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1. LUNG VOLUMES AND CAPACITIES PULMONARY CIRCULATION/BLOOD FLOW AND EDEMA Group 5 members Jemal Saido Merga Tilahun Murteda Aliyi Negash Tesfaye Nesru Awol

2. OUTLINES OF PRESENTATION Objectives Introduction Lung volumes and capacities Pulmonary circulation / blood flow and edema References

3. objectives At the end of this presentation, participants will understand lung volumes and capacities Pulmonary circulation/blood flow and edema

4. Introduction Functional Anatomy

5. 5 LUNG VOLUMES AND CAPACITIES On average, in healthy young adults , the maximum air that the lungs can hold is about 5.7 liters in males (4.2 liters in females). Anatomic build , age , the distensibility of the lungs and the presence or absence of respiratory disease affect this total lung capacity. The changes in lung volume that occur with different respiratory efforts can be measured using a spirometer and the method is called spirometry .

6. 6 Spirometer Is a device that measures the volume of air breathed in and out It consists of an air-filled drum floating in a water-filled chamber . As a person breathes air in and out of the drum through a connecting tube , the resultant rise and fall of the drum are recorded as a spirogram , which is calibrated to the magnitude of the volume change. The pen records inspiration as an upward deflection and expiration as a downward deflection T he air in the lungs is subdivided into four volumes and four capacities

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9. The four standard lung volumes are: Tidal volume (TV) Inspiratory reserve volume (IRV) Expiratory reserve volume (ERV) Residual volume (RV)

10. Pulmonary Volumes The tidal volume the volume of air inspired or expired with each normal breath is 500 ml in the adult male. 2. The inspiratory reserve volume the extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force it is 3000 ml.

11. 3. The expiratory reserve volume the maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration is about 1100 ml. 4. The residual volume the volume of air remaining in the lungs after the most forceful expiration; it is 1200 ml.

12. Pulmonary Capacities In describing events in the pulmonary cycle, it is sometimes desirable to consider two or more of the volumes together . Such combinations are called pulmonary capacities .

13. The inspiratory capacity is the volume of air inspired by a maximal inspiratory effort after normal expiration is tidal volume plus the inspiratory reserve volume . IC=IRV + VT = 3500ml

14. 2. The functional residual capacity is the volume of air remaining in the lungs after normal expiration i.e expiratory reserve volume plus the residual volume . FRC = ERV + RV =2300 ml.

15. 3. The vital capacity is the volume of air expired by a maximal expiratory effort after maximal inspiration ~ 4600ml = inspiratory reserve volume + tidal volume + expiratory reserve volume. VC = IRV + VT + ERV=IC + ERV

16. 4 . The total lung capacity is the maximum volume of air that can be accommodated in the lungs ~ 5800ml = vital capacity + residual volume. it is equal to the vital capacity plus the residual volume . TLC = VC + RV = IC + FRC

17. Minute Respiratory Volume is the volume of air breathed in or out of the lungs each minute is equal to the tidal volume times the respiratory rate per minute . MRV=RR XTV 12 X 500ml = 6 L/min . These values apply to conditions of normal, quiet breathing; tidal volume and breathing frequency (RR) increase substantially during exercise

18. All lung volume and capacity are about 20 to 25% less in women than in men and are greater in athletic persons than the non-athletic. 18

19. Pulmonary volumes and capacities 19

20. 20 Factors affecting lung volumes & capacities Age , sex, posture, body type, physical training, pulmonary resection, tumor, pneumonia, lung collapse, edema, fibrosis FRC increase is caused by by h yperinflation, emphysema, asthma  TLC is caused by restrictive pulmonary disease, interstitial fibrosis RV increases in age groups with impaired exhalation

21. Two general categories of respiratory dysfunction yield abnormal results during spirometry . 1.Obstructive lung disease e.g. asthma or bronchitis, emphysema. There is a difficulty in moving gas out of the lung due to high airway resistance and obstruction. In COPD TLV increased

22. 2.Restrictive lung disease e.g . pulmonary fibrosis Replacement of delicate lung tissue with thick, fibrous tissue Lungs are less compliant (not expand easily) than normal, so it is difficult to move gas into the lungs Expiration is normal lung recoil forces are increased Acute respiratory distress syndrome(ARDS) Characterized by reduced TLV , FVC

23. Two general categories of respiratory dysfun con’t … These are detected and quantified by spirometer which measures volume, time and flow The spirometer particularly electronic hand held is objective , noninvasive , sensitive to early change and it is portable and can be performed almost anywhere. It is performed to detect the presence or absence of lung disease, quantify lung impairment.

