Respiration8

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Respiration8

  1. 1. HYPOXIA, ASPHYXIA and other conditions Lecture 8
  2. 2. Important Terminology <ul><li>• Hypoventilation: Ventilation inappropriately low for the metabolic demands. Alveolar/arterial PCO2 is elevated, alveolar/arterial PO2 is low.Antonym: hyperventilation </li></ul><ul><li>• Eupnea: Normal spontaneous breathing. Ventilation is matched to metabolic demands. </li></ul><ul><li>• Tachypnea: Increased frequency of breathing. Ventilation may or may not be changed depending on tidal volume. Antonym: bradypnea </li></ul><ul><li>• Dyspnea: Subjective sensation of difficult or labored breathing. Orthopnea is dyspnea associated with lying down. </li></ul><ul><li>• Apnea: temporary absence or cessation of breathing (airflow)- normally occurs after hyperventilating or swallowing. </li></ul>
  3. 3. APNEA is a nonspecific indicator of distress <ul><li>Failure of a system </li></ul><ul><li>Early indicator of deterioration </li></ul>Many known cause of apnea can be diagnosed and treated.
  4. 4. PERIODIC BREATHING Thought to be benign PB  Apnea  SIDS??? Definition of Periodic Breathing: is the abnormal or uneven respiratory rhythm
  5. 5. APNEA Cessation of respiratory airflow <ul><li>CENTRAL </li></ul><ul><ul><li>No respiratory effort, no nasal airflow </li></ul></ul><ul><ul><li>Developmental phenomenon </li></ul></ul><ul><li>OBSTRUCTIVE </li></ul><ul><ul><li> respiratory effort, no nasal airflow,  HR. </li></ul></ul><ul><ul><li>Caused by aspiration, laryngospasm or poor airway control </li></ul></ul><ul><li>MIXED </li></ul><ul><ul><li>Both obstructive and central </li></ul></ul>
  6. 6. Sleep Disordered Breathing • Can’t Breath = Obstructive Sleep Apnea (OSA) • Won’t Breath = Central Sleep Apnea -Cheyne Stokes Respiration (CSR)
  7. 7. Cheyne-Stokes Breathing • Periodic waxing and waning of ventilation without pharyngeal obstruction • Common in heart failure and cerebral vascular disease
  8. 8. Biot’s breathing
  9. 9. HYPOXIA <ul><li>A condition where there is decreased Oxygen supply to the tissues </li></ul>
  10. 10. HYPOXIA: CLASSIFICATION <ul><ul><li>1. Hypoxic Hypoxia : </li></ul></ul><ul><ul><ul><li>Arterial P O 2 is less. </li></ul></ul></ul><ul><ul><li>2. Anemic Hypoxia : </li></ul></ul><ul><ul><ul><li>Decreased Hemoglobin causing  O 2 carriage </li></ul></ul></ul><ul><ul><li>3. Stagnant Hypoxia : </li></ul></ul><ul><ul><ul><li>Due to slow & low blood flow. </li></ul></ul></ul><ul><ul><li>4. Histotoxic Hypoxia : </li></ul></ul><ul><ul><ul><li>Tissue toxins deny O 2 to the cells. </li></ul></ul></ul>
  11. 11. HYPOXIC HYPOXIA <ul><li>The arterial PO 2 is decreased. </li></ul><ul><li>This may be due to: </li></ul><ul><ul><li>1. Decreased Atmospheric PO 2 : </li></ul></ul><ul><ul><ul><li>High Altitude </li></ul></ul></ul>
  12. 12. Arterial PO 2 decreased due to: <ul><ul><li>2. Decreased Ventilation: </li></ul></ul><ul><ul><ul><li>Respiratory Paralysis. </li></ul></ul></ul><ul><ul><ul><li>Bronchial Asthma </li></ul></ul></ul><ul><ul><ul><li>Emphysema </li></ul></ul></ul><ul><ul><li>3. Defective Gas exchange: </li></ul></ul><ul><ul><ul><li>Pulmonary Edema </li></ul></ul></ul><ul><ul><ul><li>Pneumoconiosis </li></ul></ul></ul><ul><li>All these cause a decreased partial pressure of Oxygen and so Hypoxic Hypoxia. </li></ul>
  13. 13. ANEMIC HYPOXIA <ul><li>A decrease in hemoglobin or RBC count causes decreased Oxygen carriage and so hypoxia. </li></ul><ul><li>Can also be due to CO Poisoning . </li></ul><ul><ul><li>CO combines irreversibly with Hb. </li></ul></ul><ul><li>Abnormal Hemoglobins such as Sickle Hb can also cause Anemic Hypoxia. </li></ul>
  14. 14. STAGNANT HYPOXIA <ul><li>Also called “Ischemic” or “Hypo-perfusion Hypoxia”. </li></ul><ul><li>Blood flow to tissues is slow or low. </li></ul><ul><li>The Oxygen reaching the tissues per unit time is less. </li></ul><ul><li>This situation is seen in: </li></ul><ul><ul><li>Heart failure </li></ul></ul><ul><ul><li>Venous obstruction </li></ul></ul><ul><li>May lead to Adult Respiratory Distress Syndrome if it occurs in the lungs. </li></ul>
