1. PREHOSPITAL EMERGENCY CARE CHAPTER Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Prehospital Emergency Care, 10 th edition Mistovich | Karren TENTH EDITION Pathophysiology 8

2. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Learning Readiness EMS Education Standards, text p. 164

3. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Learning Readiness Objectives Please refer to page 164 of your text to view the objectives for this chapter.

4. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Learning Readiness Key Terms Please refer to pages 164 and 165 of your text to view the key terms for this chapter.

5. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Setting the Stage Overview of Lesson Topics  Cellular Metabolism  Components Necessary for Adequate Perfusion

6. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study Introduction EMTs Patty Mirabal and Gus Oakes are on the scene of a 52-year-old man who is complaining of difficulty breathing. The patient is breathing shallowly and rapidly. He gasps, "Need … help … can't … breathe."

7. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study What purposes does breathing serve? In what ways does a problem with breathing affect the body?

8. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Introduction Oxygen and glucose are necessary for normal cell function. Illnesses and injuries can disturb the delivery of oxygen and glucose and removal of waste by-products. A fundamental purpose of emergency care is maintaining adequate delivery of oxygen and glucose.

9. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Cellular metabolism is the process in which the body breaks down molecules of glucose to produce energy. Aerobic metabolism takes place when oxygen is available. When there is a lack of oxygen, the body uses a less effective process called anaerobic metabolism. continued on next slide

10. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Aerobic metabolism  The initial steps of cellular metabolism do not require oxygen, but produce only small amounts of energy.  Oxygen is required to complete the process of extracting energy from glucose and removing the wastes produced by the process. continued on next slide

11. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Aerobic metabolism. Glucose broken down in the presence of oxygen produces a large amount of energy (ATP). continued on next slide

12. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Aerobic metabolism  The initial steps of cell metabolism take place in the cytosol and are called glycolysis.  Glycolysis produces a small amount of ATP.  When oxygen is present, the process continues in the mitochondria, where larger amounts of ATP needed for cell function are produced. continued on next slide

13. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism By-products of aerobic metabolism include heat, carbon dioxide, and water. Increased metabolism results in increased respiratory rate to eliminate the increased carbon dioxide. Heat and water can be used or eliminated by the body. continued on next slide

14. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Aerobic metabolism  An important cell function that requires ATP is the sodium/potassium pump. continued on next slide

15. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved The sodium/potassium pump. Energy (ATP) is required to pump sodium molecules out of the cell against the concentration gradient. Potassium then moves with the gradient to flow into the cell. Sodium and potassium are exchanged in a continuous cycle that is necessary for proper cell function. The cycle continues as long as the cells produce energy through aerobic etabolism. When insufficient energy is produced, through anaerobic metabolism, the sodium/potassium pump will fail and cells will die. continued on next slide

16. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Sodium (Na + ) is primarily found outside the cell. Potassium (K + ) is found primarily inside the cell. Without a functioning sodium/potassium pump, sodium that finds its way into the cell cannot exit and accumulates inside the cell. continued on next slide

17. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism When the concentration of sodium in the cell is too high, potassium cannot enter and the cell cannot function. Excess sodium in the cell allows excess water to enter the cell. Excess water can cause the cell to swell, rupture, and die. continued on next slide

18. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism In anaerobic metabolism, the combination of inadequate energy production and accumulating lactic acid result in failure of cell processes. continued on next slide

19. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Anaerobic metabolism. Glucose broken down without the presence of oxygen produces pyruvic acid that converts to lactic acid and only a small amount of energy (ATP). continued on next slide

20. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Anaerobic metabolism  The first stage of cell metabolism is anaerobic.  The waste product produced is pyruvic acid.  Without oxygen, pyruvic acid is converted to lactic acid.  Accumulation of lactic acid is harmful to body functions. continued on next slide

21. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Cellular Metabolism Anaerobic metabolism  In the presence of extensive anaerobic metabolism, cells die, which can lead to organ failure and death.

22. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Adequate Perfusion Perfusion is the delivery of oxygen, glucose, and other substances to the cells and the elimination of waste products from the cells. continued on next slide

23. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Adequate Perfusion Perfusion requires functioning nutrient/oxygen delivery and waste removal systems. continued on next slide

24. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Adequate Perfusion 11 components of these systems are: 1.Composition of ambient air 2.Patent airway 3.Mechanics of ventilation 4.Regulation of ventilation 5.Ventilation/perfusion ratio 6.Transport of oxygen and carbon dioxide by the blood continued on next slide

25. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Adequate Perfusion 11 components of these systems are: 7.Blood volume 8.Pump function of the myocardium 9.Systemic vascular resistance 10.Microcirculation 11.Blood pressure continued on next slide

26. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Adequate Perfusion Any alteration in the components may lead to poor cellular perfusion. Inadequate perfusion can shift cells from aerobic to anaerobic metabolism. In anaerobic metabolism, production of energy is reduced and harmful by- products accumulate. Emergency care focuses on restoring and maintaining the components.

27. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study Gus quickly moves next to the patient to better assess his condition, while Patty unzips the airway kit and begins to select equipment to begin patient care. continued on next slide

28. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study What, specifically, will Gus be assessing to determine the patient's condition? How will Patty know what equipment and treatment the patient needs? What is happening to the patient at the cellular level? What will happen if the EMTs do not intervene quickly?

29. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Composition of Ambient Air The concentration of oxygen in the ambient air determines the amount of oxygen that ends up in the alveoli for gas exchange. Ambient air contains approximately 79% nitrogen, 21% oxygen, and trace amounts of argon and carbon dioxide. continued on next slide

30. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Table 8-1 Partial Pressure of Gases in Ambient Atmosphere at Sea Level continued on next slide

31. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Composition of Ambient Air FiO 2 is the fraction of inspired oxygen. A patient breathing air that contains 21 percent oxygen has an FiO 2 of 0.21. One way to improve cellular oxygenation to increase the patient's FiO 2 by administering supplemental oxygen. continued on next slide

32. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Composition of Ambient Air Some toxic gases displace the amount of oxygen in the air, which suffocates the patient. Carbon monoxide disrupts the ability of the blood to carry oxygen to the cells. Cyanide interferes with oxygen use by the cell. Each of these situations leads to hypoxia.

33. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Patent Airway A patent airway is open and not obstructed by any substance. Establishing an open airway is one of the first steps in emergency care. Failure to establish or maintain a patent airway leads to cellular hypoxia and patient death. continued on next slide

34. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Airway obstruction can occur at several levels of the upper and lower airway, including the nasopharynx, oropharynx, posterior pharynx, epiglottis, larynx, trachea, and bronchi.

35. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Patent Airway Airway obstruction can occur at several levels and has many causes.  Obstruction of nasopharynx, oropharynx, or pharynx  Swelling of epiglottis  Laryngeal spasm or edema  Obstruction of trachea or bronchi

36. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation An intact thoracic cavity is integral to normal ventilation.  Thoracic cavity boundaries  Mediastinum  Parietal and visceral pleura continued on next slide

37. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Boyle's law  The volume of a gas is inversely proportional to the pressure.  Increasing and decreasing the volume of the thoracic cavity changes the pressure of air inside it. continued on next slide

38. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Boyle's law  Contracting the diaphragm and intercostal muscles increases the thoracic volume, creating negative pressure.  The negative pressure causes the pleura and lungs within the thorax to expand, creating negative pressure within the lungs. continued on next slide

39. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Boyle's law  The pressure of atmospheric air is 760 mmHg at sea level.  Just prior to inhalation, the pressure within the chest is 758 mmHg.  Air flows from the higher pressure of the atmosphere toward the lower pressure of the lungs. continued on next slide

40. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Boyle's law  On exhalation, the diaphragm and intercostal muscles relax.  The volume of the thorax and lungs decreases.  Pressure inside the chest rises to 761 mmHg.  Air flows from the higher pressure in the lungs to the lower pressure of the atmosphere. continued on next slide

41. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved A. The diaphragm relaxes. B. The size of the chest cavity decreases. C. Pressure within the chest decreases. D. The intercostal muscles relax. Click on the event that occurs just prior to the movement of air into the lungs on inhalation. continued on next slide

42. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Accessory muscles  Used when extra effort is needed for inhalation or exhalation  Increases energy use  If energy production fails from insufficient oxygen, the muscles of respiration fail. continued on next slide

43. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Table 8-2 Accessory Muscles continued on next slide

44. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Compliance and airway resistance  High resistance and low compliance increase the effort needed to breathe and lead to hypoxia. continued on next slide

45. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Compliance and airway resistance  Compliance is the ease with which the lungs or chest wall expand.  Pneumonia, pulmonary edema, and some chest injuries can decrease compliance. continued on next slide

46. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Compliance and airway resistance  Resistance is the ease of airflow into and out of the airway structures.  Edema of the airway and constriction of the bronchioles can lead to increased airway resistance. continued on next slide

47. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Pleural space  Negative pressure is maintained in the pleural space.  An injury to the chest wall or lung that opens the space can draw air, by way of negative pressure, into the space.  The lung may collapse from the air accumulation. continued on next slide

48. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Minute ventilation, or minute volume, is the amount of air moved in and out of the lungs in one minute. Minute volume = tidal volume × frequency of ventilation continued on next slide

49. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Average minute volume is: 500 mL × 12/minute = 6,000 mL (6 L) continued on next slide

50. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation A decrease in tidal volume decreases the minute volume. A decrease in respiratory rate decreases the minute volume. A decrease in minute volume reduces the air available for gas exchange in the alveoli. continued on next slide

51. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation A decrease in minute ventilation can lead to cellular hypoxia. To ensure adequate ventilation, both the tidal volume and respiratory rate must be adequate. continued on next slide

52. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation An increase in ventilatory rate can compensate for reduced tidal volume in maintaining minute volume, to a point. With low tidal volume, the volume of air may not be sufficient to reach the alveoli for gas exchange. continued on next slide

53. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Alveolar ventilation is the amount of air moved in and out of the alveoli in one minute. Air that does not reach the alveoli, remaining in the trachea and bronchi, is called dead space air. 150 mL of a 500 mL tidal volume remains in the dead air space; 350 mL reaches the alveoli. continued on next slide

54. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Alveolar ventilation = (tidal volume – dead air space) × frequency of ventilation/minute continued on next slide

55. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Dead air spaces fill first with ventilation. If tidal volume decreases, alveolar volume decreases. An increase in ventilation rate does not mean more air volume is reaching the alveoli. continued on next slide

56. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Providing oxygen alone to a patient with poor tidal volume does not correct hypoxia. The patient needs assisted ventilation to increase tidal volume. continued on next slide

57. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation Hypoxia can occur from:  A low tidal volume  A slow ventilatory rate  A fast ventilatory rate continued on next slide

58. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation When the ventilatory rate is too fast  There is inadequate time between breaths to fill the lungs.  A very fast rate requires a large amount of energy that may not be able to be sustained, setting up the patient for respiratory failure. continued on next slide

59. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Mechanics of Ventilation When the ventilatory rate is too fast  Ventilatory rates of 40/minute or greater in the adult patient and greater than 60/minute in the pediatric patient are too fast to be sustainable or to allow adequate time for a normal tidal volume.

60. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Breathing is an involuntary process controlled by the autonomic nervous system. Receptors measure oxygen (O 2 ), carbon dioxide (CO 2 ), and hydrogen ions (pH). Receptors send signals to the brain to adjust the rate and depth of respiration. continued on next slide

61. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Respiration is controlled by the autonomic nervous system. Receptors within the body measure oxygen, carbon dioxide, and hydrogen ions and send signals to the brain to adjust the rate and depth of respiration. continued on next slide

62. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Chemoreceptors are specialized receptors that monitor the pH, CO 2, and O 2 levels in arterial blood. There are central chemoreceptors and peripheral chemoreceptors. continued on next slide

63. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Central chemoreceptors are located near the respiratory center in the medulla.  Sensitive to CO 2 and changes in the pH of the cerebrospinal fluid (CSF)  The pH in CSF reflects the CO 2 level of arterial blood.  The more CO 2 in the blood, the greater the amount of acid continued on next slide

64. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Small changes in pH stimulate a response in the rate and depth of breathing. Faster, deeper breathing eliminates more CO 2. Slower, shallower breathing eliminates less CO 2. continued on next slide

65. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Peripheral chemoreceptors are located in the aortic arch and the carotid bodies. As O 2 in the blood decreases, peripheral chemoreceptors signal the respiratory center in the brainstem to increase the rate and depth of respiration. continued on next slide

66. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation A significant decrease in the arterial oxygen content causes an increase in the rate and depth of respiration. continued on next slide

67. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Normally, rate and depth of breathing are regulated by the amount of CO 2 in the blood. continued on next slide

68. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation COPD patients have a tendency to retain CO 2  They become insensitive to small changes in CO 2.  Their respirations are controlled by decreased oxygen levels; this is called the hypoxic drive. continued on next slide

69. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Three types of receptors within the lungs provide impulses to regulate respiration.  Irritant receptors  Stretch receptors  J-receptors continued on next slide

70. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Irritant receptors  Found in the airways  Sensitive to irritating gases, aerosols, and particles  Simulate coughing, bronchoconstriction, and increased ventilatory rate continued on next slide

71. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Stretch receptors  Found in the smooth muscle of the airways  Protect against over inflation of the lungs continued on next slide

72. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Stretch receptors  Measure the size and volume of the lungs  Stimulate a decrease in the rate and volume of ventilation when stretched by high tidal volumes continued on next slide

73. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation J-receptors  Found in the capillaries surrounding the alveoli  Sensitive to increases in capillary  When activated, they stimulate rapid, shallow ventilation continued on next slide

74. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Respiratory control centers in the brainstem  Dorsal respiratory group (DRG)  Ventral respiratory group (VRG)  Pontine respiratory center (pneumotaxic center) continued on next slide

75. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Ventral respiratory group  Located in medulla oblongata  Receives sensory input and sends it to the spinal cord to stimulate the diaphragm and intercostal muscles  Contains inspiratory and expiratory neurons  Controls basic pattern of breathing continued on next slide

76. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Dorsal respiratory group  Located in medulla oblongata  Receives sensory input and communicates it to the VRG for further input on rate and depth of breathing continued on next slide

77. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Pontine respiratory center  Sends inhibitory impulses to the inspiratory neurons of the VRG to turn off the inhalation  Promotes a smooth transition between inhalation and exhalation continued on next slide

78. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Regulation of Ventilation Illness or injury can disrupt the respiratory centers in the brainstem. Pattern and depth of ventilation can be affected. Gas exchange may be inadequate; cellular hypoxia may result.

79. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study The patient is working hard to breathe, and has pale, moist skin. He is using accessory muscles to breathe, but seems to be moving very little air. The patient seems on the verge of complete exhaustion, and appears sleepy. Patty selects a bag-mask device to assist the patient's ventilations, and connects it to supplemental oxygen. continued on next slide

80. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study What medical problems could lead a patient to have such severe difficulty breathing?

81. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion (V/Q) Ratio V/Q ratio is the relationship between alveolar ventilation and perfusion of the alveolar capillaries. The relationship influences gas exchange. Can be used to explain causes of hypoxemia continued on next slide

82. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Overview of ventilation and perfusion. continued on next slide

83. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio In an ideal state the amount of ventilation is equally matched to the amount of perfusion. Physiologically, based on gravity and the nature and distribution of alveoli in the lungs, a perfect match does not occur. Overall, perfusion exceeds ventilation, but the situation is highly functional. continued on next slide

84. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio When ventilation is better than perfusion, there is wasted ventilation. When perfusion is better than ventilation, there is wasted perfusion. continued on next slide

85. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio Pressure imbalance  If the air pressure in an alveolus exceeds the blood pressure in the capillary bed, blood flow through the capillary stops.  Occurs normally in the apex of the lungs  Occurs when the systemic blood pressure decreases continued on next slide

86. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Possible causes of ventilation disturbances. continued on next slide

87. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio Ventilatory disturbances  A condition that decreases the amount of air reaching the alveoli, such as asthma, results in wasted perfusion.  Hypoxemia and hypoxia result.  Treatment is aimed at increasing lung ventilation. continued on next slide

88. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio Perfusion disturbances  Ventilation is normal, or even increased, but blood flow through the lungs is decreased.  There is wasted ventilation, leading to hypoxemia and hypoxia.  Administering oxygen may help, but the perfusion disturbance must be corrected. continued on next slide

89. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Ventilation/Perfusion Ratio Various conditions lead to V/Q mismatch and resultant hypoxia. Treatment is aimed at improving ventilation, oxygenation, and perfusion to the lungs.

90. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Oxygen must be continuously delivered by the blood to the cells for normal cellular metabolism. Carbon dioxide must be carried back to the lungs to be blown off in exhalation. A disturbance in the transport system may lead to cellular hypoxia and hypercarbia. continued on next slide

91. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Gases move from areas of higher concentration to areas of lower concentration. continued on next slide

92. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Oxygen Transport  1,000 mL of O 2 are delivered to the cells every minute.  O 2 is transported in the blood in two ways. 1.5 to 3% is dissolved in plasma. 97 to 98.5% is attached to hemoglobin molecules. continued on next slide

93. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Oxygen is transported in the blood two ways: attached to hemoglobin and dissolved in plasma. Carbon dioxide is transported in the blood three ways: as bicarbonate, attached to hemoglobin, and dissolved in plasma. continued on next slide

94. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Hemoglobin is a protein molecule that contains iron. There are four iron sites per hemoglobin molecule for oxygen to bind to. Each molecule can carry up to four oxygen molecules. continued on next slide

95. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport If one oxygen molecule is attached to the hemoglobin molecule, it is 25% saturated; if four molecules are attached, it is 100% saturated. Attachment of one oxygen molecule to hemoglobin increases the affinity for the other sites to also bind with oxygen. continued on next slide

96. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Hemoglobin to which oxygen is bound is called oxyhemoglobin. Hemoglobin with no oxygen attached is called deoxyhemoglobin. continued on next slide

97. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Without hemoglobin, the blood cannot carry enough oxygen to sustain life. Loss of hemoglobin, such as through bleeding, can lead to cellular hypoxia, even though an adequate amount of oxygen is available in the alveoli. continued on next slide

98. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Carbon dioxide is transported in the blood in three ways.  7% is dissolved in plasma.  23% is attached to hemoglobin in RBCs.  70% as bicarbonate. continued on next slide

99. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport The largest amount of CO 2 diffuses from the cell, into the blood, and then into RBCs. In the RBC, CO 2 combines with water to form carbonic acid, which then dissociates into hydrogen and bicarbonate. continued on next slide

100. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Bicarbonate exits the RBC and is transported in plasma. When blood reaches the lungs, bicarbonate diffuses back into RBCs, where it combines with hydrogen and then dissociates into water and CO 2. CO 2 diffuses from the blood into the alveoli and is released through exhalation. continued on next slide

101. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Alveolar/capillary gas exchange  After inhalation, the alveolar air is high in O 2 and low in CO 2.  Venous blood in the capillaries surrounding the alveoli is low in O 2 and high in CO 2. continued on next slide

102. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Gas molecules move from areas of high concentration to areas of low concentration.  O 2 moves into the capillaries where the oxygen content is very low.  Simultaneously, CO 2 moves in the opposite direction. continued on next slide

103. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport Blood ejected from the left ventricle into the arteries is high in O 2 and low in CO 2. This blood travels into the capillaries in the tissues to reach the cells. continued on next slide

104. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Gas Transport As a result of metabolism, cells are higher in CO 2 and lower in O 2. O 2 leaves the blood and enters the cells; CO 2 leaves the cells and enters the blood. continued on next slide

105. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved A. Bound to hemoglobin B. In the form of bicarbonate C. Dissolved in plasma D. Carried by white blood cells Click on the mechanism by which most of the oxygen in blood is transported.

106. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume A determinant of blood pressure and perfusion is blood volume.  Adults have 70 mL of blood/kg of body weight.  A 70-kg adult has 4,900 mL (4.9 L) of blood. continued on next slide

107. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Blood composition  45% formed elements 42% to 48% red blood cells White blood cells Platelets  55% plasma 91% water Plasma proteins Albumin, clotting factors, antibodies continued on next slide

108. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Table 8-3 Distribution of Blood in the Cardiovascular System continued on next slide

109. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Hydrostatic pressure is the force inside the vessel or capillary bed generated by the contraction of the heart and the blood pressure. Hydrostatic pressure exerts a "push" inside the vessel or capillary. High hydrostatic pressure promotes edema. continued on next slide

110. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Hydrostatic pressure pushes water out of the capillary. Plasma oncotic pressure pulls water into the capillary. continued on next slide

111. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume In left heart failure, the ventricle does not empty completely, so it cannot receive the full amount of blood returning from the lungs. Blood backs up into the pulmonary circulation, resulting in increased hydrostatic pressure. continued on next slide

112. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Fluid is forced out of the pulmonary capillaries, where it surrounds the alveoli and reduces gas exchange. continued on next slide

113. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Plasma oncotic pressure keeps fluid inside the vessels to oppose hydrostatic pressure. The large plasma proteins have the effect of "pulling" water into the capillaries. continued on next slide

114. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Hydrostatic and oncotic pressures must be balanced.  High hydrostatic pressure pushes fluid out of capillaries and promotes edema.  Low hydrostatic pressure pushes less fluid out of the vessel. continued on next slide

115. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Volume Hydrostatic and oncotic pressures must be balanced.  High oncotic pressure draws excessive amounts of fluid into the capillary and promotes blood volume overload.  Low oncotic pressure does not exert enough pull to counteract the push of hydrostatic pressure, promoting loss of vascular volume and edema.

116. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function The myocardium must be an effective pump to maintain perfusion.  Cardiac output (CO) is the amount of blood ejected from the heart in one minute.  CO = heart rate × stroke volume continued on next slide

117. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Several factors affect the heart rate.  Sympathetic and parasympathetic nervous systems affect heart rate through the cardiovascular control system in the brain stem.  The cardiovascular control center is composed of the cardioexcitatory center and the cardioinhibitory center. continued on next slide

118. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function An increase sympathetic stimulation increases the heart rate. A decrease in sympathetic stimulation decreases the heart rate. An increase in parasympathetic stimulation decreases the heart rate. A decrease in parasympathetic stimulation increases the heart rate. continued on next slide

119. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Stroke volume is the amount of blood ejected from the heart with each contraction. Stroke volume is determined by preload, myocardial contractility, and afterload. continued on next slide

120. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Preload  Preload pressure is created by the blood volume in the left ventricle at the end of diastole.  The available venous volume plays a major role in determining preload.  An increase in preload increases stroke volume, which increases the cardiac output. continued on next slide

121. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Frank-Starling law of the heart  As blood fills the left ventricle, it stretches the muscle fibers.  The stretch of the muscle fiber determines the force available to eject the blood from the ventricle.  There is a limit to the Frank-Starling law. continued on next slide

122. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Damage to the heart from heart failure or myocardial infarction can decrease the myocardial contractility, thereby decreasing stroke volume and cardiac output. continued on next slide

123. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Afterload is the resistance in the aorta that must be overcome by contraction of the left ventricle to eject the blood. High diastolic blood pressure creates high afterload, which increases myocardial workload. Over time, high afterload can lead to left ventricular failure. continued on next slide

124. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Factors that decrease cardiac output  Decreased heart rate  Decreased blood volume  Decreased myocardial contractility  Parasympathetic nervous stimulation  Beta 1 blockade (beta blockers)  Higher diastolic BP over time continued on next slide

125. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Myocardial Function Factors that increase cardiac output  Increased heart rate (to a point)  Increased blood volume  Increased myocardial contractility  Sympathetic nervous system stimulation  Beta 1 stimulation from epinephrine  Lower diastolic BP

126. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR is the resistance to blood flow through a vessel. Vasoconstriction increases SVR, increased SVR increases BP. Vasodilation decreases SVR, decreased SVR decreases BP. continued on next slide

127. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance Sympathetic stimulation increases the SVR and BP. Epinephrine and norepinephrine stimulate alpha 1 receptors, which cause vasoconstriction and increased SVR. Parasympathetic stimulation decreases SVR and BP. continued on next slide

128. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance If the volume of blood decreases, decreasing the vessel size to increase SVR can help maintain BP. Decreasing vessel size through vasoconstriction decreases cellular perfusion and increases anaerobic metabolism. Patients with anaerobic metabolism may have a poor general appearance. continued on next slide

129. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR and pulse pressure  Pulse pressure is the difference between the systolic and the diastolic BP readings.  Systolic BP is an indicator of cardiac output. continued on next slide

130. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR and pulse pressure  Diastolic BP indicates systemic vascular resistance.  Decreasing systolic BP indicates falling cardiac output. continued on next slide

131. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR and pulse pressure  A narrow pulse pressure is less than 25% of the systolic BP.  With a BP of 132/74 mmHg, the pulse pressure is 58 mmHg (132 – 74 = 58).  A narrow pulse pressure for that patient is 33 mmHg (132 × 25% = 33 mmHg). continued on next slide

132. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR and pulse pressure  In a patient with blood or fluid loss, narrow pulse pressure is a significant sign. Blood loss lowers venous volume, which lowers preload, which lowers stroke volume, which lowers cardiac output Systolic BP decreases from the drop in cardiac output. continued on next slide

133. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Systemic Vascular Resistance SVR and pulse pressure  In a patient with blood or fluid loss, narrow pulse pressure is a significant sign. Increased SVR increases diastolic BP. The result is a narrow pulse pressure.

134. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Microcirculation is the flow of blood through the arterioles, capillaries, and venules. continued on next slide

135. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation is the flow of blood through the smallest blood vessels: arterioles, capillaries, and venules. Precapillary sphincters control the flow of blood through the capillaries. continued on next slide

136. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Precapillary sphincters control the movement of blood through the capillaries.  If the precapillary sphincter is relaxed, blood moves through the capillary.  If the precapillary sphincter is contracted, the blood is shunted away from the true capillary. continued on next slide

137. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Precapillary sphincters help to maintain arterial pressure.  Three regulatory influences control blood flow through the capillaries. Local factors Neural factors Hormonal factors continued on next slide

138. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Local factors  Temperature  Hypoxia  Acidosis  Histamine continued on next slide

139. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Neural factors  Sympathetic nervous system causes vasoconstriction  Parasympathetic nervous system causes vasodilation continued on next slide

140. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Microcirculation Hormonal factors  Epinephrine stimulates alpha 1 receptors, which cause precapillary sphincters to constrict.

141. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure Blood pressure (BP) = cardiac output (CO) × systemic vascular resistance (SVR)  Increased CO increases BP.  Decreased CO decreases BP.  Increased HR increases CO and BP.  Decreased HR decreases CO and BP. continued on next slide

142. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure Blood pressure (BP) = cardiac output (CO) × systemic vascular resistance (SVR)  Increased SV increases CO and BP.  Decreased SV decreases CO and BP.  Increased SVR increases BP.  Decreased SVR decreases BP. continued on next slide

143. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure The general effect of blood pressure on perfusion is:  Increased BP increases cellular perfusion  Decreased BP decreases cellular perfusion continued on next slide

144. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure BP is monitored and regulated by baroreceptors and chemoreceptors.  Baroreceptors located in the aortic arch and carotid sinuses detect changes in blood pressure.  Signals are sent to the vasomotor and cardioregulatory centers in the brainstem. continued on next slide

145. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure An increase in BP results in signals to decrease the heart rate and dilate blood vessels. A decrease in BP results in signals to increase the heart rate and constrict blood vessels. continued on next slide

146. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Blood Pressure Chemoreceptors  A decrease in blood oxygen level stimulates the sympathetic nervous system.  Heart rate increases and blood vessels constrict.  Hypoxia can present with pale, cool skin, and increased heart rate.

147. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Review of Aerobic Metabolism Components Oxygen content in ambient air Patency of the airway Minute ventilation  Ventilatory rate  Tidal volume Alveolar ventilation  Ventilatory rate  Tidal volume continued on next slide

148. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Review of Aerobic Metabolism Components Perfusion in the pulmonary capillaries  Venous volume  Right ventricular pump function Gas exchange between the capillaries and the alveoli continued on next slide

149. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Review of Aerobic Metabolism Components Content of blood  Red blood cells  Hemoglobin  Plasma continued on next slide

150. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Review of Aerobic Metabolism Components Cardiac output  Heart rate  Preload  Stroke volume  Myocardial contractility  Afterload continued on next slide

151. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Review of Aerobic Metabolism Components Systemic vascular resistance  Sympathetic nervous system stimulation  Parasympathetic nervous system stimulation Gas exchange between the capillaries and the cells

152. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study Conclusion The patient has a history of chronic obstructive lung disease and heart failure. He has been increasingly short of breath for two days, with a sudden worsening today. With the assistance of an engine crew, Patty and Gus continue assisting the patient's ventilations and providing supplemental oxygen. continued on next slide

153. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Case Study Conclusion The crew recognizes the seriousness of the patient's condition and is prepared to take further measures, if needed, to maintain the patient's airway. Gus calls in a report to the receiving hospital. When they arrive at the ED, a physician, nurse, and respiratory therapist are waiting to continue the patient's care.

154. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Lesson Summary Cells require oxygen and glucose to produce energy and perform work. Without adequate ventilation and perfusion, cells engage in anaerobic metabolism, which produces less energy and more waste. A fundamental purpose of emergency care is to restore and maintain cell perfusion.

155. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Correct! Your answer is supported by two principles of physics. First, according to Boyle's law, the pressure of a gas varies inversely with its volume. Second, air (a mixture of gases) moves from areas of higher pressure to areas of lower pressure. continued on next slide

156. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Correct! When the diaphragm and intercostal muscles contract, the thoracic cavity increases in volume, which lowers the pressure in the thorax and lungs. Air flows from the higher atmospheric pressure into the area of lower pressure within the lungs. Click here to continue the program.

157. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Incorrect When the diaphragm relaxes, it rises into the chest cavity, making it smaller, which promotes exhalation. Click here to return to the quiz.

158. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Incorrect According to Boyle's law, when the volume of a gas decreases, such as happens to the gas within the thorax when the size of the thorax decreases, the pressure of the gas increases. In the case of ventilation, this action promotes exhalation. Click here to return to the quiz.

159. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Incorrect When the intercostal muscles relax, the volume of the thoracic cavity decreases in size, which increases the pressure within thorax. This action promotes exhalation. Click here to return to the quiz.

160. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Correct! Most oxygen transported in the blood is carried by hemoglobin. Each molecule of hemoglobin contains iron, to which the oxygen can bind. Each hemoglobin molecule provides four binding sites, which allow it to carry up to four molecules of oxygen. continued on next slide

161. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Correct! The loss of hemoglobin-containing red blood cells, such as through hemorrhage, is a loss of oxygen- carrying capacity. Controlling bleeding is a critical way to help preserve a patient's ability to deliver oxygen to his cells. Click here to continue the program.

162. Prehospital Emergency Care, 10 th edition Mistovich | Karren Copyright © 2014, 2010, 2008 by Pearson Education, Inc. All Rights Reserved Incorrect This is not the way most oxygen is transported in the blood. Return to the quiz to try again. Click here to return to the quiz.