Respiratory system

Respiration Includes

• Pulmonary ventilation– Air moves in and out of lungs– Continuous replacement of gases in alveoli (air sacs)

• External respiration– Gas exchange between blood and air at alveoli– O2 (oxygen) in air diffuses into blood– CO2 (carbon dioxide) in blood diffuses into air

• Transport of respiratory gases– Between the lungs and the cells of the body– Performed by the cardiovascular system– Blood is the transporting fluid

• Internal respiration– Gas exchange in capillaries between blood and tissue cells– O2 in blood diffuses into tissues– CO2 waste in tissues diffuses into blood

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3

The Respiratory Organs

Nose

Pharynx

Larynx

Trachea

Bronchi

Lungs –alveoli

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Upper Respiratory Tract

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Nose

• Provides airway

• Moistens and warms air

• Filters air

• Resonating chamber for speech

• Olfactory receptors

Olfactory receptors are located in the mucosa on the superior surface

The rest of the cavity is lined with respiratory mucosa

Moistens air

Traps incoming foreign particles

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Structure of Nose

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Lateral walls have projections called conchae

Increases surface area

Increases air turbulence within the nasal cavity

The nasal cavity is separated from the oral cavity by the palate

Anterior hard palate (bone)

Posterior soft palate (muscle)

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Paranasal sinuses

Cavities within bones surrounding the nasal cavity– Frontal, sphenoid, ethmoid and maxillary bones

– Open into nasal cavity

– Lined by same mucosa as nasal cavity and perform same functions

– Also lighten the skull

– Can get infected: sinusitis

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The Pharynx (throat)

• 3 parts: naso-, oro- and laryngo pharynx

• Houses tonsils (they respond to inhaled antigens)

• Uvula closes off nasopharynx during swallowing so food doesn’t go into nose

• Epiglottis posterior to the tongue: keeps food out of airway

• Oropharynx and laryngopharynx serve as common passageway for food and air

• Lined with stratified squamous epithelium for protection

Tonsils of the pharynx

Pharyngeal tonsil (adenoids) in the nasopharynx

Palatine tonsils in the oropharynx

Lingual tonsils at the base of the tongue

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Nasopharynx

• Lies posterior to the nasal cavity, inferior to the sphenoid, and superior to the level of the soft palate

• Strictly an air passageway

• Lined with pseudostratified columnar epithelium

• Closes during swallowing to prevent food from entering the nasal cavity

• The pharyngeal tonsil lies high on the posterior wall

• Pharyngotympanic (auditory) tubes open into the lateral walls

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Oropharynx

• Extends inferiorly from the level of the soft palate to the epiglottis

• Opens to the oral cavity via an archway called the fauces

• Serves as a common passageway for food and air• The epithelial lining is protective stratified

squamous epithelium• Palatine tonsils lie in the lateral walls of the

fauces• Lingual tonsil covers the base of the tongue

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Laryngopharynx

• Serves as a common passageway for food and air

• Lies posterior to the upright epiglottis

• Extends to the larynx, where the respiratory and digestive pathways diverge

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The Larynx (voice box)

• Extends from the level of the 4th to the 6th

cervical vertebrae• Attaches to hyoid bone superiorly• Inferiorly is continuous with trachea (windpipe)• Three functions:

1. Produces vocalizations (speech)2. Provides an open airway (breathing)3. Switching mechanism to route air and food into

proper channels• Closed during swallowing• Open during breathing

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• Framework of the larynx– 9 cartilages connected by membranes and ligaments– Thyroid cartilage with laryngeal prominence (Adam’s

apple) anteriorly– Cricoid cartilage inferior to thyroid cartilage: the only

complete ring of cartilage: signet shaped and wide posteriorly

– Behind thyroid cartilage and above cricoid: 3 pairs of small cartilages

1. Arytenoid: anchor the vocal cords

2. Corniculate

3. Cuneiform

– 9th cartilage: epiglottis

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Epliglottis* (the 9th cartilage)Elastic cartilage covered by mucosaOn a stalk attached to thyroid cartilageAttaches to back of tongueDuring swallowing, larynx is pulled superiorlyEpiglottis tips inferiorly to cover and seal laryngeal inletKeeps food out of lower respiratory tract

*

*

Posterior views

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Vocal Ligaments

• Attach the arytenoid cartilages to the thyroid cartilage

• Composed of elastic fibers that form mucosal folds called true vocal cords

– The medial opening between them is the glottis

– They vibrate to produce sound as air rushes up from the lungs

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• Pair of mucosal vocal folds (true vocal cords) over the ligaments: white because avascular.