  15. 15. HISTOTOXIC HYPOXIA <ul><li>Oxygen is available at tissue levels </li></ul><ul><li>But the cells cannot use it due to a toxic agent. </li></ul><ul><li>Seen in Cyanide poisoning. </li></ul>
  16. 16. <ul><li>Cyanide inhibits the intracellular enzyme, “Cytochrome oxidase” </li></ul><ul><li>This problem can be treated with Methylene Blue. </li></ul><ul><ul><li>Methylene blue converts Cyan Hb into CyanmetHb which is nontoxic. </li></ul></ul>HISTOTOXIC HYPOXIA
  17. 17. EFFECTS OF HYPOXIA <ul><li>Severe Hypoxia < 20mm Hg </li></ul><ul><ul><li>In 10 – 20 seconds: Loss of consciousness. </li></ul></ul><ul><ul><li>In 4 – 5 minutes: DEATH </li></ul></ul><ul><li>Mild Hypoxia: </li></ul><ul><ul><li>Symptoms are similar to alcoholism </li></ul></ul><ul><ul><li>Impaired Judgment. </li></ul></ul><ul><ul><li>Drowsiness. </li></ul></ul><ul><ul><li>Dulled sensitivity to pain. </li></ul></ul>EFFECTS OF HYPOXIA
  18. 18. CYANOSIS <ul><li>Bluish discoloration of the skin & mucous membranes. </li></ul><ul><li>Cause: the presence of Reduced Hemoglobin in the blood. </li></ul><ul><li>Seen only when the absolute amount of Reduced Hb is > 5 Grams/dLt . </li></ul>
  19. 19. OXYGEN THERAPY <ul><li>Given to patients of Hypoxic hypoxia </li></ul><ul><li>Can be given through: </li></ul><ul><ul><li>A Nasal catheter. </li></ul></ul><ul><ul><li>Venturi mask. </li></ul></ul><ul><li>Pure Oxygen is not given </li></ul><ul><li>A mixture of Air & Oxygen is given. </li></ul><ul><li>Useful in all cases of Hypoxic Hypoxia. </li></ul>
  20. 20. ASPHYXIA <ul><li>“ Improper aeration of blood continued for sometime produces two pathological changes: </li></ul><ul><ul><li>Hypoxia :  O 2 </li></ul></ul><ul><ul><li>Hypercapnia :  CO 2 </li></ul></ul>
  21. 21. TYPES OF ASPHYXIA <ul><li>LOCAL: Due to obstruction of blood supply: </li></ul><ul><ul><li>Too tight tourniquet, for too long. </li></ul></ul><ul><ul><li>Blue painful, swollen congested limb. </li></ul></ul><ul><li>GENERAL: </li></ul><ul><ul><li>ACUTE: </li></ul></ul><ul><ul><ul><li>Strangulation: Occlusion of trachea </li></ul></ul></ul><ul><ul><ul><li>Airtight room: suffocation. </li></ul></ul></ul>
  22. 22. GENERAL ASPYXIA: CHRONIC <ul><li>Chronic Lung Disease. </li></ul><ul><li>Chronic Bronchiectasis. </li></ul><ul><li>Emphysema </li></ul>
  23. 23. ASPHYXIA: STAGES <ul><li>I STAGE: </li></ul><ul><ul><li>Violent Respiratory Efforts </li></ul></ul><ul><ul><li>Tachypnea & Hyperpnea. </li></ul></ul><ul><ul><li>Hypoxia </li></ul></ul><ul><ul><li>Loss of consciousnesss. </li></ul></ul><ul><li>II STAGE: </li></ul><ul><ul><li> Sympathetic discharge </li></ul></ul><ul><ul><li>Hypertension & Tachycardia </li></ul></ul><ul><ul><li>Ventricular fibrillations </li></ul></ul><ul><ul><li>Convulsions </li></ul></ul>
  24. 24. ASPHYXIA : STAGE III <ul><li>Gasping : </li></ul><ul><ul><li>Slow deep inspiration </li></ul></ul><ul><li>Hyporeflexia </li></ul><ul><li>Pupillary Dilatation </li></ul><ul><li>Hypotension </li></ul><ul><li>Bradycardia </li></ul><ul><li>Cardiac Arrest </li></ul><ul><li>Death. </li></ul>
  25. 25. <ul><li>What is Hyperbaric Oxygen Therapy? </li></ul><ul><li>entirely enclosed chamber </li></ul><ul><li>breathing oxygen, </li></ul><ul><li>greater than one atmosphere </li></ul>
  26. 26. Hyperbaric Oxygen Therapy (HBO) <ul><li>Primary therapy for: </li></ul><ul><ul><li>Decompression sickness </li></ul></ul><ul><ul><li>Air embolism </li></ul></ul><ul><ul><li>Carbon monoxide poisoning </li></ul></ul><ul><li>Adjunct therapy for: </li></ul><ul><ul><li>Surgical intervention </li></ul></ul><ul><ul><li>Antibiotics </li></ul></ul>
  27. 27. Basic Mechanisms <ul><li>Boyle’s Law – pressure and volume inversely proportional under constant temperature </li></ul><ul><ul><li>By increasing ambient pressure to 2 atm, decreases the volume by ½ </li></ul></ul><ul><ul><li>Therapeutic for bubble forming diseases such as decompression sickness or arterial gas embolism </li></ul></ul><ul><li>Henry’s Law – at a given temperature, the amount of gas dissolved in solute is directly proportional to the partial pressure of the gas. </li></ul><ul><ul><li>By increasing ambient pressure, more oxygen can be dissolved in the plasma </li></ul></ul>

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