Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a method used for the treatment most severe cases of decompensated heart failure. The purpose of this study was to evaluate the risk of the formation of microembolisms during VA-ECMO-based therapy. Heart failure was induced with simultaneous detection of microembolisms and the measurement of blood flow rate in the common carotid artery (CCA) without VA-ECMO (0 l/min) and at the VA-ECMO blood flow rate of 1, 2, 3 and 4 l/min. If embolisms for VA-ECMO 0 l/min and the individual regimes for VA-ECMO 1, 2, 3, 4 l/min are compared, a higher VA-ECMO flow rate is accompanied by a higher number of
microembolisms. The final microembolism value at 16 min was for the VA-ECMO flow rate of 0 l/min 0.0 (0, 1), VA-ECMO l/min 7.5 (4, 19), VA-ECMO 2 l/min 12.5 (4, 26), VA-ECMO 3 l/min, 21.0 (18, 57) and VA-ECMO 4 l/min, 27.5 (21, 64). Such a comparison is statistically significant if VA-ECMO 0 vs. 4 l/min p<0.0001, 0 vs. 3 l/min p<0.01 and 1 vs. 4 l/min p<0.01 are compared. The results confirm that high VA-ECMO flow rates pose a risk with regards to the formation of a significantly higher number of microemboli in the blood circulation and that an increase in blood flow rates in the CCA corresponds to changes in the VA-ECMO flow rates.
This article engages critically with the theory of expression proposed by Mitchell S. Green in his Self-Expression (2007). In this book, Green argues that expressions are signals designed to convey information about mental states. By putting pressure on one of the examples Green uses in his book, I will challenge this thesis. I will then deepen this challenge by developing a contrast between two philosophical perspectives on expression, which I name the 'instrumental' and the 'descriptive'. I take Green’s theory of expression to be an exemplar of the instrumental perspective. Expression, in the instrumental perspective, is a means for transmitting information about mental states from organism to organism. The descriptive perspective I articulate with the help of Maurice Merleau-Ponty and Ludwig Wittgenstein. On the descriptive view, expression is (at least a part of) an answer to the question what it is so much as to have mental states and a living body. I suggest at the end of the article that if we remain within the instrumental perspective, we will not be able to use expression to satisfactorily answer this question.