Carbon Monoxide Poisoning

Abstract Carbon monoxide (CO) is a byproduct of a significant number of chemical and biological processes. In high amounts, it can be fatal because of its ability to bind to the hemoglobin (Hb) molecule with an affinity more than 200 times that of oxygen (O2), creating a carboxyhemoglobin (COHb) molecule. This reduces the number of hemoglobin molecules available to bind oxygen and decreases the blood oxygen content. CO also changes the conformation of the hemoglobin molecule in a way that reduces its ability to release bound O2, creating a leftward shift in the oxyhemoglobin dissociation curve. Anesthesiologists need to be mindful of CO because under certain conditions it can build up in the anesthesia circuit and cause dangerously high patient carboxyhemoglobin levels. Carbon monoxide poisoning is difficult to detect because CO is a colorless and odorless gas, and early symptoms of poisoning in an awake patient, like headaches and fatigue, are very nonspecific. No single sign or symptom is pathognomonic for CO poisoning, which puts the onus on the clinician to suspect, diagnose, and treat it properly.