If you give 100% oxygen, under atmospheric pressure, the level in oxygen in blood will be –
Correct Answer: 100-150
Description: (A) (100 - 150) (540 - Guyton 12th) (481 - A.K. Jain 5th)Normal ValuesValues at sea level:Partial pressure of oxygen (PaO2) - 75 - 100 mmHgPartial pressure of carbon dioxide (PaCO2) - 38 - 42 mmHgArterial blood pH of 7.38 - 7.42Oxygen saturation (SaO2) - 94 - 100%Bicarbonate - (HCO3) - 22 - 28 mEq/LNote: mEq/L = milliequivalents per liter; mmHg=millimeters of mercuryIn oxygen poisoning, the central nervous system condition was called the Paul Bert effect, and the pulmonary condition the Lorrain Smith effect.Normobaric conditionsOxygen content = oxygen carried by hemoglobin + oxygen dissolved in plasmaArteria oxygen content = 1.34 (hemoglobin) (%saturation) + 0.003 (PaO2)= 1.34 (15) (100%) + 0.003(100)= 20.1+0.3= 20.4 vol%Venous oxygen content = 1.34 (15) (70%)= 14vol%Hyperbaric conditions - 3 atmospheres absoluteArterial oxygen content = 1.34 (15) (100%) + 0.003 (2200)= 20.1+ 6.6 vol%Inhalation of 100% oxygen yields a fivefold to sevenfold increase in arterial blood oxygen tension at normal atmospheric pressure and may reach values close to 2000 mmHg during hyperbaric exposure to oxygen at 0.3 MPa (three ATA).At one ATA* of pressure (the standard air pressure or sea level), the partial pressure of oxygen in alveolar air amounts to about 673 mm of mercury (mmHg). However, when a person is placed in a hyperbaric chamber and delivered pure oxygen 3 ATA or 2280 mmHg the alveolar oxygen pressure increases to 2193 mmHg. Theoretically, arterial and tissue oxygen pressure closely follow alveolar oxygen pressure. This is dramatic increase in the amount of oxygen going into the blood.When the body is at rest, it normally consumes about 6 ml of oxygen per 100 ml of blood, but of this amount only 0.3 ml is transported by the hemoglobin in the red blood cells. When the hyperbaric pressure is raised to 2 ATA of pure hyperbaric oxygen therapy. At 3 ATA approximately 6.4 volumes per cent of oxygen are physically dissolved in the plasma, which is sufficient to sustain life even in the absence of hemoglobin.Exposure to 100% O2 at 2 - 3 atm can increased dissolved O2 in arterial blood to the point that arterial O2 tension is greater than 2000 mgHg and tissue 02 tension is 400 mmHg (654- Ganong 244).HYPERBARIC OXYGEN THERAPY (Inhalation of 100% pure O2 at high barometric pressure)The oxygen is usually administered at PO2s of 2 to 3 atmosphere of pressure through a mask or intratracheal tube, whereas the gas around the body is normal air compressed to the same high pressure.Uses:* Gas gangrene (Histotoxic hypoxia)* Decompression sickness* Arterial gas embolism* Carbon monoxide poisoning (Anaemic hypoxia)* Osteomyelitis* Myocardial infarction.Inhalation of 100% pure 02 at 1 atmospheric pressure i.e. at 760 MMHGOnly useful in hypoxic hypoxia specially when it is due to decreased IpO2.
Category:
Physiology
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