Hemoglobin Mass as a Determinant of Inter-Individual Susceptibility to Carbon Monoxide Poisoning

Background: An estimated 28,900 deaths around the world in 2021 were attributed to unintentional CO poisoning. Following inhalation, CO binds to hemoglobin with an affinity 220–240 times greater than that of oxygen to form carboxyhemoglobin (COHb). While the constituents of CO exposure are known to determine CO uptake in the blood, much less is understood regarding individual variability of the response to a given CO stimulus. Thus, the purpose of this paper was to explore the relationship between hemoglobin mass (HbM, a proxy for blood hemoglobin content) and the magnitude of the ensuing carboxyhemoglobinemia. Methods: This is a theoretical work based solely on considerations and published data. Discussion: Currently considered the gold standard for HbM assessment, the CO-rebreathing technique relies on the dilution principle i.e. the lower the HbM values the higher the ΔCOHb following a standardized CO bolus administration or an outdoors exposure. Accordingly, previously published prediction equations with HbM and ΔCOHb as the predictor and outcome variables, respectively, are reviewed with particular reference to the (confounding) factor of pulmonary ventilation. As far as treatment to CO poisoning is concerned, dynamic exercise emerges as a supplement to oxygen therapy to facilitate CO removal from human body. Screening procedures aiming to identify individuals susceptible to CO poisoning should henceforth include HbM assessments.