Hyperbaric Oxygenation Therapy Alone for Carbon Monoxide Poisoning: Time for Reinforcements?

Abstract

L ee et al (1) addressed hyperbaric oxygenation (HBO 2 ) treatment for carbon monoxide (CO) poisoning in their recent study, concluding that early treatment improved neurocognitive prognosis at 6 months. However, they stated that no other current therapy could be expected to prevent cognitive sequelae due to cellular injuries sustained during CO exposure (1). Though we do not dispute the role of early HBO 2 therapy in CO intoxication (1), its use remains controversial as evidence for efficacy is sparse, as confirmed by the authors themselves (1, 2). Side effects derived from oxygen toxicity may play a role (2).A number of alternative (or possibly adjuvant) therapies have been described (2). A study by Feldman et al (3) described a combined therapy of HBO 2 with therapeutic hypothermia with a successful result. Neurologic sequelae were mitigated by initial intravascular cooling and subsequent HBO 2 treatment, whereas hypothermia was sustained by using ice bags inside the chamber (3). Potent anti-inflammatory steroids such as dexamethasone may limit severe inflammation in the case of CO poisoning (4). A patient with a case of CO poisoning was revived by a series of 3 HBO 2 sessions and steroid treatment from a semicoma state, without signs or symptoms of cognitive sequelae (4). Erythropoietin, a glycoprotein hormone that produces RBCs, may a have a protective role to play (5). In hypoxic states such as stroke, erythropoietin may protect neuronal cells by reducing S100B, limiting neurologic sequelae (5). Erythropoietin has been demonstrated to ameliorate cardiac complications because of CO poisoning (5), and similarly, neuronal damage was prevented by erythropoietin (5). In conclusion, it seems likely that early HBO 2 therapy alone may not suffice. In the light of the evidence described above (2-5), a new critical care neuroprotection therapy bundle for CO poisoning seems timely. Further studies, based on this new bundle, could be the next step to reduce dramatically the cognitive sequelae associated with severe CO intoxication. ACKNOWLEDGMENTWe thank Prof. David De Bels for his contribution.

The authors reply

“…We appreciate Honore et al (1) for their interest in our recent study published in Critical Care Medicine on early hyperbaric oxygen therapy (HBOT) for acute carbon monoxide poisoning (ACOP) improved neurocognitive prognosis at 6 months (2). As Honore et al (1) mentioned in their letter, our study (2) focused on the initiation time of HBOT for ACOP patient.…”

“…We appreciate Honore et al (1) for their interest in our recent study published in Critical Care Medicine on early hyperbaric oxygen therapy (HBOT) for acute carbon monoxide poisoning (ACOP) improved neurocognitive prognosis at 6 months (2). As Honore et al (1) mentioned in their letter, our study (2) focused on the initiation time of HBOT for ACOP patient. We designed the study referenced from the double-blind, randomized controlled trial (RCT) by Weaver et al (3) satisfying all Consolidated Standards for the Reporting of Trials guidelines.…”