Pulmonary 2 Lung Volumes and Ventilation

Summary

This lecture delves into the mechanics of a spirometer, a device measuring lung volumes and capacities. It explains the traditional water displacement method and modern alternatives, and covers both static and dynamic lung function assessments. The importance of understanding lung volumes, such as vital capacity and total lung capacity, is highlighted, along with dynamic measures like forced vital capacity and maximum voluntary ventilation, crucial for diagnosing respiratory conditions. The lecture also touches on concepts like dead space and alveolar ventilation, essential for gas exchange efficiency.

Takeaways

• 🌊 A spirometer is a device used to measure lung volumes and capacities, traditionally involving a water-filled chamber and a tube for breathing.
• 📏 The movement of air due to breathing causes the water level in the spirometer to rise and fall, which is directly proportional to the volume of air displaced.
• 📊 Lung volume measurements are calibrated using markers or scales on the spirometer for precise readings.
• 🚀 Modern spirometers have evolved to be smaller, with examples like turbine models and clinical ear displacement boxes.
• 🔍 Lung volumes can vary significantly based on factors such as age, gender, body size, and height.
• 🏗️ Static lung volume tests measure the dimensional aspects of air movement without time limitations, providing a snapshot of lung volume.
• 🌪️ Dynamic lung volume tests assess air movement over time, focusing on expiratory power and resistance to air movement in the lungs.
• 📉 The ratio of forced expired volume in 1 second to forced vital capacity (FEV1/FVC) is a key dynamic measure, with lower ratios indicating potential lung obstruction.
• 🏋️‍♂️ Maximum voluntary ventilation (MVV) measures the maximum volume of air a person can breathe in one minute, with elite athletes showing remarkably high values.
• 🌀 Dead space refers to the portion of the respiratory tract where gas exchange does not occur, including both anatomic and physiological dead spaces.
• 🔄 Alveolar ventilation is the portion of minute ventilation that reaches the alveoli for gas exchange, affected by the presence of dead space.

Q & A

What is a spirometer and what is its primary function?

A spirometer is a device used to measure lung volumes and capacities in respiratory physiology. It operates by having a subject breathe in and out through a tube connected to a chamber filled with water. The fluctuation in water level, which is proportional to the volume of air displaced, is used to measure lung function.

How are the markers or scales on a spirometer used?

The markers or scales on a spirometer are calibrated to specific volume measurements, allowing for precise readings of the water level changes. This enables researchers and clinicians to quantify various lung parameters with accuracy.

What are the two types of measurements used to assess lung volumes and capacities?

The two types of measurements used to assess lung volumes and capacities are static and dynamic measurements. Static lung volume tests focus on the dimensional aspects of air movement within the pulmonary tract without time limitation, while dynamic tests assess expiratory power and resistance to air movement in the lungs.

What is the significance of the forced vital capacity (FVC) in lung function testing?

The forced vital capacity (FVC) represents the total lung volume moved in one breath from full inspiration to maximum expiration. It is a crucial measure in lung function testing as it provides insights into the overall lung capacity and can indicate the presence of respiratory conditions.

How does the forced expiratory volume in 1 second (FEV1) relate to FVC and why is it important?

The FEV1 is the volume of air expired during the first second of a forced vital capacity maneuver. The ratio of FEV1 to FVC is important as it provides diagnostic insights into expiratory power and resistance in the lungs. A decreased ratio can indicate conditions like severe obstructive pulmonary disease or asthma.

What is the maximum voluntary ventilation (MVV) and how is it measured?

The maximum voluntary ventilation (MVV) is the volume of air breathed during rapid and deep breathing for 15 seconds, multiplied by four to represent the volume breathed for 1 minute. It is an assessment of ventilatory capacity and can vary significantly among individuals, including elite athletes.

What is the role of the tidal volume in respiratory physiology?

Tidal volume refers to the volume of air moved during either the inspiratory or expiratory phase of each breathing cycle under resting conditions. It is a key parameter in understanding the efficiency of the respiratory system and gas exchange.

What is the significance of the residual lung volume (RLV) in lung function?

The residual lung volume (RLV) is the volume of air that remains in the lungs after maximal exhalation. It contributes to the total lung capacity and can be affected by various factors, including the individual's height and potential genetic influences.

