volume Control-Continuous Mandatory Ventilation (VC-CMV) may lead to patient ventilator asynchrony [1] and dyspnea. The main reason for these issues is the fixed (constant) flow rate associated with VC-CMV.

A recent study revealed that responsive patients ventilated with VC-CMV had dyspnea scores two times greater than patients ventilated with Pressure Support ventilation (Variable flow) [2]. When the flow rate was adjusted in the patients receiving VC-CMV, 35% of the patients’ dyspnea decreased.

To decrease dyspnea associated with mechanical ventilation the easiest thing to do would be to ventilate the patient in a pressure based modality (PC-CMV, APC, CSV-PS, ASV, PAV, NAVA).  This provides the patient with a variable flow rate based on the patients inspiratory demands.

Switching to a pressure based mode may not resolve asynchrony and/or dyspnea the operator still needs to consider additional factors which influence patient comfort & synchrony which may include:

  • Pressurization Rate Speed (fast, slow)

[2]. Intelligent Ventilation. Volume 7 (4). September 2011.
[3]. Ventilator Graphics