Carbon monoxide (CO) poisoning is one of the most common causes of injury and death from poisoning. Once inhaled, CO enters the bloodstream via the lungs. There it binds, competitively with oxygen to hemoglobin (Hb), creating carboxyhemoglobin (COHb). Unfortunately, the affinity of hemoglobin for CO is more than 200 times greater than that for oxygen, inhibiting oxygen delivery to organs and tissues, and resulting in hypoxia. The primary objective of therapy is to eliminate CO from the patient as quickly as possible to prevent acute and long-term effects. The ideal treatment is hyperbaric oxygen (HBO) in a pressure chamber. However, pressure chambers are scarce, and therefore, the most common treatment is normobaric oxygen (NBO), which, however, has limited efficacy. To address these limitations, Extracorporeal Hyperoxygenation Therapy (EHT) was developed as a novel treatment option that enhances CO elimination by treating extracorporeally blood at elevated oxygen partial pressure. Initially, the proof of principle was demonstrated in vitro in two different small-scale systems: a hollow fiber membrane oxygenator (HFMO) and a custom-designed batch oxygenator (BO) based on the bubble oxygenator principle, both operated at increased pressures (1, 3 bar). An increase in pressure resulted in a faster CO elimination in both oxygenators, with a superior performance of the BO of more than 3.5 compared to an HFMO, when comparing the average COHb half-lives of at a pressure of 3 bar. Subsequently, the BO was redesigned and tested for a broader range of pressures (1, 3, 5, 7 bar) and temperatures (23, 30, 37 °C). The shortest measured COHb half-life in blood was 21.32 minutes. Finally, a full-scale batch system, based on the BO, was developed and characterized in vitro, achieving a minimum COHb half-life of 3.26 ± 0.11 minutes. For the in vivo feasibility study, the EHT system was expanded by an automated blood loop that allowed a quasi-continuous operation. The in vivo results demonstrated a 42% reduction in the median COHb half-life (29.77 min with EHT vs. 70.8 min with NBO). However, EHT initially induced oscillations in hemodynamic pressures due to transient changes in circulatory volume. In summary, further optimization is required, particularly to eliminate the oscillations in hemodynamic pressures. Once achieved, the EHT system could provide an easily available and effective method for the treatment of CO poisoning.
Niklas B. Steuer (Wed,) studied this question.