Respiratory Mechanics and Lung Function

Flashcards covering key vocabulary related to respiratory mechanics and lung function.

Respiratory Mechanics

Interaction of pressures and forces allowing lungs and chest wall to operate in unison during breathing.

Lung Function

Expression of respiratory mechanics measured by pressure, volume, and flow.

Compliance

Measurement of the elastic capability of an organ or system, indicating how easily it can be stretched.

High Lung Compliance

Lungs that are easily inflated.

Low Lung Compliance

Lungs that are difficult to inflate.

Static Compliance

Compliance measured in the absence of flow, at the end of inspiration or exhalation.

Dynamic Compliance

Compliance measured during airflow, such as during inhalation.

Specific Compliance

Compliance calculated by unit of lung volume, correcting for size differences in adults, infants, and children.

Chest Wall Compliance

Measure of transmural pressure across the chest wall compared to the volume of the chest cavity.

Total Respiratory Compliance

The normal compliance of the chest wall and the lungs working together (approximately 0.1 L/cm H2O).

Pressure-Volume Curves

Graphs that plot changes in volume on the y-axis and pressure on the x-axis to illustrate mechanics of ventilation.

Elastance

Ability of the lungs to spring back after expansion; also known as elastic recoil.

Lung Hysteresis

The difference between inspiratory and expiratory arches in a pressure-volume curve, illustrating differences in lung volumes during inspiration versus expiration.

Pressure Gradient

Change in pressure per unit distance; air flows from high to low pressure.

Transrespiratory Pressure

Difference between alveolar pressure and body surface area; pressure required to inflate lungs and airways.

Transpulmonary Pressure

Pressure needed for maintaining alveolar inflation; pressure difference between alveolar space and pleural space.

Transthoracic Pressure

Total pressure required to expand or contract the lungs and chest wall; difference between transpulmonary pressure and body surface.

Airway Resistance

Friction of the airways and lung tissue to airflow during inhalation and exhalation.

Laminar Flow

Uninterrupted movement of particles in parallel paths; smooth movement associated with low RAW.

Turbulent Flow

Erratic or choppy air movement with molecules churning and bumping, resulting in higher airway resistance.

Tracheobronchial Flow (Transitional Flow)

Mixture of laminar and turbulent flow, often occurring where airways branch.

Reynolds Number

Mathematical expression used to calculate the type of airflow moving through the lungs.

Ventilation Time Constant

Measure of the time in seconds to inflate a portion of the lung, specifically the time for alveolar pressure to reach 63% of the change in airway pressure.

Positive End-Expiratory Pressure (PEEP)

Pressure in the lungs above atmospheric pressure that exists at the end of expiration.

Peak Airway Pressure (Ppeak)

Maximum pressure applied to the lungs during the inspiratory cycle.

Plateau Pressure (Pplat)

Airway pressure after a pause before exhalation, reflecting elastic recoil ability of lungs and chest wall.

Mechanical Ventilation

Use of an external device to provide or support air movement into and out of the lungs.

Positive Pressure Ventilation

Blowing air into the airway to inflate the lungs.

Negative Pressure Ventilation

Use of an external device that pulls the chest wall upward and outward, causing air to rush into the nose/mouth and airways.