The largest volume of air which can be expelled from the lungs during expiration is called?

Appeared in: AIIMS Raipur NO - 2017 (Shift-1)

Explanation

Expiratory Reserve Volume (ERV) is defined as the maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration.
This volume represents the reserve amount of air that can be exhaled beyond the normal, passive exhalation of a tidal breath.
The typical value for ERV in a healthy young adult male is approximately 1100 mL.

Option A: Tidal volume is the amount of air moved during normal, quiet breathing. It is not a maximal or forced volume.
Option B: Residual volume is the air that remains in the lungs after a maximal forced exhalation. This volume cannot be expelled voluntarily.
Option C: Inspiratory reserve volume is the extra volume of air that can be forcefully inhaled, not exhaled.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Lung Volumes as background academic context rather than a clinical decision trigger.
Expiratory Reserve Volume (ERV) is a key measurement in pulmonary function tests (PFTs), which are used to diagnose and monitor respiratory diseases.
A significantly reduced ERV can indicate a restrictive lung disease (e.g., pulmonary fibrosis, scoliosis) or conditions that limit lung expansion, such as obesity or ascites.
In obstructive diseases like COPD, the ERV may be normal or decreased, but the time taken to exhale it is prolonged.

How to Approach the Question

First, carefully read the question and identify the key terms: 'largest volume,' 'expelled,' and 'expiration.' This means you are looking for a maximal volume that is exhaled.
Next, recall the definitions of the four basic lung volumes provided in the options.
Eliminate options that do not fit the criteria. 'Residual volume' is not expelled, and 'Inspiratory reserve volume' is inhaled, so both are incorrect.
Differentiate between the remaining options. 'Tidal volume' is for normal, not maximal, breathing. 'Expiratory reserve volume' is specifically the maximal volume that can be forcefully exhaled after a normal breath.
Conclude that Expiratory Reserve Volume is the best fit for the description among the given choices.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 2A p. 56-58

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