A Study of NT-ProBNP and ETCO2 in Patients Presenting with Acute Dyspnoea

In patients presenting with acute dyspnoea in the emergency department (ED), the early and correct diagnosis may present a significant clinical challenge. The most common diagnoses of acute shortness of breath and manifesting signs of respiratory distress are decompensated heart failure (HF), pneumonia, chronic obstructive pulmonary disease (COPD), pulmonary embolism (PE), asthma, and acute respiratory distress syndrome (ARDS) and other causes like anaemia. The aim of the study was to measure NT-pro brain natriuretic peptide (BNP) and exhaled end-tidal carbon dioxide (ETCO2) in patients presenting with dyspnoea. This prospective, cross-sectional and observational study was performed at the Government Medical College and Hospital, Nagpur, between October 2019 and October 2021 in patients admitted to the medicine intensive care unit. Three groups of patients were compared: (1) HF-related acute dyspnoea group (n = 52), (2) pulmonary (COPD/PE)-related acute dyspnoea group (n = 31) and (3) sepsis with ARDS-related dyspnoea group (n = 13). All patients underwent initial clinical examination with a recording of initial vital parameters along with on-admission ETCO2 measurement, NT-proBNP testing, arterial blood gas testing, lung ultrasound examination, 2D echocardiography, chest X-rays, and other basic diagnostic laboratory testing. We included 96 patients during the study period. Median NT-proBNP was found to be maximum for the HF group (11,480 pg/ml) followed by the sepsis group (780 pg/ml) and pulmonary group (231 pg/ml). The mean ETCO2 value was found to be maximum in the pulmonary group (48.610 mmHg) followed by HF (31.51 mmHg) and the sepsis group (19.46 mmHg). All results were found to be statistically significant (P < 0.05). NT-proBNP has high diagnostic accuracy in differentiating acute HF-related dyspnoea from pulmonary (COPD and ARDS)-related acute dyspnoea. The higher levels of ETCO2 help in diagnosing patients with COPD.