Tidal volume of adult lung is -

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

Tidal Volume (TV) is defined as the volume of air inspired or expired with each normal, quiet breath.
For an average healthy adult male, this value is approximately 500 mL.
This volume is sufficient for adequate gas exchange at rest without causing unnecessary strain on the lung tissues.

Option A: A volume of 100 mL is insufficient for effective gas exchange in an adult. This value is closer to the anatomical dead space (around 150 mL), which is the portion of inhaled air that does not participate in gas exchange.
Option C: A volume of 1000 mL is double the normal resting tidal volume. This represents a deep breath, not a quiet one. This value is closer to the Expiratory Reserve Volume (ERV), which is about 1100 mL.
Option D: A volume of 1600 mL is not a primary lung volume. It represents a combination of other volumes, approximately the sum of the Tidal Volume (500 mL) and the Expiratory Reserve Volume (1100 mL).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of Respiration and Lung Volumes as background academic context rather than a clinical decision trigger.
Nurses in critical care set and monitor tidal volume on mechanical ventilators, typically based on the patient's ideal body weight (e.g., 6-8 mL/kg), to ensure adequate ventilation and prevent lung injury.
A spontaneous decrease in a patient's tidal volume can be an early sign of respiratory muscle fatigue or worsening respiratory distress, requiring prompt nursing assessment and intervention.
What if? If a patient has Acute Respiratory Distress Syndrome (ARDS), the target tidal volume on the ventilator would be set lower (e.g., 4-6 mL/kg) as part of a lung-protective strategy to minimize ventilator-induced lung injury in the stiff, non-compliant lungs.

How to Approach the Question

Identify the core of the question: It asks for a specific, standard physiological value – the resting tidal volume in an adult.
Recognize this as a factual recall question based on fundamental respiratory physiology.
Access your knowledge of the four primary lung volumes: Tidal Volume, Inspiratory Reserve Volume, Expiratory Reserve Volume, and Residual Volume.
Recall the average value for tidal volume, which is the amount of air in a single, normal breath.
Compare the options to the known value. The standard average tidal volume is 500 mL.
Eliminate the other options by identifying them as either too low (100 mL), too high for a resting breath (1000 mL), or a combination of volumes (1600 mL).

Concept Tested & Keywords

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

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