Oxygen Therapy 1205496568618301 4

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Oxygen Therapy 1205496568618301 4

  1. 1. <ul><li>DR. Vishram Buche </li></ul><ul><li>OM Child Trust Hospital </li></ul><ul><li>NAGPUR </li></ul>OXYGEN THERAPY
  2. 2. Principles of O2 therapy <ul><li>O2 is a drug, like other drugs, always use optimum to obtain desired effects and avoid unnecessary usage. </li></ul><ul><li>Dose response approach and assess. </li></ul><ul><li>Dynamic O2 Goal </li></ul><ul><ul><ul><li>Keep SpO2 around 95% with minimum FiO2 range. </li></ul></ul></ul><ul><ul><ul><li>Around 90-92% in patients with risk o2 induced hypoventilation. </li></ul></ul></ul>
  3. 3. Goals of O2 therapy <ul><li>To correct arterial hypoxemia and suspected tissue hypoxia </li></ul><ul><li>To decrease the symptoms associated with hypoxemia. </li></ul><ul><li>To minimize cardiopulmonary workload associated with compensatory response to hypoxemia. </li></ul>
  4. 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. 5. Clinical implication…… Any interference to the delivery of O2 at any point in the cascade, Significant injury can occur downstream
  6. 6. 2 TISSUES CaO 2 = (SAT x Hb x 1 . 3 4 ) + .0 0 3(PaO 2 )
  7. 7. Tissue oxygenation depends on: <ul><li>Adequate ventilation </li></ul><ul><li>efficient gas exchange at lung level </li></ul><ul><li>adequate circulatory distribution </li></ul><ul><li> Failure of any of these 3 elements results in tissue hypoxia </li></ul>
  8. 8. Body compensation for tissue Hypoxia 1 ) Increase in cardiac output 2 ) Tissues extract more Oxygen 3 ) Anaerobic metabolism begins
  9. 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. 10. Oxygen content CaO2 = 2% Dissolved O2 ( PaO2  0.003 ml )  98% O 2 is bound to Hb. ( Hb  1.34  SaO2 )
  11. 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. 12. OXYGEN DELIVERY IS A CARDIO-RESPIRATORY FUNCTION
  13. 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. 14. Offloading Oxygen in Tissues Pressure Saturation oxyhemeglobin deoxyhemeglobin pH 7.4 pH 7.35 40 20 18
  15. 15. Onloading Oxygen in Lungs Pressure Saturation oxyhemeglobin deoxyhemeglobin
  16. 16. ODC Pressure Saturation oxyhemeglobin deoxyhemeglobin <ul><li>temp. </li></ul><ul><li>2,3DPG </li></ul><ul><li> ‘ offloading’ to tissues </li></ul>↓ temp. ↓ 2,3DPG <ul><li> ‘ onloading’ in lungs </li></ul>
  17. 17. <ul><li>Chronic hypoxia triggers an increase in 2,3-DPG in RBCs </li></ul><ul><li>2,3-DPG lowers the binding affinity of O2 for hemoglobin; this shifts the curve to the right. </li></ul><ul><li>After prolonged exposure to high altitude, what effect will increased 2,3-DPG have on O2 delivery? </li></ul>
  18. 18. GLUCOSE O2 36 A.T.P. 2 A.T.P. L.ACID
  19. 19. Anaerobic? So What? Inadequate Cellular Oxygenation Anaerobic Metabolism Metabolic Failure Metabolic Acidosis Inadequate Energy Production Lactic Acid Production Cell Death!
  20. 20. Hemoglobin Extinction Curves……. ‘CO’ Carboxyhemoglobin is read as oxyhemoglobin Saturation by pulse ox is falsely high!
  21. 21. Hemoglobin Extinction Curves…… MethHb Methemoglobin is read as reduced hemoglobin Saturation by pulse ox is falsely low !
  22. 22. <ul><li>Fetuses Live in a Low Oxygen Environment and Require a Special Hemoglobin </li></ul><ul><ul><li>The developing fetus cannot breathe and must get all of its oxygen from the placenta </li></ul></ul><ul><ul><li>Fetal blood has a very low pO2, about 30 mm Hg, equivalent to living at 26,000 feet altitude </li></ul></ul><ul><ul><li>This is like &quot;Everest in utero&quot; </li></ul></ul><ul><ul><li>To extract more oxygen from the mother's blood fetuses have a special hemoglobin (hemoglobin F) which has a very high affinity for oxygen </li></ul></ul>
