# How do you measure lung resistance?

## How do you measure lung resistance?

Airway resistance (Raw) is calculated as the change in alveolar pressure (Palv) divided by flow, which is derived by multiplying the slope of the closed shutter maneuver and the inverse slope of the open shutter maneuver, with the lung volume terms cancelling out.

How is airflow resistance calculated?

One formula for airway resistance then is a ratio of the change in pressure to the flow rate of air. To calculate the change in pressure, all we need to do is subtract the alveolar pressure from the atmospheric pressure. Normal airway resistance is around 2 cmH2O per L per sec.

### What is lung compliance and resistance?

Lung compliance is inversely proportional to elastance. This elastic resistance is both due to the elastic property of lung tissue or parenchyma and the surface elastic force. Any changes occurring to these forces could lead to changes in compliance. Compliance determines 65% of the work of breathing.

What causes lung resistance?

One of the most important factors influencing airway resistance is the diameter of the airway. In general, the opposition of flow can be described as the pressure divided by the rate of flow (R = change in P/V). However, factors such as turbulent or laminar flow also impact the resistance to flow in the lungs.

## What is the difference between compliance and resistance?

Resistance is the change in pressure divided by flow. Compliance is volume divided by change in pressure.

What increases lung compliance?

Some factors that influence the static lung compliance (including emphysema) are listed in Table 1….4. Lung Compliance.

Aspect Low compliance High compliance
Pulmonary blood volume Mitral stenosis isocapnoeic hypoxia
Left ventricular failure Pulmonary stenosis

### What is normal lung resistance?

Airway resistance is the friction caused by the movement of air throughout the respiratory system and conducting airways. In a spontaneously breathing adult, normal airway resistance is estimated at 2 to 3 cm H2O/L/sec.

What are the factors affecting airway resistance?

Multiple factors can influence airway resistance, including airflow velocity, the diameter of the airway, and lung volume. These are some of the most significant contributing factors and will be discussed further on how these variables exert change and why this is important for managing patient airways.

## What are causes of increased airway resistance?

Bronchospasm, mucus plugging, and edema in the peripheral airways result in increased airway resistance and obstruction. Air trapping results in lung hyperinflation, ventilation/perfusion (V/Q) mismatch, and increased dead space ventilation.