lung volumes and capacities hala salah2012

7/31/2019 Lung Volumes and Capacities HALA SALAH2012

1/71


2/71

Lung volumes and

capacities

BY

Dr/HALA SALAHPhysiologyofProf.


3/71

Determination of lung volumes is

used to :

1-assess the efficiency of the respiratory system.

2-diagnose respiratory diseases.Most of these volumes can be measured

using a simplespirometer


4/71

THE SPIROMETER Old version

spirometer bell

kymograph pen

New version


5/71

LUNG

VOLUMES


6/71

It is the volume of air inspired or

expired each breath during normalquiet breathing. It is about 500 ml.

Tidal volume (VT)


7/71

Tidal volume


8/71

Inspiratory reserve volume (IRV)

It is maximal

volume of air

which can beinspired after a

normal

inspiration. It is

about 3000 ml.


9/71

Expiratory reserve volume (ERV)

It is the maximal

volume of air

which can be

expired after a

normalexpiration. It is

about 1100 ml.


10/71

Residual volume (RV)

It is the volume ofair remaining in

the lungs after

maximal

expiration.

It is about 1200ml.


11/71

Tidal volume

Dead space

Tidal volume

Inspiratory reserve

volume

Expiratory reserve

volume

LUNG VOLUMES

Residual

Volume


12/71

LUNGCAPACITIES


13/71

PULMONARY CAPACITIES

A capacity is two volumes or more added

together.


14/71

Inspiratory capacity (IC)

It is the maximalvolume of air that

can be inspired

from the resting

expiratory

volume.IC3500 mL

IC500+ 3000

ICTV + IRV


15/71


16/71

Functional residual capacity (FRC)

It is the volume of air which remains in the lung

at the resting expiratory level (after normal

expiration).

FRC = RV + ERV

= 1200 + 1100

2300 ml


17/71


18/71

Vital capacity (VC)

It is the maximum volumeof air that can beexpelled from lung bya maximal expiration

after a maximalinspiration.

VC = IRV + TV + ERV

3000 +500 +1100 =4600It is a good index for

pulmonary efficiency.


19/71

Total lung capacity (TLC)

It the volume of air contained in the lung at

the end of maximal inspiration.TLC = IRV + TV + ERV + RV

= 3000 + 500+ 1100 + 1200 =

5800 ml.


20/71


21/71


22/71

Lung volumes and capacities are

Decreased in

The recumbent position than in standing.

Women than in men by about 20-25% .Small and athenic persons.

Old age.

Increased in :Larger and athletic persons.

Vao day nghe bai nay di banhttp://nhatquanglan.xlphp.net/


23/71


24/71

All lung volume and capacities are measured

except:spirometerdirectly by

Functional Residual capacity FRC.

Total lung capacity TLC.

Residual volume RV.

Because the air in the residual volume of the lung cannot be

expired into the spirometer and this volume constitutes

part of FRC, TLC.


25/71

Lung volumes measured by spirometer

For the others parameters additional measurements needed

Values obtained by simple spirometry


26/71

Race Weight Height Sex Age

Factors affecting lung volumes and

capacities


27/71

% Predicted Value

Observed value/predicted value x100%


28/71


29/71

Determination of RV and FRC

They are measured indirectly using

helium dilution method


30/71


31/71

Helium dilution

Spirometer of known volume (Vs)and HeConc .(C1) connected to the patient.

At end of normal expiration.

-Closed circuit

-After several minutes of breathing.

-C1XV1=C2X(Vs+VL)

-C2= final He conc,VL=FRC.

At beginning After several minutes

Unknown lung volume can be calculated

[He] initial Vs = [He] final (Vs + VL)

Determination of RV and FRC


32/71

Clinical significance of FRCFRC maintains gas exchange with blood in between

breaths.

The large volume of FRC prevents marked rise in

alveolar pressure of oxygen i.e. it provides stability of

oxygen pressure in the arterial blood.

Normally the residual volume should be less than30%

of the total lung capacity. It exceeds that level insome pathological conditions e.g. Bronchial asthma

(RV/TLC>30 % ).


33/71

Factors affecting the vital capacity

Posture .

Movement of diaphragm.

Strength of Respiratory Muscles.Thoracic wall expansibility.

Resistance to air flow.

Lung elasticity.Restrictive lung disease.


34/71


35/71


36/71

Timed vital capacity

It is the volume of expired air at the end of the

first, second or third second, when measuring

vital capacity.

also called forced expiratory volume (FEV).


37/71

TIMED VITAL CAPACITY (FVC)

Importance of the timed VC

The timed vital capacity is a useful test to

differentiate between obstructive lungdiseases (COPD) as emphysema and

chronic bronchitis and restrictive lung

diseases as interstitial lung fibrosis.


38/71

How to measure FVC ?

The patient is asked to

inspire as deep as

possible and expires as

deep and as rapid as hecan into the spirometer

that measures not only

the volume expired but

also the time taken in

expiration. Normally

the FVC takes place in

4 seconds.