  23. 23. Clinical Effects of Hypoxia <ul><li>Respiration… </li></ul><ul><li>Cardiovascular System… </li></ul><ul><li>Central Nervous System……. </li></ul><ul><li>Cellular and Metabolic Effects…… </li></ul> R/R, depth……  MV.  H/R.(↑CO)  H/R….. Circulatory Failure Altered sensorium  DO2 to tissues  Anaerobic metabolism  cell death
  24. 24. Cyanosis +/- Low SpO2
  25. 25. VENTILATION & PERFUSION RELATIONSHIP
  26. 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. 27. Is there any single test which will pickup tissue hypoxia early ?
  28. 28. M.A.P. F.I.O <ul><li>C.P.A.P / PEEP </li></ul><ul><li>P.I.P. </li></ul><ul><li>INSP. TIME </li></ul><ul><li>FLOW </li></ul><ul><li>R.R. </li></ul>Improving Oxygenation 2
  29. 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. 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. 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. 32. LOW FLOW S. HIGH FLOW S. C.P.A.P. HYPERBAIC O2
  33. 34. (24,28,35,40,60%)
  34. 35. SIMPLE OX. MASK FIO2 VARIABLE 30 TO 60 % FEEDING PROBLEM REBREATHING……
  35. 36. NASAL CANNULA MAX FLOW……2LIT/MIN FIO2 DIF. TO CONTROL HUMIDI. NOT NEC. MOUTH / NOSE BREAT.?
  36. 37. NASOPHARYN. CATH . <ul><li>Oropharynx….Anat. Resvr. </li></ul><ul><li>Oclsn of dist Opening. </li></ul><ul><li>Gastric Distension </li></ul><ul><li>FiO2 difficult to control. </li></ul><ul><li>Secretions </li></ul><ul><li>CATHER MORE THAN 8 FR. </li></ul>
  37. 38. The colour of the mask’s aperture reflects the FiO2 achieved Venturi masks…….. 28% 35% 40% 60%
  38. 39. <ul><li>Can provide 24%-50% oxygen by mixing room air with a precise amount of oxygen thereby delivering a precise FiO2. The size of the port and the oxygen liter flow determine the FiO2. The mask should be fitted to the patient as best as possible to prevent entrainment of room air around the mask which would alter the FiO2. </li></ul>
  39. 40. PATIENT AIR AIR OXYGEN O 2
  40. 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
  41. 43. YOU ALMOST NEVER NEED 100 % OXYGEN VENTURI VALVES
  42. 44. HEAD BOX
  43. 45. PATIENT O2 PARTIAL REBREATH. M. RES. BAG
  44. 46. O2 NON REBREATH. M. RESE. B. PATIENT 100% OXYGEN
  45. 47. BLENDED HUMIDIFIED OXYGEN/AIR SOURCE CPAP
  46. 48. Laryngeal mask
  47. 49. OXYGEN CONCENTRATOR LOW PRESSURE OUTLET
  48. 50. <ul><li>Maintain…… </li></ul><ul><li>H/R…Cardiac output </li></ul><ul><li>HEMOGLOBIN…Avoid anaemia </li></ul><ul><li>Reduce O2 requirement…. </li></ul><ul><li>sedation/paralysis </li></ul><ul><li>Maintain temp….. Avoid fever </li></ul><ul><li>AND t/t of Basic disease </li></ul>
  49. 52. <ul><li>O2 is used at the cellular level to produce ATP. O2 molecule is reduced by cytochrome oxidase and forms OH . and H2O2 (free radicals) </li></ul><ul><li>increases in free radicals lead to cell damage, wherein leakage from these cells leads to an inflammation process </li></ul><ul><li>glutathione, peroxidase, Vitamins C & E protect against free radicals </li></ul>
  50. 53. Oxygen therapy <ul><li>Like any drug has Potential ADRs </li></ul><ul><li>Supervision must during administration </li></ul><ul><li>Surveys indicate 21% of O2 prescriptions inappropriate and 85% of patients not adequately supervised. </li></ul>
  51. 54. Key Message………….. <ul><li>Never reduce, withhold or deny a patient oxygen therapy based on pulse oximetry readings. </li></ul><ul><li>Use your training and judgment to make the decision. </li></ul><ul><li>When in doubt.....give oxygen in adequate amounts. </li></ul><ul><li>Treat the patient....not the number! </li></ul>

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