Although its use is becoming increasingly controversial, hyperbaric oxygen therapy (in a chamber at 2 to 3 atmospheres of 100% oxygen) typically should be considered for patients who have any of the following: Life-threatening cardiopulmonary complications Ongoing chest pain Altered consciousness Loss of consciousness (no matter how brief) A carboxyhemoglobin level > 25% Hyperbaric oxygen therapy should also be considered for pregnant patients, possibly at lower serum CO levels than in nonpregnant patients.