Patients with severe poisoning are vulnerable to pressure trauma to skin, subcutaneous tissue, and muscle, especially at sites that support body weight or that are pinned under fallen objects The history may suggest which sites are most vulnerable, and pain is an early symptom Muscle breakdown and myoglobin deposition in renal tubular cells may precipitate acute renal failure ECG obtained in patients with carbon monoxide poisoning may show nonspecific cardiac repolarization changes and arrhythmias Two long-term neurologic syndromes have been described with carbon monoxide poisoning: permanent neurologic sequelae (PNS) and delayed neurologic sequelae (DNS) PNS is defined by central nervous system symptoms such as headache, mood disorders, personality changes and memory loss that persist for more than months Patients with DNS appear to recover with treatment and then exhibit a broad spectrum of neurologic and psychiatric abnormalities days to weeks after the exposure Studies of DNS, many of which are methodologically flawed, have elucidated neither an exact mechanism nor a consensus on prevention and treatment Management and Diagnostic Studies After removal from the contaminated environment, 100% oxygen should be administered ( Table 90.2 ) If the patient is breathing spontaneously, this can be accomplished with a nonrebreather face mask The half-life of carboxyhemoglobin is approximately hours in a patient breathing room air at sea level and approximately hour if pure oxygen is inspired The half-life is further reduced to less than 30 minutes if the patient has access to hyperbaric oxygen (HBO) at to atmospheres of pressure There is no widespread agreement on indications for HBO, and transfer to a hyperbaric chamber should not jeopardize cardiopulmonary stabilization However, HBO administration may have effects beyond the mere reduction in carboxyhemoglobin half-life Some studies in adults suggest a role for HBO in reducing the incidence of mortality and DNS, but there are no studies in children addressing its effectiveness Early consultation with a poison control center or an HBO facility should be considered ( Table 90.3 )