Basics for Respiratory System which are useful for the budding clinical pharmacists

2. 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. 3
The Respiratory Organs
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs –
alveoli
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4. Upper Respiratory Tract
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5. 5
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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6. Structure of Nose
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7.  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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8. 81/6/2015

9. 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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10. 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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11. 11
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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12. 12
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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13. 13
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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14. 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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15. • 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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16. 161/6/2015

17. 17
Epliglottis* (the 9th cartilage)
Elastic cartilage covered by mucosa
On a stalk attached to thyroid cartilage
Attaches to back of tongue
During swallowing, larynx is pulled superiorly
Epiglottis tips inferiorly to cover and seal laryngeal
inlet
Keeps food out of lower respiratory tract
*
*
Posterior views
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18. 18
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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19. 19
• 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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20. 20
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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21. 21
Movements of Vocal Cords
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22. 22
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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23. 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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24. 24
• 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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25. 25
• 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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26. 261/6/2015

27. 27
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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28. 28
• 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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29. 29
• 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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30. 30
• Main= primary bronchi divide into
secondary= lobar bronchi, each supplies
one 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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31. 31
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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32. 32
• 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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33. 33
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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34. 34
• 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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35. 35
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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36. Respiratory Membrane
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37. 37
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
Respiratory
bronchiole
Alveolar
duct
Alveoli
(air on one side;
blood on the other)
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38. 38
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 layer
Visceral pleura – directly on lung
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39. 39
• Pleura also divides thoracic cavity in three
– 2 pleural, 1 mediastinal
• Pathology
– Pleuritis
– Pleural effusion
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40. 40
Relationship of organs in thoracic cavity
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41. 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
41
apex apex
base base
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42. 42
• 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
Medial view R lung Medial view of L lung
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43. 43
• Right lung: 3 lobes
– Upper lobe
– Middle lobe
– Lower lobe
• Left lung: 2 lobes
– Upper lobe
– Lower lobe
Oblique 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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44. 44
• Each lobe is made up of bronchopulmonary segments
separated 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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45. 45
• 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
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46. 46
• 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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47. 47
• 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)
(supplying
left lower
lobe)
Does this clarify a little?
*
Understand the concepts; you don’t need
to know the names of the tertiary
bronchi
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48. 48
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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49. 49
Muscles of Inspiration
• During inspiration, the dome
shaped diaphragm flattens
as it contracts
– This increases the height of
the thoracic cavity
• The external intercostal
muscles contract to raise the
ribs
– This increases the
circumference of the thoracic
cavity
Together:
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50. 50
• 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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51. 51
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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52. 52
• 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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53. 53
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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54. 54
Peripheral chemoreceptors
regulating 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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55. 55
• 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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56. 56
you might want to think twice about smoking….
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57. 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?
1/6/2015 57

58. 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
1/6/2015 58

59. PFT are specially helpful when
patients
a. are older than 60-65 years of age
b. are known to have pulmonary disease
c. are obese (as in pathologically obese)
d. have a history of smoking, cough or
wheezing
e. will be under anesthesia for a lengthy
period of time
f. are undergoing an abdominal or a thoracic
operation
1/6/2015 59

60. 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 spirometer
which measures the movement of gas in
and out of the chest and is referred to as a
spirograph.
1/6/2015 60

61. 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.

62. 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)

63. • 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.

64. • 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.

65. • 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)

66. Lung Volumes

67. Normal Spirometry

68. Obstructive Pattern
■ Decreased FEV1
■ Decreased FVC
■ Decreased FEV1/FVC
- <70% predicted
■ FEV1 used to follow severity in COPD

69. Restrictive Pattern
 Decreased FEV1
 Decreased FVC
 FEV1/FVC normal or increased

70. Spirometry Patterns

71. 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

72. Upper Airway Obstruction

73. SYMPTOMS
PFTs
OBSTRUCTION?
YES NO
TREAT
BRONCHOPROVOCATION
Obstruction?
TREAT
No Obstruction?
Other Diagnosis
↓
↓
↓ ↓
↓
↓ ↓

74. Lung Volumes

75. Lung Volumes
IRV
TV
ERV
• 4 Volumes
• 4 Capacities
– Sum of 2 or more
lung volumes
RV
IC
FRC
VC
TLC
RV

76. Normal Spirometry

77. Obstructive Pattern
■ Decreased FEV1
■ Decreased FVC
■ Decreased FEV1/FVC
- <70% predicted
■ FEV1 used to follow severity in COPD

78. Restrictive Pattern
 Decreased FEV1
 Decreased FVC
 FEV1/FVC normal or increased

79. Spirometry Patterns

80. 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

81. Upper Airway Obstruction

82. ↓
SYMPTOMS
PFTs
OBSTRUCTION?
YES NO
TREAT
BRONCHOPROVOCATION
Obstruction?
TREAT
No Obstruction?
Other Diagnosis
↓
↓
↓ ↓
↓
↓ ↓

83. INTERPRETATION
General rule: When flow is
↓→ lesion is obstructive.
When volume is↓→ lesion is restrictive.

84. 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

85. Restricted Airflow
• A. Intrinsic Restrictive Lung Disorders
• 1. Sarcoidosis
2. Tuberculosis
3. Pnuemonectomy (loss of lung)
4. Pneumonia
• B. Extrinsic Restrictive Lung Disorders
• 1. Scoliosis, Kyphosis
2. Ankylosing Spondylitis
3. Pleural Effusion (fluid in the pleural cavity)
4. Pregnancy
5. Gross Obesity
6. Tumors
7. Ascites
8. Pain on inspiration - pleurisy, rib fractures
• C. Neuromuscular Restrictive Lung Disorders
• 1. Generalized Weakness - malnutrition
2. Paralysis of the diaphragm
3. 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 Dystrophy
5. Poliomyelitis
6. Amyotrophic Lateral Sclerosis - Lou Gerig's Disease

86. 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.

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

88. 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

89. 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.

90. 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.

91. 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

92. Predicted
Values
Measured
Values
%
Predicted
FVC 5.68 liters 4.43 liters 78 %
FEV1 4.90 liters 3.52 liters 72 %
FEV1/FVC 84 % 79 % 94 %
Decision : This person is restricted

93. Decision: normal
Predicted
Values
Measured
Values
%
Predicted
FVC 5.04 liters 5.98 liters 119 %
FEV1 4.11 liters 4.58 liters 111 %
FEV1/FVC 82 % 77 % 94 %

94. Decision: mild restrictive lung disease
Predicted
Values
Measured
Values
%
Predicted
FVC 3.20 liters 2.48 liters 77 %
FEV1 2.51 liters 2.19 liters 87 %
FEV1/FVC 78 % 88 % 115 %

95. Decision: moderate obstruction
Predicted
Values
Measured
Values
%
Predicted
FVC 3.20 liters 3.01 liters 94 %
FEV1 2.51 liters 1.19 liters 47 %
FEV1/FVC 78 % 39 % 50 %

96. 1/6/2015 96