What is meant by 'anatomic dead space' in the respiratory tract?

Anatomic dead space refers to the portion of the respiratory tract, such as the nose, mouth, and trachea, where air remains and does not participate in gas exchange. It is a part of the total volume of air inhaled but does not contribute to alveolar ventilation.

How does physiological dead space differ from anatomic dead space?

Physiological dead space refers to the portion of alveolar volume with poor tissue perfusion or inadequate ventilation, which does not participate in gas exchange. Unlike anatomic dead space, physiological dead space can increase significantly in certain conditions due to inadequate perfusion or ventilation.

What factors can affect the efficiency of alveolar ventilation?

Factors that can affect the efficiency of alveolar ventilation include the presence of dead space, the depth of breathing, and the individual's overall lung function. Efficient alveolar ventilation is crucial for maintaining consistent alveolar air composition and stable arterial blood gases.

Outlines

00:00

🌡️ Understanding the Spirometer and Lung Volumes

This paragraph introduces the concept of measuring lung volumes and capacities using a spirometer, a device traditionally involving a water-filled chamber. The movement of air by the subject's breathing causes the water level to fluctuate, which is proportional to the air volume displaced. Markers or scales on the spirometer allow for precise volume readings. The paragraph also explains the evolution of spirometers and the importance of factors like age, gender, body size, and height in lung volume variations. It distinguishes between static and dynamic lung measurements, with static measurements providing a snapshot of lung volume at a specific time without time constraints, and dynamic measurements assessing the power and resistance of air movement in the lungs.

05:02

🏃‍♂️ Dynamic Lung Function Measurements and Ventilation

This section delves into dynamic lung function measurements, focusing on the forced vital capacity (FVC) and the speed of air movement, which is influenced by the resistance of the pulmonary airways and lung compliance. The forced expiratory volume in one second (FEV1) to FVC ratio is highlighted as a key diagnostic tool for conditions like obstructive pulmonary disease and asthma. The maximum voluntary ventilation (MVV) test, which measures the volume of air breathed during rapid and deep breathing, is also discussed, with variations in MVV among healthy individuals, athletes, and those with lung diseases. The paragraph concludes with an explanation of minute ventilation, anatomical dead space, and the physiological significance of alveolar ventilation in maintaining stable arterial blood gases.

10:04

🌬️ Alveolar Ventilation and Dead Space

The final paragraph discusses the intricacies of alveolar ventilation and the concept of dead space in the respiratory system. It explains the difference between anatomical dead space, which is the volume of air that does not reach the alveoli, and physiological dead space, which refers to alveolar regions with poor tissue perfusion or inadequate ventilation. The paragraph illustrates how changes in breathing patterns, such as shallow or deep breathing, affect minute ventilation and alveolar ventilation. It emphasizes the importance of understanding the relationship between these two types of ventilation for assessing lung function and gas exchange efficiency.

Keywords

💡Sphygmomanometer

A sphygmomanometer is a device used to measure blood pressure, but in the context of this video, it refers to a spirometer, which is used to measure lung volumes and capacities. The spirometer is central to the video's theme of pulmonary physiology, as it is the primary tool for assessing lung function. The script describes a water-filled chamber that measures air displacement through the rise and fall of the water level as a subject breathes.

💡Lung Volumes

Lung volumes refer to the amount of air that can be inhaled or exhaled at different stages of breathing. The video discusses lung volumes in the context of respiratory physiology, explaining how they are measured using a spirometer. The script mentions various lung volumes such as tidal volume, inspiratory reserve volume, and expiratory reserve volume, which are essential for understanding lung capacity and function.

💡Tidal Volume

Tidal volume is the amount of air that is inhaled and exhaled during normal, resting breathing. The video script provides a specific range for tidal volume in healthy individuals, which is between 0.4 and 1 L of air per breath. Tidal volume is a fundamental concept in the video, as it is a standard measurement for assessing lung function.

💡Inspiratory Reserve Volume (IRV)

Inspiratory reserve volume is the additional volume of air that can be inhaled after a normal inhalation. The script describes it as a volume of 2.5 to 3.5 L above the tidal volume, which is reserved for deep inhalation. IRV is a key concept in the video, as it helps to understand the maximum lung capacity beyond normal breathing.

