Hypoxia

Presentation on Hypoxia in which I tried to cover all the essential points

1. Hypoxia is O 2 deficiency at the tissue level. A pathological condition in which the whole body as a whole or a region of the body is deprived of adequate oxygen supply. It is the decrease below normal levels of oxygen in inspired gases, arterial blood, or tissues, without reaching anoxia.

2. High altitude. Low hemoglobin level. Decreased oxygen supply to an area. Low oxygen carrying capacity. Poor tissue perfusion. Impaired ventilation. Decreased diffusion of oxygen.

3. Inadequate oxygenation of the blood in the lungs because of extrinsic reasons. Deficiency of oxygen in the atmosphere. Hypoventilation (neuromuscular disorders).

4. Pulmonary disease. Hypoventilation caused by increased airway resistance or decreased pulmonary compliance. Abnormal alveolar ventilation-perfusion ratio. Diminished respiratory membrane diffusion.

5. Venous to arterial shunts. Inadequate oxygen transport to the tissues by the blood. Anemia or abnormal hemoglobin. General circulatory deficiency. Localized circulatory deficiency. Tissue edema.

6. Inadequate tissue capability of using oxygen. Poisoning of cellular oxidation enzymes. Diminished cellular metabolic capacity for using oxygen, because of toxicity, vitamin deficiency, or other factors.

7. Hypoxic hypoxia. Anemic hypoxia. Stagnant hypoxia. Histotoxic hypoxia.

8. Hypoxemic hypoxia. Arterial hypoxia. Hypoxic hypoxia is a result of insufficient oxygen available to the lungs or decreased oxygen tension.

9. Low arterial pO 2 . Low arterial O 2 content. Low arterial % O 2 saturation of hemoglobin. Low A-V pO 2 difference.

10. Low oxygen tension in inspired air. High altitude. Breathing in closed space. Breathing gas mixture containing low pO 2.

11. Respiratory disorders associated with decreased pulmonary ventilation. Asthma. Brain tumor. Sleep apnoea. Pneumothorax. Bulbar polio myelitis.

12. Respiratory disorders associated with inadequate oxygenation of blood in lungs. Emphysema. Fibrosis. Pulmonary hemorrhage. Pneumonia. Bronchiolar obstruction. Bronchiectasis.

13. Cardiac disorders. Congestive heart failure. Low cardiac output. Hypoxic hypoxia is characterized by reduced oxygen tension in arterial blood while all the other features are normal.

14. Hypoxia in which arterial pO 2 is normal but the amount of haemoglobin available to carry oxygen is reduced.

15. Decreased no. of RBCs Decreased haemoglobin content in blood Formation of altered haemoglobin Combination of haemoglobin with gases other than O 2 and CO 2.

16. Anemic hypoxia is characterized by low oxygen carrying capacity of blood while the other features remain normal.

17. Ischaemic hypoxia. Hypoxia in which the blood flow to the tissues is so low or slow that adequate oxygen is not delivered to them despite a normal arterial pO 2 .

18. Congestive cardiac failure. Hemorrhage. Surgical stroke. Vasospasm. Thrombosis. Embolism.

19. Stagnant hypoxia is characterized by decreased velocity of blood flow while the other features remain normal.

20. Hypoxia in which the amount of oxygen delivered to the tissues is adequate , but because of the action of a toxic agent the tissue cells cannot make use of the oxygen supplied to them.

21. Cyanide poisoning: Cyanide destroys the cellular oxidative enzymes completely paralyzing the cytochrome oxidase system.

22. TYPES OF HYPOXIAS ARTERIAL pO 2 HEMOGLOBIN COUNT RATE OF BLOOD FLOW TO TISSUES Hypoxic hypoxia Decreases Normal Normal Anemic hypoxia Normal Decreases Normal Stagnant hypoxia Normal Normal Decreases Histotoxic hypoxia Normal Normal Normal

23. TYPES OF HYPOXIAS CAUSES Hypoxic hypoxia Decreases inspired pO2; decreased pulmonary ventilation ; defective V/P ratio Anemic hypoxia Total Hb content decreases due to anemia; haemorrhage; presence of abnormal Hb Stagnant hypoxia Circulatory failure; haemorrhage; heart failure Histotoxic hypoxia Cyanide poisoning

24. TYPES OF HYPOXIA ARTERIAL pO 2 ARTERIAL O 2 CONTENT ARTERIAL % -O 2 SATURATION OF HEMOGLOBIN Hypoxic hypoxia Decreased Decreases Decreases Anemic hypoxia Normal Markedly reduced Decreases Stagnant hypoxia Normal Normal Normal Histotoxic hypoxia Normal Normal Normal

25. TYPES OF HYPOXIA A-V PO 2 DIFFERENCE CYANOSIS STIMULATION OF PERIPHERAL CHEMORECEPTORS Hypoxic hypoxia Decreases Present Present Anemic hypoxia Normal Absent Absent Stagnant hypoxia More than normal Present Present Histotoxic hypoxia Less than normal Absent Present

26. To counter the effects of high-altitude diseases, the body must return arterial pO 2  towards normal.   Acclimatization , the means by which the body adapts to higher altitudes, only partially restores pO 2  to standard levels.   Hyperventilation , the body’s most common response to high-altitude conditions, increases alveolar pO 2  by raising the depth and rate of breathing. Polycythemia , in which the body increases the number of red blood cells in circulation, thickens the blood, raising the danger that the heart can’t pump it.

27. Successful treatment of chronic hypoxemia in patients with COPD, cystic fibrosis, emphysema, severe asthma, and other lung diseases has been demonstrated clinically by more than 600 Russian MDs.