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Air medical transport

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Introduction to air medical issues and aviation physiology

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Air medical transport

  1. 1. Air medical transport <ul><li>What do I need to know? </li></ul>
  2. 2. Hazards / limitations <ul><li>Lighting </li></ul><ul><li>Noise </li></ul><ul><li>Motion </li></ul><ul><li>Vibration </li></ul><ul><li>Space </li></ul><ul><li>Temperature </li></ul><ul><li>Pressure </li></ul>
  3. 3. Question 1 <ul><li>A patient is on room air at sea level. What FiO 2 will they be breathing if they ascend to an altitude of 4000 ft and breathe cabin air? </li></ul><ul><li>Which gas law is at play here? </li></ul>
  4. 4. Question 2 - EC 145 mission <ul><li>A patient is requiring 15 l / min via non-rebreather mask giving a pO 2 of 80 mmHg </li></ul><ul><li>The total retrieval time will be 1.5 hours from leaving the hospital to landing at the receiving hospital helipad </li></ul><ul><li>Assuming an altitude of 5000’... </li></ul><ul><li>Will the patient be able to be oxygenated via facemask at altitude? </li></ul>
  5. 5. Question 3 - EC 145 mission <ul><li>How much oxygen is carried on the EC-145? </li></ul><ul><li>How long will this last? </li></ul>
  6. 6. Question 4 <ul><li>What if we intubated her and ventilated her on air mix on the Oxylog 2000? </li></ul><ul><li>How long would the oxygen last then? </li></ul>
  7. 7. Question 5 <ul><li>How does air pressure change with altitude (draw a graph representing atmospheric pressure vs altitude)? </li></ul><ul><li>What happens to gas within body cavities during ascent? </li></ul><ul><li>Which gas law does this pertain to? </li></ul>
  8. 8. Question 6 <ul><li>List some examples of issues related to altitude-induced expansion of gases in: </li></ul><ul><li>physiological air spaces </li></ul><ul><li>pathological air spaces </li></ul><ul><li>air containing equipment </li></ul>
  9. 9. Question 7 <ul><li>How much does the volume of a gas expand by when ascending from sea level to the normal fixed wing cabin pressure? </li></ul><ul><li>Fixed wings can provide a sea level cabin pressure. Why not request this routinely? </li></ul>
  10. 10. Question 8: Motion (acceleration) <ul><li>In which vehicles is acceleration a potential issue? </li></ul><ul><li>In which patients is acceleration a potential issue? </li></ul>
  11. 11. Question 9 <ul><li>A SCUBA diver in Shellharbour is acutely short of breath with cough and pleuritic pain after ascent. Vital signs stable apart from resp rate of 32. SpO 2 96% on air. Physical exam is otherwise normal </li></ul><ul><li>What is the differential diagnosis? </li></ul><ul><li>Where should he be taken? </li></ul><ul><li>What mode of transport should be used? </li></ul><ul><li>What precautions should be taken? </li></ul>
  12. 12. Question 1 <ul><li>A patient is on room air at sea level. What FiO 2 will they be breathing if they ascend to an altitude of 4000 ft and breathe cabin air? </li></ul><ul><li>Which gas law is at play here? </li></ul>
  13. 13. Dalton’s Law the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressur es of each indivi dual component in a gas mixture.
  14. 14. Question 2 - EC 145 mission <ul><li>A patient is requiring 15 l / min via non-rebreather mask giving a pO 2 of 80 mmHg </li></ul><ul><li>The total retrieval time will be 1.5 hours from leaving the hospital to landing at the receiving hospital helipad </li></ul><ul><li>Assuming an altitude of 5000’... </li></ul><ul><li>Will the patient be able to be oxygenated via facemask at altitude? </li></ul>
  15. 19. Question 3 - EC 145 mission <ul><li>How much oxygen is carried on the EC-145? </li></ul><ul><li>How long will this last? </li></ul>
  16. 20. EC 145 <ul><li>D cylinder 1640 l </li></ul><ul><li>15 l/min </li></ul><ul><li>1640 / 15 = 109 minutes = 1 hr 49 mins </li></ul>
  17. 21. Question 4 <ul><li>What if we intubated her and ventilated her on air mix on the Oxylog 2000? </li></ul><ul><li>How long would the oxygen last then? </li></ul>
  18. 22. <ul><li>60 kg </li></ul><ul><li>MV 80-100 ml/kg/min </li></ul><ul><li>Air mix 50% of MV </li></ul><ul><li>Control 1 l/min </li></ul><ul><li>6 l/min x 50% = 3 l/min + 1 = 4 l/min </li></ul><ul><li>1640 / 4 = 420 min = 7 hours! </li></ul>
