Serum pro-B-type natriuretic peptide levels and cardiac index as adjunctive tools of blunt cardiac injury

Background: Blunt cardiac injury (BCI) has a variety of symptoms that may be a potentially life-threatening injury that can lead to death. Depending on the diagnosis of BCI, treatment direction and length of stay may vary. In addition, the utility of other diagnostic tests for cardiac disease as diagnostic tools for BCI remain unclear. The purpose of this study was to investigate the competence of N-terminal pro-B-type natriuretic peptide (NT pro-BNP) and cardiac index (C.I) as adjunctive diagnostic tools for BCI. Methods: From January 2018 to March 2020, severe trauma patients with sternum fracture who were admitted to the traumatic intensive care unit (TICU) were included this study. Patients with sternum fracture, 18 years of age or older, and with an injury severity score > 16 who required intensive care were included. Invasive measurement for the analysis of the pulse contour for C.I monitoring and intravenous blood sampling for NT pro-BNP measurement were performed. Sampling and 12-lead electrocardiogram were performed at different time points as follows: immediately after TICU admission and at 24 h and 48 h after trauma. Results: Among 103; 33 patients with factors that could affect NT pro-BNP were excluded; therefore, 63 patients were included in this study. According to the American Association for the Surgery of Trauma Cardiac Injury Scale, 33 patients were diagnosed with non-BCI, and 30 patients constituted with BCI. The median ages of the patients were 58 (52–69), and 60 (45–69) years in the non-BCI and BCI groups, respectively (p = 0.77). The median NT pro-BNP values were higher in the BCI group on admission, hospital day (HD) 2, and HD 3, however, no statistical difference was observed (125 (49–245) vs. 130 (47–428) pg/mL, p = 0.08, 124 (68–224) vs. 187 (55–519) pg/mL, p = 0.09, and 121(59–225) vs. 133 (56–600) pg/mL, p = 0.17, respectively). On the contrary, significantly lower values were observed in the median C.I measurement on admission and HD 3 in the BCI group (3.2 (2.8–3.5) vs. 2.6 (2.3–3.5) L/min/m², p < 0.01 and 3.2 (3.1–3.9) vs. 2.9 (2.4–3.2) L/min/m², p < 0.01, respectively); however, no significant difference was observed on HD 2 (3.4 (3.0–3.7) vs. 2.6 (2.4–3.4) L/min/m², p = 0.17), Furthermore, The median lactate levels in the BCI group upon admission, HD 2, and HD 3 were significantly higher than those in the non-BCI group (1.8 (1.1–2.6) vs. 3.1 (2.1–4.4) mmol/L, p < 0.01; 1.3 (0.8–2.3) vs. 3.0 (2.2–4.7) mmol/L, p < 0.01; and 1.5 (0.9–1.5) vs. 2.2 (1.3–3.7) mmol/L, p < 0.01, respectively). Conclusion: Consecutive values of NT pro-BNP and C.I show no correlation with ECG-based BCI diagnosis. However, lactate level measurement may help in the early recognition of BCI as an adjunctive tool. It should be noted that this is a hypothesis-generating study for BCI diagnosis. Further studies should be conducted in larger populations with a prospective approach.