title: The use of pulse pressure variation and stroke volume variation in spontaneously breathing patients to assess dynamic arterial elastance and to predict arterial pressure response to fluid administration.
abstract: BACKGROUND
  Dynamic arterial elastance (Eadyn), defined as the pulse pressure variation (PPV) to stroke volume variation (SVV) ratio, has been suggested as a predictor of the arterial pressure response to fluid administration. In this study, we assessed the effectiveness of Eadyn to predict the arterial blood pressure response to a fluid challenge (FC) in preload-dependent, spontaneously breathing patients.
  
  
  METHODS
  Patients admitted postoperatively and monitored with the Nexfin monitor (BMEYE, Amsterdam, The Netherlands) were enrolled in the study. Patients were included in the analysis if they were spontaneously breathing and had an increase in cardiac output ≥10% during an FC. Patients were classified according to the increase in mean arterial blood pressure (MAP) after FC into MAP-responders (MAP increase ≥10%) and MAP-nonresponders (MAP increase <10%). Eadyn was continuously calculated from the PPV and SVV values obtained from the monitor.
  
  
  RESULTS
  Thirty-four FCs from 26 patients were studied. Seventeen FCs (50%) induced a positive MAP response. Preinfusion Eadyn was significantly higher in MAP-responders (1.39 ± 0.41 vs 0.85 ± 0.23; P = 0.0001). Preinfusion Eadyn predicted a positive MAP response to FC with an area under the receiver-operating characteristic curve of 0.92 ± 0.04 of standard error (95% confidence interval, 0.78-0.99; P < 0.0001). A preinfusion Eadyn value ≥1.06 (gray zone: 0.9-1.15) discriminated MAP-responders with a sensitivity and specificity of 88.2% (approximate 95% confidence interval, 64%-99%), respectively.
  
  
  CONCLUSIONS
  Noninvasive Eadyn, defined as the PPV to SVV ratio, predicted the arterial blood pressure increase to fluid administration in spontaneously breathing, preload-dependent patients.
authors.affiliation: From the Department of Intensive Care Medicine, St. George's Healthcare NHS Trust and St. George's University of London, London, United Kingdom; and Servicio de Cuidados Intensivos y Urgencias, Hospital SAS de Jerez, Jerez de la Frontera, Spain.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cecconi
authors.forename: M Ignacio
authors.initials: MI
authors.lastname: Monge García
authors.forename: Manuel
authors.initials: M
authors.lastname: Gracia Romero
authors.forename: Johannes
authors.initials: J
authors.lastname: Mellinghoff
authors.forename: Francesca
authors.initials: F
authors.lastname: Caliandro
authors.forename: Robert Michael
authors.initials: RM
authors.lastname: Grounds
authors.forename: Andrew
authors.initials: A
authors.lastname: Rhodes
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D013318:Stroke Volume / Q000502:physiology*; D059289:Vascular Stiffness / Q000502:physiology*