key: cord-0783371-qlxfu0vy
authors: Zante, Bjoern; Berger, David C.; Schefold, Joerg C.; Bachmann, Kaspar F.
title: Dissociation of arterial oxygen saturation and oxygen delivery in VV-ECMO: the trend is your friend
date: 2020-07-03
journal: J Cardiothorac Vasc Anesth
DOI: 10.1053/j.jvca.2020.06.084
sha: 6ad5007d42914bf2edcf9ec2fc0f9f90f31296c0
doc_id: 783371
cord_uid: qlxfu0vy

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In VV-ECMO treated patients, arterial oxygen saturation (SaO 2 ) is dependent on VV-ECMO (blood) flow to cardiac output (CO) ratio and pulmonary shunt. Changes in CO impact on the ratio of fully oxygenated blood from VV-ECMO and desaturated blood from the body due to pulmonary shunt and oxygen consumption. Hence, if CO increases at stable VV-ECMO flow and pulmonary function, the admixture of less oxygenated blood increases and SaO 2 decreases. Nevertheless, this leads to an improvement in where CO is approximately twice as high as VV-ECMO flow (VV-ECMO to CO ratio about 1:2.18, Figure 1B ). Because of this nadir, increased SaO 2 may not indicate increased DaO 2 and left from the nadir, DaO 2 will inevitably fall despite increasing SaO 2 .

On the right side from the nadir, DaO 2 rises in parallel with increasing SaO 2 , mainly due to increased cardiac output ( Figure 1B) . The position of the nadir SaO 2 varies with VV-ECMO flow, CO and their ratio, and further with recirculation rate, and pulmonary shunt.

This dissociation between SaO 2 and DaO 2 was previously shown for beta-blocker 4 therapy in VV-ECMO treatment, which may improve arterial oxygenation but reduces CO and DaO 2 [3] .

In conclusion, increased SaO 2 may be a sign of decreased CO (approaching the ECMO flow rate) in VV-ECMO treatment and may therefore have adverse effects on DaO 2 . The recognition of this underlying physiological process seems paramount in order to optimize oxygen delivery in VV-ECMO treated critically ill patients. 

A mathematical model of oxygenation during venovenous extracorporeal membrane oxygenation support

L (2012) β-Blockers to Optimize Peripheral Oxygenation During Extracorporeal Membrane Oxygenation: A Case Series

Arrow 2: DO 2 =713mL/min, CO 6.5l/min, SpO 2 =92%, Hb=8.9g/dl; Arrow 3: DO 2 =792mL/min, CO=8.2l/min, SpO 2 =81%, Hb=8.9g/dl (dissolved oxgyen is neglected and SpO 2 instead of SaO 2 was used for approximation

SvO 2 (mixed venous saturation before VV-ECMO flow admixture) at stable VV-ECMO flow

Oxygen consumption: 250 ml/min; hemoglobin: 8 g/dl