Mechanical ventilation


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Mechanical ventilation

  1. 1. MECHANICAL VENTILATION Marc Charles Parent
  2. 2. Presentation <ul><li>Different settings to consider </li></ul><ul><li>Monitoring of the patient </li></ul><ul><li>Different type of patient </li></ul><ul><ul><li>COPD, Asthma </li></ul></ul><ul><ul><li>ARDS </li></ul></ul><ul><li>Trouble shooting </li></ul>
  3. 3. Ventilator settings
  4. 4. Ventilator settings <ul><li>Ventilator mode </li></ul><ul><li>Respiratory rate </li></ul><ul><li>Tidal volume or pressure settings </li></ul><ul><li>Inspiratory flow </li></ul><ul><li>I:E ratio </li></ul><ul><li>PEEP </li></ul><ul><li>FiO2 </li></ul><ul><li>Inspiratory trigger </li></ul>
  5. 5. CMV
  6. 6. A/CV
  7. 7. SIMV
  8. 8. PSV(pressure support ventilation) <ul><li>Spontaneous inspiratory efforts trigger the ventilator to provide a variable flow of gas in order to attain a preset airway pressure. </li></ul><ul><li>Can be used in adjunct with SIMV. </li></ul>
  9. 9. Respiratory Rate <ul><li>What is the pt actual rate demand? </li></ul>
  10. 10. Tidal Volume or Pressure setting <ul><li>Maximum volume/pressure to achieve good ventilation and oxygenation without producing alveolar overdistention </li></ul><ul><li>Max cc/kg? = 10 cc/kg </li></ul><ul><li>Some clinical exceptions </li></ul>
  11. 11. Inspiratory flow <ul><li>Varies with the Vt, I:E and RR </li></ul><ul><li>Normally about 60 l/min </li></ul><ul><li>Can be majored to 100- 120 l/min </li></ul>
  12. 12. I:E Ratio <ul><li>1:2 </li></ul><ul><li>Prolonged at 1:3, 1:4, … </li></ul><ul><li>Inverse ratio </li></ul>
  13. 13. FIO2 <ul><li>The usual goal is to use the minimum Fio2 required to have a PaO2 > 60mmhg or a sat >90% </li></ul><ul><li>Start at 100% </li></ul><ul><li>Oxygen toxicity normally with Fio2 >40% </li></ul>
  14. 14. Inspiratory Trigger <ul><li>Normally set automatically </li></ul><ul><li>2 modes: </li></ul><ul><ul><li>Airway pressure </li></ul></ul><ul><ul><li>Flow triggering </li></ul></ul>
  15. 15. Positive End-expiratory Pressure (PEEP) <ul><li>What is PEEP? </li></ul><ul><li>What is the goal of PEEP? </li></ul><ul><ul><li>Improve oxygenation </li></ul></ul><ul><ul><li>Diminish the work of breathing </li></ul></ul><ul><ul><li>Different potential effects </li></ul></ul>
  16. 16. PEEP <ul><li>What are the secondary effects of PEEP? </li></ul><ul><ul><li>Barotrauma </li></ul></ul><ul><ul><li>Diminish cardiac output </li></ul></ul><ul><ul><li>Regional hypoperfusion </li></ul></ul><ul><ul><li>NaCl retention </li></ul></ul><ul><ul><li>Augmentation of I.C.P.? </li></ul></ul><ul><ul><li>Paradoxal hypoxemia </li></ul></ul>
  17. 17. PEEP <ul><li>Contraindication: </li></ul><ul><ul><li>No absolute CI </li></ul></ul><ul><ul><li>Barotrauma </li></ul></ul><ul><ul><li>Airway trauma </li></ul></ul><ul><ul><li>Hemodynamic instability </li></ul></ul><ul><ul><li>I.C.P.? </li></ul></ul><ul><ul><li>Bronchospasm? </li></ul></ul>
  18. 18. PEEP <ul><li>What PEEP do you want? </li></ul><ul><ul><li>Usually, 5-10 cmH2O </li></ul></ul>
  19. 19. Monitoring of the patient
