Lung Volumes and Capacities PDF

Lung volumes and capacities Dr. Ghada Elgarawany Assistant Professor of Medical Physiology www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES Rules before lectures Learning Objectives  Describe Static Lung functions (lung volumes and capacities)  Describe dynamic lung functions  Explain FEV1 and FVC and st...

Lung volumes and capacities Dr. Ghada Elgarawany Assistant Professor of Medical Physiology www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES Rules before lectures Learning Objectives  Describe Static Lung functions (lung volumes and capacities)  Describe dynamic lung functions  Explain FEV1 and FVC and state its importance.  Explain FEF25-75% and state its importance.  Describe expiratory flow rate and its importance Lung Function tests Definition Tests to assess the efficiency of breathing mechanism Indication: 1. For assessing health of the respiratory system and the efficacy of the breathing mechanisms. 2. Assist in diagnosis of respiratory diseases. 3. Helps in monitoring the progress of pulmonary disease and the effectiveness of treatment  Lung function tests is measured using spirometer Spirometer It records the lung volumes and capacities Types of Lung Function tests Static Lung function Dynamic Lung function Not related to time Related to time They are: 1. Tidal volume 2. Inspiratory reserve volume 3. Expiratory reserve volume 4. Residual volume 5. Inspiratory capacity 6. Vital capacity 7. Functional residual capacity 8. Total lung capacity They are: 1. Forced vital capacity FVC 2. Peak Expiratory Flow Rate PEFR 3. Respiratory Minute volume MV 4. Maximum Voluntary Ventilation MVV Static Lungs Volumes and Capacities Lung volumes recorded by a spirometer. Lung capacities are determined from volume Lungs Volumes 1. Tidal volume (TV) 2. Inspiratory Reserve volume (IRV) 3. Expiratory Reserve volume (ERV) 4. Residual volume ( RV ) Lungs Volumes 1. Tidal Volume (TV) It is the volume of air that is inspired or expired in a quiet normal respiration. Its value is 500 ml 2. Inspiratory Reserve Volume (IRV) It is the volume of air that can be maximally inspired by a forced inspiration after a normal inspiration. Its value is 3000 ml Lungs Volumes 3. Expiratory Reserve Volume (ERV) It is the volume of air that can be maximally expired from the end of normal expiration. Its value is 1100 ml 4. Residual Volume (RV) It is the volume of air that remains in the lungs after a maximal expiration. Its value is 1200 ml Residual volume is increased in old age, (obstructive lung disease like emphysema). Helium dilution method is used to measure residual volume. Lung Capacities Sum of two or more volumes = Capacities 1. Inspiratory capacity (TV + IRV ) 2. Vital capacity (TV+IRV+ERV) 3. Functional residual capacity (RV+ERV) 4. Total lung capacity (TV+IRV+ERV+RV ) Lung Capacities 1. Inspiratory capacity (TV + IRV ) Maximum volume of air that can be inspired by forced inspiration after a normal expiration. Normal Value: 3500 ml 2. Vital capacity (VC ) (TV+IRV+ERV) Maximum volume of air that can be maximally expired from the lungs following a maximum inspiration. Normal Value: 4600 ml Lung Capacities 3. Functional residual capacity (FRC ) (RV+ERV ) Volume of air remaining in the lungs at the end of a normal expiration. Normal value: 2300ml Significance: Helps in continuous exchange of gases across the lungs and blood between breaths. FRC is increased in Obstructive Lung diseases FRC is decreased in Pathological: Restrictive lung diseases, ascites Physiological: Supine position, obesity, pregnancy Lung Capacities 4. Total lung capacity (TV+IRV+ERV+RV ) Volume of air contained in the lungs at the end of a maximal inspiration. Normal Value: 6000ml N.B: Most pulmonary volumes and capacities are usually 20% to 30% less in women than in men greater in large and athletic people than in small, asthenic and old age people. Which of the followings volumes and capacities are not measured completely by spirometer Residual volume, Functional residual capacity and Total lung capacity 14 Dynamic Lung Functions Related to time 1- Forced Vital Capacity FVC (Timed Vital Capacity) This is the vital capacity related to seconds FVC and VC record similar information because they both measure the amount of air you can exhale after maximally inhaling. But FVC refers to the amount of air you can exhale forcefully, while VC records the maximum amount of air that exhale when breathing normally. The majority of FVC can be exhaled in