💡Expiratory Reserve Volume (ERV)

Expiratory reserve volume is the volume of air that can be exhaled after a normal exhalation. The video script specifies that ERV ranges between 1 and 1.5 L for men and is about 10 to 20% lower for women. ERV is an important part of the video's discussion on lung function, as it contributes to the total lung capacity.

💡Forced Vital Capacity (FVC)

Forced vital capacity is the total volume of air that can be expelled from the lungs after a full inhalation. The video script explains that FVC represents the volume moved in one breath from full inspiration to maximum expiration and is a crucial measurement for assessing lung health. It is used to diagnose conditions that affect lung function.

💡Residual Lung Volume (RLV)

Residual lung volume is the volume of air that remains in the lungs after a maximal exhalation. The script provides average values for RLV, which are between 0.9 and 1.2 L for young adult women and 1.1 and 1.7 L for men. RLV is an important concept in the video, as it contributes to the total lung capacity and is an indicator of lung health.

💡Total Lung Capacity (TLC)

Total lung capacity is the sum of all the lung volumes, including tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual lung volume. The video script notes that TLC averages 6 L for males and 4.2 L for females. TLC is a key concept in the video, as it represents the maximum volume of air the lungs can hold.

💡Forced Expiratory Volume in 1 Second (FEV1)

Forced expiratory volume in 1 second is the volume of air that can be expelled from the lungs during the first second of a forced exhalation. The video script discusses the FEV1 to FVC ratio, which is a diagnostic tool for assessing expiratory power and resistance to air movement in the lungs. A decrease in this ratio can indicate lung diseases such as severe obstructive pulmonary disease.

💡Maximum Voluntary Ventilation (MVV)

Maximum voluntary ventilation is the maximum volume of air that can be breathed in one minute during rapid and deep breathing. The video script provides average MVV values for healthy young men and women and notes that elite athletes can achieve remarkably high MVV values. MVV is an important concept in the video, as it reflects the maximum ventilatory capacity of the lungs.

💡Dead Space

Dead space refers to the portion of the respiratory tract where gas exchange does not occur. The video script distinguishes between anatomic dead space, which is the volume of air that fills the conducting airways, and physiological dead space, which is the portion of alveolar volume with poor tissue perfusion or inadequate ventilation. Dead space is a key concept in the video, as it affects the efficiency of gas exchange in the lungs.

Highlights

Introduction to the water-filled spirometer, a device for measuring lung volumes and capacities in respiratory physiology.

Explanation of how the spirometer works, with the water level fluctuating in proportion to the volume of air displaced by breathing.

Description of the markers or scales on the spirometer for precise readings of lung volume changes.

Evolution of spirometers over the last century, with modern devices being smaller and more portable.

Importance of considering factors like age, gender, body size, and height when measuring lung volumes.

Introduction to static and dynamic measurements for assessing lung volumes and capacities.

Static lung volume tests provide a snapshot of lung dimensions without time limitations.

Dynamic lung function tests assess expiratory power and resistance to air movement in the lungs.

Definition and explanation of various lung volumes, including tidal volume, inspiratory reserve volume, and expiratory reserve volume.

Forced vital capacity (FVC) represents the total lung volume moved in one breath from full inspiration to maximum expiration.

Residual lung volume (RLV) is the air remaining in the lungs after maximal exhalation.

Total lung capacity is calculated by adding various lung volume measurements together.

Forced expiratory volume in 1 second (FEV1) and its ratio to FVC are important dynamic lung function measures.

Decreased FEV1/FVC ratio indicates compromised lung function, such as in obstructive pulmonary disease.

Maximum voluntary ventilation (MVV) test assesses the volume of air breathed during rapid and deep breathing.

Elite athletes can achieve remarkably high MVV values, exceeding 240 liters per minute.

Minute ventilation is calculated by multiplying the breathing rate by the tidal volume.

Alveolar ventilation refers to the portion of minute ventilation that reaches the alveoli for gas exchange.

Anatomic dead space is the volume of air that does not reach the alveoli and is fully saturated with water vapor.

Physiological dead space refers to alveolar volume with poor tissue perfusion or inadequate ventilation.

The relationship between minute ventilation and alveolar ventilation is crucial for understanding gas exchange efficiency.