• False vocal cords

– Mucosal folds superior to the true vocal cords

– Have no part in sound production

• Glottis is the space between the vocal cords• Laryngeal muscles control length and size of

opening by moving arytenoid cartilages• Sound is produced by the vibration of vocal

cords as air is exhaled

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Vocal Production

• Speech – intermittent release of expired air while opening and closing the glottis

• Pitch – determined by the length and tension of the vocal cords

• Loudness – depends upon the force at which the air rushes across the vocal cords

• The pharynx resonates, amplifies, and enhances sound quality

• Sound is “shaped” into language by action of the pharynx, tongue, soft palate, and lips

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Movements of Vocal Cords

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Sphincter Functions of the Larynx

• The larynx is closed during coughing, sneezing, and Valsalva’s maneuver

• Valsalva’s maneuver– Air is temporarily held in the lower respiratory tract

by closing the glottis

– Causes intra-abdominal pressure to rise when abdominal muscles contract

– Helps to empty the rectum

– Acts as a splint to stabilize the trunk when lifting heavy loads

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Trachea (the windpipe)

• Descends: larynx through neck into mediastinum

• Divides in thorax into two main (primary) bronchi

• 16-20 C-shaped rings

of hyaline cartilage

joined by fibroelastic

connective tissue

• Flexible for bending

but stays open despite

pressure changes

during breathing

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• Flexible and mobile tube extending from the larynx into the mediastinum

• Composed of three layers

– Mucosa – made up of goblet cells and ciliated epithelium

– Submucosa – connective tissue deep to the mucosa

– Adventitia – outermost layer made of C-shaped rings of hyaline cartilage

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• Posterior open parts of tracheal cartilage abut esophagus• Trachealis muscle can decrease diameter of trachea

– Esophagus can expand when food swallowed– Food can be forcibly expelled

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Bronchi

• The carina of the last tracheal cartilage marks the end of the trachea and the beginning of the right and left bronchi

• Air reaching the bronchi is:– Warm and cleansed of impurities

– Saturated with water vapor

• Bronchi subdivide into secondary bronchi, each supplying a lobe of the lungs

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• Tissue walls of bronchi mimic that of the trachea

• As conducting tubes become smaller, structural changes occur– Cartilage support structures change

– Epithelium types change

– Amount of smooth muscle increases

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• Bronchial tree bifurcation– Right main bronchus (more susceptible to aspiration)– Left main bronchus

• Each main or primary bronchus runs into hilus of lung posterior to pulmonary vessels

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• Main= primary bronchi divide into secondary= lobar bronchi, each suppliesone lobe– 3 on the right– 2 on the left

• Lobar bronchi branch into tertiary = segmental bronchi• Continues dividing: about 23 times

• Tubes smaller than 1 mm called bronchioles• Smallest, terminal bronchioles, are less the 0.5 mm diameter• Tissue changes as becomes smaller

– Cartilage plates, not rings, then disappears– Pseudostratified columnar to simple columnar to simple cuboidal

without mucus or cilia– Smooth muscle important: sympathetic relaxation

(“bronchodilation”), parasympathetic constriction (“bronchoconstriction”)

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Respiratory Zone

• Defined by the presence of alveoli; begins as terminal bronchioles feed into respiratory bronchioles

• Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of alveoli

• Approximately 300 million alveoli:– Account for most of the lungs’ volume

– Provide tremendous surface area for gas exchange

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• Respiratory bronchioles lead into alveolar ducts: walls consist of alveoli• Ducts lead into terminal clusters called alveolar sacs – are microscopic

chambers

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Alveoli

• Surrounded by fine elastic fibers

• Contain open pores that:

– Connect adjacent alveoli

– Allow air pressure throughout the lung to be equalized

• House macrophages that keep alveolar surfaces sterile

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• Alveoli surrounded by fine elastic fibers• Alveoli interconnect via alveolar pores• Alveolar macrophages – free floating “dust cells”• Note type I and type II cells and joint membrane

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Respiratory Membrane

• This air-blood barrier is composed of: – Alveolar and capillary walls

– Their fused basal laminas

• Alveolar walls:– Are a single layer of type I epithelial cells

– Permit gas exchange by simple diffusion

– Secrete angiotensin converting enzyme (ACE)

