Differentiating Cardiac and Pulmonary Causes of Dyspnea Using Ultrasonography and Dyspnea Discrimination Index

BACKGROUND: One of the most common reasons for emergency room (ER) visits is acute dyspnea. The challenge is in differentiating a cardiac and pulmonary cause of acute breathlessness. Hence, we have studied the effectiveness of the dyspnea discrimination index (DDI) used in conjunction with ultrasonography (USG) in distinguishing between cardiac and pulmonary causes of dyspnea. METHODS: This was a prospective study conducted in the ER and general medicine wards to evaluate the efficacy of the DDI and USG in dyspneic patients. Data were entered in a standard data sheet and analysis was done using SPSS software. RESULTS: The majority of the patients were between the ages of 45 and 60, with a male predominance. Risk factors like smoking were more common in the pulmonary group (36%). Pulmonary cause of breathlessness was seen in 62% of patients and cardiac pathology was noted in 28%. The mean (SD) DDI value and DDI% are as follows: pulmonary group (DDI)—5.47 (SD: 2.82); cardiac group (DDI)—8.34 (SD: 3.75); pulmonary group (DDI%)—1.31 (SD: 0.68); cardiac group (DDI%)—2.34 (SD: 1.14). There was a significant difference in DDI% between the pulmonary and cardiac groups (p = 0.001). DDI was found to have a sensitivity and specificity of 77.3% and 70%, respectively. While for DDI%, sensitivity and specificity were 72.7% and 72%, respectively. Lung USG had 98% sensitivity and 95.5% specificity, with a narrow confidence interval. The positive likelihood ratio was noted to be 21.6, indicating a very high post-test probability. CONCLUSION: The DDI and USG in conjunction had good discriminative power, when it came to distinguishing between cardiac and pulmonary causes of dyspnea. USG had a high specificity and sensitivity, making it suitable for identifying the cause of dyspnea in a tertiary care ER setting. HOW TO CITE THIS ARTICLE: Chandy GM, Sathyendra S, Pichamuthu K, Hazra D, Abhilash KPP. Differentiating Cardiac and Pulmonary Causes of Dyspnea Using Ultrasonography and Dyspnea Discrimination Index. Indian J Crit Care Med 2022;26(1):33–38.