SESSION TITLE: Cardiovascular Disease Posters I
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM
PURPOSE: Patients in cardiac arrest with an initial rhythm of asystole or pulseless electrical activity (PEA) have a poor rate of survival to hospital discharge despite adequate CPR. Manual chest compressions are estimated to provide 30% of normal cardiac output. Support with veno-arterial extracorporeal membrane oxygenation (VA ECMO) has been successfully used in patients experiencing sudden cardiac arrest. VA ECMO is performed with large bore cannulae in the venous and arterial vasculature with targeted flows of 50 to 70 ml/kg/min. We hypothesized that lower flow rates provide coronary perfusion pressure (CPP) comparable to CPR in a porcine model of minimal cardiac output which may then allow for the use of smaller cannulae resulting in wider access to ECMO support.
METHODS: Five 50 kg adult pigs were intubated and sedated with inhaled isoflurane. A 21 Fr 50 cm long Medtronic cannula was inserted via the femoral vein into the inferior vena cava to the level of the diaphragm. A 15 Fr 18 cm long Medtronic arterial cannula was inserted into the femoral artery. Pressures in the aortic arch and right atrium were measured with Millar catheters with coronary perfusion pressure (CPP) calculated as the difference. Rapid pacing was triggered via a transcutaneous pacing wire inserted into the right ventricle. After onset of rapid pacing, ECMO was initiated with a Medtronic 550 Console and Maquet adult oxygenator with pump speeds gradually increased from 1500 rpm to higher speeds until vessel collapse was encountered with simultaneous measurement of flow and CPP.
RESULTS: Rapid pacing was performed at a rate of 240 bpm which induced minimal cardiac output as evidenced by the lack of deflections in the aortic pressure tracing. ECMO mechanical support was started with an initial pump speed of 1500 bpm and a flow rate of 25 ml/kg/min and maintenance of a CPP of 40 mm Hg. The pump speed was gradually increased until suction events at 4000 rpm resulted in reduced flow rates. Prior to vessel collapse, peak flow of 80 ml/kg/min was produced. Calculated CPP gradually increased as flow increased from 40 ml/kg/min to 60 ml/kg/min and then remained roughly constant even as flow rates further increased.
CONCLUSIONS: Low flow VA ECMO support is able to provide comparable CPPs to CPR which may permit the use of smaller access cannulae resulting in wider access to ECMO support during cardiac arrest.
CLINICAL IMPLICATIONS: Increased use of ECMO utilizing smaller vascular cannulae may lead to increased survival from sudden cardiac arrest.
DISCLOSURE: The following authors have nothing to disclose: Steven Keller, Sarah Fink, Henry Halperin, Muz Zviman
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