Carboxyhemoglobin and methemoglobin levels as prognostic markers in acute pulmonary embolism

Carboxyhemoglobin (COHb) and methemoglobin (MetHb) levels have been associated with a poor outcome in patients with various pathological conditions including cardiovascular diseases. Our aim was to retrospectively assess the prognostic value of arterial COHb and MetHb in patients with acute pulmonary embolism (PE).

We conducted a retrospective study of 156 patients admitted in a pulmonary clinic due to acute PE. Measured variables during emergency department evaluation that were retrospectively analyzed included the ratio of the partial pressure of oxygen in arterial blood to the fraction of oxygen in inspired gas, Acute Physiology and Chronic Health Evaluation II score, risk stratification indices, and arterial blood gases. The association between arterial COHb and MetHb levels and disease severity or mortality was evaluated using bivariate tests and logistic regression analysis.

Arterial COHb and MetHb levels correlated with Acute Physiology and Chronic Health Evaluation II and pulmonary severity index scores. Furthermore, arterial COHb and MetHb levels were associated with troponin T and N-terminal pro-B-type natriuretic peptide levels. In univariate logistic regression analysis, COHb and MetHb levels were both significantly associated with an increased risk of death. However, in multivariate analysis, only COHb remained significant as an independent predictor of in-hospital mortality.

Our preliminary data suggest that arterial COHb and MetHb levels reflect the severity of acute PE, whereas COHb levels are independent predictors of in hospital death in patients in this clinical setting. These findings require further prospective validation.