Different breathing patterns, such as shallow or deep breathing, impact alveolar ventilation and gas concentrations at the alveolar-capillary membrane.

Transcripts

welcome to the second of the pulmonary

physiology lectures this short video

will provide you with the information to

be able to address the following

learning

objectives let's uncover the inner

workings of a water field spherometer a

device used to measure lung volumes and

capacities in respiratory

physiology picture this at the heart of

the spherometer is a chamber filled with

water typically contained within a

sealed container

connected to this chamber is a tube or

mouthpiece through which the subject

breathes as the subject breathes in and

out the movement of air causes the water

level within the chamber to rise and

fall and it's this fluctuation in water

level which is directly proportional to

the volume of air displaced by the

subject's

breathing now to measure lung volumes

accurately the spirometer is equipped

with a series of markers or scales that

allow for precise readings of the water

level changes now these markers are

calibrated to specific volume

measurements enabling researchers and

clinicians to quantify various lung

parameters with

Precision overall the water field

barometer provides a simple yet

effective means of assessing lung

function now while this is the

traditional me method to measure lung

volumes spirometers have evolved over

the last century with more common

devices now being much smaller such as a

turbine model pictured at the top right

or the clinical ear displacement box

seen at the bottom

right let's take a closer look at aung

volume tracing now it's important to

note that these lung volumes can and

will vary significantly based on factors

such as age gender body size and

composition with the person's height

playing a particularly significant

role let's explore the two types of

measurements used to assess lung volumes

and capacities these are static and

dynamic measurements now a static lung

volume tests focus on the dimensional

aspects of air movement within the

pulmonary tract unlike Dynamic tests

static measurements impose no time

limitation on the individual undergoing

the test instead they provide a snapshot

of the volume dimensions of the lungs at

a specific point in time offering

valuable insights into lung function

let's dive into the intricacies of

static lung function measurement where

the spirometer Bell serves as our guide

falling and Rising with each inhalation

and exhalation to record ventilatory

volume and breathing rate total volume

is our starting point point and it

describes the air move during e either

the inspiratory or the expiratory phase

of each breathing cycle under resting

conditions tital volume ranges between

point4 and 1 L of air per breath for

healthy

individuals moving on WE encounter the

inspect Reserve volume or the

Irv an additional volume of 2.5 to 3.5 L

above tital volume reserved for deep

inhalation to measure inpat Reserve

volume individuals Inspire normally and

then maximally after recording several

representative title

volumes now let's explore the expert

Reserve volume or Erv and this ranges

between 1 and 1 and 1/2 L for men and

it's about 10 to 20% lower for women

following a normal exhalation

individuals continue to Exhale

forcefully to determine their expert

Reserve

volume now the force votal capacity or

fvc represents the total ear volume

moved in one breath from Full

inspiration to maximum expiration or

vice versa and values usually aage

between 4 to 5 l in healthy young men

and 3 to 4 L in healthy young

women interestingly large lung volumes

such as Force votal capacities of 6 to 7

l or even higher are not uncommon for

tall individuals and some professional

athletes now these variations likely

reflect genetic factors rather than

training

effects and finally we encounter the

residual lung volume or the rlv the

volume of air that remains in the lungs

after maximal

exhalation residual lung volume averages

between .9 and 1.2 L for young adult

women and 1.1 and 1.7 L for men now this

gives a total lung capacity of 6 L on

average for males and 4.2 L on average

for

females note that capacities are

produced by adding one or more volume

measurements together

let's unravel the dynamic measures of

pulmonary ventilation which hinge on two

crucial factors firstly we have the

maximum ear volume expired known as the

force vital capacity or fvc and secondly

we consider the speed of moving a volume

of air which relies on two key factors

the resistance of the pulmonary Airways

to smooth air flow and the resistance or

stiffness presented by chest and lung

tissue to changes in their shapee during

breathing termed lung

compliance now let's delve into the

ratio of forced expired volume in 1

second to force vital

capacity now unlike static lung function

measures Dynamic measures like the F1

provide valuable diagnostic insights as

they assess expiratory power and overall

resistance to ear movement in the

lungs under normal conditions the fv1 to

fvc ratio averages around

85% however in conditions like severe

obstructive pulmonary osma and bronchial

