Lung Volumes 172022 Lung Volumes 1 Lung Volumes

Lung Volumes 1/7/2022 Lung Volumes 1

Lung Volumes Tidal volume 500 ml Anatomical dead space 150 ml Alveolar gas 3000 ml Pulmonary capillary blood 70 ml 1/7/2022 Total ventilation 7500 ml/min Frequency = 15 per min Alveolar ventilation 5250 ml/min Pulmonary blood flow 5000 ml/min Lung Volumes 2

Determination of Lung Volumes Recoding drum Mouth piece Water filled spirometer 1/7/2022 Lung Volumes 3

Lung Volumes Inspiration l 6 VC IRV IC TV 1. 7 l 1. 2 ERV 1. 1 0 TLC RV FRC Volume of air in the lungs can be subdivided into 8 components Most important • Tidal volume • Vital capacity • Functional residual • • Expiration 1/7/2022 Lung Volumes capacity Residual volume Total lung capacity 4

Tidal Volume Inspiration l 6 during breathing IC 1. 7 TLC l l 1. 2 ERV 1. 1 0 • Inspired or expired VC IRV TV Volume of air RV FRC It is about 500 ml One of the determinants of minute ventilation • Pulmonary ventilation Expiration • MV = TV * RR 1/7/2022 Lung Volumes 5

Inspiratory Reserve Volume IRV l Inspiration 6 IC 1. 7 1. 2 ERV 1. 1 0 • That can be taken in VC IRV TV Volume of air TLC • • by maximal inspiratory effort Over and above TV It is about 3000 ml FRC RV Expiration 1/7/2022 Lung Volumes 6

Expiratory Reserve Volume ERV Inspiration l 6 IC 1. 7 1. 2 ERV 1. 1 0 • That can be expelled VC IRV TV Volume of air FRC TLC • • by most powerful expiratory effort After tidal air has been expelled It is about 1100 ml RV Expiration 1/7/2022 Lung Volumes 7

Residual Volume Inspiration l 6 VC IRV IC TV l 1. 7 1. 2 ERV 1. 1 0 TLC Volume of gas in lungs at end of maximal Voluntary effort (1200 ml) Will increase if • FRC force required to decrease lung vol. Becomes greater • Decrease in elasticity - RV • Expiration 1/7/2022 Lung Volumes emphysema Stiffer chest wall pleural thickening, oesteoarthritis 8

Residual Volume • Voluntary muscular Inspiration force decreases 6 • Pain, VC IRV IC TV 1. 7 TLC l 1. 2 ERV 1. 1 0 neuromuscular weakness FRC Will increase • Presence of airway obstruction • Air trapping RV Expiration 1/7/2022 Lung Volumes 9

Vital Capacity l Inspiration 6 VC IRV IC TV TLC l 1. 7 1. 2 ERV 1. 1 0 FRC l l RV Vol of air expelled by maximal voluntary expiration following maximal inspiration (IRV + Vt + ERV) = 4600 ml Great variation Depends on height & age Expiration 1/7/2022 Lung Volumes 10

Vital Capacity Inspiration l 6 • VC IRV IC TV 1. 7 1. 2 ERV 1. 1 0 Reduction in vital capacity TLC • • FRC Decrease lung gas volume Space occupying lesion Decreased ability to expire or inspire maximally • decrease muscular RV force, pain, neurological diseases Expiration 1/7/2022 Lung Volumes 11

Vital Capacity Inspiration 6 • VC IRV IC TV • Increase resistance to TLC chest cage expansion Increase resistance to expansion of lung • Pleural thickening, 1. 7 asthma 1. 2 ERV 1. 1 0 FRC RV Expiration 1/7/2022 Lung Volumes 12

Inspiratory Capacity l Inspiration 6 VC IRV IC Vt • IRV + Vt • It is about 3500 1. 7 1. 2 ERV 1. 1 0 TLC Volume of air that can be inspired from the end of expiration FRC RV Expiration 1/7/2022 Lung Volumes 13

Functional Residual Capacity l Inspiration 6 Volume of gas in the lungs • VC IRV IC TV • TLC l 1. 7 1. 2 ERV 1. 1 0 Position at which tendency of • FRC • RV Expiration l 1/7/2022 At the end of normal expiration (ERV + RV) Lung to collapse is equal to Elastic and muscular force of chest cavity causing it to expand Affected by • Lung Volumes Body position, anxiety, pregnancy 14

Functional Residual Capacity l Inspiration 6 VC IRV l IC TV TLC FRC is the lung volume • With each tidal breath • 1. 7 l 1. 2 ERV 1. 1 0 FRC Gas exchange takes place Fresh gas mixes with alveolar gas Small fluctuation of • RV Alveolar & arterial gas tensions Expiration 1/7/2022 Lung Volumes 15

Functional Residual Capacity l Inspiration 6 l IC TV • VC IRV 1. 7 TLC l 1. 2 ERV 1. 1 0 FRC acts as a buffer Maintain relative constant Prevent rapid change in alveolar gas • FRC RV l Expiration When there is change in ventilation or inspired gas ↑ Lung volume during quiet breathing • 1/7/2022 Alveolar & arterial gas tension Lung Volumes ↓Work of breathing 16

Total Lung Capacity Inspiration l 6 • 5800 ml VC IRV IC TV 1. 7 1. 2 ERV 1. 1 0 Vital capacity + Residual volume FRC TLC l All pulmonary volumes are 20 to 25% less in females RV Expiration 1/7/2022 Lung Volumes 17

Forced Expiratory Volume l Inspiration 6 l l TV 1. 7 FEVt or Timed vital capacity Subject inspires to TLC • Then exhales as 1. 2 rapidly as possible to RV 1. 1 0 0 1 2 3 Time in seconds 1/7/2022 Lung Volumes 18

Forced Expiratory Volume Inspiration l 6 The spirometer record both • • TV l 1. 7 1. 2 It is a measurement of the • 1. 1 0 0 1 2 Volume expired over Preset time interval 3 Rate at which a maximal inspiration can be completely exhaled Time in seconds 1/7/2022 Lung Volumes 19

Forced Expiratory Volume Inspiration l 6 • 68% of VC at 0. 5 sec • 77% of VC at 0. 75 sec • 84% of VC at 1 sec • 94% of VC at 2 sec • 97% of VC at 3 sec FEV 1 FVC TV 1. 7 1. 2 1. 1 l 0 0 1 2 3 Normal person can exhale Ratio known as FEV 1/FVC % Time in seconds 1/7/2022 Lung Volumes 20

Forced Expiratory Volume Inspiration l 6 TV Measure evaluates • Muscle power • Pulmonary, thoracic • 1. 7 compliance Overall resistance 1. 2 1. 1 0 0 1 2 3 Time in seconds 1/7/2022 Lung Volumes 21