1. Physiology of respiration EMS 352 ADVANCED AIRWAY MANAGEMENT DR AQEELA BANO

3. Physiology of Breathing Respiratory and cardiovascular systems work together. – Bring oxygen and nutrients to cells – Remove waste

4. DEFINITIONS…..

5. Ventilation  Process of moving air into and out of lungs  Two phases  Inhalation (inspiration)  Exhalation (expiration) You must ensure adequate ventilation.

6. Inhalation Active, muscular Part of breathing Air enters the mouth and nose, moves to the trachea. – Diaphragm and intercostal muscles contract. Boyle’s law: The pressure of gas is inversely proportional to its volume.

7. Inhalation  Diaphragm  Specialized skeletal muscle (voluntary and involuntary)  Lungs  Have no muscle tissue  Depend on movement of the chest and supporting structures  The thoracic cage expands during inhalation and air pressure within the thorax decreases.  Negative-pressure ventilation  Inhalation stops when pressure is equalized.

8. Inhalation

9. Oxygenation Deoxygenated arterial blood from the heart has a partial pressure of oxygen (PaO 2 ) that is lower than the partial pressure of oxygen in the alveoli. Body attempts to equalize the partial pressure

10. Oxygenation

11. Respiration

13. Lung Volumes  Tidal volume: amount of air moved into or out of the respiratory tract during one breath  Adult: 5 to 7 mL/kg  Infants/children: 6 to 8 mL/kg Breathing becomes deeper as tidal volume responds to increased demand for oxygen  Alveolar volume: volume of air that reaches the alveoli

14. Dead space volume: portion of tidal volume that does not reach the alveoli Minute volume: amount of air moved through the respiratory tract in 1 minute – Including anatomic dead space Inspiratory reserve volume: amount of air inhaled in addition to normal tidal volume

15. Expiratory reserve volume: amount of air exhaled following normal exhalation Residual volume: air that remains in the lungs after maximal exhalation Vital capacity: amount of air that can be forcefully exhaled after a full inhalation

16. Lung volumes and capacities

17. Exhalation Passive process Stretch receptors signal apneustic center as chest expands – Exhalation occurs Feedback loop: Herring- Breuer reflex

18. Regulation of Ventilation  The need for oxygen changes constantly.  Respiratory system responds by altering the rate and depth of ventilation  Primarily regulated by pH of CSF  Receptors and feedback loops send messages about gas concentrations to the respiratory center.  Rising oxygen level suspends breathing.  Rising CO 2 level stimulates breathing

19. Neural Control of Ventilation Originates in medulla oblongata and pons – Medulla Controls rate, depth, and rhythm of breathing in interaction with the pons – Apneustic center of the pons Secondary control center if the medulla fails

20. Chemical Control of Ventilation  Chemoreceptors  Three sets affect respiratory function  Those in the carotid bodies  Those in the aortic arch  Central chemoreceptors  Affect respiratory rate and depth  Monitor chemical composition of body fluids  Provide feedback on metabolic processes

21. Chemical Control of Ventilation Chemoreceptors in the carotid bodies and the aortic arch – Measure carbon dioxide in arterial blood Central chemoreceptors – Monitor the pH of the CSF

23. Hypoxic Drive Patients with COPD have trouble eliminating carbon dioxide through exhalation. – Always have higher blood levels Can alter primary respiratory drive Body uses backup system

24. Hypoxic Drive Hypoxic drive: secondary control – Stimulates breathing when arterial oxygen level falls – Providing high concentrations of oxygen over time will increase PaO 2.

25. Other factors Controlling Ventilation Fever Certain medications Pain, strong emotions Excessive amounts of narcotic analgesics and benzodiazepines Hypoxia and acidosis Metabolic rate

26. Oxygenation Oxygen molecules loaded onto hemoglobin molecules in the bloodstream Required for ventilation but does not guarantee it

27. Oxygenation Fraction of inspired oxygen (FIO 2 ) – Percentage of oxygen in inhaled air – Increases with supplemental oxygen – Commonly documented as a decimal number

28. Oxyhemoglobin Dissociation Curve Hemoglobin – Protein necessary for life – Normal values Men: 14–16 g/dL Women: 12–14 g/dL Hematocrit values – Percentage of red blood cells in whole blood – Normal values Men: 45%–52% Women: 37%–48%

29. Oxyhemoglobin Dissociation Curve Oxygen saturation – SpO 2 /SaO 2 is proportional to the amount of oxygen dissolved in the plasma (PaO 2 ).

30. Oxyhemoglobin Dissociation Curve Acidosis and increased carbon dioxide – Curve shifts to the right – Hemoglobin gives up oxygen faster Alkalosis and decreased carbon dioxide – Curve shifts to the left – Hemoglobin holds on to more oxygen

31. Respiration Metabolism: process of cells taking energy from nutrients Respiration: process of exchanging oxygen and carbon dioxide – Involves ventilation, diffusion, and transport of oxygen and carbon dioxide

32. External Respiration Exchange of O 2 and CO 2 between alveoli and blood in pulmonary capillaries – Adequate ventilation is necessary but does not guarantee it.

