007_Oxygenation and ventilation information.ppt
- 1. ONTARIO BASE HOSPITAL GROUP 2007 Ontario Base Hospital Group ADVANCED ASSESSMENT Ventilation & Oxygenation QUIT
- 2. OBHG Education Subcommittee AUTHORS Rob Theriault AEMCA, RCT(Adv.), CCP(F) Peel Region Base Hospital 2007 Ontario Base Hospital Group ADVANCED ASSESSMENT Ventilation & Oxygenation REVIEWERS/CONTRIBUTORS Donna Smith AEMCA, ACP Hamilton Base Hospital
- 3. OBHG Education Subcommittee Inhaled air passes through the mouth and nose trachea right & left mainstem bronchi secondary & tertiary bronchi, etc Gas exchange region MENU QUIT p. 5 of 56 Lung anatomy
- 4. OBHG Education Subcommittee Gas exchange takes place in the respiratory bronchioles, the alveolar ducts and the alveoli. gas exchanging surface area is approximately 70 m2 . Alveoli have a rich capillary network for gas exchange Lung anatomy MENU QUIT p. 6 of 56
- 5. OBHG Education Subcommittee Respiratory rate: number of breaths per minute (bpm) Tidal volume (TV): volume of air inhaled in one breath - exhaled tidal volume can also be measured Minute volume (VM) = R.R. x tidal volume Relevant lung volumes/values MENU QUIT p. 7 of 56
- 6. OBHG Education Subcommittee Ventilation vs. Oxygenation MENU QUIT p. 8 of 56
- 7. OBHG Education Subcommittee Ventilation vs. Oxygenation Often thought of as synonymous two distinct processes MENU QUIT p. 9 of 56
- 8. OBHG Education Subcommittee Ventilation vs. Oxygenation What is PaCO2 and PaO2 ? PaCO2 is the partial pressure exerted by dissolved CO2 in arterial blood. Normal PaCO2 is: 35-45 mmHg MENU QUIT p. 10 of 56 PaO2 is the partial pressure exerted by dissolved O2 in arterial blood. Normal PaO2 is: 80-100 mmHg Think of RBC’s as a magnet that is affected by blood ph
- 9. OBHG Education Subcommittee e.g. if you were to hyperventilate someone without supplemental O2 , you would notice that their PaCO2 level would drop (below 35 mmHg), while their PaO2 would remain unchanged or increase marginally. p. 11 of 56 Ventilation vs. Oxygenation PaCO2 is affected by ventilation
- 10. OBHG Education Subcommittee e.g. if you were to provide the patient with supplemental O2, now you would see their PaO2 begin to rise significantly (above 100 mmHg). Meanwhile, if their R.R. and tidal volume remained unchanged, you would see no change in their PaCO2. p. 11 of 56 Ventilation vs. Oxygenation PaO2 is affected by providing supplementation oxygen
- 11. OBHG Education Subcommittee Exception If there is a ventilation to perfusion (V/Q) mismatch that can be improved by providing positive pressure ventilation (e.g. ventilating a patient who has pulmonary edema) , this may help to increase the PaO2 . Positive pressure ventilation does this by opening up a greater number of alveoli and increasing the surface area across which oxygen can diffuse. …more about this later p. 12 of 56
- 12. OBHG Education Subcommittee Ventilation to perfusion ratio: V/Q Review MENU QUIT p. 13 of 56
- 13. OBHG Education Subcommittee GOOD AIR ENTRY GOOD BLOOD FLOW = V/Q MATCH V/Q ratio MENU QUIT p. 14 of 56
- 14. OBHG Education Subcommittee Let’s look at some examples of V/Q mismatch, i.e. shunting and dead space ventilation MENU QUIT p. 15 of 56
- 15. OBHG Education Subcommittee WHAT IS A SHUNT? Results when something interferes with air movement to the gas exchanging areas MENU QUIT p. 16 of 56
- 16. OBHG Education Subcommittee WHAT IS A SHUNT? EXAMPLES? F.B.O. bronchospasm mucous plugging pneumonia pulmonary edema hypoventilation positional etc. MENU QUIT p. 17 of 56
- 17. OBHG Education Subcommittee WHAT IS DEAD SPACE? ANATOMICAL PATHOLOGICAL air passages where there is no gas exchange mouth & nose, trachea, mainstem bronchi, secondary, tertiary, etc ~ 150 cc in the adult pulmonary embolus Shock (vasoconstriction) MENU QUIT p. 18 of 56
- 18. OBHG Education Subcommittee Normal blood flow Blocked or impaired blood flow Pathological dead space MENU QUIT p. 19 of 56
- 19. OBHG Education Subcommittee EXAMPLE emphysema pulmonary edema Mixed shunt & dead space Shunt from fluid in the airways Dead space: interstitial edema separates the airways from the capillaries MENU QUIT p. 21 of 56
- 20. OBHG Education Subcommittee SUMMARY Shunt vs. Dead Space MENU QUIT p. 20 of 56 Results from anything that interferes with the movement of air down to the gas exchanging areas •Non-gas exchanging areas - or •Areas of the lungs normally involved in gas exchange, however blocked or impaired blood flow preventing this.