  19. 23. Question 5 <ul><li>How does air pressure change with altitude (draw a graph representing atmospheric pressure vs altitude)? </li></ul><ul><li>What happens to gas within body cavities during ascent? </li></ul><ul><li>Which gas law does this pertain to? </li></ul>
  20. 25. Boyle’s Law For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one increases, the other decreases)
  21. 26. Question 6 <ul><li>List some examples of issues related to altitude-induced expansion of gases in: </li></ul><ul><li>physiological air spaces </li></ul><ul><li>pathological air spaces </li></ul><ul><li>air containing equipment </li></ul>
  22. 27. Question 6 <ul><li>physiological air spaces </li></ul><ul><ul><ul><li>sinuses, gut, middle ear </li></ul></ul></ul><ul><li>pathological air spaces </li></ul><ul><ul><ul><li>pleura, head, gut, lung, gas emboli, teeth </li></ul></ul></ul><ul><li>air containing equipment </li></ul><ul><ul><ul><li>tube cuffs, balloon tamponade, PA catheters, PASG, drainage bags, IABP, air splints, ventilators </li></ul></ul></ul>
  23. 30. <ul><li>Ventilators were assessed using either air-mix (60% oxygen) or 100% oxygen and tested against models simulating a normal lung, a low compliance (ARDS) lung and a high-resistance (asthma) lung. </li></ul><ul><li>Tested at a range of simulated altitudes between sea level and 3048 m (10 000 ft). </li></ul><ul><li>V T delivered by the Oxylog 2000 ventilator increased by 29% </li></ul><ul><li>V T remained constant with the Oxylog 3000 over the same range of altitudes. </li></ul><ul><li>Changes were consistent with each ventilator regardless of oxygen content or lung model. </li></ul>
  24. 31. Oxylog 3000 <ul><li>body temperature pressure saturated correction </li></ul><ul><li>ambient pressure correction </li></ul>
  25. 32. Question 7 <ul><li>How much does the volume of a gas expand by when ascending from sea level to the normal fixed wing cabin pressure? </li></ul><ul><li>Fixed wings can provide a sea level cabin pressure. Why not request this routinely? </li></ul>
  26. 34. Sea level cabin pressure <ul><li>Max pressure differential between inside and outside aircraft depends on aircraft type </li></ul><ul><li>Most turboprop air ambulances can provide a cabin altitude of 3000 ft when flying at 20000 ft </li></ul><ul><li>Once max differential achieved need lower flight to lower cabin altitude </li></ul><ul><li>Issues then may be lowest safe altitude, fuel, turbulence, slower flight </li></ul>
  27. 35. Effective Performance Time
  28. 36. Question 8: Motion (acceleration) <ul><li>In which vehicles is acceleration a potential issue? </li></ul><ul><li>In which patients is acceleration a potential issue? </li></ul>
  29. 37. Motion (acceleration) <ul><li>Issue in fixed wing </li></ul><ul><li>Helicopter forces low magnitude = ground </li></ul><ul><li>LVF, raised ICP, hypovolaemia </li></ul><ul><li>Position patient so vector of greatest anticipated acceleration is perpendicular to patient’s long axis (eg. torso as upright as possible in raised ICP during takeoff and landing) </li></ul>
  30. 38. Question 9 <ul><li>A SCUBA diver in Shellharbour is acutely short of breath with cough and pleuritic pain after ascent. Vital signs stable apart from resp rate of 32. SpO 2 96% on air. Physical exam is otherwise normal </li></ul><ul><li>What is the differential diagnosis? </li></ul><ul><li>Where should he be taken? </li></ul><ul><li>What mode of transport should be used? </li></ul><ul><li>What precautions should be taken? </li></ul>
  31. 39. Interfacility Transport of Patients With Decompression Illness: Literature Review and Consensus Statement  Prehospital Emergency Care , Volume 10, Issue 4 December 2006 , pages 482 - 487
  32. 41. Exposure <ul><li>Temperature decreases linearly by 2 ºC per 1000 ft up to ~ 35 000 ft (about -57ºC) </li></ul><ul><li>eg. sea level 16ºC on a Winter’s day, 0ºC at 8000 ft </li></ul>
  33. 42. Summary <ul><li>Gas laws </li></ul><ul><li>Planning oxygen therapy </li></ul><ul><li>Oxygen supplies </li></ul><ul><li>Ventilator issues </li></ul><ul><li>Fixed wing cabin pressures </li></ul><ul><li>Decompression illness </li></ul><ul><li>Temperature, acceleration, humidity </li></ul>
  34. 43. <ul><li>&quot;I hope I die peacefully in my sleep like my grandfather. . .not screaming in terror like his passengers.&quot; </li></ul><ul><li>- Anonymous </li></ul>

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