Regional Perfusion during Venoarterial Extracorporeal Membrane Oxygenation: A Case Report and Educational Modules on the Concept of Dual Circulations

A challenging aspect of managing patients on venoarterial extracorporeal
membrane oxygenation (V-A ECMO) is a thorough understanding of the
relationship between oxygenated blood from the ECMO circuit and blood
being pumped from the patient’s native heart. We present an adult V-A
ECMO case report, which illustrates a unique encounter with the concept
of “dual circulations.” Despite blood gases from the ECMO arterial line
showing respiratory acidosis, this patient with cardiogenic shock
demonstrated regional respiratory alkalosis when blood was sampled from
the right radial arterial line. In response, a sample was obtained from
the left radial arterial line, which mimicked the ECMO arterial blood
but was dramatically different from the blood sampled from the right
radial arterial line. A retrospective analysis of patient data revealed
that the mismatch of blood gas values in this patient corresponded to an
increased pulse pressure. Having three arterial blood sampling sites
and data on the patient’s pulse pressure provided a dynamic view of
blood mixing and guided proper management, which contributed to a
successful patient outcome that otherwise may not have occurred. As a
result of this unique encounter, we created and distributed graphics
representing the concept of “dual circulations” to facilitate the
education of ECMO specialists at our institution.