1. Ins and outs of respiratory physiology David Taylor dcmt@liv.ac.uk All illustrations and text © The University of Liverpool and David Taylor 2008

2. Why?....Dr Al-Ghabra and the medical student with her, Sally Lawrence, review ventilation, gas exchange, and control of breathing related to anatomical landmarks on the film....

3. Why?....Dr Al-Ghabra and the medical student with her, Sally Lawrence, review ventilation, gas exchange, and control of breathing related to anatomical landmarks on the film....

4. Expected outcomes of this be able to....... Explain the different respiratory tests that could be used Recognise, draw and label a lung volume graph Recognise normal volumes and flow rates Understand the difference between obstructive and restrictive lung disease

5. and Relate this new understanding to a patient with asthma

6. Explain the different respiratory tests that could be used Two things matter – Volumes – Flow rates But (vital capacity) differences due to – Age (younger>older – Gender (male>female) – Size (tall>short) – physical condition(thin fit>obese less active)

7. Volumes Tidal volume 500ml Time (each breath about 5s) Minute volume 500 x 12 = 6l min -1

8. Vital capacity Maximum inspiration Maximum expiration Inspiratory Reserve volume 3000ml Expiratory reserve Volume 1100ml TV Vital Capacity 4600ml

9. And the others.... Residual volume 1200ml Expiratory reserve Volume 1100ml Functional residual capacity 2300ml Total lung capacity 5800ml

10. Flow rate... Vital Capacity Forced vital capacity

11. Expanded

12. Forced volumes FEV1 = Forced expiratory volume in 1 second FVC=Forced Vital Capacity In normal adult FEV1/FVC = 75% This patient FEV1/FVC = 44% Obstructive lung disease

13. Chronic airflow limitation In (obstructive) diseases like asthma there is difficulty in breathing out. Over long periods of time this tends to lead to an increase in residual volume

14. Just for completeness If FVC is lower than predicted, then the patient has restrictive lung disease – Expansion of the lung is restricted Fibrosis Pneumonia Pulmonary oedema Pregnancy pain

15. Simplest and cheapest test is Peak expiratory flow rate – Reproducible, but only measures flow over a few milliseconds – And people don’t always try hard – But values over 500 lmin -1 in men – And 400 lmin -1 in women are in the right region – Best used for tracking changes (measure at same time each day for several days)

17. 510 l/min

18. Expected outcomes of this be able to....... Explain the different respiratory tests that could be used Recognise, draw and label a lung volume graph Recognise normal volumes and flow rates Understand the difference between obstructive and restrictive lung disease