- 21. OBHG Education Subcommittee Once again... IMPORTANT CLINICAL NOTE Ventilation alone has virtually no effect on PaO2 - except where there is a shunt and when positive pressure ventilation can help to open up additional alveoli to the surface area for oxygen diffusion MENU QUIT p. 22 of 56
- 22. OBHG Education Subcommittee FLOW OF OXYGEN O2 crosses the alveolar-capillary membrane then dissolves in plasma then binds to hemoglobin (98%) - 2% remains dissolved in blood plasma O2 bound to hemoglobin then comes off hemoglobin, dissolves in plasma and diffuses to the tissues MENU QUIT p. 24 of 56
- 23. OBHG Education Subcommittee NOTE: Pulse oximetry (SpO2) is the measurement of O2 bound to hemoglobin - i.e. the percentage of hemoglobin saturated with O2 molecules. MENU QUIT p. 25 of 56 Whatever O2 is not bound to hemoglobin gets transported in its dissolved form in blood plasma – this the PaO2
- 24. OBHG Education Subcommittee Hemoglobin’s affinity for oxygen ...It’s like a magnet MENU QUIT p. 26 of 56
- 25. OBHG Education Subcommittee Before we begin discussion of the Bohr effect, we need to review a little about blood pH normal blood pH is 7.35 to 7.45 a pH below 7.35 is called an acidosis, while a pH above 7.45 is called an alkalosis CO2 is part of the carbonic acid buffer equation - when CO2 is blown off, it’s like blowing off acids - therefore the blood pH shifts toward the alkaline side. CO2 diffuses 20 times more readily that O2 - i.e. 20:1 ratio. MENU QUIT p. 27 of 56 Bohr Effect
- 26. OBHG Education Subcommittee The Bohr effect describes the body’s ability to take in and transport oxygen and release it at the tissue level. According to the Bohr effect, hemoglobin is like a magnet that becomes stronger in an alkaline environment and weaker in an acidotic environment. Bohr Effect Let’s look now at how the Bohr effect is put in to practice in the process of breathing... MENU QUIT p. 28 of 56
- 27. OBHG Education Subcommittee when we exhale, we blow off CO2. This shifts the blood pH toward the alkaline side. Hemoglobin becomes a stronger magnet and attracts O2 as air is inhaled. At the tissue level, CO2, a by-product of cellular metabolism, diffuses from the tissue to the blood. This shifts the blood pH toward the acidic side, weakening hemoglobin’s hold on O2 (weaker magnet), and releasing O2 to the tissues. This occurs on a breath by breath basis MENU QUIT p. 29 of 56 Bohr Effect
- 28. OBHG Education Subcommittee Clinical application - Bohr Effect If you over-zealously hyperventilate a patient, they will become alkalotic. When the blood pH becomes persistently alkalotic, hemoglobin strongly attracts O2 at the level of the lungs, but doesn’t release it well at the tissue level. i.e. blowing off too much CO2 may result in impairment of oxygenation at the tissue level. MENU QUIT p. 30 of 56
- 29. OBHG Education Subcommittee What did they teach you to do when you encounter a patient who is “hyperventilating”? 1. Don’t give them oxygen ”?” 2. Coach their breathing to slow them down MENU QUIT p. 31 of 56 Clinical application - Bohr Effect
- 30. OBHG Education Subcommittee MENU QUIT p. 32 of 56 Ventilation: Clinical Issues When the patient hyperventilates When we hyperventilate the patient
- 31. OBHG Education Subcommittee When the patient hyperventilates When you first encounter a patient who is hyperventilating, always assume there’s an underlying medical condition responsible. Differential: Acute RDS, asthma, atrial fibrillation, atrial flutter, cardiomyopathy, exacerbated COPD, costochondritis, diabetic ketoacidosis, hyperthyroidism, hyperventilation syndrome, metabolic acidosis, myocardial infarct, pleural effusion, panic disorder, bacterial pneumonia, pneumothorax, pulmonary embolism, smoke inhalation, CO poisoning, withdrawal syndromes, drug overdose (e.g. salycilates)… MENU QUIT p. 33 of 56 Benign or life-threatening
