As you scan the ED trackboard, you recognize the name of a 22 year old patient who you saw the week before after a house fire.  At that time, the patient was treated for carbon monoxide (CO) poisoning and briefly admitted to the hospital. Today’s chief complaint is dyspnea and chest pain.  You note that the patient is tachycardic, hypoxic, and complained of pleuritic chest pain at triage. You wonder if the prior exposure to carbon monoxide should raise your pre-test probability for certain diagnoses.

CO exposure is associated with accelerating the formation and increasing the strength of thrombus(1).  A recent publication followed 22,699 patients with CO poisoning in Korea for one year(2). Their findings demonstrated a strong association between CO toxicity and venous thromboembolism (VTE).  During the first 30 days after CO poisoning, patients were 22 times more likely to have a PE (OR 22.00, 95% confidence interval 5.33-90.75) and over 10 times more likely to have a DVT (OR 10.33, 95% confidence interval 3.16-33.80).  Because this study used claims data, it is limited insofar as identifying particular risk factors between intentional and unintentional CO poisoning. Further, because the severity of a given CO exposure could not be assessed, a relationship between CO dose and the probability of developing VTE could not be established.  Nevertheless, this study indicates patients who present in the first 30 days after CO poisoning and with symptoms of PE or DVT should receive extra scrutiny to rule out the diagnosis.

1. Nielsen VG, Kirklin JK, George JF. Carbon monoxide releasing molecule-2 increases the velocity of thrombus growth and strength in human plasma. Blood Coagulation & Fibrinolysis. 2009;20(5):377-380.

2. Cho Y, Kang H, Oh J, Lim TH, Ryu J, Ko BS. Risk of Venous Thromboembolism After Carbon Monoxide Poisoning: A Nationwide Population-Based Study. Annals of Emergency Medicine. November 2019.