• Type II cells secrete surfactant

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Respiratory Membrane

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Gas Exchange

• Air filled alveoli account for most of the lung volume• Very great area for gas exchange (1500 sq ft)• Alveolar wall

– Single layer of squamous epithelial cells (type 1 cells) surrounded by basal lamina

– 0.5um (15 X thinner than tissue paper)– External wall covered by cobweb of capillaries

• Respiratory membrane: fusion of the basal laminas of– Alveolar wall– Capillary wall

Alveolar sac

Respiratorybronchiole

Alveolarduct

Alveoli

(air on one side; blood on the other)

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Lungs and Pleura

Pleural cavity – slit-like potential space filled with pleural fluid• Lungs can slide but separation from pleura is resisted (like film

between 2 plates of glass)• Lungs cling to thoracic wall and are forced to expand and

recoil as volume of thoracic cavity changes during breathing

Around each lung is a flattened sac of serous membrane called pleura

Parietal pleura – outer layerVisceral pleura – directly on lung

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• Pleura also divides thoracic cavity in three– 2 pleural, 1 mediastinal

• Pathology– Pleuritis– Pleural effusion

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Relationship of organs in thoracic cavity

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Lungs

• Each is cone-shaped with anterior, lateral and posterior surfaces contacting ribs

• Superior tip is apex, just deep to clavicle

• Concave inferior surface resting on diaphragm is the base

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apex apex

base base

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• Hilus or (hilum)– Indentation on mediastinal (medial) surface– Place where blood vessels, bronchi, lymph vessel, and nerves

enter and exit the lung

• “Root” of the lung– Above structures attaching lung to mediastinum– Main ones: pulmonary artery and veins and main bronchus

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• Right lung: 3 lobes

– Upper lobe

– Middle lobe

– Lower lobe

• Left lung: 2 lobes

– Upper lobe

– Lower lobeOblique fissure

Oblique fissure

Horizontal fissure

Abbreviations in medicine:e.g.” RLL pneumonia”

Each lobe is served by a lobar (secondary) bronchus

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• Each lobe is made up of bronchopulmonary segmentsseparated by dense connective tissue– Each segment receives air from an individual segmental

(tertiary) bronchus

– Approximately 10 bronchopulmonary segments in each lung

– Limit spread of infection

– Can be removed more easily because only small vessels span segments

• Smallest subdivision seen with the naked eye is the lobule– Hexagonal on surface, size of pencil eraser

– Served by large bronchiole and its branches

– Black carbon is visible on connective tissue separating individual lobules in smokers and city dwellers

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• Pulmonary arteries bring oxygen-poor blood to the lungs for oxygenation– They branch along with the bronchial tree– The smallest feed into the pulmonary capillary network

around the alveoli

• Pulmonary veins carry oxygenated blood from the alveoli of the lungs to the heart1/6/2015

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• Stroma – framework of connective tissue holding the air tubes and spaces – Many elastic fibers

– Lungs light, spongy and elastic

– Elasticity reduces the effort of breathing

• Blood supply– Lungs get their own blood supply from bronchial arteries

and veins

• Innervation: pulmonary plexus on lung root contains sympathetic, parasympathetic and visceral sensory fibers to each lung– From there, they lie on bronchial tubes and blood vessels

within the lungs

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• Bronchopulmonary – means both bronchial tubes and lung alveoli together– Bronchopulmonary segment – chunk receiving air from a

segmental (tertiary) bronchus*: tertiary means it’s the third order in size; also, the trachea has divided three times now

• “Anatomical dead space”– The conducting zone which doesn’t participate in gas

exchange

Primary bronchus:(Left main)

Secondary:(left lower lobar bronchus)

(supplyingleft lowerlobe)

Does this clarify a little?