24. Spirometric measures include the following. Forced expiratory volume in 1sec (FEV1) (2.1-3.5l)- is the amount of air that you can quickly and forcefully exhale in 1 sec.after maximal inhalation(timed). Forced vital capacity (FVC), the maximum amount of air that can be exhaled when blowing out as fast as possible, after fully inhaling. ( 3.0-5.0l for adults ) FEV1/FVC ratio (70-80%)

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26. 26 Patient positioning Correct measurement posture is as follows. Sit upright: there should be no difference in the amount of air the patient can exhale from a sitting position compared to a standing position as long as they are sitting up straigh t and there are no restrictions. Feet flat on floor with legs uncrossed : no use of abdominal muscles for leg position.

27. Loosen tight-fitting clothing : if clothing is too tight, this can give restrictive pictures on spirometr y (give lower volumes than true). Use a chair with arms : when exhaling maximally, patients can become light-headed and possibly sway or faint. NB Physician/examiner must wash their hand between patients. Bacterial–viral filters should be used for all patients and thrown away by the patient at the end of testing. 27

28. Contraindications If any of the following have occurred recently, then it may be better to wait until the patient has fully recovered before carrying out spirometry . Haemoptysis of unknown origin Pneumothorax Unstable cardiovascular status, recent myocardial infarction or pulmonary embolism Thoracic, abdominal or cerebral aneurysms Recent eye surgery Acute disorders affecting test performance, such as nausea or vomiting Recent thoracic or abdominal surgical procedures

29. Technique There are a number of different techniques for performing spirometry . Before performing the forced expiration, tidal (normal) breaths can be taken first, then a deep breath taken in while still using the mouthpiece, followed by a further quick, full inspiration. Alternatively, a deep breath can be taken in then the mouth placed tightly around the mouthpiece before a full expiration is performed . The patient can be asked to completely empty their lungs then take in a quick full inspiration, followed by a full expiration

30. For FVC and FEV1, the patient takes a deep breath in, as large as possible, and blows out as hard and as fast as possible and keeps going until there is no air left. For VC, the patient takes a deep breath in, as large as possible, and blows steadily for as long as possible until there is no air left. Nose clips are essential for VC as air can leak out due to the low flow. 30

31. The patient needs to keep blowing until no more air comes out and subjects needs encouragement Some patients, particularly those with obstructive disease, may find it difficult to exhale completely on a forced manoeuvre so patients may need 30s in between manoeuvres & even minutes in asthmatics. 31

32. 32 FEV1/FVC Ratio from spirometre to diagnose COPD and RLD FVC and VC difference time that means FVC is timed but not VC w/c is not timed VC has higher value than FVC because VC has higher time to exhale than FVC w/c is in shorter time Normal value for VC is 4600mL but FVC is 3600mL(you are asked to exhale forcefully and quickly as possible as you can)

33. FEV1 is the amount of air that you can quickly and forcibly exhale in 1 sec. after maximal inhalation(timed). FVC is the amount of air that you can exhale forcibly and quickly after maximal inhalation FEV1/FVC ratio is FEV1 divided by FVC normal is 80%(4L/5L) 33

34. Dead space Some of the volume of air a person breathes never reaches the gas exchange areas but simply fills respiratory passages where gas exchange does not occur( conducting airways) , such as the nose , pharynx , and trachea . This air is called dead space air because it is not useful for gas exchange

35. There are three dead spaces Anatomical dead space Alveolar dead space Physiological dead space

36. Anatomical dead space: equal to the volume of the conducting airways (= 150 ml ). This volume is considered anatomic dead space b/c air within these airways is useless for exchange . NB : Conducting airways do not contain alveoli to participate in gas exchange

37. Alveolar dead space - Is the volume of air that enters unperfused alveoli . - In other words, these alveoli receive airflow but no blood flow ; with no blood flow to the alveoli, gas exchange cannot take place.

