EC Full Form

EC stands for Expiratory Capacity in medical biology. Expiratory capacity is a term used to describe the maximum amount of air an individual exhales, given the duration and depth. Several factors determine exhalation capacity, including age, gender, height, lung volume and lung elasticity. A patient’s exhalation capacity can be determined by performing a simple test; it is often used along with spirometry to estimate total lung capacity. Exhalation capacity is the ability of a person’s lungs to exhale air. It is observed that 80-90% of people have a reduced expiratory capacity compared to their life expectancy (60 yrs).

Definition of Expiratory Capacity

EC is the measurement of exhalation, an action taken to remove waste gases from the lungs. Expiratory capacity measures the lung volume exhaled at maximal force, typically expressed as litres of air breathed out in one second. The measurement is done by spirometry and is reported as a value in millilitres (ml) or litres (L). A reduced expiratory capacity compared to their life expectancy is because most people no longer breathe air instead of exhaling it. Having a higher expiratory capacity is that more air can be exhaled, decreasing a person’s risk of developing pneumonia and other lung diseases. A patient’s expiratory capacity can also be used to indicate their breathing status. Storage capacities of the lungs are measured by spirometry ranging from 1 to 10 litres. The millilitres quantify the capacity and are recorded as an average during the test.

Function and significance of Expiratory Capacity

Function: Exhalation capacity is the ability of a person’s lungs to exhale air. It is said that 80-90% of people have a reduced expiratory capacity compared to their life expectancy (60 yrs). This is because most people no longer breathe air instead of exhaling it. Having a higher expiratory capacity is that more air can be exhaled, decreasing a person’s risk of developing pneumonia and other lung diseases. A patient’s expiratory capacity can also be used to indicate their breathing status.

Significance: It is commonly known that people with lower exhalation capacity have a higher risk of respiratory diseases such as pneumonia, bronchitis and asthma. However, the exact relationship between exhalation capacity and a person’s disease condition has not been fully understood. Some of the major causes of reduced expiratory capacity include heart diseases, asthma, chronic obstructive pulmonary disorders (COPD) and pneumonia. The patient needs to know that they have reduced expiratory capacity so that they can seek treatment if needed.

The formula of Expiratory Capacity

EC = TV + ERV, where TV: Tidal volume, EC: Expiratory Capacity, ERV: Exhaled Residual Volume.

Estimation of Expiratory Capacity

A physician or nurse usually administers a spirometry test to estimate expiratory capacity. This test objectively estimates the person’s lung function and symptoms of obstructive or restrictive pulmonary conditions such as asthma, chronic bronchitis, emphysema, and pneumonia. The patient is asked to exhale into a mouthpiece at maximum speed for about 6 seconds. The spirometer measures the volume of air that flows out of their lungs. The test only evaluates forced exhalation against the airway resistance, which is the resistance to airflow in and out of the lungs. Once this measurement is recorded, lung elasticity and lung function are considered when estimating a person’s total lung capacity.

This can also be done by manually measuring how much time it takes a person to exhale as much as possible in a normal state with an empty stomach. The person’s tummy and chest are palpated, and a specially made probe is used to measure the time it takes for the person to exhale as much as possible in a normal state. This number can be converted into an estimation of their expiratory volume in cubic centimetres (or litre-minutes) or the volume of air that can be exhaled at rest (estimated by the expiratory capacity). However, this is usually not recommended for patients with other respiratory diseases such as asthma, chronic bronchitis or emphysema. Thus, the spirometry test is considered to be more accurate and reliable in estimating a person’s lung capacity.

Conclusion 

Expiratory Capacity is the maximum amount of air exhaled following a maximal expiration. It is the maximum amount of air expired in a passive state, without any additional respiratory effort after full inspiration. This measure has been used to differentiate various respiratory disorders and conditions. Expiratory Capacity is measured by passive exhalation against a closed airway using a spirometer. During the forced expiration, the pressure at which airflow ceases (the maximal expiratory pressure) provides information about the mechanical properties of lung tissue. Expiratory Capacity is calculated by adding the tidal volume and Residual volume.