1. One night in A+E

2. Topics for discussion Acid Base Balance and Disorders Arterial Blood Gas Measurement Lung volumes Cardiac Cycle

3. Objectives Understand the basic principles of Acid Base Balance Use a systematic approach to interpret ABGs Interpret and name lung volumes on a graph Understand the difference between Obstructive and Restrictive patterns of lung disease Be able to name and understand the curves on a cardiac cycle diagram

4. https://www.youtube.com/watch?v=ERj9N7TY CSE https://www.youtube.com/watch?v=ERj9N7TY CSE

5. You are a junior doctor on your very first day working in the A&E department at the Royal Free. 2021??

6. Them Values pH7.35-7.45 PaCO 2 Normal range: 4.7-6.0kPa or 35-45 mmHg HCO 3 - Normal range: 22-28 mmol/L

7. What is an “arterial blood gas” (ABG)? What does it measure? Turn to your colleague…

8. Volatile acid Non volatile acids? CO 2 + H 2 O H 2 CO 3 H + + HCO3 -

9. Buffering

10. Compensation CO 2 + H 2 O H 2 CO 3 H + + HCO3 -

11. With this background knowledge in mind, you proceed to meet your first patient!

12. Mr. Jones You meet a 60-year-old male with a history of chronic obstructive pulmonary disease. He is obviously unwell, with severe shortness of breath, pyrexia (fever) and productive cough. His ABGs are shown below: pH7.20 PaCO 2 9.3kPa (or 70 mmHg) HCO 3 - 29mmol/L pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg HCO 3 - 22-28 mmol/L

13. How not to kill someone – an approach to ABGs pO2 (determine oxygenation) pH (acidosis/alkalosis) PaCO2 HCO3- What’s the primary disturbance? Is there any compensation? Is it appropriate?

15. Mr. Jones You meet a 60-year-old male with a history of chronic obstructive pulmonary disease. He is obviously unwell, with severe shortness of breath, pyrexia (fever) and productive cough. His ABGs are shown below: pH7.20 PaCO 2 9.3kPa (or 70 mmHg) HCO 3 - 29mmol/L pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg HCO 3 - 22-28 mmol/L

16. Jim Your next patient is an 18 year-old male. He has been vomiting for the last 24 hours and feels unwell. His ABGs are shown below: pH7.49 PaCO 2 6.3kPa (or 47 mmHg) HCO 3 - 31mmol/L pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg HCO 3 - 22-28 mmol/L

17. Ben You next meet an 8 year-old male who appears lethargic and has a strangely “fruity” smell to his breath. He has a previous history of polyuria (increased frequency and volume of urination), polydipsia (increased thirst) and weight loss. pH7.30 PaCO 2 3.3kPa (or 25 mmHg) HCO 3 - 10mmol/L pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg HCO 3 - 22-28 mmol/L

18. Ronald Your next patient is a 20 year-old with Duchenne muscular dystrophy admitted with urinary tract infection (UTI). He has a temperature of 39 o C, feels warm and peripherally vasodilated with a blood pressure of 90/60. pH7.28 PaCO 2 6.3kPa (or 47 mmHg) HCO 3 - 18mmol/L pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg HCO 3 - 22-28 mmol/L

19. As you begin to rest your heavy head… https://www.youtube.com/watch?v=ERj9N7TY CSE https://www.youtube.com/watch?v=ERj9N7TY CSE

20. OMG The paramedics have brought in a 50 year-old man suspected of having an upper GI bleed. His BP is 90/40. pH7.30 PaCO 2 3.3kPa (or 25 mmHg) HCO 3 - 20mmol/L Lactate5 mmol/L (normal: 0.5-2.0) pH7.35-7.45 PaCO 2 4.7-6.0kPa or 35-45 mmHg) HCO 3 - About 24mmol/L (Normal range: 22-28 mmol/L)

21. On your way out at 8am, you decide to revise some Year 1 physiology..

24. Obstructive almostadoctor.co.uk

25. Restrictive almostadoctor.co.uk

26. Any Questions?