- 32. OBHG Education Subcommittee too much CO2 is blown off respiratory alkalosis potassium and calcium shift intracellular tetany vessel spasm MENU QUIT p. 34 of 56 When the patient hyperventilates
- 33. OBHG Education Subcommittee withholding oxygen from someone who is hyperventilating serves no benefit and may be harmful making the patient re-breath their own CO2 can be dangerous and even fatal MENU QUIT p. 34 of 56 When the patient hyperventilates
- 34. OBHG Education Subcommittee Shift in thinking 1. don’t judge the patient MENU QUIT p. 35 of 56 2. give them all oxygen 3. don’t coach their breathing - at least not at first 4. don’t use a paper bag or oxygen mask (without oxygen) 5. begin assessment on the assumption that there is an underlying metabolic (or structural) cause When the patient hyperventilates
- 35. OBHG Education Subcommittee MENU QUIT p. 36 of 56 Brain Injury: Increased ICP CO2 is a potent vasodilator When we hyperventilate the patient hyperventilating the patient causes cerebral vasoconstriction which helps decrease ICP good in theory – not so good in practice
- 36. OBHG Education Subcommittee MENU QUIT p. 36 of 56 Secondary Brain Injury: Watershed The vessels within the injured area are damaged constricting the vessels surrounding the damaged area from overzealous hyperventilation results in blood flow into the damaged area resulting in worsened edema and further secondary brain damage. Injury Secondary injury When we hyperventilate the patient
- 37. OBHG Education Subcommittee SUMMARY Ventilation & Oxygenation Not the same thing MENU QUIT p. 39 of 56
- 38. OBHG Education Subcommittee QUIZ MENU QUIT p. 37 of 56
- 39. OBHG Education Subcommittee A B C D a very small volume the amount of air inhaled with each breath (TV) the volume of inhaled air over one minute (R.R. x TV) a quiet sound Question # 1 What does the term “minute volume” mean? p. 38 of 56
- 40. OBHG Education Subcommittee A B C D Question # 1 What does the term “minute volume” mean? a very small volume the amount of air inhaled with each breath (TV) the volume of inhaled air over one minute (R.R. x TV) a quiet sound p. 37 of 56
- 41. OBHG Education Subcommittee A B C D The mouth, nose and trachea the respiratory bronchioles, alveolar ducts and alveoli the mainstem bronchi the lining of the stomach Question # 2 The gas exchanging areas of the lungs include: p. 38 of 56
- 42. OBHG Education Subcommittee A B C D The mouth, nose and trachea the respiratory bronchioles, alveolar ducts and alveoli the mainstem bronchi the lining of the stomach Question # 2 The gas exchanging areas of the lungs include: p. 39 of 56
- 43. OBHG Education Subcommittee PaO2 PaCO2 A B Question # 3 What blood gas component does ventilation affect? p. 40 of 56
- 44. OBHG Education Subcommittee Ventilation affects primarily the PaCO2 level e.g. if you were to hyperventilate someone without supplemental O2, you would notice that their PaCO2 level would drop (below 35 mmHg), while their PaO2 would remain unchanged or increase only marginally. PaO2 PaCO2 A B Question # 3 What blood gas component does ventilation affect? p. 41 of 56
- 45. OBHG Education Subcommittee A B C D vintage quality various quantities verbal question ventilation to perfusion ratio Question # 4 The short form V/Q stands for: p. 42 of 56
- 46. OBHG Education Subcommittee A B C D vintage quality various quantities verbal question ventilation to perfusion ratio Question # 4 The short form V/Q stands for: p. 43 of 56
- 47. OBHG Education Subcommittee A B C D pulmonary embolus foreign body obstruction bronchospasm mucous plugging of the terminal bronchioles Question # 5 All of the following are examples of a shunt except: p. 44 of 56