  20. 20. Look at your patient <ul><li>Question your pt </li></ul><ul><li>Examine your pt </li></ul><ul><li>Monitor your pt </li></ul><ul><li>Look at the synchronicity of your pt breathing </li></ul>
  21. 21. Pressures
  22. 22. Compliance pressure (Pplat) <ul><li>Represent the static end inspiratory recoil pressure of the respiratory system, lung and chest wall respectively </li></ul><ul><li>Measures the static compliance or elastance </li></ul>
  23. 23. Pplat <ul><li>Measured by occluding the ventilator 3-5 sec at the end of inspiration </li></ul><ul><li>Should not exceed 30 cmH2O </li></ul>
  24. 24. Peak Pressure (Ppeak) <ul><li>Ppeak = Pplat + Pres </li></ul><ul><li>Where Pres reflects the resistive element of the respiratory system (ET tube and airway) </li></ul>
  25. 25. Ppeak <ul><li>Pressure measured at the end of inspiration </li></ul><ul><li>Should not exceed 50cmH2O? </li></ul>
  26. 26. Auto-PEEP or Intrinsic PEEP <ul><li>What is Auto-PEEP? </li></ul><ul><ul><li>Normally, at end expiration, the lung volume is equal to the FRC </li></ul></ul><ul><ul><li>When PEEPi occurs, the lung volume at end expiration is greater then the FRC </li></ul></ul>
  27. 27. Auto-PEEP or Intrinsic PEEP <ul><li>Why does hyperinflation occur? </li></ul><ul><ul><li>Airflow limitation because of dynamic collapse </li></ul></ul><ul><ul><li>No time to expire all the lung volume ( high RR or Vt) </li></ul></ul><ul><ul><li>Expiratory muscle activity </li></ul></ul><ul><ul><li>Lesions that increase expiratory resistance </li></ul></ul>
  28. 28. Auto-PEEP or Intrinsic PEEP <ul><li>Auto-PEEP is measured in a relaxed pt with an end-expiratory hold maneuver on a mechanical ventilator immediately before the onset of the next breath </li></ul>
  29. 29. Auto-PEEP or Intrinsic PEEP <ul><li>Adverse effects: </li></ul><ul><ul><li>Predisposes to barotrauma </li></ul></ul><ul><ul><li>Predisposes hemodynamic compromises </li></ul></ul><ul><ul><li>Diminishes the efficiency of the force generated by respiratory muscles </li></ul></ul><ul><ul><li>Augments the work of breathing </li></ul></ul><ul><ul><li>Augments the effort to trigger the ventilator </li></ul></ul>
  30. 30. Different types of patient
  31. 31. COPD and Asthma <ul><li>Goals: </li></ul><ul><ul><li>Diminish dynamic hyperinflation </li></ul></ul><ul><ul><li>Diminish work of breathing </li></ul></ul><ul><ul><li>Controlled hypoventilation (permissive hypercapnia) </li></ul></ul>
  32. 32. Diminish DHI <ul><li>Why? </li></ul>
  33. 33. Diminish DHI <ul><li>How? </li></ul><ul><ul><li>Diminish minute ventilation </li></ul></ul><ul><ul><ul><li>Low Vt (6-8 cc/kg) </li></ul></ul></ul><ul><ul><ul><li>Low RR (8-10 b/min) </li></ul></ul></ul><ul><ul><ul><li>Maximize expiratory time </li></ul></ul></ul>
  34. 34. Diminish work of breathing <ul><li>How: </li></ul><ul><ul><li>Add PEEP (about 85% of PEEPi) </li></ul></ul><ul><ul><li>Applicable in COPD and Asthma. </li></ul></ul>
  35. 35. Controlled hypercapnia <ul><li>Why? </li></ul><ul><ul><li>Limit high airway pressures and thus diminish the risk of complications </li></ul></ul>
  36. 36. Controlled hypercapnia <ul><li>How? </li></ul><ul><ul><li>Control the ventilation to keep adequate pressures up to a PH > 7.20 and/or a PaCO2 of 80 mmHg </li></ul></ul>
