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2014-06-15 17:16:12
hyperbaric study gas laws decompression dive tables

Study guide for CHT exam
Show Answers:

  1. UHMS accepted list
    • 1. Air or gas embolism
    • 2. Carbon monoxide poisoning - and complicated by cyanide poisoning
    • 3. Clostridial myositis and myonecrosis (gas gangrene)
    • 4. Crush injury, compartment syndrome and other acute tramatic ischemias
    • 5. Decompression sickness
    • 6. Arterial insufficiencies - central retinal artery occlusion, enhancement of healing in selected problem wounds
    • 7. Severe anemia
    • 8. Intracranial abscess
    • 9. Necrotizing soft tissue inflections
    • 10. Osteomyelitis (refractory)
    • 11. Delayed radiation injury (soft tissue and bony necrosis)
    • 12. Compromised grafts and flaps
    • 13. Acute thermal burn injury
    • 14. Idiopathis sudden sensorineural hearing loss
  2. Equivalents to 1 ATA

    1 ATA

    • 760 mmHg
    • 14.7 psi
    • 33 fsw
    • 10 msw
  3. A.R. Behnke
    principally responsible for developing the U.S. Naval Medical Research Institute, separated the symptoms of arterial gas embolism from those of decompression sickness and suggested the use of oxygen in recompression therapy, first used the term oxygen window in 1967 when using partial pressures of O2 and He as high as 2-3 ATA to create a maximal partial pressure vacancy
  4. P. Bert
    central nervous system oxygen toxicity was first described in his 'La Pression Barometriques" and is referred to as the Paul Bert effect
  5. I. Boerema
    proposed using HBO2 in cardiac surgery to prolong the patient's tolerance to cardiac arrest, published "Life Without Blood" in 1960 showing pigs kept alive via oxygen transport by plasma, treatment of anaerobic infections (e.g. gas gangrene) infection controlled at >250mmHg PO2 which paved the way for HBO2 in wound healing, was teacher to Brummelkamp
  6. G.F. Bond
    Project Genesis began in 1957, proving that humans could withstand prolonged exposure to different breathing gases and increased environmental pressures - this was the beginning of saturation diving
  7. R. Boyle
    1657 created a "pneumatical engine" and began the experiments which led to the creation of Boyle's law
  8. W.H. Brummelkamp
    pioneer in the treatment of gas gangrene through hyperbaric submersion - oxygen drenching
  9. J.A. Fontaine
    built a pressurized mobile operating room in 1878
  10. J.B.S. Haldane
    Haldane's Principle: sheer size defines what bodily equipment an animal must have, the larger the animal, the more complicated the oxygen pumping and distributing system it requires
  11. N. Henshaw
    built the Domicilium, driven by organ bellows with valves to control the flow of air, sealed chamber used to create both hyper and hypo -baric conditions in 1662
  12. O.D. Yarborough
    demonstrated that gases other than Nitrogen can cause narcosis
  13. to convert temperature from Kelvin
    • C = K-273.15
    • F = Kx1.8-459.67
    • R = Kx1.8
  14. to convert temperature from Celsius
    • K = C+273.15
    • F = Cx1.8+32
    • R = Cx1.8+491
  15. to convert temperature from Fahrenheit
    • K = (F+459.67)/1.8
    • C = (F-32)/1.8
    • R = F=459.67
  16. to convert temperature from Rankine
    • K = R/1.8
    • C = R/1.8-273.15
    • F = R-459.67
  17. Boyle's law
    at a constant temperature the volume of an ideal gas varies inversely with the pressure, expressed mathematically as P1V1 = P2V2
  18. Charles' law
    at a constant pressure, the volume of an ideal gas varies directly with the absolute temperature, expressed mathematically as V1T2 = V2T1
  19. Dalton's law
    the pressure exerted by one gas of a mixture of gases is equal to the pressure the single gas would exert if it alone occupied the same volume (partial pressure), expressed mathematically as Ptotal = P1+P2+ ... +Pn
  20. Gay-Lussac's law
    at a constant volume the pressure of an ideal gas varies directly with the absolute temperature, expressed mathematically as P1T2 = P2T1
  21. General gas law
    Boyle's and Charles' laws conveniently combined into what is known as the general gas law, expressed mathematically as P1V1T2 = P2V2T1
  22. Graham's law
    diffusivity is inversely proportional to the square root of molecular weight; the law is rather accurate in gases but only approximately so in liquids
  23. Henry's law
    at a constant temperature, the amount of a gas that dissolves in a liquid with which it is in contact is proportional to the partial pressure of that gas, expressed mathematically as P1A2 = P2A1
  24. Ideal gas law
    a law that defines the relationships among pressure, temperature, volume and quantities of substance (moles) of any ideal gas, expressed PV = NRT

