Respiratory system

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

1. Respiratory System

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 11/17/2014 2

3. 3 The Respiratory Organs Nose Pharynx Larynx Trachea Bronchi Lungs – alveoli 11/17/2014

4. Upper Respiratory Tract 4 11/17/2014

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 11/17/2014

6. Structure of Nose 11/17/2014 6

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) 11/17/2014 7

8. 8 11/17/2014

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 9 11/17/2014

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 10 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

14. The Larynx (voice box) Extends from the level of the 4 th to the 6 th cervical vertebrae Attaches to hyoid bone superiorly Inferiorly is continuous with trachea (windpipe) Three functions: Produces vocalizations (speech) Provides an open airway (breathing) Switching mechanism to route air and food into proper channels Closed during swallowing Open during breathing 14 11/17/2014

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 Arytenoid: anchor the vocal cords Corniculate Cuneiform 9 th cartilage: epiglottis 15 11/17/2014

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17. 17 Epliglottis* (the 9 th 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 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

21. 21 Movements of Vocal Cords 11/17/2014

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 11/17/2014

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 23 11/17/2014

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 11/17/2014

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 11/17/2014

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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 11/17/2014

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 11/17/2014

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 11/17/2014

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 ”) 11/17/2014

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 11/17/2014

32. 32 Respiratory bronchioles lead into alveolar ducts: walls consist of alveoli Ducts lead into terminal clusters called alveolar sacs – are microscopic chambers 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

36. Respiratory Membrane 11/17/2014 36

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) 11/17/2014

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 11/17/2014

39. 39 Pleura also divides thoracic cavity in three 2 pleural, 1 mediastinal Pathology Pleuritis Pleural effusion 11/17/2014

40. 40 Relationship of organs in thoracic cavity 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

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 alveoli of the lungs to the heart 11/17/2014

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 11/17/2014

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 11/17/2014

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 11/17/2014

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: 11/17/2014

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 12 th 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) 11/17/2014

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 11/17/2014

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) 11/17/2014

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) 11/17/2014

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 ) * + 11/17/2014

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 11/17/2014

56. 56 you might want to think twice about smoking…. 11/17/2014

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? 11/17/2014 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 11/17/2014 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 11/17/2014 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 . 11/17/2014 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 FEV 1 Decreased FVC Decreased FEV 1 /FVC - <70% predicted FEV 1 used to follow severity in COPD

69. Restrictive Pattern Decreased FEV 1 Decreased FVC FEV 1 /FVC normal or increased

70. Spirometry Patterns

71. Bronchodilator Response Degree to which FEV 1 improves with inhaled bronchodilator Documents reversible airflow obstruction Significant response if: - FEV 1 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 FEV 1 Decreased FVC Decreased FEV 1 /FVC - <70% predicted FEV 1 used to follow severity in COPD

78. Restrictive Pattern Decreased FEV 1 Decreased FVC FEV 1 /FVC normal or increased

79. Spirometry Patterns

80. Bronchodilator Response Degree to which FEV 1 improves with inhaled bronchodilator Documents reversible airflow obstruction Significant response if: - FEV 1 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? Expire all the way to Residual Volume . Inspire all the way to Total Lung Capacity, breathing from a supply of test gas. Hold breath for ten seconds. 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. 11/17/2014 96