PHGY 312 Lecture Notes - Lecture 10: Nitrogen Narcosis, Decompression Sickness, Hyperoxia
24 May 2016
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N2 toxicity (inert gas narcosis: when n2 is under high pressure, solubility can increase, if it goes into lipids, cns, it can make you dizzy/unable to think clearly. Helium-oxygen tanks: lowers airway resistance and decompression sickness. O2 toxicity (convulsion, cns toxicity: rbcs hemolysis, renal damage, heart, liver, kidney all tissues affected by hyperoxia, closure of periphery of the lungs = atelectasis. Pao2 = pio2-(paco2/r), where paco2 =(vco2/va)pb: lower at higher altitudes. But if climber decreases va of co2 5 fold, then pao2 = 43-(8/0. 8) = 33. Hyperventilation is absolutely crucial at high altitude (to lower alveolar co2) to increase. Other obstacles: hypocapnea = low pco2 brain vasoconstriction can"t think clearly, birds don"t change blood flow much even in hypocapnea so they can survive at high altitudes, pulmonary hypertension, arterial and csf alkalosis. Effect of airway hypoxia on pvr: pulmonary airways constrict during period of hypoxia.
