Airway resistance

Examples of Airway resistance in the following topics:

• Factors Affecting Pulmonary Ventilation: Airway Resistance

  • Airway resistance refers to resistance in the respiratory tract to airflow.
  • Airway resistance can change over time, especially during an asthma attack when the airways constricts causing an increase in airway resistance.
  • Resistance in an airway is inversely proportional to the radius of the airway.
  • Below is the equation for calculating airway resistance (R).
  • The number of airways also plays a large role in the resistance to air, with more airways reducing resistance because there are more paths for the air to flow into.

• The Work of Breathing

  • Breathing includes several components, including flow-resistive and elastic work; surfactant production; and lung resistance and compliance.
  • When the respiratory rate is increased, the flow-resistive work of the airways is increased and the elastic work of the muscles is decreased.
  • This same principle applies to the airways.
  • Two main causes of decreased gas exchange are compliance (how elastic the lung is) and resistance (how much obstruction exists in the airways).
  • Explain the roles played by surfactant, flow-resistive and elastic work, and lung resistance and compliance in breathing

• Aging and the Respiratory System

  • Chronic obstructive pulmonary disease (COPD), is the occurrence of chronic bronchitis or emphysema, a pair of commonly co-existing diseases of the lungs in which the airways become narrowed.
  • When requirements increase, the abdominal muscles resist expansion.
  • This forced expiration increases pressure across walls of airways, and may lead to narrowing or even perhaps to wheezing.

• Tracheotomy and Intubation

  • Tracheotomy consists of making an incision on the anterior aspect of the neck and opening a direct airway via an incision in the trachea.
  • In extreme cases, the procedure may be indicated as a treatment for severe obstructive sleep apnea seen in patients intolerant of Continuous Positive Airway Pressure (CPAP) therapy.
  • The highest priority in an emergency is to enable a patient to breathe by securing their airway (passage from the nose and mouth into the lungs).
  • Endotracheal intubation is one of various ways to secure the airway.
  • A Cochrane review, examines whether emergency endotracheal intubation, as opposed to other airway management techniques, improves the outcome and no difference was found between endotracheal intubation and other airway securing strategies for reducing deaths after acute illness or injury.

• Factors Affecting Pulmonary Ventilation: Surface Tension of Alveolar Fluid

  • Because the alveoli of the lungs are highly elastic, they do not resist surface tension on their own, which allows the force of that surface tension to deflate the alveoli as air is forced out during exhalation by the contraction of the pleural cavity.
  • The force of surface tension in the lungs is so great that without something to reduce the surface tension, the airways would collapse after exhalation, making re-inflation during inhalation much more difficult and less effective.
  • Therefore prematurely born infants are at a high risk of respiratory distress syndrome from airway collapse, which can cause death if untreated.

• Adjustments of the Infant at Birth

  • With the first breaths, there is a fall in pulmonary vascular resistance and an increase in the surface area available for gas exchange.
  • A positive airway pressure should be maintained and neonatal sepsis must be ruled out.
  • Potential neonatal respiratory problems include apnea, transient tachypnea of the newborn (TTNB), respiratory distress syndrome (RDS), meconium aspiration syndrome (MAS), airway obstruction, and pneumonia.

• Intubation During Anesthesia

  • Tracheal intubation is the placement of a flexible tube into the trachea to maintain an open airway or to facilitate drug administration.
  • Actual or impending airway obstruction is a common indication for decreased O2 saturation requiring intubation of the trachea.
  • Life-threatening airway obstruction may occur when a foreign body becomes lodged in the airway; this is especially common in infants and toddlers.
  • Tracheotomy consists of making an incision on the front of the neck and opening a direct airway through an incision in the trachea.
  • These are typically of short duration, such as sore throat, lacerations of the lips or gums or other structures within the upper airway.

• Inspiration

  • In humans it is the movement of ambient air through the airways, and into the alveoli of the lungs.
  • Resistance in any part of the respiratory tract can cause problems.

• Asthma

  • Asthma is a common chronic inflammatory disease of the airways characterized by reversible airflow obstruction and bronchospasm.
  • Asthma is a common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.
  • Unlike these diseases, the airway obstruction in asthma is usually reversible; however, if left untreated, the chronic inflammation from asthma can lead the lungs to become irreversibly obstructed due to airway remodeling.
  • During an asthma episode, inflamed airways react to environmental triggers such as smoke, dust, or pollen.
  • The airways narrow and produce excess mucus, making it difficult to breathe.

• Types of Epithelial Tissue

  • Ciliated epithelium is found in the airways (nose, bronchi), but is also found in the uterus and fallopian tubes of females, where the cilia propel the ovum to the uterus.
  • They contain a tough, resistant protein called keratin.