38. Physiological dead space - anatomical dead space + alveolar dead space - determined by measuring the amount of CO 2 in the expired air. NB : Only 350 ml are exchanged between the atmosphere and alveoli because of the 150 ml occupying the anatomic dead space.

39. Pulmonary Circulation/blood flow In the lung there are two types of circulation : 1. pulmonary circulation – for oxygenation of Deoxygenated blood from Rt atrium  Rt ventricle  pulmonary artery  lung (oxygenation)  Lt atrium then left ventricle 2 . Bronchial circulation: contain 1-2% of cardiac output Oxygenated blood from Lt ventricle  aorta  bronchial artery  supplies O2 to surrounding tissues of the lung

40. 1. Pulmonary circulation Is Low-pressure (25/8mmHg ), Low- resistance, High -flow circulation It supplies venous blood from all parts of the body to the alveolar capillaries where oxygen (O2) is added and carbon dioxide (CO2) is removed. The pulmonary artery receives blood from the right ventricle and its branches carry blood to the alveolar capillaries for gas exchange

41. The pulmonary veins then return the blood to the left atrium to be pumped by the left ventricle though the systemic circulation. The arteries of the pulmonary circulation are thin walled, with minimal smooth muscle. They are 7x more compliant than systemic vessels, and they are easily distensible, so it has high flow and this high compliance allow it to accommodate the stroke volume output of the right ventricle. 41

42. 2. Bronchial circulation It is a High-pressure, High resistance , Low-flow circulation It supplies systemic arterial blood to trachea , the bronchial tree (including the terminal bronchioles), the supporting tissues of the lung , and the outer coats (adventitia) of the pulmonary arteries and veins . The bronchial arteries branched from thoracic aorta , supply most of this systemic arterial blood at a pressure that is only slightly lower than the aortic pressure. Perfuse the upper respiratory tract. 42

43. => Bronchial blood become deoxygenated after it supplies the tissue from systemic circulation and its amount is about 1-2% of CO or after exchange of 02 and Co2 in tissues of lung supporting tissues   Then the deoxygenated blood meets the pulmonary vein which initially containing pure or oxygenated blood and enters in to the left atrium rather than passing back to RA  Therefore the addition of this deoxygenated blood reduces the purity of pulmonary blood ( O2 partial pressure) is reduced

44. 3 important physiologic fact from this specialty are Thus the bronchial blood does not involve in gas exchange The Lt ventricular CO is 1 -2% greater than Rt ventricular CO Slight difference/decrease in PaO2 in pulmonary blood that diffuses to the LV

45. Lymphatics Lymphatic system contributes the pulmonary circulation significantly Lymph vessels surrounds all the supportive tissues of the lung , - B eginning in t he connective tissue spaces that surround the terminal bronchioles - Coursing to the hilum of the lung , - And then mainly drains into the right thoracic lymph duct .

46. The Lymphatic System function in pulmonary circulation as… Particulate matter entering the alveoli is partly removed by way of these channels. Plasma protein leaking from the lung capillaries is also removed from the lung tissues by lymphatic vessels. This prevents pulmonary edema.

47. Blood Volume of the Lungs The blood volume of the lungs is about 450ml , It is about 9% of the total blood volume of the entire circulatory system. Approximately 70ml of this pulmonary blood volume is in the pulmonary capillaries T he remainder is divided about equally between the pulmonary arteries and the veins.

48. Blood flow through the lung and its distribution Blood Flow through the lung is essentially equal to CO The factors that control CO regulate pulmonary BF specially the peripheral factors are more important and the flexibility of pulmonary vessel is also important Usually pulmonary vessels are passive, distensible that enlarge with  in pressure and narrow with  in pressure For adequate aeration of the blood to occur, blood should be distributed to the segment of lung where alveoli is best oxygenated. This distribution is achieved by varies mechanism.

49. Blood is redistributed to a well ventilated areas of the lung When alveolar O 2 concentration falls below 70% normal (<73mmHg),  The adjacent blood vessels constrict during the coming 3 to 10 minutes  The vascular resistance increases more than 5x at extremely low O2 levels - This leads to the redistribution of blood in to well-ventilated alveoli.

