Pressure measures force per unit area, with SI units of pascals (1 Pa = 1 N/m2). As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Atmospheric pressure, atm Definition:ĭefinition of Atmospheric pressure, atm provided by WikiPedia:Ītmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth (or that of another planet). One millimeter of mercury is approximately 1 torr, which is 1/760 of standard atmospheric pressure (101325760 =133.322368421 pascals). Although not an SI unit, the millimeter of mercury is still routinely used in medicine, meteorology, aviation, and many other scientific fields. Millimeter of mercury, mmhg Definition:ĭefinition of Millimeter of mercury provided by wikipedia: Conversion formulas Kilopound per square inch , Pounds per square inch (ksi, psi): It is speculated that anesthetic levels of hypercapnia may be utilized to improve tissue oxygenation during O2 therapy in newborns, without increasing the risk of pulmonary and CNS O2 poisoning.Online pressure converter. These data indicate unique and dose-dependent cerebral and pulmonary responses to hyperoxic-hypercapnia in newborn rats. Supercapnia, at PICO2 of 380 mmHg, with HBO also produced no visible neurologic effect, but it caused an early apnea with severe pulmonary damage. In contrast, PICO2 at the anesthetic levels of 140 and 190 mmHg attenuated the visible pulmonary and neurologic manifestations of O2 toxicity, and significantly reduced post-decompression mortality, compared to moderate hypercapnia of 60-90 mmHg. Hypercapnia at PICO2 of 60 and 90 mmHg with HBO produced extensive pulmonary damage with a high post-decompression mortality, compared to HBO alone.
The PCO2 values studied corresponded with 0, 8, 12, 18, 25, and 50 kPa, respectively, at a total pressure of 507 kPa. Four- to seven-day-old rats were exposed to HBO with inspired PCO2 (PICO2) of approximately 0, 60, 90, 140, 190, and 380 mmHg at a total pressure of 5 atm abs. We examined the modifying effects of CO2 on the CNS and pulmonary manifestations of hyperbaric oxygenation (HBO) in newborn rats.
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