*

Understand the concepts; you don’t need to know the names of the tertiary bronchi

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Ventilation

• Breathing = “pulmonary ventilation”– Pulmonary means related to the lungs

• Two phases– Inspiration (inhalation) – air in– Expiration (exhalation) – air out

• Mechanical forces cause the movement of air– Gases always flow from higher pressure to lower– For air to enter the thorax, the pressure of the air in it has

to be lower than atmospheric pressure• Making the volume of the thorax larger means the air inside it is

under less pressure(the air has more space for as many gas particles, therefore it is under less pressure)

• The diaphragm and intercostal muscles accomplish this

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Muscles of Inspiration

• During inspiration, the dome shaped diaphragm flattens as it contracts– This increases the height of

the thoracic cavity

• The external intercostalmuscles contract to raise the ribs– This increases the

circumference of the thoracic cavity

Together:

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• Intercostals keep the thorax stiff so sides don’t collapse in with change of diaphragm

• During deep or forced inspiration, additional muscles are recruited:– Scalenes

– Sternocleidomastoid

– Pectoralis minor

– Quadratus lumborum on 12th rib

– Erector spinae

(some of these “accessory muscles” of ventilation are visible to an observer; it usually tells you that there is respiratory distress – working hard to breathe)

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Expiration

• Quiet expiration in healthy people is chiefly passive

– Inspiratory muscles relax

– Rib cage drops under force of gravity

– Relaxing diaphragm moves superiorly (up)

– Elastic fibers in lung recoil

– Volumes of thorax and lungs decrease simultaneously, increasing the pressure

– Air is forced out

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• Forced expiration is active– Contraction of abdominal wall muscles

• Oblique and transversus predominantly

– Increases intra-abdominal pressure forcing the diaphragm superiorly

– Depressing the rib cage, decreases thoracic volume• Some help from internal intercostals and latissimus dorsi

(try this on yourself to feel the different muscles acting)

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Neural Control of Ventilation• Reticular formation in medulla

– Responsible for basic rate and rhythm– Can be modified by higher centers

• Limbic system and hypothalamus, e.g. gasp with certain emotions• Cerebral cortex – conscious control

• Chemoreceptors– Central – in the medulla– Peripheral: see next slide

• Aortic bodies on the aortic arch• Carotid bodies at the fork of the carotid artery: monitor O2 and CO2

tension in the blood and help regulate respiratory rate and depth

The carotid sinus (dilated area near fork) helps regulate blood pressure and can affect the rate (stimulation during carotid massage can slow an abnormally fast heart rate)

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Peripheral chemoreceptorsregulating respiration

• Aortic bodies*– On aorta

– Send sensory info to medulla through X (vagus n)

• Carotid bodies+– At fork of common carotid

artery

– Send info mainly through IX

(glossopharyngeal n)

*

+

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• There are many diseases of the respiratory system, including asthma, cystic fibrosis, COPD (chronic obstructive pulmonary disease – with chronic bronchitis and/or emphysema)

normal emphysema

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you might want to think twice about smoking….

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Pulmonary Function Test

• How much air volume can be moved in and out of the lungs?

• How fast the air in the lungs can be moved in and out ?

• How stiff are the lungs and chest wall - a question about compliance?

• The diffusion characteristics of the membrane through which the gas moves (determined by special tests) .

• How the lungs respond to chest physical therapy procedures?

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Reasons to use PFT

• Screening for the presence of obstructive and restrictive diseases

• Evaluating the patient prior to surgery• Evaluating the patient's condition for weaning

from a ventilator. If the patient on a ventilator can demonstrate a vital capacity (VC) of 10 - 15 ml/Kg of body weight, it is generally thought that there is enough ventilatory reserve to permit (try) weaning and extubation.

• Documenting the progression of pulmonary disease - restrictive or obstructive

• Documenting the effectiveness of therapeutic intervention

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PFT are specially helpful when patients

a. are older than 60-65 years of ageb. are known to have pulmonary diseasec. are obese (as in pathologically obese)d. have a history of smoking, cough or wheezinge. will be under anesthesia for a lengthy period of timef. are undergoing an abdominal or a thoracic operation

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Equipment

The primary instrument used in pulmonary function testing is the spirometer. It is designed to measure changes in volume and can only measure lung volume compartments that exchange gas with the atmosphere . Spirometers with electronic signal outputs (pneumotachs) also measure flow (volume per unit of time). A device is usually always attached to the spirometerwhich measures the movement of gas in and out of the chest and is referred to as a spirograph.

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Variables that have impact on values of PFT

• Age: aging ↓ lung elasticity→ smaller lung volume &capacities.

• Gender: volumes & capacities in ♂ > ♀.

• Body height & size:

• Race: blacks, Hispanics,& native Americans differ from Caucasians.