  37. 37. Controlled hypercapnia <ul><li>CI: </li></ul><ul><ul><li>Head pathologies </li></ul></ul><ul><ul><li>Severe HTN </li></ul></ul><ul><ul><li>Severe metabolic acidosis </li></ul></ul><ul><ul><li>Hypovolemia </li></ul></ul><ul><ul><li>Severe refractory hypoxia </li></ul></ul><ul><ul><li>Severe pulmonary HTN </li></ul></ul><ul><ul><li>Coronary disease </li></ul></ul>
  38. 38. A.R.D.S. <ul><li>Ventilation with lower tidal volume as compared with traditional volumes for acute lung injury and the ARDS </li></ul><ul><li>The Acute Respiratory Distress Syndrome Network </li></ul><ul><li>N Engl J Med 2000;342:1301-08 </li></ul>
  39. 39. Methods <ul><li>March 96 – March 99 </li></ul><ul><li>10 university centers </li></ul><ul><li>Inclusion: </li></ul><ul><ul><li>Diminish PaO2 </li></ul></ul><ul><ul><li>Bilateral infiltrate </li></ul></ul><ul><ul><li>Wedge < 18 </li></ul></ul><ul><li>Exclusion </li></ul><ul><li>Randomized </li></ul>
  40. 40. Methods <ul><li>A/C 28d or weaning </li></ul><ul><li>2 groups: </li></ul><ul><ul><li>1. Traditional Vt (12cc/kg) </li></ul></ul><ul><ul><li>2. Low Vt (6cc/kg) </li></ul></ul><ul><li>End point: </li></ul><ul><ul><li>1. Death </li></ul></ul><ul><ul><li>2. Days of spontaneous breathing </li></ul></ul><ul><ul><li>3. Days without organ failure or barotrauma </li></ul></ul>
  41. 41. Results <ul><li>The trails were stopped after 861 pt because of lower mortality in low Vt group </li></ul>
  42. 42. Trouble Shooting
  43. 43. Trouble Shooting <ul><li>Doctor, doctor, his pressures are going up!!! </li></ul><ul><li>What is your next step? </li></ul>
  44. 44. Trouble Shooting <ul><li>Call the I.T., he will take care of it! </li></ul><ul><li>Where is the staff? </li></ul><ul><li>I dont know this pt, and run! </li></ul><ul><li>Ask which pressure is going up </li></ul>
  45. 45. Trouble Shooting <ul><li>Ppeak is up </li></ul><ul><ul><li>Look at your Pplat </li></ul></ul>
  46. 46. Trouble Shooting <ul><li>If your Pplat is high, you are faced with a COMPLIANCE problem </li></ul><ul><li>If your Pplat is N, you are faced with a RESISTIVE problem </li></ul><ul><li>DD? </li></ul>
  47. 47. Trouble Shooting
  48. 48. Trouble Shooting <ul><li>Doctor, doctor, my patient is very agitated! </li></ul><ul><ul><li>What is your next step? </li></ul></ul>
  49. 49. Trouble Shooting <ul><li>Give an ativan to the nurse! </li></ul><ul><li>Give haldol 10mg to the patient! </li></ul><ul><li>Take 5mg of morphine for yourself! </li></ul><ul><li>Look at your pt! </li></ul>
  50. 50. Trouble Shooting <ul><li>At the time of intubation, fighting is largely due to anxiety </li></ul><ul><li>But what do you do if pt is stable and then becomes agitated? </li></ul>
  51. 51. Trouble Shooting <ul><li>Remove pt from ventilator </li></ul><ul><li>Initiate manual ventilation </li></ul><ul><li>Perform P/E and assess monitoring indices </li></ul><ul><li>Check patency of airway </li></ul><ul><li>If death is imminent, consider and treat most likely causes </li></ul><ul><li>Once pt is stabilized, undertake more detailed assessement and management </li></ul>
  52. 52. Trouble Shooting
  53. 53. Conclusion