Hyperbaric phototherapy augments blood carbon monoxide removal

Background and objectives: Carbon monoxide (CO) poisoning is responsible for nearly 50,000 emergency department visits and 1200 deaths per year. Compared to oxygen, CO has a 250-fold higher affinity for hemoglobin (Hb), resulting in the displacement of oxygen from Hb and impaired oxygen delivery to tissues. Optimal treatment of CO-poisoned patients involves the administration of hyperbaric 100% oxygen to remove CO from Hb and to restore oxygen delivery. However, hyperbaric chambers are not widely available and this treatment requires transporting a CO-poisoned patient to a specialized center, which can result in delayed treatment. Visible light is known to dissociate CO from carboxyhemoglobin (COHb). In a previous study, we showed that a system composed of six photo-extracorporeal membrane oxygenation (ECMO) devices efficiently removes CO from a large animal with CO poisoning. In this study, we tested the hypothesis that the application of hyperbaric oxygen to the photo-ECMO device would further increase the rate of CO elimination.

Study design/material and methods: We developed a hyperbaric photo-ECMO device and assessed the ability of the device to remove CO from CO-poisoned human blood. We combined four devices into a "hyperbaric photo-ECMO system" and compared its ability to remove CO to our previously described photo-ECMO system, which was composed of six devices ventilated with normobaric oxygen.

Results: Under normobaric conditions, an increase in oxygen concentration from 21% to 100% significantly increased CO elimination from CO-poisoned blood after a single pass through the device. Increased oxygen pressure within the photo-ECMO device was associated with higher exiting blood PO₂ levels and increased CO elimination. The system of four hyperbaric photo-ECMO devices removed CO from 1 L of CO-poisoned blood as quickly as the original, normobaric photo-ECMO system composed of six devices.

Conclusion: This study demonstrates the feasibility and efficacy of using a hyperbaric photo-ECMO system to increase the rate of CO elimination from CO-poisoned blood. This technology could provide a simple portable emergency device and facilitate immediate treatment of CO-poisoned patients at or near the site of injury.