50. Blood distribution… This effect is opposite to that in systemic vasculatures which dilate in response to low O2 level. Although the mechanisms that promote pulmonary vasoconstriction during hypoxia are not completely understood low O2 concentration may stimulate release of vasoconstrictor substances or decrease release of a vasodilator , such as nitric oxide, from the lung tissue.

51. 51 Some studies suggest that hypoxia may directly induce vasoconstriction by inhibition of oxygen-sensitive potassium ion channels in pulmonary vascular smooth muscle cell membranes. With low partial pressures of oxygen, these channels are blocked , leading to depolarization of the cell membrane and activation of calcium channels , causing influx of calcium ions. The rise of calcium concentration then causes constriction of small arteries and arterioles.

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54. 54 Hypoxic pulmonary vasoconstriction Low P A O 2 reduces pulmonary blood flow Rapid ascent to high altitude cause pulmonary vasoconstriction ( hypertension ) Important physiological roles In fetus , it shunts blood away from the lungs After birth , the first breath ( alveolar oxygenation ) dilates pulmonary vessels and allow oxygenation After birth , hypoxic vasoconstriction shunts blood away from poorly ventilated alveoli improving V/Q

55. 55 S= saturation

56. Pulmonary arterial pressure in the uppermost portion of the lung and the pressure in the lowest portion of the lungs varies. Such pressure differences have profound effects on blood flow through the different areas of the lung Because the pulmonary circulation is a low-pressure/low-resistance system , it is influenced by gravity much more dramatically than that of the systemic circulation. This gravitational effect and other factors contribute to an uneven distribution of blood flow in the lun g. 56

57. Zones of the lung & blood flow Zone 1 – zone of no BF no blood flow during all portion of cardiac cycle Because alveolar air pressure > capillary pulmonary pressure Zone 2 – zone of intermittent systolic blood flow - because systolic pressure > alveolar air pressure Zone 3 – in all the lower areas of the lung - continuous blood flow - because alveolar capillary pressure( both systolic, & diastolic) remains greater than the alveolar air pressure( zero alveolar pressure) When alveolar pressure > capillary pressure  the capillaries close and no BF 57

58. Therefore, the apical systolic pressure is only 10 mm Hg (25 mm Hg at heart level minus 15 mm Hg hydrostatic pressure difference ). This 10 mm Hg apical blood pressure is greater than the zero alveolar air pressure , so blood flows through the pulmonary apical capillaries during cardiac systole. 58

59. Cont … Conversely, during diastole , the 8 mm Hg diastolic pressure at the level of the heart is not sufficient to push the blood up the 15 mm Hg hydrostatic pressure gradient required to cause diastolic capillary flow. Therefore, blood flow through the apical part of the lung is intermittent, with flow during systole but cessation of flow during diastole; this is called zone 2 blood flow

60. Exercise Increases Blood Flow Through All Parts of the Lungs. the blood flow in all parts of the lung increases during exercise . Convert the lung apices from a zone 2 pattern into a zone 3 pattern of flow . 1.by increasing the number of open capillaries, sometimes as much as threefold; 2. by distending all the capillaries and increasing the rate of flow through each capillary more than twofold; and 3. by increasing the pulmonary arterial pressure . 60

61. 61 Pulmonary Edema Pulmonary edema occurs in the same way that edema occurs elsewhere in the body. Any factor that increases fluid filtration out of the pulmonary capillaries or that impedes pulmonary lymphatic function and causes the pulmonary interstitial fluid pressure to rise from the negative range into the positive range will cause rapid filling of the pulmonary interstitial spaces and alveoli with large amounts of free fluid.

62. The most common causes of pulmonary edema are as follows: 1 . Left-sided heart failure or mitral valve disease , with consequent great increases in pulmonary venous pressure and pulmonary capillary pressure and flooding of the interstitial spaces and alveoli. 62

63. 2. Damage to the pulmonary blood capillary membranes caused by infections such as pneumonia or by breathing noxious substances such as chlorine gas or sulfur dioxide gas. Each of these mechanisms causes rapid leakage of both plasma proteins and fluid out of the capillaries and into both the lung interstitial spaces and the alveoli. Pulmonary edema…

64. References 1. Guyton and Hall text book of Medical Physiology;13 th Edition 2. Fox: Human physiology; 8 th Edition 3. Vander et.als Human physiology; 9 th Edition 4. BRS Physiology; 6 th Edition