Monday, November 30, 2015

Changing Flow Patterns vs. Changing Ventilator Modes

Figure 1: Various flow patterns within VC-CMVs on the Hamilton G5 Ventilator.
When a device operator thinks about changing the inspiratory flow pattern while administering a Volume-Controlled breathing pattern they do not assume it will change the mode of ventilation. 

However newer software in the Servo-i allows the operator to change the flow pattern 
from the traditional constant flow pattern, to either a fully decelerating  flow pattern (similar to PC-CMV) or to adaptive flow (Fig. 2).  The Adaptive Flow pattern was the default in older software which makes Volume Control a Dual Control mode [1].  The operator now has a choice of using Volume Control as a traditional VC-CMV mode by selecting the square waveform or providing a Dual Control breathing pattern by selecting the Adaptive Flow icon. 

Figure 2: Flow patterns available on the Servo-i, courtesy of Robert Chatburn. 
For more information on flow patterns and Dual Control see the below links.