Snapshot A 34-year-old male complains of several weeks of headaches, lightheadedness, nausea, and myalgias. He reports that his wife and teenage children have all be experiencing similar symptoms. The family uses a wood-burning stove for both heat and cooking. Introduction Carbon monoxide is an odorless, colorless, tasteless, initially nonirritating gas Often produced in domestic or industrial settings Highly toxic to human beings Carbon monoxide has a higher affinity for hemoglobin than does oxygen, therefore, in carbon monoxide poisoning, oxygen is displaced from the hemoglobin molecule, leading to decreased delivery of oxygen to tissues and tissue dysfunction History involves exposure to automobile exhaust, smoke inhalation, barbecues, or old appliances in poorly ventilated locations Presentation Symptoms confusion headache Physical exam cherry-red skin this is a rare finding Chronic low-level exposure may cause flu-like symptoms nausea headache myalgia Evaluation Oxygen saturation usually NORMAL though actualy O2 content is LOW this is because pulse oximeter reads carboxyyhemoglobin as normally saturated hemoglobin ABG and serum carboxyhemoglobin level normal carboxyhemoglobin level is <5% in nonsmokers and <10% in smokers anion-gap metabolic acidosis due to the build-up of lactic acid ECG check in elderly and those with history of cardiac disease due to increased risk for ischemia Treatment Conservative 100% oxygen must displace carbon monoxide from hemoglobin note: when a patient has smoke inhalational injuries, carbon monoxide and cyanide poisoning should be empirically treated with 100% oxygen and hydroxycobalamin plus sodium thiosulfate, respectively hyperbaric oxygen in patients who are pregnant, nonresponsive, or experiencing signs of CNS or cardiac ischemia