Flashcards for:
Physiological Lung Volumes and Capacities

Compliance refers to the lung's ability to stretch, while elasticity refers to the lung's ability to recoil. Both are important for proper lung function.

In restrictive lung diseases, there is decreased lung compliance leading to reduced lung volumes and capacities, especially Total Lung Capacity (TLC) and Vital Capacity (VC).

Tidal Volume (TV) is the volume of air inhaled or exhaled in a normal breath, typically about 500ml.

Residual Volume (RV) is the volume of air remaining in the lungs after maximal exhalation, normally around 1200ml.

Fibrosis leads to decreased lung compliance and preserved or increased elasticity, resulting in reduced lung volumes and capacities, characteristic of a restrictive pattern.

Inspiratory Reserve Volume (IRV) is the maximum volume of air inhalable after normal inspiration, up to about 3000ml.

In obstructive lung diseases, there is increased airway resistance, resulting in a lower FEV1 and FEV1/FVC ratio, and a higher Residual Volume (RV) due to air trapping.

Asthma typically shows an obstructive pattern with normal or increased compliance but decreased elasticity due to airway narrowing.

Functional Residual Capacity (FRC) is the volume of air remaining in the lungs after a normal expiration, given by FRC = ERV + RV.

COPD is characterized by increased Residual Volume (RV) and a decreased FEV1/FVC ratio due to airway obstruction, manifesting as an obstructive pattern on spirometry.

Total Lung Capacity (TLC) is the sum of all lung volumes, typically almost 6000ml.

Vital Capacity (VC) is the total volume of air that can be exhaled after maximum inhalation, calculated as VC = TV + IRV + ERV, typically around 4800ml.

Forced Expiratory Volume in one second (FEV1) is the volume of air expelled in the first second of a forced exhalation. It is crucial for assessing lung function and diagnosing obstructive lung diseases.

Expiratory Reserve Volume (ERV) is the maximum volume of air exhalable after normal expiration, approximately 1100ml.

Inspiratory Capacity (IC) is the maximum volume of air that can be inhaled after a normal exhalation, calculated as IC = TV + IRV.

The FEV1/FVC ratio is used to diagnose obstructive and restrictive lung diseases. A normal value is >80%, while values <70% suggest obstructive diseases.

FEV1 and FVC measurements are important for diagnosing and differentiating obstructive and restrictive lung diseases, aiding in effective management and treatment.