Anes cons in altered envir

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Anes cons in altered envir

  1. 1. ANAESTHETIC CONSIDERATION IN ALTERED ENVIRONMENT
  2. 2. INTRODUCTION <ul><li>Hyperbaric oxygen therapy means in a pressurized chamber patient is exposed to oxygen tensions exceeding the ambient barometric pressure(>760 mm Hg at sea level). </li></ul><ul><li>Until 20 th century hyperbaric treatment involved the use of air. clinical application of hyperbaric oxygen therapy (HBO) began in late 1950s,in parallel to increase understanding of blood gas analysis and gas exchange physiology. </li></ul>
  3. 3. PHYSIOLOGICAL EFFECT OF INCREASED GAS PRESSURE <ul><li>Increased barometric pressure </li></ul><ul><li>Increased partial pressure of oxygen. </li></ul><ul><li>It shows four pharmacological effects </li></ul><ul><li>Increased oxygen content of blood. </li></ul><ul><li>Vasoconstriction </li></ul><ul><li>Antibacterial action </li></ul><ul><li>Inhibition of endothelial leucocytic adhesions in injured tissue </li></ul><ul><li>Elevation of inert gas pressure </li></ul>
  4. 4. CONTD…. <ul><li>Elevation of absolute pressure during compression phase of deep diving. </li></ul><ul><li>Pressure reversal of anesthesia </li></ul><ul><li>Animal studies have shown that high pressure (50ATA) has a tendency to reverse general anesthesia. </li></ul><ul><li>Effect of hyper baric exposure on drug disposition </li></ul><ul><li>Major pharmacokinetic or pharmacodynamic differences wont be expected for most drugs up to the pressure used for most clinical purposes (6 ATA). </li></ul>
  5. 5. Indication of HBO therapy <ul><li>Gas bubble disease </li></ul><ul><li>Poisoning </li></ul><ul><li>Infection </li></ul><ul><li>Acute ischemia </li></ul><ul><li>Chronic ischemia </li></ul><ul><li>Acute hypoxia </li></ul><ul><li>Thermal injury </li></ul><ul><li>Envenomation </li></ul>
  6. 6. RATIONAL FOR TREATMENT OF SPECIFIC SYNDROMES <ul><li>CO POISONING: </li></ul><ul><li>Pathophysiology: </li></ul><ul><li>Functional anaemia </li></ul><ul><li>Shift of O-D curve to left </li></ul><ul><li>Binding with intracellular pigments. </li></ul><ul><li>Diagnosis : </li></ul><ul><li>H/o exposure </li></ul><ul><li>Carboxy Hb level in blood </li></ul><ul><li>Brain imaging </li></ul>
  7. 7. CO POISONING <ul><li>Role of HBO therapy – guidelines </li></ul><ul><li>H/o neurological impairment </li></ul><ul><li>Evidence of cardiac abnormalities </li></ul><ul><li>Carboxy Hb >25% </li></ul><ul><li>Pregnant woman who fulfills the above criteria </li></ul><ul><li>Mechanism: </li></ul><ul><li>Half life of carboxy Hb is greatly reduced </li></ul><ul><li>Increased dissolved oxygen in plasma </li></ul>
  8. 8. GAS EMBOLISM AND DECOMPRESSION SICKNESS <ul><li>Etiopathogenesis: </li></ul><ul><li>Scuba divers during ascent from a dive while breathing compressed gas. </li></ul><ul><li>Iatrogenic causes like diagnostic arteriogram,heamodialysis,neurosurgical procedures, total hip replacement,arthroscopy. </li></ul><ul><li>Effects : </li></ul><ul><li>Obstruction of vessels </li></ul><ul><li>Bubble endothelial interaction </li></ul><ul><li>Cerebral microcirculation impaired vaso regulation </li></ul>
  9. 9. CONTD…. <ul><li>Decompression sickness </li></ul><ul><li>The gas bubbles in this situation occur because of a </li></ul><ul><li>decrease in ambient pressure at a rate sufficient to induce local inert gas super saturation and subsequent formation of bubble insitu. </li></ul><ul><li>The decision to administer recompression treatment should be based on clinical evaluation. </li></ul><ul><li>TREATMENT: </li></ul><ul><li>Fluid resuscitation </li></ul>
  10. 10. CONTD…. <ul><li>High inspired oxygen concentration </li></ul><ul><li>HBO therapy will cause diminution of gas volume </li></ul><ul><li>ACUTE INFECTION: </li></ul><ul><li>Clostridial myonecrosis </li></ul><ul><li>Etiological agent – C.perfringens </li></ul><ul><li>Manifestation </li></ul><ul><li>Treatment - surgical debridement, antibiotics , HBO therapy </li></ul>
  11. 11. SUPPORT OF ARTERIAL OXYGENATION <ul><li>In cases of cyanotic heart disease </li></ul><ul><li>In Open heart surgery with the advantage of reduction in transfusion requirements </li></ul><ul><li>During therapeutic lung lavage performed under GA with one lung ventilation. </li></ul>
  12. 12. MAINTENANCE OF O 2 TRANSPORT IN SEVERE ANAEMIA <ul><li>Ability of hyperbaric oxygen to increase arterial content of oxygen in plasma to clinically useful level may allow support of tissue oxygen delivery even in absence of Hb temporarily pending the availability of definitive therapy in the form of cross matched blood </li></ul>
  13. 13. THERAPEUTIC SYSTEMS <ul><li>Multiplace chamber – </li></ul><ul><li>These chamber are compressed with air and patient breathes oxygen with a head tent. </li></ul><ul><li>Monitoring is relatively easy. </li></ul><ul><li>Expensive and large space needed. </li></ul><ul><li>Monoplace chamber – </li></ul><ul><li>Compressed with 100% oxygen. </li></ul><ul><li>Low cost and easy installation. </li></ul><ul><li>Monitoring and emergency care difficult </li></ul>
  14. 14. MULTI PLACE CHAMBER
  15. 15. MONOPLACE CHAMBER
  16. 16. HYPERBARIC TREATMENT SCHEDULE <ul><li>Factors limiting dose and duration of HBO therapy </li></ul><ul><li>Oxygen toxicity, decompression obligation for nursing staff, difficulty in monitoring, patient boredom. </li></ul><ul><li>Gas embolism and Decompression sickness </li></ul><ul><li>U.S Navy Table 6 </li></ul><ul><li>U.S Navy Table 6A </li></ul><ul><li>Clostridial myonecrosis </li></ul><ul><li>Duke therapeutic protocol </li></ul><ul><li>Osteoradio necrosis </li></ul>
  17. 17. THERAPEUTIC SCHEDULE
  18. 18. PATIENT EVALUATION <ul><li>Whether a sufficient elevation in PaO 2 can be obtained. </li></ul><ul><li>Whether pt can equilibrate middle ear pressure. </li></ul><ul><li>Adequacy of control of seizure disorder. </li></ul><ul><li>Presence of pulmonary bullae or blebs. </li></ul><ul><li>Hyperoxic myopia. </li></ul><ul><li>Whether claustrophobia might occur during treatment. </li></ul>
  19. 19. REFERENCES: <ul><li>MILLER’S anesthesia 6 th edition: </li></ul><ul><li>MORGAN’S clinical anesthesiology 4 th edition: </li></ul><ul><li>GUYTON and HALL physiology: </li></ul>
  20. 20. THANK YOU

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