Acute respiratory failure

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Acute respiratory failure

  1. 1. ACUTE RESPIRATORY FAILUREIhab B Abdalrahman, MBBS, MD, ABIM, SSBBIhab TarawaConsultant of Acute Care Medicine, Soba University Hospital 10/2/2012 1
  2. 2. BASIC RESPIRATORY PHYSIOLOGY Ihab Tarawa 10/2/2012 2
  3. 3. Respiratory system maderidiculously easy It is as simple as moving the air in and out. Allowing gas exchange. Ihab Tarawa 10/2/2012 3
  4. 4. CO2 O2 Ihab Tarawa 10/2/2012 4
  5. 5. 1,2,3 Bottom line of the respiratory system is to  Let oxygen in,  And carbon dioxide out. Ihab Tarawa 10/2/2012 5
  6. 6. Definitions acute respiratory failure occurs when:  pulmonary system is no longer able to meet the metabolic demands of the body hypoxaemic respiratory failure:  PaO2  8 kPa when breathing room air hypercapnic respiratory failure:  PaCO2  6.7 kPa Ihab Tarawa 10/2/2012 6
  7. 7. Oxygen inDepends on  Ventilation  PAO2  Perfusion  Ventilation-perfusion matching  Diffusing capacity Ihab Tarawa 10/2/2012 7
  8. 8. PAO2 The alveolar pressure is equal to the sum of the partial pressures of the gases within the alveolus. The partial pressure of each gas is proportional to the concentration of the gas. Ihab Tarawa 10/2/2012 8
  9. 9. Oxygen Carbon dioxide Water vapour NitrogenAlveolarpressure PAO2  PACO2  PAH2O  PAN2 Ihab Tarawa 10/2/2012 9
  10. 10. Oxygen Carbon dioxide Water vapour NitrogenAlveolarpressure PAO2  PACO2  PAH2O  PAN2 Ihab Tarawa 10/2/2012 10
  11. 11. Oxygen Carbon dioxide Water vapour NitrogenAlveolarpressure PAO2  PACO2  PAH2O  PAN2 Ihab Tarawa 10/2/2012 11
  12. 12. Oxygen in Depends on  PAO2  FIO2  Alveolar pressure  PACO2  Ventilation  Ventilation-perfusion matching  Perfusion  Diffusing capacity Ihab Tarawa 10/2/2012 12
  13. 13. Ventilation-perfusionmatching Ihab Tarawa 10/2/2012 13
  14. 14. Carbon dioxide out Largely dependent on alveolar ventilation Alveolar ventilation  RR x (V - V ) T D Anatomical dead space constant but physiological dead space depends on ventilation- perfusion matching Ihab Tarawa 10/2/2012 14
  15. 15. Carbon dioxide out Respiratory rate Tidal volume Ventilation-perfusion matching Ihab Tarawa 10/2/2012 15
  16. 16. PATHOPHYSIOLOGY Ihab Tarawa 10/2/2012 16
  17. 17. Normalventilation & perfusion PAO2=14.74 kPa PACO2=5 kPa 75% 100% Ihab Tarawa 10/2/2012 17
  18. 18. Pathophysiology Low inspired Po2  Although, in theory, acute respiratory failure may result from a low inspired PO2 this is rarely a problem in Intensive Care except in locations at high altitude. Ihab Tarawa 10/2/2012 18
  19. 19. Pathophysiology Low inspired oxygen concentration Hypoventilation Ihab Tarawa 10/2/2012 19
  20. 20. Oxygen Carbon dioxide Water vapour NitrogenAlveolarpressure PAO2  PACO2  PAH2O  PAN2 Ihab Tarawa 10/2/2012 20
  21. 21. Hypoventilation PAO2=9.74 kPa PACO2=10 kPa 75% 92% Ihab Tarawa 10/2/2012 21
  22. 22. Brainstem Spinal cord Airway Nerve root Lung Nerve Pleura NeuromuscularChest wall junction Respiratory muscle Sites at which disease may cause hypoventilation Ihab Tarawa 10/2/2012 22
  23. 23. Brainstem Spinal cord Airway Nerve root Lung Nerve Pleura NeuromuscularChest wall junction Respiratory muscle Sites at which disease may cause hypoventilation Ihab Tarawa 10/2/2012 23
  24. 24. Pathophysiology Low inspired oxygen concentration Hypoventilation Shunting Dead space ventilation Diffusion abnormality Ihab Tarawa 10/2/2012 24
  25. 25. Shunt Ihab Tarawa 10/2/2012 25
  26. 26. oxygen therapyhas relativelylittle effect onhypoxia due toshunting. 75% 75% 100% 75% 87.5% Ihab Tarawa 10/2/2012 26
