reating Carbon Monoxide Poisoning – Is Continuous Positive Airway Pressure Advantageous over Oxygen Therapy?

Respected Editor, Carbon monoxide (CO), a leading cause of poisoning, causes its noxious effects by depriving the living tissues of Oxygen (O2). It does so by binding to hemoglobin (Hb) with a significantly higher affinity than O2. The resulting Carboxyhemoglobin (COHb) decreases the blood’s O2 carrying capacity and even impairs the release of O2 from Hb [1]. As organs’ vitality becomes progressively compromised, the symptoms of CO poisoning aggravate from vague complaints such as headache, dizziness, blurred vision, nausea and vomiting to hypotension, arrhythmias, cardiac and respiratory arrest, seizures, and ultimately coma [1]. The most toxic amounts of CO typically exist in indoor air. Wood burning stoves, furnaces, inappropriately adjusted gas appliances, improperly vented gas generators inside a house or building are potential contributors to CO poisoning [2]. Oxygen therapy delivered via a non-rebreather mask or endotracheal tube has historically been the mainstay of treatment in CO poisoning. Hyperbaric Oxygen therapy has also been suggested, especially in severe cases, with evidence supporting the fact that it lowers the half-life of CO faster than normobaric oxygen. However, its use is severely limited due to cost constraints, lack of expertise, and the undersupply of equipment, even more so in the developing world [1]. A relatively new approach is being investigated, which involves delivering continuous positive airway pressure (CPAP) through non-invasive mechanical ventilation [3-5]. The resulting positive pressure in the airways improves the exchange of gases and leads to a rise in alveolar pressure. The increased inspiratory and expiratory pressures in the alveoli, in turn, have a favorable impact on the ventilation/perfusion ratio, which is hypothesized to cause an increase in the partial pressure of O2, increased O2 binding with hemoglobin, and CO decomposition [4]. Turgut et al. [3] compared the lowering of CO between patients given 15 L/min O2 via non-rebreather mask and patients given FiO2 100% via CPAP. In this study, they observed a statistically significant lowering of CO at 30, 60, and 90 minutes with CPAP compared to normobaric O2. Furthermore, the duration of stay in the Emergency department decreased from a median of 185 minutes to 125 minutes in normobaric Oxygen and CPAP groups, respectively. The half-life of CO was also lowered from a median of 105 minutes in the normobaric oxygen group to 45 minutes in the CPAP group [3]. Anot