39/71

Spirometry


40/71


41/71


42/71

FEV1 & FVC

Forced expiratory volume

in 1 second (FEV1) in

young trained athletes: 4 L

FVC in young trainedathletes: 5 L

FEV1/FVC %=

80%-83%

FEV1

FVC

FVC


43/71

In obstructive lung diseases, the air way

resistance is greatly increased, the vital

capacity is reduced and FEV1 is markedly

reduced FEV1/FVC is less than 80%. While inrestrictive lung disease FEV1/FVC is normal or

even increased 90% due to proportionate

decrease in both FEV1 and FVC.

S i t I t t ti Ob t ti R t i ti


44/71

Spirometry Interpretation: Obstructive vs. Restrictive

diseases

Obstructive Disorders

FEV1/FVC

Restrictive Disorders

FEV1/FVC normal or


45/71


46/71

Restrictive lung diseases


47/71


48/71


49/71

Minute Respiratory Volume

Minute Ventilation=

VT X breathing frequency

= 500 ml X12 b/min

= 6000 ml/min

= 6 L/min


50/71

Maximal voluntary ventilation

M i l V l t V til ti


51/71

Maximal Voluntary Ventilation

(MVV)

It is the maximal volume of air that can be breathed per minuteusing the fastest rate and the deepest respiratory effortpossible.

The subject breathes as fast and as deep as possible for 15

seconds only-To avoid fatigue of the respiratory muscles.

-To avoid wash out of CO2 .

Normal MVV = 80-160 L/min for male,

= 60-120 L /min for females,average 100 L/minute .

It is a better index for:

1- respiratory efficiency.

2- physical fitness .


52/71

Breathing reserve (BR)

It is the difference between MVV and minute

Respiratory volume

BR = MVVMRV

1006 = 94 L/min.

It is a good test for the functional reserve of the respiratory

system and the higher is the BR, the better the state of

physical fitness.


53/71

THANK

YOU


54/71


55/71


56/71

Al l d d


57/71

Alveolar dead space


58/71


59/71

Dead space

It is the volume of air which does notundergo gas exchange with pulmonarycapillaries .

Types of dead space:

Anatomical dead space.

Alveolar dead space.

Physiological dead space.


60/71

Dead Space Ventilation [VDS]

Includes ventilation of both:

1. the anatomic dead space: the portion of the

breath that enters and leaves the conductingzones of the airways (nose terminalbronchioles)

2. the alveolar dead space: air that reaches the

alveoli but does not participate in gas exchangeAlveolar DS + Anatomic DS= Physiologic DS


61/71

Measurement of dead space

By using Bohr's equation (physiological DS):

DS =TVXPCO2 in alveolar airPCO2 in expired air

PCO2 in alveolar air

PCO2 in arterial blood 40mmHgPCO2 in expired air 28mmHgT.V 500ml

= 500 X

40

2840


62/71

Nitrogen-meter method

Fowlers Method

(Anatomic DS)

M t f A t i D d S


63/71

Measurement of Anatomic Dead Space.[ Fowlers Method ]

The Fowlers method is based of the

principle that the last bit of air you breath

in, you breath out first & it represents gasin the anatomic dead space (conductingairways).

The remaining expired gas represents amixture of gas in the alveoli and anatomicdead space.


64/71


65/71

Nitrogen-meter method


66/71

Procedure

maximal expiration to RV maximal inspiration to TLC of100% O2 maximal expiration to RV performed slowly

measure the [N2] during expiration.Phase Ifirst bit of gas expired from TLC, 0% N2:pure anatomic dead spacegasPhase IItransition phase, mixture of 100% O2 in anatomic DS & alveolargasPhase IIIalveolar plateau, gas from alveoli(40 %N2)

VDS measured as the volume expired between beginning ofexpiration & mid point determined geometrically


67/71

Functions of the dead space:-

Conduction of air to and from the alveoli.

Conditioning of inspired air.

Filtration of inspired air.Initiation of sneezing and cough reflexes.

Secretion of immunoglobulin (antibodies).

Perception of smell sensation.

Production of sound (phonation


68/71

Alveolar Ventilation

Alveolar ventilation

the portion of breathing

that reaches the alveoli

& participates ingas exchange

Ventilation: Minute(MRV)


69/71

Ventilation: Minute(MRV),Alveolar(VA )& Dead Space(VDS)

MRV=VT X breathing frequency =

500ml X12= 6.0 L/min.

VA=VA X breathing frequency =

(VT-VDS)XR.R=

(500-350)X12=350ml X12= 4.2 L/min


70/71

Dyspneic index

It is the ratio between BR and MVV and it isusually about 90%. If it is decreased below 60%

dyspnea (difficulty in breathing) occurs onslightest effect and the person is consideredphysically unfit.


71/71

Vao day nghe bai nay di banhttp://nhatquanglan.xlphp.net/

C:\WINDOWS\hinhem.scr

lung volumes and capacities hala salah2012

Documents