Diagnosis and prognostic importance of methemoglobin and carboxyhemoglobine levels in pulmonary thromboembolism

The diagnosis of pulmonary embolism is difficult and may be misdiagnosed because it does not occur with a specific clinical picture. On the other hand, early diagnosis is very important because early treatment is highly effective. Pulmonary Embolism does not have a definite diagnostic laboratory marker. For this reason, studies focus on an ideal diagnostic marker. Ideal prognostic and diagnostic markers should be easy to work with and easy to evaluate. In our study, the parameters that can be easily measured in blood gases such as carboxyhemoglobin (COHb) and methemoglobin (MetHb) were investigated in the diagnosis and prognosis of pulmonary embolism. The study was retrospectively conducted to investigate the effects of Carboxyhemoglobin (COHb) and Methemoglobin (MetHb) levels on the diagnosis and prognosis of Pulmonary Thromboembolism. Pulmonary Computed Tomography Angiography (ABTA) or Ventilation / Perfusion Scintigraphy confirmed PTE diagnosis accepted as Pulmonary Embolism. Patients with pulmonary embolism excluded by the same method were included as control group. Patients who were taking medication (sulfonamides, dapsone, phenacetin, primaquine, benzocaine) that could cause Methemoglobinemia and patients who had diseases that could cause carboxyhemoglobinemia, such as; chronic obstructive pulmonary disease, sepsis, pneumonia, asthma, idiopathic pulmonary fibrosis, bronchiectasis, decompensated heart failure were not included in the study. In our study, it was determined that 762 patients were diagnosed with Pulmonary Thromboembolism (PTE) in Medical School of Akdeniz University between 01.11.2015 and 31.08.2016. Among these patients, 107 patients who met the inclusion criteria were included in the study. The mean age of all cases was 56.44 ± 17.3 (21-86). The mean age of the patients who were diagnosed with PTE was 55.3 and the patients with PTE excluded were 59 (p: 0.27). The most common comorbid diseases were hypertension (24%) and diabetes mellitus (20.6%). Of the patients who had PTE, 79.7% (59) had non-massive PTE, 13.51% (10) sub-mass PTE and 6.7% (5) massive PTE. When the blood gas parameters were compared in both groups, COHb levels were found to be significantly higher (p: 0.001) in the PTE-diagnosed group and PO2 levels were found to be statistically higher in the PTE-discarded group (p: 0.028). In our study, 6 (8,1%) patients died early due to PTE. Of the patients who died, 66.6% (4) were male and 33.3% (2) were female. When the patients who died and the patients who live were compared, the average of Wells and PESI score, D-dimer and troponin levels were statistically significantly higher in the patients who died. No significant difference was found in all other parameters examined. In our study, COHb levels were found to be statistically higher in PTE-diagnosed group with compared PTE-diagnosed discarded group. However, this value is not higher than the normal level of COHb. Unlike the only study in the literature, we found that the levels of MetHb and COHb did not differ statistically in the diagnosis and prognosis of PTE.