Pressure of End Tidal CO2 Versus Clinical Differentiation of Acute Dyspnea

Introduction: Acute dyspnea is a common presentation in the Emergency Department and critical care setting. Early differentiation of cardiac causes of dyspnea from pulmonary related causes is of great significance. Clinical data including history and clinical examination may sometimes fail to differentiate the cause of dyspnea. Point of care pressure end tidal CO2 may add more diagnostic accuracy.Objectives: Our study compared the diagnostic accuracy of clinical criteria for diagnosis of heart failure related acute dyspnea as calculated with modified Boston criteria to pressure of end tidal CO2 and to b lines on lung ultrasound.Methods: We conducted a prospective study. In Cairo University Hospitals, between December 2012 to February 2014, 250 patients with acute dyspnea were recruited, of whom 25 patients were excluded. 225 patients were subdivided based on final hospital diagnosis into heart failure related acute dyspnea group (n= 118) and pulmonary (asthma/COPD) related acute dyspnea group (n=107). History, clinical examination, standard laboratory tests, chest X-ray, and pressure end tidal Co2 level were collected.Results: Clinical evaluation using modified Boston criteria had sensitivity 85% and specificity of 83% and AUROC 0.96. The pressure of end tidal CO2 had sensitivity 79% and specificity of 79% and AUROC 0.94.Conclusions: Structured clinical criteria gives accurate differentiation between cardiac related acute dyspnea from pulmonary related acute dyspnea.