Oxygen and Hyperbaric Oxygen
Pharmacology. Oxygen is a necessary oxidant to drive biochemical reactions. Room air contains 21% oxygen. Hyperbaric oxygen (HBO), which is 100% oxygen delivered to the patient in a pressurized chamber at 2–3 atm of pressure, may be beneficial for patients with severe carbon monoxide (CO) poisoning. It can hasten the reversal of CO binding to hemoglobin and intracellular myoglobin and provide oxygen independently of hemoglobin, and it may have protective actions in reducing post-ischemic brain damage. Randomized controlled studies have reported conflicting outcomes with HBO treatment, but there may be a marginal benefit in preventing subtle neuropsychiatric sequelae.
Indications
Supplemental oxygen is indicated when normal oxygenation is impaired because of pulmonary injury, which may result from aspiration (chemical pneumonitis) or inhalation of toxic gases. The Po2 should be maintained at 70– 80 mm Hg or higher if possible.
Supplemental oxygen usually is given empirically to patients with altered mental status or suspected hypoxemia.
Oxygen (100%) is indicated for patients with carbon monoxide poisoning to increase the conversion of carboxyhemoglobin and carboxymyoglobin to hemoglobin and myoglobin, respectively, and to increase the oxygen saturation of the plasma and subsequent delivery to tissues.
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