  27. 27. hypoxic vasoconstriction↓perfusion to non-ventilated alveoli↑perfusion to ventilated alveoli,↓ magnitude of the shunt↑and increasing the arterial saturation 75% 75% 100% 75% 90% Ihab Tarawa 10/2/2012 27
  28. 28. Shunting Intra-pulmonary  Pneumonia  Pulmonary oedema  Atelectasis  Collapse  Pulmonary haemorrhage or contusion Intra-cardiac  Any cause of right to left shunt  eg Fallot’s, Eisenmenger,  Pulmonary hypertension with patent foramen ovale Ihab Tarawa 10/2/2012 28
  29. 29. Pathophysiology Low inspired oxygen concentration Hypoventilation Shunting Dead space ventilation Diffusion abnormality Ihab Tarawa 10/2/2012 29
  30. 30. Dead spaceventilated but notperfused Ihab Tarawa 10/2/2012 30
  31. 31. Pathophysiology Low inspired oxygen concentration Hypoventilation Shunting Dead space ventilation Diffusion abnormality Ihab Tarawa 10/2/2012 31
  32. 32. Ihab Tarawa 10/2/2012 32
  33. 33. Diffusion abnormalities. These can result from a failure of diffusion across the alveolar membrane or a reduction in the number of alveoli resulting in a reduction in the alveolar surface area. Causes include ARDS and fibrotic lung disease Ihab Tarawa 10/2/2012 33
  34. 34. RESPIRATORY MONITORING Ihab Tarawa 10/2/2012 34
  35. 35. Clinical Respiratory compensation Sympathetic stimulation Tissue hypoxia Haemoglobin desaturation Ihab Tarawa 10/2/2012 35
  36. 36.  Bottom line of the respiratory system is to let oxygen in and CO2 out. Some sensors will go off  Hypoxia  Acidosis Ihab Tarawa 10/2/2012 36
  37. 37. Ihab Tarawa 10/2/2012 37
  38. 38. Clinical Respiratory compensation  Tachypnoea  Accessory muscles  Recession  Nasal flaring Ihab Tarawa 10/2/2012 38
  39. 39. Clinical Sympathetic stimulation Ihab Tarawa 10/2/2012 39
  40. 40. Clinical Sympathetic stimulation  HR  BP (early)  sweating Ihab Tarawa 10/2/2012 40
  41. 41. Point of making a difference Coming for help Or coming with a coffin Ihab Tarawa 10/2/2012 41
  42. 42. Clinical Tissue hypoxia  Altered mental state  HR and BP (late) Ihab Tarawa 10/2/2012 42
  43. 43. Clinical Haemoglobin desaturation  cyanosis Ihab Tarawa 10/2/2012 43
  44. 44. If we wait for thepatient to becomecyanosed Ihab Tarawa 10/2/2012 44
  45. 45. Pulse oximetry, notice thesigmoid curve 90 Hb saturation (%) 8 PaO2 (kPa) Ihab Tarawa 10/2/2012 45
  46. 46.  The oxygen content of blood is mainly dependent on:  the haemoglobin saturation,  with the a very small contribution from dissolved oxygen. Ihab Tarawa 10/2/2012 46
  47. 47. Oxygen deliveryO2 delivery  Cardiac output  O2 content  10O2 content  O2 saturation Hb  1.37  0.003  PaO2 Ihab Tarawa 10/2/2012 47
  48. 48. Monitoring Ihab Tarawa 10/2/2012 48
  49. 49. 123 80 40 87% HR=95Ihab Tarawa 10/2/2012 49
  50. 50. Sources of error Poor peripheral perfusion Poorly adherent/positioned probe False nails or nail varnish Lipaemia Bright ambient light Excessive motion Carboxyhaemoglobin or methaemoglobin Ihab Tarawa 10/2/2012 50
  51. 51. Thing to rememberSaturation is not a measure of ventilation Ihab Tarawa 10/2/2012 51
  52. 52. Summary worry if  RR > 30/min (or < 8/min)  unable to speak 1/2 sentence without pausing  agitated, confused or comatose  cyanosed or SpO2 < 90%  deteriorating despite therapy remember  normal SpO2 does not mean severe ventilatory problems are not present Ihab Tarawa 10/2/2012 52
  53. 53. TREATMENT Ihab Tarawa 10/2/2012 53
  54. 54. Treatment Treat the cause Supportive treatment  Oxygen therapy  CPAP  Mechanical ventilation Ihab Tarawa 10/2/2012 54
  55. 55. Oxygen therapy Fixed performance devices Variable performance devices Ihab Tarawa 10/2/2012 55
