Pitfalls in the assessment of ventriculo-arterial coupling from peripheral waveform analysis in septic shock. Comment on Br J Anaesth 2020; 125: 1018–1024
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Tags: Arterial waveform, VA coupling
Abstract
Notes
“the dicrotic notch on a peripheral arterial wave is often considered a surrogate of the ../../Knowledge/Medicine/aortic incisura, but more than mere terminology separates the two. The incisura and the following dicrotic wave reflect, respectively, aortic valve closure and rebound of the aortic root at the termination of retrograde flow; they both become less evident distally from the ascending aorta and disappear on arterial signals recorded 35-40 cm from it. The appearance of one (sometimes multiple) late dicrotic notch and wave on peripheral arterial waveforms may not represent aortic valve closure, but rather the impact of backward waves reflected at the arterio-arteriolar junction. In young healthy individuals, the timing of wave reflection almost coincides with the beginning of diastole to facilitate coronary perfusion” Go to annotation (Giosa et al., 2021, p. e101)
“The architecture of the arterial tree of the fluid-resuscitated septic shock patient (as in Morelli and colleagues1) has been investigated in animal models and it is characterised by
- peripheral vasodilation,
- aortic wall stiffness with oedema, and
- low compliance of muscular arteries.
In such a deranged arterial tree, propagation of backward waves to the aorta is not predictable from analysis of a peripheral arterial waveform,” Go to annotation (Giosa et al., 2021, p. e101)
“The radial artery is a middle-size muscular artery, and its elasticity is not significantly affected by HR reduction in the high HR range of patients studied by Morelli and colleagues. Increased tone at this level could then coexist with a more pronounced increased elasticity of larger elastic arteries explaining the global decrease in Ea when HR is reduced.” Go to annotation (Giosa et al., 2021, p. e102)
“Ea is, in fact, an overall indicator of afterload, but it does not allow evaluation of its individual components that play a role in wave speed and reflection, such as total peripheral resistance and compliance of muscular and elastic arteries” (Giosa et al., 2021, p. e102)