4. Oxygen Cascade Dry Atmosph: 160 Humidified Tracheal gas: 150 Alveolar gas: 105 Arterial blood: 100 Capillary blood: 45 Mitochondria: 5 Venous blood: 45

5. Clinical implication…… Any interference to the delivery of O2 at any point in the cascade, Significant injury can occur downstream

6. 2 TISSUES CaO 2 = (SAT x Hb x 1 . 3 4 ) + .0 0 3(PaO 2 )

8. Body compensation for tissue Hypoxia 1 ) Increase in cardiac output 2 ) Tissues extract more Oxygen 3 ) Anaerobic metabolism begins

9. PaO2 SaO2 OXY (Sat) 98% HAEMOGLOBIN 2 % Dissolved Oxygen O. D. C. PAO2 A.C.I. CaO2 Content of oxygen Ml/100 of blood Delivery Of Oxygen To Tissues DaO2 O2 Cardiac output A.C.I.( Alveolar capillary interface)

10. Oxygen content CaO2 = 2% Dissolved O2 ( PaO2  0.003 ml )  98% O 2 is bound to Hb. ( Hb  1.34  SaO2 )

11. HB% 12 SAT 100% HB% 12 SAT 50% HB 6 SAT 100% HB 13 SAT 90% PaO2 SATURATION O2 content Normal ↓ ↓ ↓ or N

12. OXYGEN DELIVERY IS A CARDIO-RESPIRATORY FUNCTION

13. Onloading Oxygen in Lungs Pressure Saturation oxyhemeglobin deoxyhemeglobin pH 7.4 pH 7.45  pH shifts curve to left  ‘ onloading’ in lungs Remember: CO 2  [H + ]

14. Offloading Oxygen in Tissues Pressure Saturation oxyhemeglobin deoxyhemeglobin pH 7.4 pH 7.35 40 20 18

15. Onloading Oxygen in Lungs Pressure Saturation oxyhemeglobin deoxyhemeglobin

18. GLUCOSE O2 36 A.T.P. 2 A.T.P. L.ACID

19. Anaerobic? So What? Inadequate Cellular Oxygenation Anaerobic Metabolism Metabolic Failure Metabolic Acidosis Inadequate Energy Production Lactic Acid Production Cell Death!

20. Hemoglobin Extinction Curves……. ‘CO’ Carboxyhemoglobin is read as oxyhemoglobin Saturation by pulse ox is falsely high!

21. Hemoglobin Extinction Curves…… MethHb Methemoglobin is read as reduced hemoglobin Saturation by pulse ox is falsely low !

24. Cyanosis +/- Low SpO2

25. VENTILATION & PERFUSION RELATIONSHIP

26. If there are obvious signs that the patient is deteriorating –  BP,  HR & RR it is a good idea to request an ABG analysis even if the SpO2 value is normal.

27. Is there any single test which will pickup tissue hypoxia early ?

29. Table 1. Principle stores of oxygen in the body While breathing AIR While breathing 100% O2 In the lungs (FRC) 450ml 3000ml In the blood 850ml 950ml Dissolved or bound in tissues (FRC) 250ml 300ml Total 1550ml 4250ml

30. Causes….Mechanism…. D/D of Hypoxia/Hypoxemia…….. Non R E S P I R A T O R Y Does supplemental O2(↑FiO2)increase PaO2 substantially PaO2 SaO2 CaO2 P(A-a)O2 R-L shunt      No ANAEMIA N  N  N NO CO / MethHb N   N Possibly  ventilation    N NO Tissue (histo) N N N N NO

31. Causes….Mechanism…. D/D of Hypoxia/Hypoxemia…….. R E S P I R A T O R Y Does supplemental O2(↑FiO2)increase PaO2 substantially PaO2 SaO2 CaO2 P(A-a)O2 R-L shunt     No (depends on magnitude of shunt) V-Q mismatch     Yes Diffusion Barrier     Yes  ventilation    N Yes  PiO2    N Yes

32. LOW FLOW S. HIGH FLOW S. C.P.A.P. HYPERBAIC O2

34. (24,28,35,40,60%)

35. SIMPLE OX. MASK FIO2 VARIABLE 30 TO 60 % FEEDING PROBLEM REBREATHING……

36. NASAL CANNULA MAX FLOW……2LIT/MIN FIO2 DIF. TO CONTROL HUMIDI. NOT NEC. MOUTH / NOSE BREAT.?

38. The colour of the mask’s aperture reflects the FiO2 achieved Venturi masks…….. 28% 35% 40% 60%

40. PATIENT AIR AIR OXYGEN O 2

42. 24% 4lit 105 28 6 68 31 8 63 35 10 56 40 12 50 50 12 33 FI O2 O2/L/MIN FLOW

43. YOU ALMOST NEVER NEED 100 % OXYGEN VENTURI VALVES

44. HEAD BOX

45. PATIENT O2 PARTIAL REBREATH. M. RES. BAG

46. O2 NON REBREATH. M. RESE. B. PATIENT 100% OXYGEN

47. BLENDED HUMIDIFIED OXYGEN/AIR SOURCE CPAP

48. Laryngeal mask

49. OXYGEN CONCENTRATOR LOW PRESSURE OUTLET