The volume of air that moves in and out of lungs with each respiration is

Appeared in: KGMU 2024

Explanation

Tidal volume (TV) is the specific physiological term for the volume of air that is moved into or out of the lungs during a quiet, unforced respiratory cycle.
For an average, healthy adult at rest, the tidal volume is approximately 500 mL per breath.
This volume ensures the continuous refreshment of air within the gas exchange areas of the lungs (alveoli).

Option B: Minute volume is the total volume of air moved over one minute, not during a single breath. It is a measure of the overall rate of ventilation.
Option C: Lung capacity refers to combinations of different lung volumes (e.g., Vital Capacity, Total Lung Capacity), not the volume of a single normal breath.
Option D: Lung reserve refers to the volumes that can be inhaled or exhaled forcefully, beyond a normal breath (Inspiratory and Expiratory Reserve Volumes).

Visual 1: Diagram: A spirogram trace showing the different lung volumes (Tidal Volume, Inspiratory Reserve Volume, Expiratory Reserve Volume, Residual Volume) and capacities (Vital Capacity, Total Lung Capacity). This visual helps differentiate between the terms and understand their relationships.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definitions of Pulmonary Lung Volumes as background academic context rather than a clinical decision trigger.
In nursing, monitoring tidal volume is critical for patients on mechanical ventilation. Incorrect settings can lead to lung injury (volutrauma) or inadequate gas exchange.
A patient's spontaneous tidal volume can be a key indicator of respiratory distress. A decreasing tidal volume may signal worsening respiratory muscle fatigue, requiring intervention.
What if? If a patient on a ventilator has a set tidal volume of 500 mL but their peak airway pressures are consistently high, the nurse should anticipate a potential order to decrease the tidal volume and increase the respiratory rate to maintain minute ventilation while protecting the lungs. This is a common lung-protective strategy.

How to Approach the Question

Identify the core concept being asked: The question is asking for the specific term for the volume of a single, normal breath.
Analyze the keywords: "volume of air," "in and out," and "each respiration" all point to a single respiratory cycle.
Evaluate each option against the definition:
'Tidal volume' is the volume per breath.
'Minute volume' is the volume per minute.
'Lung capacity' is a combination of volumes.

Concept Tested & Keywords

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Practise the full KGMU 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.