33. Internal Respiration Exchange of O 2 and CO 2 between the systemic circulation and the cells Aerobic metabolism: The mitochondria of the cells convert glucose into energy.  Energy is produced in the form of ATP.

34. Phathophysiology of respiration

35. Pathophysiology of Respiration Disruption of pulmonary ventilation, oxygenation, and respiration causes immediate effects. – Must recognize and correct immediately

36. Pathophysiology of Respiration Every cell needs a constant supply of oxygen to survive. – Perfusion: circulation of blood in adequate amounts to meet cells’ needs

37. Hypoxia Tissues and cells do not receive enough oxygen Varying signs and symptoms, including: – Early signs: restlessness, irritability, tachycardia, and anxiety – Late signs: mental status changes, a weak pulse, and cyanosis

38. Ventilation-Perfusion Ratio and Mismatch Air and blood flow must be directed to the same place at the same time. – Ventilation and perfusion must be matched. If not, V/Q mismatch results. – Blood passes over alveolar membranes without gas exchange. – Carbon dioxide is recirculated into bloodstream.

39. Factors Affecting Ventilation Patent airway is critical for the provision of oxygen to tissues Intrinsic and extrinsic factors can cause an airway obstruction.

40. Factors Affecting Ventilation Intrinsic factors: infection, allergic reactions, unresponsiveness – The tongue is the most common obstruction in an unresponsive patient. – Factors may not be directly part of the respiratory system.

41. Factors Affecting Ventilation Extrinsic factors: trauma and foreign body airway obstruction – Trauma requires immediate intervention. Blunt/penetrating trauma and burns can disrupt airflow into the lungs. Trauma to the chest wall can lead to inadequate pulmonary ventilation.

42. Factors Affecting Ventilation Hypoventilation – Carbon dioxide production exceeds elimination. Hyperventilation – Carbon dioxide elimination exceeds production.

43. External Factors Affecting Oxygenation and Respiration Factors in ambient air – High altitudes: partial pressure decreases – Closed environments: oxygen decreases Toxic gases displace oxygen in the environment.

44. Internal Factors Affecting Oxygenation and Respiration Conditions that reduce surface area for gas exchange also decrease oxygen supply – Nonfunctional alveoli inhibit diffusion. – Fluid in the alveoli inhibits gas exchange. Submersion victims Patients with pulmonary edema Exposure to environmental conditions or occupational hazards

45. Internal Factors Affecting Oxygenation and Respiration Hypoglycemia – Oxygen and glucose levels decrease Infection – Increases metabolic needs Hormonal imbalances – May result in ketoacidosis

46. Circulatory Compromise Inadequate perfusion; oxygen demands will not be met. – Obstruction of blood flow is typically related to trauma. Inhibits gas exchange at the tissue level

47. Circulatory Compromise Heart conditions reduce blood flow to tissues. Blood loss and anemia reduce the blood’s oxygen-carrying ability. Shock: oxygen is not delivered efficiently. – Poor tissue perfusion; anaerobic metabolism

48. Acid-Base Balance Can be disrupted by – Hypoventilation – Hyperventilation – Hypoxia May rapidly lead to deterioration, death

49. Acid-Base Balance Respiratory and renal systems help maintain homeostasis. – Tendency toward stability in the body – Requires balance between acids and bases Acid in the body can be expelled as carbon dioxide from the lungs.

50. Acid-Base Balance Acidosis can develop if respiratory function is inhibited. Alkalosis can develop if the respiratory rate is too high. – Respiratory acidosis/alkalosis – Metabolic acidosis/alkalosis

51. Adequate breathing – Patient is responsive, alert, able to speak – Rate between 12 and 20 breaths/min – Adequate depth – Regular pattern of inhalation and exhalation – Clear and equal breath sounds

52. Recognizing Inadequate Breathing Breathing rate of less than 12 breaths/min or more than 20 breaths/min Cyanosis: indicator of low blood oxygen

53. Causes of Inadequate Breathing – Severe infection – Trauma – Brainstem insult – Renal failure – Upper and/or lower airway obstruction – Respiratory muscle impairment – Central nervous system impairment – Oxygen-poor environment

54. Assessment of Breath Sounds Auscultate breath sounds with stethoscope. – Should be clear and equal

55. Assessment of Breath Sounds

56. Abnormal Breath Sounds Wheezing: continuous, high-pitched Rhonchi: continuous, low- pitched Crackles: discontinuous Stridor: loud, high- pitched, heard during inspiration Pleural friction rub: surfaces of visceral and parietal pleura rub together

57. Pulse Oximetry Pulse oximeter: measures oxygen saturation of hemoglobin (Hb) – Normal: SpO 2 of greater than 95%

58. Pulse Oximetry Used for: – Monitoring oxygenation status during intubation attempt or suctioning – Identifying deterioration in a patient with trauma or cardiac disease – Identifying high-risk patients – Assessing vascular status in orthopaedic trauma

59. Arterial Blood Gas Analysis Blood is analyzed for pH, PaO 2, HCO 3 −, base excess, and SaO 2. – pH, HCO 3 − : acid- base status – PaCO 2 : effectiveness of ventilation – PaO 2 and SaO 2 : oxygenation

60. Normal values

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