Recommendations / 11/12/2019

What conditions can increase 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.

What are some diseases that could affect airway resistance?

Pathological conditions which affect airway diameter:

Mechanical obstruction or compression. Extrinsic, eg. by tumour.
Decreased internal crossection. Oedema. Mucosal or smooth muscle hypertrophy.
Decreased smooth muscle tone. Bronchodilators. Sympathetic nervous system agonists.
Increased smooth muscle tone. Bronchospasm.

What would cause increased resistance to airflow?

Turbulent flow refers to when air is not flowing in parallel layers, and direction, velocity and pressure within the flow of air become chaotic. If airflow becomes turbulent, the pressure difference required to maintain airflow will need to be increased, which in turn would increase turbulence and therefore resistance.

Does COPD increase airway resistance?

Expiratory flow limitation is a key characteristic in chronic obstructive pulmonary disease (COPD). Increased airway resistance occurs due to bronchoconstriction, destruction of elastic tissue in the airways, and mucus hypersecretion from goblet cells caused by irritation of the epithelium.

Does bronchodilation increase airway resistance?

Heliox is often an adjunctive therapy alongside albuterol for reducing airway resistance. With severe airway narrowing, gas velocity increases, and airflow becomes turbulent. This turbulent airflow increases airway resistance.

What causes airway resistance in COPD?

The air spaces become larger and the surface area of gas exchange becomes much smaller. The reduced recoil tendency no longer holds open the bronchioles and so these tend to collapse, producing the increased airway resistance that characterizes COPD.

Where is the major site of airway resistance?

upper airways
Most airway resistance resides in the upper airways. The presence of an endotracheal tube markedly increases the airway resistance (Figure 49-21) and contributes to the work of breathing.

What are 3 pathophysiological causes of airflow limitation in COPD?

Processes contributing to obstruction in the small conducting airways include disruption of the epithelial barrier, interference with mucociliary clearance apparatus that results in accumulation of inflammatory mucous exudates in the small airway lumen, infiltration of the airway walls by inflammatory cells, and …

Which is a disease that increases airway resistance?

Diseases in which airway narrowing occurs, such as chronic obstructive pulmonary disease and asthma, increase airway resistance. Increased airway resistance can result in the following: Increased time required for inflation and deflation of the lungs, which contributes to air trapping, high airway pressures, and hypoxemia in ventilated patients.

How is airway resistance related to lung volume?

Another important fact is that airway resistance is inversely related to lung volumes because the airways expand a bit as they inflate, so the airways in a fully inflated lung will have lower resistance than a lung after exhalation.

What are the effects of airway resistance in children?

Increased airway resistance can result in the following: Increased time required for inflation and deflation of the lungs, which contributes to air trapping, high airway pressures, and hypoxemia in ventilated patients. Matthias Ochs MD, Hugh O’Brodovich MD, in Kendig’s Disorders of the Respiratory Tract in Children (Ninth Edition), 2019

When does airway resistance increase during an asthma attack?

Turbulent flow: Air with disorganized layers that has higher resistance. It is often located in areas where the airways branch or diverge. Airway resistance can change over time, especially during an asthma attack when the airways constricts causing an increase in airway resistance.

How are lung diseases related to airway resistance?

Most lung diseases increase airway resistance in many different ways. For example, in asthma attacks the bronchioles spasm and constrict, which increases resistance. Emphysema also increases airway resistance because the lung tissue becomes too pliable and it the airways become more difficult to hold open by the flow of air.

What causes Airways to collapse in emphysema patients?

Smooth muscle within the wall of the same bronchi can contract and increase airways resistance. Secretions in airways or edema in the airway wall can also increase airways resistance. In patients with emphysema, loss of tethering of small airways open during exhalation leads to collapse and an increase in resistance to airflow.

What are the main determinants of airway resistance?

The main determinants of airway resistance are the size of the airway and the properties of the flow of air itself. Resistance in an airway is inversely proportional to the radius of the airway. However the ratio for this relationship is not 1:1.