asthma this ratio typically decreases

below 40% of vital

capacity a clinical demarcation for

Airway obstruction is established when

an individual expels less than 70% of

the force vital capacity in 1 second

indicating a compromised lung function

another Dynamic assessment of

ventilatory capacity is the maximum

voluntary ventilation test during this

test individuals engage in Rapid and

deep breathing for 15 seconds the volume

of air breathe during this time is then

multiplied by four to represent the

volume breathe for 1 minute giving us

the maximum voluntary ventilation or

mvv in healthy young men mvv typically

ranges between 140 and 180 L per minute

while women generally have an average

mvv ranging from 80 to 120 L per minute

it's fascinating to note that Elite

athletes can achieve remarkable mvv

values for instance male members of the

United States Nordic ski team have been

known to average 192 lers per minute

with individuals reaching values in

excess of 240 L per

minute at the other end of the Continuum

is individuals with obstructive lung

disease who face significant challenges

in achieving mvv values comparable to

those predicted for their normal age and

height match controls typically they

only achieve about 40% of what is

predicted during quiet breathing at rest

adults typically breathe at a rate of

around 12 breaths per minute with each

breath moving around half a liter of air

this means we move 6 l or 6,000 M of air

into and out of our lung each minute to

calculate our minute ventilation we

simply multiply the breathing rate by

the tital

volume the alola ventilation refers to

the portion of minute ventilation that

actually reaches the alola chambers

where gas exchange with the bloodstream

occurs however not all inspired air

makes it to the alvioli

a portion remains in the non- diffusible

conducting portions of the respiratory

tract such as the nose mouth and trache

this portion is known as the anatomic

dead space in healthy individuals the

anatomic Dead Space volume equals

approximately 150 to 200 mL or about 30%

of a resting total volume despite its

composition being almost equivalent to

ambient air Dead Space air is fully

saturated with water

vapor now due to the presence of Dead

Space only a portion of the ambient ear

inspired in each breath about 350 of the

500 mL of the title volume mixes with

existing lvol air however it's important

to note that this doesn't mean only 350

mL of air enter and leave the LVL with

each breath in reality the full total

volume of 500 m enters the

Alvi but only 350 ml represents fresh

air which is about 17th of the total air

in the

alvolo this seemingly inefficient

alviola ventilation is actually an

evolutionary protective mechanism to

maintain consistency in alveola air

composition and ensure stable arterial

blood gases throughout the breathing

cycle

now the only remaining component of the

tital volume is the physiological Dead

Space a term used to describe the

portion of alveola volume with poor

tissue Regional profusion or inadequate

ventilation as Illustrated in the figure

healthy lungs typically have only a

negligible amount of physiological Dead

Space however in certain conditions

physiological Dead Space can increase

significantly reaching up to 50% of the

resting title volume

this increase can occur due to two main

factors firstly inadequate perfusion may

occur during condition such as

Hemorrhage or an embolism which is a

blood clot that blocks pulmonary

circulation in such cases blood flow to

certain regions of the lungs may be

compromised leading to an increase in

physiological Dead

Space secondly inadequate lvol

ventilation may result from chronic

pulmonary diseases further contributing

to an increase in physiological Dead

Space now then let's look at this table

which sheds light on the complexity of

minute ventilation and its relationship

to real alola

ventilation in the first example of

shallow breathing where total volume

decreases to 150 ml minute ventilation

remains at 6 L per minute due to an

increase in breathing rate to 40 breaths

per

minute conversely the same minute

ventilation of 6 L per minute can be

achieved by decreasing breathing rate to

12 breaths and increasing tidal volume

to 500

mL now let's consider the example of

deep breathing where tidal volume is

doubled and ventilatory rate is

halfed again we achieve a minute

ventilation of 6 L per minute however

each ventilatory adjustment drastically

impact and impacts lvol

ventilation in the case of shallow

breathing dead SP space ear represents

the entire ear volume moved as no alola

ventilation

occurs conversely in the other examples

involving deeper breathing a larger

portion of the a breath of it sorry of

each breath mixes with existing alveola

air leading to effective alviola

ventilation it's crucial to note that

alveola ventilation and not dead space

ventilation determines the gaseous

concentrations at the elola capillary

membrane highlighting the significance

of understanding the relationship

between minute ventilation and Lola

ventilation but now you should feel well

prepared to tackle the learning

objectives