11.12.08(b): Respiratory Mechanics I

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11.12.08(b): Respiratory Mechanics I

  1. 1. Author(s): Louis D’Alecy, 2009License: Unless otherwise noted, this material is made available under the terms of theCreative Commons Attribution–Non-commercial–Share Alike 3.0 License:http://creativecommons.org/licenses/by-nc-sa/3.0/We have reviewed this material in accordance with U.S. Copyright Law and have tried to maximize your ability to use,share, and adapt it. The citation key on the following slide provides information about how you may share and adapt thismaterial.Copyright holders of content included in this material should contact open.michigan@umich.edu with any questions,corrections, or clarification regarding the use of content.For more information about how to cite these materials visit http://open.umich.edu/education/about/terms-of-use.Any medical information in this material is intended to inform and educate and is not a tool for self-diagnosis or areplacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. Please speak to yourphysician if you have questions about your medical condition.Viewer discretion is advised: Some medical content is graphic and may not be suitable for all viewers.
  2. 2. Citation Key for more information see: http://open.umich.edu/wiki/CitationPolicyUse + Share + Adapt { Content the copyright holder, author, or law permits you to use, share and adapt. } Public Domain – Government: Works that are produced by the U.S. Government. (USC 17 § 105) Public Domain – Expired: Works that are no longer protected due to an expired copyright term. Public Domain – Self Dedicated: Works that a copyright holder has dedicated to the public domain. Creative Commons – Zero Waiver Creative Commons – Attribution License Creative Commons – Attribution Share Alike License Creative Commons – Attribution Noncommercial License Creative Commons – Attribution Noncommercial Share Alike License GNU – Free Documentation LicenseMake Your Own Assessment { Content Open.Michigan believes can be used, shared, and adapted because it is ineligible for copyright. } Public Domain – Ineligible: Works that are ineligible for copyright protection in the U.S. (USC 17 § 102(b)) *laws in your jurisdiction may differ { Content Open.Michigan has used under a Fair Use determination. } Fair Use: Use of works that is determined to be Fair consistent with the U.S. Copyright Act. (USC 17 § 107) *laws in your jurisdiction may differ Our determination DOES NOT mean that all uses of this 3rd-party content are Fair Uses and we DO NOT guarantee that your use of the content is Fair. To use this content you should do your own independent analysis to determine whether or not your use will be Fair.
  3. 3. Respiratory Mechanics I M1 – Cardiovascular/Respiratory Sequence Louis D’Alecy, Ph.D.Fall 2008 3
  4. 4. Wednesday 11/12/08, 10:00 Respiratory Sequence 40 slides, 50 minutes1. Introduction a) Text b) Testable content c) Respiratory disease d) Anatomy2. Functions of Respiratory System3. Mechanics of Ventilation I 4
  5. 5. PULMONARY PHYSIOLOGY BY Levitzky 6th ed “…a solid background in the aspects of pulmonary physiology essential to understanding clinical medicine.” 5
  6. 6. Testable Content Levitzky’s Chapter ObjectivesHandouts, Keywords and Lecture Content Quiz # 3 11/16/07 will include bothcardiovascular and respiratory questions. REMINDER: Final Comprehensive with Cardiovascular & Respiratory 6
