The toxicology literature of 2011: issues impacting the emergency physician.

Annane D, Chadda K, Gajdos P, et al. Hyperbaric oxygen therapy for acute domestic carbon monoxide poisoning: two randomized controlled trials. Intensive Care Med. 2011;37(3):486–492. Carbonmonoxide (CO) is a colorless and odorless gas that is formed during incomplete combustionof carbonproducts. Clinical effects canbe nonspecific and range from malaise, headache, and nausea to more severe effects such as myocardial suppression, coma, and multisystem organ failure. Carbon monoxide is considered the leading cause of accidental poisoning deaths in the United States. Treatment of CO poisoning includes supplemental oxygen, but the use of hyperbaric oxygen (HBO) remains controversial. Prior research regarding the use of HBO in CO poisoning is confounding as patient populations differ as do specific HBO treatment protocols. Hyperbaric oxygen is known to reduce the half-life of carboxyhemoglobin by 5-fold, but the benefit is unclear. A study in 2002 by Weaver et al [1] showed a decrease in delayed neurologic sequelae at 6 and 12months in thehyperbaric group compared with the normobaric (NBO) group. However, other studies have shown nobenefit and even potential harmwith the use of HBO [2]. In an attempt to further define the role of HBO in the CO-poisoned patient, the authors of this study conducted 2 randomized controlled trials to evaluateHBOvsNBOforCOpoisoning. The studywasdivided into 2 trials: Trial A included noncomatose patients, and trial B included comatose patients. Patients were randomized to groups as diagrammed below. Normobaric oxygen was given through a facemask or ventilator with a fraction of inspired oxygen of 100%. Hyperbaric oxygen sessions were of 2 hours' duration in amultiplace chamberwith aplateaupressure of 2 atmospheres absolute. A total of 385 patients were enrolled in the study: 179 patients in trial A and 206 patients in trial B.