  56. 56.  Nasal canula Simpler mask Other Ihab Tarawa 10/2/2012 56
  57. 57. Other devices Reservoir face mask Bag valve resuscitator Ihab Tarawa 10/2/2012 57
  58. 58. CPAP reduces shunt by recruiting partially collapsed alveoli Ihab Tarawa 10/2/2012 58
  59. 59. Ihab Tarawa 10/2/2012 59
  60. 60. Lung compliance and FRC reduces work of breathing Volume Pressure Ihab Tarawa 10/2/2012 60
  61. 61. Mechanical ventilation Decision to ventilate  Complex  Multifactorial  No simple rules Ihab Tarawa 10/2/2012 61
  62. 62. Ventilate? Severity of respiratory failure Ihab Tarawa 10/2/2012 62
  63. 63. Ventilate? Severity of respiratory failure Cardiopulmonary reserve Ihab Tarawa 10/2/2012 63
  64. 64. Ventilate? Severity of respiratory failure Cardiopulmonary reserve Adequacy of compensation  Ventilatory requirement Ihab Tarawa 10/2/2012 64
  65. 65. Ventilate? Severity of respiratory failure Cardiopulmonary reserve Adequacy of compensation  Ventilatory requirement Expected speed of response  Underlying disease  Treatment already given Ihab Tarawa 10/2/2012 65
  66. 66. Ventilate? Severity of respiratory failure Cardiopulmonary reserve Adequacy of compensation  Ventilatory requirement Expected speed of response  Underlying disease  Treatment already given Risks of mechanical ventilation Ihab Tarawa 10/2/2012 66
  67. 67. Ventilate? Severity of respiratory failure Cardiopulmonary reserve Adequacy of compensation  Ventilatory requirement Expected speed of response  Underlying disease  Treatment already given Risks of mechanical ventilation Non-respiratory indication for intubation Ihab Tarawa 10/2/2012 67
  68. 68. Ventilate? 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 68
  69. 69. Yes 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 69
  70. 70. Yes 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask O2 O2 Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 70
  71. 71. Yes 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 71
  72. 72. Yes 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 72
  73. 73. Yes 43 year old male Community acquired pneumonia Day 1 of antibiotics PaO2 8 kPa (60 mmHg), PaCO2 4 kPa (30 mmHg), pH 7.15 on 15 l/min O2 via reservoir facemask Respiratory rate 35/min Agitated Ihab Tarawa 10/2/2012 73
  74. 74. Ventilate? 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 74
  75. 75. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 75
  76. 76. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 76
  77. 77. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 77
  78. 78. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 78
  79. 79. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 79
  80. 80. No 24 year old woman Presents to A&E with acute asthma  SOB for 2 days Salbutamol inhaler, no steroids PFR 60 L/min, HR 105/min pH 7.25 PaCO2 6.8 kPa (51 mmHg), PaO2 42 kPa (315 mmHg) on FiO2 0.6 RR 35/min Alert Ihab Tarawa 10/2/2012 80
  81. 81. Pathway Airway patent  Secure airway Patient breathing  Ventilat Is he hypoxic Ihab Tarawa 10/2/2012 81
  82. 82. HypoxicYes No Acidosis Shock PE Asthma Pumonary edema Anxiety Ihab Tarawa 10/2/2012 82
  83. 83. Hypoxic Pco2 Low Pco2High /normal pneumonia ARDS Pulmonary edema Aspiration PE pneumothorax Ihab Tarawa 10/2/2012 83
  84. 84. Hypoxic Pco2 Low Pco2 High /normal Normal A-a High A-a gradient gradientBreathing Breathing Fatigue from hard normally hypoxia Acute on Asthma CND chronic COPD Drugs PE Ihab Tarawa 10/2/2012 84
  85. 85. Ihab Tarawa 10/2/2012 85
  86. 86. QUESTIONS? Ihab Tarawa 10/2/2012 86

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