Background / Current Market Status

Dyspnea, or shortness of breath/difficult breathing, is a symptom due to either cardiovascular or non-cardiovascular (typically pulmonary) causes. Determining the causes of dyspnea, especially in patients with a history of both cardiac and pulmonary disorders, can be difficult but remains critical to patient outcome. Noninvasive hemodynamic measurements of Cardiac Index (CI) and Systolic Time Ratio (STR) have been shown to aid in classifying between cardiac and non-cardiac occurrences of dyspnea. [1,2]


By adding CI and STR to the historical and physical findings of a patient with dyspnea, it is possible to establish a hemodynamic profile for the patient and ultimately classify if the episode of dyspnea is due to cardiac related issues. [1,2] Below is an adapted diagnostic algorithm:

Using noninvasive hemodynamic testing, specifically analyzing CI and STR, has been shown to result in a 13% change in physician diagnosis, and a 39% change in chosen treatment plans. [3]

Supporting Literature/References

Publication Conclusions
[1] Springfield C, et al. Utility of Impedance Cardiography to Determine Cardiac vs Noncardiac Cause of Dyspnea in the Emergency Department. Congest Heart Fail. 2004; 10(suppl2):14-16 - Noninvasive hemodynamic measurements were able to accurately differentiate between cardiac and non-cardiac related cause of dyspnea, with greater sensitivity and specificity than an ED physician using standard criteria. [1]
- Criteria for cardiac cause of dyspnea is CI<2.4 or CI<3.0 with a STR>0.55. [1]
[2] Lo, HY, et al. Utility of impedance cardiography for dyspneic patients in the ED. Am. J. Emergency Medicine (2007) 25,437-441 - There were significant differences in stroke index, cardiac index, ICON, and STR for patients with cardiac and noncardiac dyspnea. [2]
- Noninvasive hemodynamic measurement data results in “improvement in ED physician’s differentiation of cardiac from noncardiac causes of dyspnea.” [2]
[3] Peacock WF et al. Impact of Impedance Cardiography on Diagnosis and Therapy of Emergent Dyspnea: The ED-IMPACT Trial. Acad Emerg Med. 2006; 13(4):365-371 - Noninvasive hemodynamic data results in “significant changes in diagnosis and therapeutic plan during the evaluation of dyspneic patients 65 years and older.” [3]
- Showed a 13% change in patient diagnosis, and 39% change of treatment plans. [3]
[4] Barcarse E et al. Combination of B-type natriuretic peptide levels and non-invasive hemodynamic parameters in diagnosing congestive heart failure in the emergency department. Congest Heart Fail. 2004;10:171-176. - Noninvasive hemodynamic parameters, in addition to a BNP level allow more effective diagnosis of CHF by differentiating between systolic and diastolic dysfunction in a fast and inexpensive manner, and by determining the severity of the illness. [4]