title: Can a central blood volume deficit be detected by systolic pressure variation during spontaneous breathing?
abstract: Whether during spontaneous breathing arterial pressure variations (APV) can detect a volume deficit is not established. We hypothesized that amplification of intra-thoracic pressure oscillations by breathing through resistors would enhance APV to allow identification of a reduced cardiac output (CO). This study tested that hypothesis in healthy volunteers exposed to central hypovolemia by head-up tilt.
  
  
  
  Thirteen healthy volunteers were exposed to central hypovolemia by 45° head-up tilt while breathing through a facemask with 7.5 cmH2O inspiratory and/or expiratory resistors. A brachial arterial catheter was used to measure blood pressure and thus systolic pressure variation (SPV), pulse pressure variation and stroke volume variation . Pulse contour analysis determined stroke volume (SV) and CO and we evaluated whether APV could detect a 10 % decrease in CO.
  
  
  
  During head-up tilt SV decreased form 91 (±46) to 55 (±24) mL (mean ± SD) and CO from 5.8 (±2.9) to 4.0 (±1.8) L/min (p < 0.05), while heart rate increased (65 (±11) to 75 (±13) bpm; P < 0.05). Systolic pressure decreased from 127 (±14) to 121 (±13) mmHg during head-up tilt, while SPV tended to increase (from 21 (±15)% to 30 (±13)%). Yet during head-up tilt, a SPV ≥ 37 % predicted a decrease in CO ≥ 10 % with a sensitivity and specificity of 78 % and 100 %, respectively.
  
  
  
  In spontaneously breathing healthy volunteers combined inspiratory and expiratory resistors enhance SPV during head-up tilted induced central hypovolemia and allow identifying a 10 % reduction in CO. Applying inspiratory and expiratory resistors might detect a fluid deficit in spontaneously breathing patients.
  
  
  
  ClinicalTrials.gov number NCT02549482 Registered September 10(th) 2015.
authors: Department of Anesthesiology and Intensive Care Medicine, Aalborg University Hospital, Hobrovej 18-21, DK-9000, Aalborg, Denmark. mida@rn.dk.
authors: Michael
authors: M
authors: Dahl
authors: Department of Anesthesiology and Intensive Care Medicine, Aalborg University Hospital, Hobrovej 18-21, DK-9000, Aalborg, Denmark.
authors: Chris
authors: C
authors: Hayes
authors: Department of Anesthesiology and Intensive Care Medicine, Aalborg University Hospital, Hobrovej 18-21, DK-9000, Aalborg, Denmark.
authors: Bodil
authors: B
authors: Steen Rasmussen
authors: Hedenstierna laboratory, Section of Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, ANIVA Ing. 70, 1. tv., S-75643, Uppsala, Sweden.
authors: Anders
authors: A
authors: Larsson
authors: Department of Anesthesiology, The Copenhagen Muscle Research Center Rigshospitalet 2043, University of Copenhagen, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
authors: Niels H
authors: NH
authors: Secher
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D020896:Hypovolemia / Q000175:diagnosis*; D008297:Male; D011187:Posture / Q000502:physiology; D012119:Respiration; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology; D055815:Young Adult
keywords: Fluid responsiveness; Head-up tilt; Pulse pressure variation; Spontaneous breathing; Stroke volume variation; Systolic pressure variation