- 48. OBHG Education Subcommittee Pulmonary embolus is the only one from the list that is not an example of a “shunt”. It is an example of dead space ventilation. A B C D pulmonary embolus foreign body obstruction bronchospasm mucous plugging of the terminal bronchioles Question # 5 All of the following are examples of a shunt except: p. 45 of 56
- 49. OBHG Education Subcommittee A B acidic side alkaline side Question # 6 When you exhale, blood pH in the pulmonary capillaries shifts toward the: p. 46 of 56
- 50. OBHG Education Subcommittee A B acidic side alkaline side Question # 6 When you exhale, blood pH in the pulmonary capillaries shifts toward the: p. 47 of 56
- 51. OBHG Education Subcommittee A B C D unaffected stronger weaker none of the above Question # 7 When the blood pH is acidotic, hemoglobin’s affinity for oxygen is: p. 48 of 56
- 52. OBHG Education Subcommittee A B C D unaffected stronger weaker none of the above Question # 7 When the blood pH is acidotic, hemoglobin’s affinity for oxygen is: p. 49 of 56
- 53. OBHG Education Subcommittee A B C D hold onto oxygen more tightly release oxygen more readily destroy oxygen molecules none of the above Question # 8 At the tissue level, if the blood pH is too alkalotic, hemoglobin will: p. 50 of 56
- 54. OBHG Education Subcommittee A B C D hold onto oxygen more tightly release oxygen more readily destroy oxygen molecules none of the above Question # 8 At the tissue level, if the blood pH is too alkalotic, hemoglobin will: p. 51 of 56
- 55. OBHG Education Subcommittee A B C D less than perfusion the same as perfusion greater than perfusion all of the above Question # 9 A shunt means that ventilation is: p. 52 of 56
- 56. OBHG Education Subcommittee A B C D less than perfusion the same as perfusion greater than perfusion all of the above Question # 9 A shunt means that ventilation is: p. 53 of 56
- 57. OBHG Education Subcommittee A B C D absent markedly diminished normal absent on one side only Question # 10 Air entry to the lungs in a patient who has a massive pulmonary embolism is most likely to be: p. 54 of 56
- 58. OBHG Education Subcommittee When an embolus blocks blood flow, air entry into the lungs will be unaffected. A B C D absent markedly diminished normal absent on one side only Question # 10 Air entry to the lungs in a patient who has a massive pulmonary embolism is most likely to be: end p. 55 of 56
- 59. OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP Ontario Base Hospital Group Self-directed Education Program Well Done! START QUIT
- 60. OBHG Education Subcommittee SORRY, THAT’S NOT THE CORRECT ANSWER MENU QUIT
Editor's Notes
- #1: Instructor Notes by: Rob Theriault EMCA, RCT(Adv.), CCP(F) Donna L. Smith AEMCA, ACP References – Emergency Medicine
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- #13: Instructor Notes: Remember this from Respiratory presentation. Good review.
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- #17: Instructor Notes: FBO – Foreign Body Obstruction
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- #20: Instructor Notes: The fluid between the airway and the vessel, prevents for adequate air exchange to occur. Note that the airway, alveoli and the vessel are not the cause of the V/Q mismatch. Both are doing there job, the fluid in between is the problem.
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- #29: Instructor Notes: This is a good slide to refer to when someone is ventilating too zealously …they are actually doing more harm than good! Remember that only one handed squeezes when ventilating or refer to ml/kg as a good reference for volumes in ventilation. Ventilate to chest rise.
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- #33: Instructor Notes: Tetany – muscle spasm due to decreased calcium levels in the blood…these symptoms include – facial spasms, as well as odd sensations in lips, hands and feet.
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