Airflow Resistance Simulator
Airflow Resistance (Raw) = Transairway pressure PTA (ΔP)/ Flow (F)
Measured with a constant square wave pattern for accuracy.
In mechanically ventilated patients, airflow in the endotracheal tube can become turbulent, causing resistance to rise nonlinearly.
This increases peak pressure (Ppeak) without affecting plateau pressure (Pplat).
This is a teaching approximation, not a precise clinical calculation.
This increases peak pressure (Ppeak) without affecting plateau pressure (Pplat).
This is a teaching approximation, not a precise clinical calculation.
PTA = 0 cmH₂O
PTA (transairway pressure) is the pressure difference between peak inspiratory pressure (Ppeak)
and plateau pressure (Pplat) during mechanical ventilation.
Clinical Tips – Airway Resistance (Ventilator)
- Airway Obstruction: Mucus, secretions, bronchospasm, ETT issues → ↑ Ppeak, normal Pplat. Tip: Suction, bronchodilator, check tube.
- Low Lung Volume / Collapse: Small airways collapse → ↑ resistance. Tip: Increase PEEP, adjust tidal volume, recruitment maneuvers.
- High Flow / Turbulent Flow: Large proximal airways or rapid inspiratory flow → ↑ Ppeak, audible wheeze. Tip: Reduce inspiratory flow, use bronchodilators if needed.
- Nervous / Chemical Factors: Parasympathetic stimulation, histamine → bronchoconstriction. Tip: β₂ agonists, antimuscarinics, remove triggers.
- Gas Properties: Dense gases increase resistance. Tip: Heliox (He + O₂) in severe obstruction.
Quick Ventilator Rule: Ppeak vs Pplat helps distinguish resistance vs compliance issues.