    • P = absolute pressure
    • V = volume
    • N = number of moles of gas
    • R = universal gas constant
    • T = absolute temperature
  25. Pascal's law
    externally applied pressure is transmitted equally throughout all fluid-filled spaces
  26. respiration
    respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction
  27. circulation
    permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from cells in the body to nourish it and help to fight diseases, stabilize body temperature and pH, and to maintain homeostasis
  28. oxygen toxicity (definition)
    a condition resulting from the harmful effects of breathing molecular oxygen (O2) at elevated partial pressures
  29. oxygen toxicity (symptoms)
    • disorientation
    • breathing problems
    • vision changes (myopia)
    • oxidative damage to cell membranes
    • collapse of alveoli in the lungs
    • retinal detachment
    • seizures
  30. narcosis (nitrogen narcosis) (definition)
    reversible alteration in consciousness that occurs while diving at depth, caused by the anesthetic effect of certain gases at high pressure and produces a state similar to drunkenness
  31. narcosis (symptoms)
    • impairment of judgment
    • vertigo
    • visual or auditory disturbances
    • exhilaration
    • giddiness
    • extreme anxiety
    • depression
    • paranoia
  32. central nervous toxicity
    Central nervous system oxygen toxicity manifests as symptoms such as visual changes (especially tunnel vision), ringing in the ears, nausea, twitching (especially of the face), irritability (personality changes, anxiety, confusion, etc.), and dizziness. This may be followed by a seizure consisting of two phases: intense muscle contraction occurs for several seconds; followed by rapid spasms of alternate muscle relaxation and contraction producing convulsive jerking. The seizure ends with a period of unconsciousness. The onset of seizure depends upon the partial pressure of oxygen in the breathing gas and exposure duration. However, exposure time before onset is unpredictable, as tests have shown a wide variation, both amongst individuals, and in the same individual from day to day. In addition, many external factors, such as underwater immersion, exposure to cold, and exercise will decrease the time to onset of central nervous system symptoms. Decrease of tolerance is closely linked to retention of carbon dioxide.
  33. pulmonary toxicity
    Pulmonary toxicity symptoms result from an inflammation that starts in the airways leading to the lungs and then spreads into the lungs. The symptoms appear in the upper chest region. This begins as a mild tickle on inhalation and progresses to frequent coughing. If breathing elevated partial pressures of oxygen is not discontinued, patients experience a mild burning on inhalation along with uncontrollable coughing and occasional shortness of breath. Physical findings related to pulmonary toxicity have included bubbling sounds heard through a stethoscope, fever, and increased blood flow to the lining of the nose. The radiological finding from the lungs shows inflammation and swelling. Pulmonary function measurements are reduced, as noted by a reduction in the amount of air that the lungs can hold and changes in expiratory function and lung elasticity. Tests in animals have indicated a variation in tolerance similar to that found in central nervous system toxicity, as well as significant variations between species. When the exposure to oxygen above 0.5 bar is intermittent, it permits the lungs to recover and delays the onset of toxicity.