  7. 7. RESPIRATORY DISEASE (1)Tuberculosis Greatest single infectious cause of mortality world wide. 2 million deaths/yrChronic Obstructive Pulmonary Disease(COPD)Forth leading cause of death in US.BronchitisEmphysemaCystic Fibrosis Most common lethal congenital diseaseAsthma Most common chronic childhood illness 7
  8. 8. RESPIRATORY DISEASE (2)Pneumonia A leading cause of death among children throughout the world. Estimated 4 million children die per yr.Influenza Can be fatal, especially among the very young or very old. 1918 pandemic estimated to have killed 20-40 million world wideRespiratory Distress Syndrome Major problem in prematurely born infantsAcute Respiratory Distress Syndrome (ARDS) Fatal in about 60% of cases 8
  9. 9. RESPIRATORY DISEASE (3)Respiratory Distress Syndrome Major problem in prematurely born infantsDiffuse Interstitial Pulmonary FibrosisAnemiaPulmonary EmbolismPulmonary HypertensionCommon Cold 9
  10. 10. MUCUS ESCALATOR cilia smokemucus toward particles esophagus & bacteria CO inhibits ciliated airway epithelium 10 D Alecy
  11. 11. Source Undetermined 11
  12. 12. Image of alveoli removedPlease see: http://www.3dscience.com/img/Products/3D_Models/Human_Anatomy/Alveoli/supporting_images/3D_Model_Anat_Alveoli3_web.jpg 12
  13. 13. Source Undetermined 13
  14. 14. ALVEOLI ARE INTERFACE Image of alveoli BETWEEN vasculature CARDIOVASCULAR removed AND RESPIRATORY SYSTEMSPlease see: http://www.virtualcancercentre.com/uploads/VMC/DiseaseImages/2293_alveoli_450.jpg 14
  15. 15. 2.54 cm2 ~ Dime! AREA for Diffusion 10 cm2 ~ 4 Tennis courtLevitzky. Pulmonary Physiology. McGraw-Hill, 2003. 6th ed. 15
  16. 16. Levitzky. Pulmonary Physiology. McGraw-Hill, 2003. 6th ed. Fig. 1-5 16
  17. 17. PHYSIOLOGY=Functions of Respiratory System (1) •1. Delivers oxygen to blood •2. Eliminates carbon dioxide •3. Regulates blood pH All depend upon bulk flow and diffusion 17
  18. 18. Air Image of alveolus structure removed Ventilation = 4 L/min BloodPlease see: http://www.kscience.co.uk/as/module1/pictures/alveolus.jpg CO = 5 L/min 18
  19. 19. PHYSIOLOGY =Functions of Respiratory System (2) • 4. Traps and dissolves blood clots –(PE = PULMONARY EMBOLUS) • 5. Forms speech sounds (phonation) •6 Facilitates smell (olfaction) • 7. Defends against microbes • 8. Adds or removes chemical »messengers 19
  20. 20. STEPS IN RESPIRATIONBulk flow--> Diff--> Bulk flow--> Diff--> Use Air BloodSource Undetermined 20
  21. 21. STEPS INRESPIRATION12345 Source Undetermined 21
  22. 22. STEPS IN RESPIRATIONAir Bulk FlowGas Diffusion Source Undetermined 22
  23. 23. STEPS IN RESPIRATIONGas Diffusion Blood Bulk Flow Source Undetermined 23
  24. 24. Bulk Flow Equation Same for blood and air Flow = P RFlow is directly proportional to the pressure difference.“pressure gradient” or P 24
  25. 25. Flow is directly proportional to P and directly proportional to airway radius to 4th power r 4Radius later.At rest No P !!!! Thus no flow.So how do we move airin and out? Make a P !! 25
  26. 26. BOYLE’S LAW: At constant temperature, the pressure of a gas is inversely proportional to its volume. If you volume pressureThusIf you volume pressure 26
  27. 27. RESPIRATORY PRESSURE UNITS = cm H2O or mm Hg 1 cm H2O = 0.76 mm Hg 1 mm Hg = 1.36 cm H2O*****atmosphere 1 atmos = 760 mm Hg BUT set to Zero… cm H2O or mmHg ****Pressure = force/area = dynes/cm21 mm Hg = 1 Torr = 1333.22 dynes/cm2 27
  28. 28. Pressure outside = Po = Pb = = atmospheric pressure = zero airway bulk flow of air P = (Po - PA) F= R R alveolus PA Need to Inspiration PA < Po PA Pout =constant Expiration PA > Po PA D Alecy 28
