LUNG VOLUME and capacity.pptx bds notes 1st yr

Bds first yr notes physio

1. Lung Volume & Capacities Pulmonary Function Tests

2. PULMONARY FUNCTION TESTS (PFT) INDICATIONS : Diagnosis of certain lung diseases As a fitness test before recruitment To monitor, effect of training in a sports person For assessing pre-operative fitness of a patient

3. Lung volumes and lung capacities refer to the volume of air associated with different phases of the respiratory cycle Lung volumes are directly measured; Lung capacities are inferred from lung volumes Instrument used is spirometry

4. SPIROGRAM

5. STATIC LUNG VOLUME & CAPACITIES

6. The maximum volume to which a lung can be expanded is divided into Four types : Tidal volume (TV) Inspiratory reserve volume (IRV) Expiratory persevere volume (ERV) Residual volume (RV) STATIC LUNG VOLUME

7. These are combinations of two or more Pulmonary lung volumes : Inspiratory capacity (IC) Functional residual capacity (FRC) Vital capacity (VC) Total lung capacity (TLC) STATIC LUNG CAPACITIES

8. 1. TIDAL VOLUME (TV) Definition: Volume of air inspired or expired during each breath during normal quiet breathing TV = 350 to 500 ml in normal adult

9. Definition: Extra volume of air that can be inhaled by a maximum inspiratory effort over & above the normal tidal volume IRV =2500 ml to 3000 ml in normal adult 2. INSPIRATORY RESERVE VOLUME (IRV)

10. Definition: Extra volume of air that can be exhaled by the maximum forceful expiration over & beyond the normal TV ERV = 900 ml to 1100 ml in a normal adul t 3. EXPIRATORY RESERVE VOLUME (ERV)

11. Definition: Volume of the air left out in lungs after most forceful expiration or complete expiration RV =1000 to 1200 ml in adults 4. RESIDUAL VOULME (RV)

12. These are combinations of two or more Pulmonary lung volumes : Inspiratory capacity (IC) Functional residual capacity (FRC) Vital capacity (VC) Total lung capacity (TLC) STATIC LUNG CAPACITIES

13. Definition: It is the maximal volume of air that can be inhaled from resting expiratory level. I.C. = T.V. + I. R.V.. Normal Value is 2800 to 3500 ml. 1. INSPIRATORY CAPACITY (IC)

14. 2. FUNCTIONAL RESIDUAL CAPACITY (FRC) Definition: It is the volume of air remaining in the lungs at the resting expiratory level. F.R.C. = R.V. + E.R.V. Normal value is 2300 ml.

15. Continues exchange of gases - So that conc of O2 and CO2 is maintained › Breath holding is made possible › Prevents colapse of lungs SIGNIFICANCE OF FRC

16. Old age Obstructive and restrictive lung diseases - Emphysema & Bronchial Asthma FACTORS AFFECTING FRC

17. 3. VITAL CAPACITY (VC) Definition: It is the volume of air that can be forcibly exhaled after a maximal inspiration. V.C. = T.V. + E.R.V. + I.R.V. Normal value is 3200 to 5000 ml.

18. To asses strength of respiratory muscles Factors affecting VC › Age - decreases with age › Sex - males have more also in athletes › Strength of respiratory muscles › Gravity › Pregnancy , Obesity- reduced › Ascites › Pulmonary diseases Myopathy , polio, Myaesthenia Gravis- decreases SIGNIFICANCE

19. 4. TOTAL LUNG CAPACITY (TLC) Definition: It is the volume of air contained in the lungs at the end of a maximal inspiration. TLC = VC + RV. Normal value is 5800 ml.

20. DYNAMIC LUNG VOLUME & CAPACITIES

21. Dynamic Lung volume & Capacities are dependent on time factor, therefore expressed as ml/ min or L/ min

22. Timed V ital C apacity (TVC) or Forced Vital Capacity ( FVC ) Definition: is volume of the air that can be expired rapidly with max force following a max inspiration , the volume of air expired can be timed by recording VC on spirograph DYNAMIC LUNG VOLUMES

23. Forced Expiratory Volume – It is the fraction of the vital capacity expired at the end of first, second and third seconds of expiration. FEV1 = Volume expired in first sec. x 100 Vital capacity

24. Peak Expiratory Flow Rate(PEFR) : It is the maximum rate at which air can be expired out after deep inspiration. Normal value 450- 500 Lit./ min

25. Ventilation/Perfusion Ratio The ratio of pulmonary ventilation to pulmonary blood flow for the whole lung at rest is about 0.8 (4.2 L/min ventilation divided by 5.5 L/min blood flow)

26. Ventilation- Perfusion Ratio VA/ Q VA= Alveolar Ventilation Q= Blood flow Top of the lungs, VA/Q is 2.5 times as great as the ideal value, causing moderate degree of physiologic dead space At bottom of lung, VA/Q is 0.6 the ideal value, physiologic shunt