title: Mini-fluid challenge can predict arterial pressure response to volume expansion in spontaneously breathing patients under spinal anaesthesia.
abstract: BACKGROUND
  The objective of this study was to test whether stroke volume (SV) variations in response to a fixed mini-fluid challenge (ΔSV100) measured by impedance cardiography (ICG) could predict an increase in arterial pressure with volume expansion in spontaneously breathing patients under spinal anaesthesia.
  
  
  METHODS
  Thirty-four patients, monitored by ICG who required intravenous fluid to expand their circulating volume during surgery under spinal anaesthesia, were studied. Haemodynamic variables and bioimpedance indices (blood pressure, SV, cardiac output [CO]) were measured before and after fluid challenge with 100mL of crystalloid, and before/after volume expansion. Responders were defined by ≥15% increase in systolic arterial pressure (SAP) after infusion of 500 mL of crystalloid solution.
  
  
  RESULTS
  SAP increased by ≥15% in 20 (59%) of the 34 patients. SAP, SV, and CO increased and HR decreased only in responders. SV variations in response to mini-fluid challenge and volume expansion differed between patients who showed arterial responsiveness and those in whom SAP did not increase with volume expansion (11.6% [9.1-19.3] versus 2.5% [1.3-7], P<0.001, and 22.4% [11.7-36.6] versus 0.9 [0-5.5], P<0.001, respectively). ΔSV100 predicted an increase of arterial pressure with an area under the receiver operating characteristic (AUC) curve of 0.89 (CI95%: 0.73-0.97, P<0.001). The cut-off was 5%. Baseline SAP and HR were not predictive of arterial responsiveness (P>0.05).
  
  
  CONCLUSIONS
  A ΔSV100 over 5% accurately predicted arterial pressure response to volume expansion during surgery.
authors.affiliation: Anaesthesiology and Critical Care Department, Amiens University Hospital, Place Victor-Pauchet, 80054 Amiens, France; Inserm U1088, Jules-Verne University of Picardy, Chemin du Thil, 80039 Amiens cedex 1, France. Electronic address: guinotpierregregoire@gmail.com.
authors.forename: Pierre-Grégoire
authors.initials: PG
authors.lastname: Guinot
authors.affiliation: Anaesthesiology and Critical Care Department, Amiens University Hospital, Place Victor-Pauchet, 80054 Amiens, France.
authors.forename: Eugénie
authors.initials: E
authors.lastname: Bernard
authors.affiliation: Clinique Sainte-Isabelle, Route d'Amiens, 80100 Abbeville, France.
authors.forename: Kévin
authors.initials: K
authors.lastname: Deleporte
authors.affiliation: Anaesthesiology and Critical Care Department, Amiens University Hospital, Place Victor-Pauchet, 80054 Amiens, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Petiot
authors.affiliation: Anaesthesiology and Critical Care Department, Amiens University Hospital, Place Victor-Pauchet, 80054 Amiens, France; Inserm U1088, Jules-Verne University of Picardy, Chemin du Thil, 80039 Amiens cedex 1, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Dupont
authors.affiliation: Anaesthesiology and Critical Care Department, Amiens University Hospital, Place Victor-Pauchet, 80054 Amiens, France; Inserm U1088, Jules-Verne University of Picardy, Chemin du Thil, 80039 Amiens cedex 1, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lorne
mesh_terms: D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal / Q000379:methods*; D062186:Arterial Pressure / Q000187:drug effects*; D001810:Blood Volume / Q000187:drug effects*; D002307:Cardiography, Impedance; D000077324:Crystalloid Solutions; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007552:Isotonic Solutions / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D010952:Plasma Substitutes / Q000627:therapeutic use*; D011446:Prospective Studies; D012372:ROC Curve; D012119:Respiration
chemical_list: D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes
keywords: Arterial hypotension; Cardiac output; Impedancemetry; Spinal anaesthesia