Pitfalls in the assessment of ventriculo-arterial coupling from peripheral waveform analysis in septic shock. Comment on Br J Anaesth 2020; 125: 1018–1024

Editor—We read with interest the paper by Morelli and colleagues1Morelli A. Romano S.M. Sanfilippo F. et al.Systolic-dicrotic notch pressure difference can identify patients septic shock at risk of cardiovascular decompensation in case heart rate reduction.Br J Anaesth. 2020; 125: 1018-1024Abstract Full Text PDF PubMed Scopus (8) Google Scholar on ability systolic-dicrotic (SDP) to predict response esmolol infusion persistent tachycardia despite 24 h haemodynamic optimisation. The message delivered this post hoc analysis2Morelli Singer M. Ranieri V.M. al.Heart reduction is associated improved arterial elastance shock: a prospective observational study.Intensive Care Med. 2016; 42: 1528-1534Crossref (69) that since ventriculo-arterial (V-A) coupling function both (Ea) contractility (artdP/dtmax), former decreases HR, effects beta-blockade efficiency depend essentially behaviour contractility. On basis, authors divided according artdP/dtmax (preserved vs decreased); they found SDP calculated from peripheral waveform (i.e. radial artery) was only variable capable differentiating two groups before after beta-blockade. This parameter consequently proposed for an overall assessment efficiency. should be congratulated their effort bringing rather complicated concepts such as V-A bedside. We believe adding more physiological point view limitations listed papers1Morelli Scholar,2Morelli may facilitate external applicability findings. While time-dependency elasticity arteries (especially large elastic arteries) not novel finding,3Giannattasio C. Vincenti Failla al.Effects changes distensibility humans.Hypertension. 2003; 253-256Crossref (72) use marker has received little attention so far definitely deserves further discussion. claim ‘…a delayed aortic valve closure indicated lower dicrotic pressure, thus increased difference…’. certainly true level, caution paid when analysing waveforms: wave often considered surrogate incisura, but than mere terminology separates two.4Klein L.W. Shahrrava incisura.Cardiol Rev. 2019; 27: 274-278Crossref (4) incisura following reflect, respectively, rebound root termination retrograde flow; become less evident distally ascending aorta disappear signals recorded 35–40 cm it.4Klein appearance one (sometimes multiple) late waveforms represent closure, impact backward waves reflected arterio-arteriolar junction.4Klein Scholar,5Murray W.B. Foster P.A. pulse wave: information overlooked.J Clin Monit. 1996; 12: 365-377Crossref (143) In young healthy individuals, timing reflection almost coincides beginning diastole coronary perfusion (Fig. 1). Recent animal models have shown effect actually negligible normal conditions.6Wang J.J. O'Brien A.B. Shrive N.G. Parker K.H. Tyberg J.V. Time-domain representation ventricular-arterial windkessel system.Am Physiol Heart Circ Physiol. 284: H1358-H1368Crossref (219) If, however, physical characteristics system are altered aging or disease, change amplitude position,7Westerhof N. Sipkema P. van den Bos G.C. Elzinga G. Forward system.Cardiovasc Res. 1972; 6: 648-656Crossref (485) reaching during systole complexity model6Wang architecture tree fluid-resuscitated patient (as Scholar) been investigated models8Cholley B.P. Lang R.M. Berger D.S. Korcarz Payen D. Shroff S.G. Alterations systemic mechanical properties role fluid resuscitation.Am 1995; 269: H375-H384PubMed it characterised vasodilation, wall stiffness oedema, low compliance muscular arteries. deranged tree, propagation predictable analysis waveform, we conclusions about drawn under these circumstances. suggest ‘…increased reflects afterload, myocardial contractility, both…’ ‘…the proportional degree coupling’.1Morelli were surprised statement widely accepted between mean systolic diastolic better efficiency9Nichols W.W. O'Rourke M.F. McDonald D.A. McDonald's blood flow arteries: theoretic, experimental, clinical principles.in: Arnold Hodder Distributed U.S.A.5th Edn. Oxford University Press, London, New York2005Google Moreover, seem here contradict previous paper: ‘…In subjects value MAP − Pdic very low. By contrast, high …’2Morelli where pressure. Septic indeed decoupling Ea,10Guarracino Ferro B. Bertini Baldassarri R. Pinsky M.R. Ventriculoarterial human shock.Crit Care. 2014; 18: R80Crossref do expect higher condition. However, decrease if improves infusion, opposed what suggest.1Morelli apparent paradox easily explained too many factors play physiology assume simple linear relationship coupling. considering separately might assistance. Indeed, coupling, likely direction suggested first paper2Morelli (the difference, generally accepted9Nichols Scholar), while discussed terms distance aorta. observed who benefit HR another mechanism finding, vascular tone (see Fig. 95Murray Scholar). artery middle-size artery, its significantly affected range studied colleagues.3Giannattasio Increased level could then coexist pronounced larger explaining global Ea reduced.1Morelli is, fact, indicator does allow evaluation individual components speed reflection, total resistance seemingly administration support hypothesis group. reflect baroreflex Although guide beta blockade intriguing, behind complex Further investigation warranted preliminary findings generalised applicable declare no conflicts interest. Systolic-dicrotic tachycardic pharmacological reductionBritish Journal AnaesthesiaVol. 125Issue 6PreviewDuring sepsis, (HR) therapeutic target, identification responders (non-compensatory tachycardia) non-responders (compensatory ‘fixed’ stroke volume [SV]) challenging. tested (SDPdifference), which given discriminating origin tachycardia. Full-Text Open ArchiveAssessment shock. Reply Br Anaesth 2021; 126: e101-2British 127Issue 1PreviewEditor—In letter, Giosa colleagues1 stated valve. As consequence, closure. Based assumption, our SDPdifference (difference [SAP] [DNP]) (V-AC) obtained analysis2 caution.