What is airway resistance in pulmonary ventilation?

Airway resistance is a concept in respiratory physiology that describes the resistance of the respiratory tract to airflow during inspiration and expiration. Airway resistance can be indirectly measured with body plethysmography.

What is airway resistance and lung compliance?

Dynamic Compliance: It is the continuous measurement of pulmonary compliance calculated at each point representing schematic changes during rhythmic breathing. [2] It monitors both elastic and airway resistance. Airway resistance depends on the air viscosity, density, and length, and radius of airways.

What is airway resistance affected by?

Therefore, a small change in diameter has a huge effect on the resistance of an airway e.g. halving the radius of an airway would cause a 16-fold increase in resistance. Therefore, individually, the smaller airways have much higher resistance than larger airways such as the trachea.

What is the major site of airway resistance?

bronchi
The site of most airway resistance is the medium-sized bronchi. The smallest airways contribute very little to resistance, because the combined cross-sectional area of these airways is much larger than that of the intermediate bronchi.

What does low airway resistance mean?

It is defined as the ratio of driving pressure to the rate of air flow. Resistance to flow in the airways depends on whether the flow is laminar or turbulent, on the dimensions of the airway, and on the viscosity of the gas. For laminar flow, resistance is quite low.

What factors increase airway resistance?

Factors which affect airway resistance by affecting airway diameter

• Increased smooth muscle tone. Bronchospasm. Irritants, eg. histamine. Parasympathetic nervous system agonists.
• Decreased smooth muscle tone. Bronchodilators. Sympathetic nervous system agonists.

What is the normal airway 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 does decreased airway resistance mean?

Simply put, during inspiration, airway resistance goes down because the lungs and airways expand, in contrast to expiration (analogous to decreased FRC), which increases airway resistance because the lung and airways deflate, narrowing the airways.[4]

How do you measure airway resistance?

The most common method for measurement of airway resistance is whole-body plethysmography. A plethysmograph consists of a rigid chamber, in which the subject breathes through a head measuring flow and volume (pneumotachograph) [4].

How does airway resistance affect airflow?

This means that the higher the pressure difference between two sites, the more air flowing between them. On the other hand, the relationship between airflow and airway resistance is inversely proportional, represented as Q ∝ 1R , where R is airway resistance, meaning if airway resistance increases, airflow decreases.

What is the airway resistance formula?

Resistance in an airway is equal to change in pressure divided by flow rate [Resistance = (Peak Pressure – Plateau Pressure) / Flow L/sec].

What are the possible 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.