pressure gradients

What is lung compliance?

Lung compliance is the relative ease with which the lungs distend, specifically the change in volume per unit of pressure.

How is lung compliance calculated?

Compliance = ΔV/ΔP, where ΔV is the change in volume and ΔP is the change in pressure.

What is normal static compliance for a healthy spontaneous breathing individual?

0.1 L/cmH20.

What is the range of compliance for intubated mechanically ventilated patients?

0.04 to 0.05 L/cmH20.

What does airway resistance measure?

Airway resistance measures the frictional force opposing inflation in the lungs.

According to Poiseuille’s Law, what factors affect airway resistance?

Gas viscosity, gas density, length and diameter of the tube, and flow rate of the gas.

What is the equation for airway resistance (Raw)?

Raw = ΔP/Flow, where ΔP is the pressure difference and Flow is the airflow rate.

What is the typical range of airway resistance (Raw) for a healthy spontaneous breathing individual?

0.6 to 2.4 cmH2O/L/sec.

What is the typical range of airway resistance (Raw) for an intubated mechanically ventilated individual?

5 to 7 cmH2O/L/sec.

What is transrespiratory pressure (Prs)?

Prs is the pressure gradient that allows gas flow between the mouth and alveoli.

What is the equation of motion in lung mechanics?

Transrespiratory Pressure = (Resistance x Flow) + (Volume/Compliance).

What is transairway pressure?

Transairway pressure is the pressure required to overcome the resistance of the conductive airways.

What is transthoracic pressure?

Transthoracic pressure is the pressure required to inflate the alveoli.

How does mechanical ventilation affect pressure gradients?

Mechanical ventilation alters the pressure gradients necessary for gas flow in the lungs.

What is Pplateau?

Pplateau is the pressure at the end of inspiration in a mechanically ventilated patient.

How is Pplateau related to compliance?

PA = ΔP = ΔV/Cs, meaning alveolar pressure is related to volume and compliance.

What does PM stand for in respiratory physiology?

PM stands for mouth pressure, which is measured during mechanical ventilation.

When does PM equal PA?

PM equals PA when flow has stopped and there is no resistive pressure in the airway.

Why is static compliance (Cs) important?

Static compliance is important for assessing lung inflation during no flow conditions.

How is static compliance (Cs) calculated?

Cs = Vt / (Pplateau - PEEP).

What is dynamic compliance?

Dynamic compliance is the measurement of lung compliance during airflow movement into the lungs.

What is the significance of inspiratory hold in measuring Pplateau?

An inspiratory hold determines Pplateau as it stops airflow and reflects alveolar pressure.

What happens to PM during positive pressure ventilation?

During positive pressure ventilation, PM is the pressure generated by the ventilator.

What is the relationship between Pplateau and compliance?

Pplateau is used to calculate compliance, indicating how well the lungs expand.