title: Dynamic arterial elastance as a predictor of arterial pressure response to fluid administration: a validation study.
abstract: BACKGROUND
  Functional assessment of arterial load by dynamic arterial elastance (Eadyn), defined as the ratio between pulse pressure variation (PPV) and stroke volume variation (SVV), has recently been shown to predict the arterial pressure response to volume expansion (VE) in hypotensive, preload-dependent patients. However, because both SVV and PPV were obtained from pulse pressure analysis, a mathematical coupling factor could not be excluded. We therefore designed this study to confirm whether Eadyn, obtained from two independent signals, allows the prediction of arterial pressure response to VE in fluid-responsive patients.
  
  
  METHODS
  We analyzed the response of arterial pressure to an intravenous infusion of 500 ml of normal saline in 53 mechanically ventilated patients with acute circulatory failure and preserved preload dependence. Eadyn was calculated as the simultaneous ratio between PPV (obtained from an arterial line) and SVV (obtained by esophageal Doppler imaging). A total of 80 fluid challenges were performed (median, 1.5 per patient; interquartile range, 1 to 2). Patients were classified according to the increase in mean arterial pressure (MAP) after fluid administration in pressure responders (≥ 10%) and non-responders.
  
  
  RESULTS
  Thirty-three fluid challenges (41.2%) significantly increased MAP. At baseline, Eadyn was higher in pressure responders (1.04 ± 0.28 versus 0.60 ± 0.14; P < 0.0001). Preinfusion Eadyn was related to changes in MAP after fluid administration (R (2) = 0.60; P < 0.0001). At baseline, Eadyn predicted the arterial pressure increase to volume expansion (area under the receiver operating characteristic curve, 0.94; 95% confidence interval (CI): 0.86 to 0.98; P < 0.0001). A preinfusion Eadyn value ≥ 0.73 (gray zone: 0.72 to 0.88) discriminated pressure responder patients with a sensitivity of 90.9% (95% CI: 75.6 to 98.1%) and a specificity of 91.5% (95% CI: 79.6 to 97.6%).
  
  
  CONCLUSIONS
  Functional assessment of arterial load by Eadyn, obtained from two independent signals, enabled the prediction of arterial pressure response to fluid administration in mechanically ventilated, preload-dependent patients with acute circulatory failure.
authors.affiliation: Servicio de Cuidados Intensivos y Urgencias, Hospital SAS de Jerez, C/Circunvalación s/n, 11407, Jerez de la Frontera, Spain. ignaciomonge@gmail.com.|Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Blackshaw Road, Tooting, London, SW17 0QT, UK. ignaciomonge@gmail.com.
authors.forename: Manuel Ignacio Monge
authors.initials: MI
authors.lastname: García
authors.affiliation: Servicio de Cuidados Intensivos y Urgencias, Hospital SAS de Jerez, C/Circunvalación s/n, 11407, Jerez de la Frontera, Spain. manuel.graciaromero@hotmail.com.
authors.forename: Manuel Gracia
authors.initials: MG
authors.lastname: Romero
authors.affiliation: Servicio de Cuidados Intensivos y Urgencias, Hospital SAS de Jerez, C/Circunvalación s/n, 11407, Jerez de la Frontera, Spain. anselgil@gmail.com.
authors.forename: Anselmo Gil
authors.initials: AG
authors.lastname: Cano
authors.affiliation: Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Blackshaw Road, Tooting, London, SW17 0QT, UK. hollmann.aya@nhs.net.
authors.forename: Hollmann D
authors.initials: HD
authors.lastname: Aya
authors.affiliation: Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Blackshaw Road, Tooting, London, SW17 0QT, UK. andyr@sgul.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Rhodes
authors.affiliation: Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Blackshaw Road, Tooting, London, SW17 0QT, UK. michael.grounds@stgeorges.nhs.uk.
authors.forename: Robert Michael
authors.initials: RM
authors.lastname: Grounds
authors.affiliation: Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Blackshaw Road, Tooting, London, SW17 0QT, UK. m.cecconi@nhs.net.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cecconi
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D005440:Fluid Therapy / Q000379:methods* / Q000639:trends; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods* / Q000639:trends; D013318:Stroke Volume / Q000502:physiology*