  29. 29. Thoracic Cavity at Rest (equilibrium) between breaths Po = 0 transmural pressures Across chest wall elastic recoil Pip - Po = - 4 chest wall -4 - 0 = - 4 PA = 0 Intraplural (ip) pressure (Intrathoracic pressure)Across lung wall PA - Pip = 4 elastic recoil Pip = - 4 mm Hg alveolar wall 0-(-4)=4 “subatmospheric” Transmural or alveolar distending pressure 29 D Alecy
  30. 30. Chest At Rest Lung “without chest” is much smaller Chest “without lungs” is much bigger When together (pulling in opposite directions)Intraplural pressure is sub-atmospheric (- 4 mmHg) 30
  31. 31. Therefore if you make a hole in either the chest wall or the lung the chest gets biggerand the lungs get smaller (collapses) as Pip goes to zero or atmospheric. Hole in chest Source Undetermined Hole in lung 31
  32. 32. PNEUMOTHORAX (air in thorax) Can be Air intrapleural space One-sided Hole in chest wall lets in air.Chest Pip = 0 Pa = 0wallexpands Lung collapses Pip = - 4 mm Hg atelectasis - collapse of (alveoli) lung (atel -Gk - incomplete, ectasis -Gk -stretching out) D Alecy 32
  33. 33. Inspiration = chest (including lungs) made bigger Pb = 0 Pb = 0 Active Pip = - 4 mm Hg Pip = - 7 mm Hg inspiratory PA = 0 PA = 0 muscle force elastic recoil alveolar wall elastic recoil chest wall End of normal inspiration**** D Alecy 33
  34. 34. Inspiration (rest & end)PA = Pip + Alveolar recoil 0 = -4 + 4 at rest 0 = -7 + 7 at end of inspiration 34
  35. 35. Respiratory Air Flow = P Inspiration Expiration FlowPb = 0 andso does PA Pip is -4 -7 -4 35 Source Undetermined
  36. 36. For Inspiration: You make the chest (volume) bigger and lower the PA By active contraction of skeletal muscle. 1. Diaphragm Contraction 2. External intercostal Contraction3. Accessory Muscles of Inspiration Contraction 36
  37. 37. BOYLE’S LAW: At constant temperature, the pressure of a gas is inversely proportional to its volume. At Rest At End InspirationThusIf you volume pressure 37
  38. 38. DIAPHRGAM CONTRACTION Inspiration Increased volume of Thoracic Cavity thoracic cavity - Decreased pressure in Skeletal muscle fibers thoracic cavity Central tendon Abdominal Cavity 38D Alecy
  39. 39. External IntercostalsGray’s Anatomy 39
  40. 40. Scalenus mediusSternocleidomastoideus Gray’s Anatomy Gray’s Anatomy 40
  41. 41. Expiration (Passive) Inspiratory muscles relax.Thoracic volume decreases.PA increases (Boyle s Law). Air flows out by P. 41
  42. 42. Normal Expiration: Elastic recoil of lung returns volume to rest. NormalExpiration Forced “relax” Expiration If you volume PA Pressure 42
  43. 43. FORCED EXPIRATION contract internal intercostal muscles ribsdecreasedthoracicvolume internal relaxed intercostal diaphragm muscles pushed into thorax contract abdominal muscles 43 D Alecy
  44. 44. Additional Source Information for more information see: http://open.umich.edu/wiki/CitationPolicySlide 10: D’AlecySlide 11: Source UndeterminedSlide 12: Please see: http://www.3dscience.com/img/Products/3D_Models/Human_Anatomy/Alveoli/supporting_images/ 3D_Model_Anat_Alveoli3_web.jpgSlide 13: Source UndeterminedSlide 14: Please see: http://www.virtualcancercentre.com/uploads/VMC/DiseaseImages/2293_alveoli_450.jpgSlide 15: Levitzky. Pulmonary Physiology. McGraw-Hill, 2003. 6th ed.Slide 16: Levitzky. Pulmonary Physiology. McGraw-Hill, 2003. 6th ed.Slide 18: Please see: http://www.kscience.co.uk/as/module1/pictures/alveolus.jpgSlide 20: Source UndeterminedSlide 21: Source UndeterminedSlide 22: Source UndeterminedSlide 23: Source UndeterminedSlide 28: D’AlecySlide 29: D’AlecySlide 31: Source UndeterminedSlide 32: D’AlecySlide 33: D’AlecySlide 35: Source UndeterminedSlide 38: D’AlecySlide 39: Gray’s AnatomySlide 40: Gray’s Anatomy; Gray’s AnatomySlide 43: D’Alecy

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