Terminology and Definitions

• FVC - Forced Vital Capacity - after the patient has taken in the deepest possible breath, this is the volume of air which can be forcibly and maximally exhaled out of the lungs until no more can be expired. (in liters)

• FEV1 - Forced Expiratory Volume in One Second -this is the volume of air which can be forcibly exhaled from the lungs in the first second of a forced expiratory maneuver. (in liters)

• FEV1/FVC - FEV1 Percent (FEV1%) - This number is the ratio of FEV1 to FVC - it indicates what percentage of the total FVC was expelled from the lungs during the first second of forced exhalation.

• FEV3 - Forced Expiratory Volume in Three Seconds - this is the volume of air which can be forcibly exhaled in three seconds. (in liters)

• FEV3/FVC - FEV3% - This number is the ratio of FEV3 to the FVC - it indicates what percentage of the total FVC was expelled during the first three seconds of forced exhalation.

• PEFR - Peak Expiratory Flow Rate - this is maximum flow rate achieved by the patient during the forced vital capacity maneuver beginning after full inspiration and starting and ending with maximal expiration. (L/S, or L/M)

• FEF - Forced Expiratory Flow - Forced expiratory Flow is a measure of how much air can be expired from the lungs. (L/S or L/M)

• FEF25% - This measurement describes the amount of air that was forcibly expelled in the first 25% of the total forced vital capacity test.

• FEF50% - This measurement describes the amount of air expelled from the lungs during the first half (50%) of the forced vital capacity test. (in liters)

• FEF25%-75% - This measurement describes the amount of air expelled from the lungs during the middle half of the forced vital capacity test. (in liters)

• MVV - Maximal Voluntary Ventilation - this value is determined by having the patient breathe in and out as rapidly and fully as possible for 12 -15 seconds. (L/S or L/M)

Lung Volumes

Normal Spirometry

Obstructive Pattern

■ Decreased FEV1

■ Decreased FVC

■ Decreased FEV1/FVC

- <70% predicted

■ FEV1 used to follow severity in COPD

Restrictive Pattern

Decreased FEV1

Decreased FVC

FEV1/FVC normal or increased

Spirometry Patterns

Bronchodilator Response

Degree to which FEV1 improves with inhaled bronchodilator

Documents reversible airflow obstruction

Significant response if:

- FEV1 increases by 12% and >200ml

Request if obstructive pattern on spirometry

Upper Airway Obstruction

SYMPTOMS

PFTs

OBSTRUCTION?

YES NO

TREATBRONCHOPROVOCATION

Obstruction?

TREAT

No Obstruction?

Other Diagnosis

↓

↓

↓ ↓

↓

↓ ↓

Lung Volumes

Lung Volumes

IRV

TV

ERV

• 4 Volumes

• 4 Capacities

– Sum of 2 or more lung volumes

RV

IC

FRC

VC

TLC

RV

Normal Spirometry

Obstructive Pattern

■ Decreased FEV1

■ Decreased FVC

■ Decreased FEV1/FVC

- <70% predicted

■ FEV1 used to follow severity in COPD

Restrictive Pattern

Decreased FEV1

Decreased FVC

FEV1/FVC normal or increased

Spirometry Patterns

Bronchodilator Response

Degree to which FEV1 improves with inhaled bronchodilator

Documents reversible airflow obstruction

Significant response if:

- FEV1 increases by 12% and >200ml

Request if obstructive pattern on spirometry

Upper Airway Obstruction

↓

SYMPTOMS

PFTs

OBSTRUCTION?

YES NO

TREATBRONCHOPROVOCATION

Obstruction?

TREAT

No Obstruction?

Other Diagnosis

↓

↓

↓ ↓

↓

↓ ↓

INTERPRETATION

General rule: When flow is ↓→ lesion is obstructive.

When volume is↓→ lesion is restrictive.

Obstructed Airflow

• narrowing of the airways due to bronchial smooth muscle contraction as is the case in asthma

• narrowing of the airways due to inflammation and swelling of bronchial mucosa and the hypertrophy and hyperplasia of bronchial glands as is the case in bronchitis

• material inside the bronchial passageways physically obstructing the flow of air as is the case in excessive mucus plugging, inhalation of foreign objects or the presence of pushing and invasive tumors

• destruction of lung tissue with the loss of elasticity and hence the loss of the external support of the airways as is the case in emphysema

• external compression of the airways by tumors and trauma

Restricted Airflow

• A. Intrinsic Restrictive Lung Disorders• 1. Sarcoidosis

2. Tuberculosis3. Pnuemonectomy (loss of lung)4. Pneumonia

• B. Extrinsic Restrictive Lung Disorders• 1. Scoliosis, Kyphosis

2. Ankylosing Spondylitis3. Pleural Effusion (fluid in the pleural cavity)4. Pregnancy5. Gross Obesity6. Tumors7. Ascites8. Pain on inspiration - pleurisy, rib fractures

