What Is Hyperbaric Oxygen Therapy And Its Use....
The greatest risk during oxygen and hyperbaric oxygen therapy is that of fire. Oxygen supports combustion much more readily than does air, because air consists of approximately 80 per cent nitrogen, an inert gas, which has a smothering effect on fire. Combustion occurs 1,000 times more readily in a 100 per cent oxygen atmosphere than in air, and after ignition the fire burns five times more rapidly in oxygen than in air. Furthermore, fires in oxygen have special characteristics and will flash over the surface of the body and, indeed, actually set light to the skin or the nap of the body and cannot be smothered. They require a very dense water spray to extinguish them.
It is essential that any possible fire risk is eliminated whenever a patient is receiving oxygen therapy. All sources of ignition, such as matches, cigarette lighters, electric bell pushes and frictional or sparking toys should be excluded from oxygen tents or hyperbaric chambers. No clothing made of nylon or man-made fibre should be worn by patients or nurses entering hyperbaric oxygen chambers, as these materials accumulate static electrical charges which cause sparking. No grease should be used on the valves of oxygen cylinders as this can cause fire when the valves are opened.
Special hazards of hyperbaric oxygen therapy. A limited number of nurses are expected to work in hyperbaric oxygen units and they should appreciate the special hazards involved. Some nurses are expected to enter the large compressed-air hyperbaric chambers in which patients have operations. Nurses entering these chambers run the risks common to all workers in a compressed-air environment. These are:
Otitic barotrauma. This is the damage which may occur to the eardrums if blockage of the Eustachian tube by catarrh prevents air from entering or leaving the middle ear when the environmental pressure is changed.
Decompression sickness. This occurs if decompression is carried out too rapidly following exposure to compressed air. Bubbles of nitrogen form in the body tissues. In simple bends (or Type I decompression sickness) the bubbles collect round the large joints and cause pain. In Type II decom¬pression sickness the bubbles may collect in the pulmonary circulation causing 'the chokes', a feeling of intense shortness of breath; in the cardiac circulation causing symptoms similar to those of coronary thrombosis; or in the blood vessels supplying the brain and spinal cord, causing neuro¬logical dist urbanises often referred to as 'the staggers'. The last is the most serious type of decompression sickness which, unless treated very rapidly by re compression, may cause permanent paralysis or death.
Rupture of lung cysts and emphysema's bullier during decompression. Lung cysts or bulked may fill with compressed gas which expands during decompression of the chamber causing rupture of the cyst. Patients and staff should have routine X-ray examinations to exclude this possibility.
Nitrogen narcosis. Nitrogen, when breathed at high pressures (and remember, air contains 80 per cent nitrogen) becomes a mildly narcotic gas and can cause slight disturbances of intellect. This shows itself in an inability to perform complicated tasks satisfactorily unless they have been learn ed thoroughly belbreliand. 7'his means that a doctor or a nurse in a
(3) In impairment of oxygen transport by the blood to the tissues.
(a) In severe anaemia, where there is deficiency of haemoglobin.
(b) In severe hemorrhage where, again, there is deficiency of haemoglobin plus loss of circulating blood volume.
(c) In carbon monoxide poisoning, where haemoglobin com¬bines preferentially with carbon monoxide rather than with oxygen.
(d) In congestive heart failure, where slowing of the circulation occurs in addition to the diffusion defect in the lungs mentioned earlier.
(4) Finally, when oxygen may fail to reach the tissues because of degenerative disease of the blood vessels.
The greatest risk during oxygen and hyperbaric oxygen therapy is that of fire. Oxygen supports combustion much more readily than does air, because air consists of approximately 80 per cent nitrogen, an inert gas, which has a smothering effect on fire. Combustion occurs 1,000 times more readily in a 100 per cent oxygen atmosphere than in air, and after ignition the fire burns five times more rapidly in oxygen than in air. Furthermore, fires in oxygen have special characteristics and will flash over the surface of the body and, indeed, actually set light to the skin or the nap of the body and cannot be smothered. They require a very dense water spray to extinguish them.
It is essential that any possible fire risk is eliminated whenever a patient is receiving oxygen therapy. All sources of ignition, such as matches, cigarette lighters, electric bell pushes and frictional or sparking toys should be excluded from oxygen tents or hyperbaric chambers. No clothing made of nylon or man-made fibre should be worn by patients or nurses entering hyperbaric oxygen chambers, as these materials accumulate static electrical charges which cause sparking. No grease should be used on the valves of oxygen cylinders as this can cause fire when the valves are opened.
Special hazards of hyperbaric oxygen therapy. A limited number of nurses are expected to work in hyperbaric oxygen units and they should appreciate the special hazards involved. Some nurses are expected to enter the large compressed-air hyperbaric chambers in which patients have operations. Nurses entering these chambers run the risks common to all workers in a compressed-air environment. These are:
Otitic barotrauma. This is the damage which may occur to the eardrums if blockage of the Eustachian tube by catarrh prevents air from entering or leaving the middle ear when the environmental pressure is changed.
Decompression sickness. This occurs if decompression is carried out too rapidly following exposure to compressed air. Bubbles of nitrogen form in the body tissues. In simple bends (or Type I decompression sickness) the bubbles collect round the large joints and cause pain. In Type II decom¬pression sickness the bubbles may collect in the pulmonary circulation causing 'the chokes', a feeling of intense shortness of breath; in the cardiac circulation causing symptoms similar to those of coronary thrombosis; or in the blood vessels supplying the brain and spinal cord, causing neuro¬logical dist urbanises often referred to as 'the staggers'. The last is the most serious type of decompression sickness which, unless treated very rapidly by re compression, may cause permanent paralysis or death.
Rupture of lung cysts and emphysema's bullier during decompression. Lung cysts or bulked may fill with compressed gas which expands during decompression of the chamber causing rupture of the cyst. Patients and staff should have routine X-ray examinations to exclude this possibility.
Nitrogen narcosis. Nitrogen, when breathed at high pressures (and remember, air contains 80 per cent nitrogen) becomes a mildly narcotic gas and can cause slight disturbances of intellect. This shows itself in an inability to perform complicated tasks satisfactorily unless they have been learn ed thoroughly belbreliand. 7'his means that a doctor or a nurse in a
(3) In impairment of oxygen transport by the blood to the tissues.
(a) In severe anaemia, where there is deficiency of haemoglobin.
(b) In severe hemorrhage where, again, there is deficiency of haemoglobin plus loss of circulating blood volume.
(c) In carbon monoxide poisoning, where haemoglobin com¬bines preferentially with carbon monoxide rather than with oxygen.
(d) In congestive heart failure, where slowing of the circulation occurs in addition to the diffusion defect in the lungs mentioned earlier.
(4) Finally, when oxygen may fail to reach the tissues because of degenerative disease of the blood vessels.
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