Resistance refers to the impedance of flow.
Clinically, resistance is the opposition to gas flow within a respiratory unit.
Resistance = ∆P/flow (cmH2O/L/s)
Hence, this ∆P is the pressure needed to vanquish the resistance of the ETT and airways to be able to get air flowing in. It is called the Resistive Pressure (PResist) and is directly porportionnal to the resistance of the system.
In intubated and mechanically ventilated patients with normal lungs, the resistance is 1-8 cmH2O/L/s.
[az_toggle_section] [toggle title=”What is the compliance of your patient’s lungs if you need 4.5cmH2O to generate a flow of 20L/min, and how would you describe your patient’s resistance?” id=”tgl-1″] Resistance = ∆P/flow (cmH2O/L/s)
Resistance = 4.5cmH2O / 20L/min = 4.5cmH2O/ 0.33L/s = 13.5 cmH2O/L/s
Your patient has a resistance slightly higher than normal. [/toggle] [/az_toggle_section]
