Prolonged use of venoarterial extracorporeal membrane oxygenation (VA ECMO) may be complicated by end-organ dysfunction. Although gaseous microemboli (GME) are thought to damage end organs during cardiopulmonary bypass, patient exposures to GME have not been well characterized during VA ECMO. We therefore performed an observational study of GME in adult VA ECMO patients, with correlation to clinical events during routine patient care. After institutional review board (IRB) approval, we used two Doppler probes to detect GME noninvasively in extracorporeal membrane oxygenation (ECMO) circuits on four patients for 15 hours total while also recording patient care events. We then conducted in vitro trials to compare Doppler signals with gold-standard measurements using an Emboli Detection and Classification EDAC quantifier (Luna Innnovations, Inc. Roanoke, VA) (Terumo Cardiovascular, Ann Arbor, MI) during simulated clinical interventions. Correlations between Doppler and EDAC data were used to estimate GME counts and volumes represented by clinical Doppler data. A total of 503 groups of Doppler peaks representing GME showers were observed, including 194 statistically larger showers during patient care activities containing 92% of total Doppler peaks. Intravenous injections accounted for an estimated 68% of GME and 88% of GME volume, whereas care involving movement accounted for an estimated 6% of GME and 3% of volume. Overall estimated embolic rates of 24,000 GME totaling 4 μl/hr rivals reported GME rates during cardiopulmonary bypass. Numerous GME are present in the postmembrane circuit during VA ECMO, raising concern for effects on microcirculation and organ dysfunction. Strategies to detect and minimize GME may be warranted to limit embolic exposures experienced by VA ECMO patients.
From the *Department of Anesthesiology, University of Connecticut School of Medicine, Farmington, Connecticut; †Department of Anesthesiology, Hartford Hospital, Hartford, Connecticut; ‡Department of Surgery, Section of Cardiothoracic Surgery, Yale School of Medicine, New Haven, Connecticut; §Department of Cardiac Surgery, Hartford Hospital, Hartford, Connecticut; ¶Department of Surgery, Section of Cardiovascular Perfusion, University of Connecticut School of Medicine, Farmington, Connecticut; and ‖Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut.
Submitted for consideration October 2016; accepted for publication in revised form April 2017.
This study was supported by departmental funds.
Disclosure: Dr. Schonberger reports that he holds an equity position in Johnson & Johnson, a publicly traded, diversified manufacturer of healthcare products.
Correspondence: Robert B. Schonberger, Yale School of Medicine; Department of Anesthesiology, 333 Cedar Street–TMP3, New Haven, Connecticut 06520. Email: email@example.com.