Lung Volumes and Capacities

Static Lung Volumes & Capacities

• Tidal Volume (TV) is the volume of air inspired or expired per breath, with typical ranges of 600 mL for males and 500 mL for females
• Inspiratory Reserve Volume (IRV) is the maximum inspiration at the end of tidal inspiration, averaging 3000 mL for males and 1900 mL for females
• Expiratory Reserve Volume (ERV) is the maximum expiration at the end of tidal expiration, typically 1200 mL for males and 800 mL for females
• Total Lung Capacity (TLC) is the volume in the lungs after a maximum inspiration, about 6000 mL in males and 4200 mL in females
• Residual Lung Volume (RLV) is the volume remaining in the lung after maximum expiration, around 1200 mL for males and 1000 mL for females
• Forced Vital Capacity (FVC) is the maximum volume expired after maximum inspiration, usually 4800 mL in males and 3200 mL in females
• Inspiratory Capacity (IC) is the maximum volume inspired following tidal expiration, approximately 3600 mL in males and 2400 mL in females
• Functional Residual Capacity (FRC) is the volume in the lungs after tidal expiration, about 2400 mL in males and 1800 mL in females

Dynamic Lung Volumes - Spirometry

• Spirometry is a lung function test
• Spirometry measures how much and how quickly air moves in and out of the lungs
• Spirometry is used to assess airflow obstructions and restrictions
• A spirometer is an instrument that measures dynamic lung volumes and flows
• Vitalographs and Parvo Medics are types of spirometers
• Vitalographs measures Forced Vital Capacity (FVC)
• Parvo Medics measures Forced Vital Capacity (FVC), Slow Vital Capacity (SVC), and Maximal Voluntary Ventilation (MVV)

Forced Vital Capacity (FVC)

• Forced Vital Capacity (FVC), is the maximum air volume expired during a manoeuvre using maximum effort after inspiration
• Reference values for FVC are in the Lab Book, page 48.

Volume/Time Curve

• FVC stands for Forced Vital Capacity
• FEV1 is the Forced Expiratory Volume in 1 second
• FEV1/FVC ratio indicates airflow obstruction

Spirometry – Ventilatory Defects

• Obstructive ventilatory defects involve difficulty expiring, with a reduced FEV1, e.g. Asthma
• Restrictive ventilatory defects involve reduced FVC and FEV1, e.g. Interstitial lung disease
• Mixed ventilatory defects involve both obstructive and restrictive components, e.g. Lung cancer
• Reduced FEV1 is indicative of obstruction
• Reduced FVC is indicative of restriction
• Reduced FEV1 with normal FVC shows obstruction
• Normal FEV1 with reduced FVC shows restriction

Flow/Volume Loop

• FVC stands for Forced Vital Capacity
• FEV1 stands for Forced Expiratory Volume in one second.
• FEF25-75% measures forced expiratory flow between 25% and 75% of the FVC.
• FEF25-75% averages air flow over the middle half of the FVC manoeuvre
• FEF25-75% is more sensitive in detecting narrowing of the smaller airways than FEV1

Flow/Volume Loop – Definitions

• Forced Vital Capacity (FVC) is the volume of air that can forcibly be expired after full inspiration
• Forced Expiratory Volume (FEV1) is the volume of air that can forcibly be expired in 1 second after full inspiration
• Peak Expiratory Flow (PEF) is the maximal flow (or speed) achieved during the maximally forced expiration initiated at full inspiration
• Forced Expiratory Flow (FEF) is the flow (or speed) of air coming out of the lung during the middle portion of a forced expiration
• Forced Inspiratory Flow (FIF) is the flow (or speed) of air coming out of the lung during the middle portion of a forced inspiration

Slow Vital Capacity (SVC)

• Slow Vital Capacity (SVC) includes 4 tidal breaths
• SVC is followed by full inspiration and slow expiration
• SVC is similar to FVC in healthy subjects
• SVC is greater than FVC in individuals with airflow obstruction

Maximum Voluntary Ventilation (MVV)

• MVV is the volume of air expired in a specified period during repetitive maximal effort
• MVV involves breathing as fast and deeply as possible for 12 seconds, then extrapolate values to 1 minute
• MVV is approximately 25% higher than maximum exercise ventilation
• Normal MVV range for males is 140 – 180 L/min
• Normal MVV range for females is 80 – 120 L/min

Exercise Induced Bronchospasm/Asthma (EIB/EIA)

• EIB/EIA is a temporary increase in airway resistance following vigorous exercise
• EIB/EIA occurs mostly in athletes with clinically diagnosed asthma
• EIB/EIA affects approximately 80% of athletes taking an inhaler and 50% of those not on medication

Exercise Induced Asthma – Pathophysiology

• Bronchoconstriction does not occur during exercise, but on recovery
• During early exercise flow rates increase
• Between 6-8 minutes into exercise flow rates decrease
• Between 5-12 minutes post-exercise there is the lowest flow rate
• Aggravating factors include pollen, cold and dry air, and allergens

EIA – Medication & Sport

• β2 agonists and corticosteroids in bronchodilators are banned by WADA
• Athletes need a Eucapnic Challenge Test for a Therapeutic Use Exemption (TUE)
• Athletes must check the WADA/ASADA status of asthma medication before use

EIA – Diagnosis

• Obtain history of asthmatic events and family history of asthma
• Perform Vitalograph testing
• Perform Indirect Challenge Testing with an Exercise or Eucapnic challenge test

EIA – Challenge Testing

• Exercise Challenge Test involves 4-8 minutes of exercise at 50% athlete’s MVV
• A limitation of the exercise challenge test, is that sufficient ventilation rates in athletes are difficult to achieve

EIA – Challenge Testing: Eucapnic Challenge Test

• Eucapnic Challenge Test involves voluntary ventilation of dry air containing 4.9% CO2
• Progressive Test: 3-minute stages at 30%, 60%, 90% of MVV
• Continuous Test: 6-minute stage at 80% MVV