What do we know about carbon monoxide poisoning and cardiac compromise?

Abstract

Carbon monoxide (CO) poisoning is one of the most common types of poisoning and the leading cause of death by poisoning worldwide. Cardiac injury caused by CO poisoning has been little described despite being a predictor of poor prognosis. We present the case of a healthy 24-year-old woman, admitted to our emergency room due to an episode of lipothymia without loss of consciousness. She reported holocranial headache for the previous two weeks associated with nausea and vomiting. Laboratory tests revealed blood gas analysis: pH 7.392, pCO2 32 mmHg, pO2 101 mmHg, lactate 3.5 mmol/l, HCO3 20.8 mmol/l; COHb 29.2%; serial troponin I 1.21 → 5.25 → 6.13 → 3.65 μg/l; myoglobin 1378 → 964 → 352 μg/l; and NT-proBNP 1330 pg/l. The electrocardiogram showed sinus rhythm, heart rate 110 bpm, and ST-segment depression of 2 mm in V4 and 1 mm in V5. Transthoracic echocardiography revealed a left ventricle with normal wall motion and preserved ejection fraction. Given the clinical and epidemiological context, myocardial and central nervous system ischemia due to prolonged CO exposure was assumed and normobaric oxygen therapy was immediately started. In view of evidence of injury to two major organ systems the indication for hyperbaric oxygen therapy was discussed with a specialist colleague, who suggested maintaining conservative treatment with oxygen therapy and in-hospital monitoring for 72 h. The patient was discharged on the third day and was still asymptomatic at 400 days of follow-up. Besides symptoms and signs of central nervous system dysfunction, myocardial damage should also always be considered in the context of CO poisoning. Hyperbaric therapy is still controversial and the lack of objective data highlights the need for new randomized studies.

Keywords: Carbon monoxide poisoning; Hyperbaric oxygen; Intoxicação por monóxido de carbono; Isquemia do miocárdio; Myocardial ischemia; Oxigénio hiperbárico.