Calculation of the Level of Pressure Support Required to Overcome the Work of Breathing During Synchronized Intermittent Mandatory Ventilation (SIMV)

 

Parameters:

(1) tidal volume delivered by the ventilator in mL

(2) inspiratory flow rate on the ventilator in L per minute

(3) peak inspiratory pressure in cm H2O

(4) plateau pressure following an inspiratory pause in cm H2O

(5) spontaneous inspiratory flow rate in L per minute by the patient

 

pressure support in cm H2O =

= ((peak inspiratory pressure) - (plateau pressure)) * ((spontaneous inspiratory flow rate) / 60)) / ((ventilator inspiratory flow rate) / 60)

 

where:

• The ventilator is set to have a square inspiratory flow waveform.

• The calculations using inspiratory flow rates in L per second.