LETTERS TO THE EDITOR
A question about Dr. Rory Spiegel's article. (Myths in Emergency Medicine: “Natriuretic Peptides Add Noise to an Already Uncertain Baseline,” EMN 2016;38:1; http://emn.online/Apr16Myths.) What about using cardiac impedance (BioZ) on those tough cases of dyspnea to sort it out? I found it almost as useful as a Swan-Ganz catheter in patients who meet the limitations criteria.
Daniel Vandenberg, DO
Dr. Spiegel responds: Thank you so much for your response. Limited data have been published about the utility of impedance cardiography for dyspneic patients in the ED. (Congest Heart Fail 2004;10[2 Suppl 2]:14; Acad Emerg Med 2006;13:365; Am J Emerg Med 2007;25:437.)
The data that do exist suggest that the use of impedance cardiography may add a small degree of diagnostic certainty to the unstructured clinical judgment of the emergency physician. These are, of course, all very small cohorts where the diagnostic accuracy of the impedance device is being tested outside clinical practice. The Peacock, et al., cohort did examine how the use of impedance cardiography changed management, but it was unable, of course, to assess whether these changes led to improvements in patient outcomes. It is unclear what benefits such a device would have when used by practicing EPs. (Acad Emerg Med 2006;13:365.)
Furthermore, the ubiquitous use of point-of-care ultrasound, which has diagnostic capabilities that seem far superior to impedance cardiography, may very well make this a moot point. Thank you again for your question and support!