• C. Neuromuscular Restrictive Lung Disorders• 1. Generalized Weakness - malnutrition

2. Paralysis of the diaphragm3. Myasthenia Gravis - lack of acetylcholine or too much cholinesterase at the myoneural junction in which the nerve impulses fail to induce normal muscular contraction. These patients suffer from fatigability and muscular weakness.4. Muscular Dystrophy5. Poliomyelitis6. Amyotrophic Lateral Sclerosis - Lou Gerig's Disease

Criterion for Obstructive and Restrictive Disease

• FVC ↓ in obstructive &restrictive diseases.

if FVC is ↑ after use of bronchodilator → it is obstruction.

if FVC is the same after bronchodilator → it is restriction.

• Slow Vital Capacity (SVC): This test is performed by having the patient slowly and completely blow out all of the air from their lungs. This eliminates bronchoconstrictive effect of rapid exhalation.

• Forced Expiratory Volume in One Second/FVC (FEV1%) : normally it is75% - 80 % of the vital capacity. Highly diagnostic of obstructive lesions.

How Do You Tell If The Patient Is Normal or Has Mild, Moderate or Severe Pulmonary Disease ?

• Normal PFT Outcomes - > 85 % of predicted values

• Mild Disease - > 65 % but < 85 % of predicted values

• Moderate Disease - > 50 % but < 65 % of predicted values

• Severe Disease - < 50 % of predicted values

Pulmonary Function Tests - A Systematic Way

To Interpretation

• Step 1. Look at the forced vital capacity (FVC) to see if it is within normal limits.

• Step 2. Look at the forced expiratory volume in one second (FEV1) and determine if it is within normal limits.

• Step 3. If both FVC and FEV1 are normal, then you do not have to go any further - the patient has a normal PFT test.

• Step 4. If FVC and/or FEV1 are low, then the presence of disease is highly likely.

• Step 5. If Step 4 indicates that there is disese then you need to go to the %predicted for FEV1/FVC. If the %predicted for FEV1/FVC is 88%-90% or higher, then the patient has a restricted lung disease. If the %predicted for FEV1/FVC is 69% or lower, then the patient has an obstructed lung disease.

PFT other than spirometry

• Flow-Volume Loops:The same general test as spirometry, except the data collected are plotted in a different way, showing flow vs. volume. The

patterns thus revealed may indicate the site and nature of any airways obstruction.

• Single Breath Diffusing Capacity: how to perform?1. Expire all the way to Residual Volume .2. Inspire all the way to Total Lung Capacity, breathing from a supply of test gas.3. Hold breath for ten seconds.4. Expire forcefully .

The concentrations of certain gases present in the "test gas" is measured prior to the test. The initial portion of the final expirate is discarded, and a portion of the remainder is analyzed. Generally, the difference between the concentrations present before the breathhold and after the breathhold indicates the amount of gas that diffuses through the lungs and into the bloodstream.

• Helium Dilution Lung Volumes: This test measures the total amount of gas in the lungs after a complete inspiration. Initially, the gas in the patient's lungs dilutes the helium present in the system, and the helium concentration falls rapidly. After a few minutes, however, the patient and the spirometer equilibrate, and the helium concentration reaches a steady value. By measuring the initial and final concentrations of helium present, and by knowing the volume of the spirometer, the amount of gas in the patient's lung at the start of the test may be calculated.

Predicted

Values

Measured

Values

% Predicted

FVC 6.00 liters 4.00 liters 67 %

FEV1 5.00 liters 2.00 liters 40 %

FEV1/FVC 38 % 50 % 60 %

Decision : This person is obstructed

Predicted

Values

Measured

Values

%

Predicted



FEV1/FVC 84 % 79 % 94 %

Decision : This person is restricted

Decision: normal

Predicted

Values

Measured

Values

%

Predicted



FEV1/FVC 82 % 77 % 94 %

Decision: mild restrictive lung disease

Predicted

Values

Measured

Values

%

Predicted



FEV1/FVC 78 % 88 % 115 %

Decision: moderate obstruction

Predicted

Values

Measured

Values

%

Predicted



FEV1/FVC 78 % 39 % 50 %

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Health & Medicine

Respiratory system