title: Systolic time intervals vs invasive predictors of fluid responsiveness after coronary artery bypass surgery.
abstract: OBJECTIVE
  Haemodynamic parameters for predicting fluid responsiveness in intensive care patients are invasive, technically challenging or not universally applicable. We compared the initial systolic time interval (ISTI), a non-invasive measure of the time interval between the electrical and mechanical activities of the heart measured by impedance cardiography, with invasively measured haemodynamic parameters in predicting fluid responsiveness after cardiac surgery.
  
  
  METHODS
  Thirty-two clinically hypovolemic patients admitted to the intensive care unit after coronary artery bypass surgery received 500 ml of gelatine solution in two volume loading steps of 250 ml at an infusion rate of 1000 ml/h. Haemodynamic and biochemical measurements were done at baseline and 15 min after each volume loading step with continuous recording of the impedance cardiogram and electrocardiogram.
  
  
  RESULTS
  Forty-four percentage (n = 14) of patients showed a stroke volume (SV) index increase >10%. ISTI predicted fluid responsiveness with an optimum threshold of >153 ms (P = 0.023) and a sensitivity of 71% and specificity of 78%. The predictive values of ISTI did not differ from those of arterial pressure or SV at baseline. A decrease of ISTI of ≥8.3 ms predicted fluid responsiveness with the highest positive predictive value (88%, P = 0.004) among the variables, and absence thereof virtually excluded fluid responsiveness (specificity 94%).
  
  
  CONCLUSIONS
  Non-invasively measured ISTI is able to predict and monitor fluid responsiveness after cardiac surgery non-inferiorly to invasively measured haemodynamic indices.
authors.affiliation: Department of Intensive Care, VU University Medical Center, Amsterdam, Netherlands.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Smorenberg
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Lust
authors.forename: Albertus
authors.initials: A
authors.lastname: Beishuizen
authors.forename: Jan H
authors.initials: JH
authors.lastname: Meijer
authors.forename: Ruud M
authors.initials: RM
authors.lastname: Verdaasdonk
authors.forename: A B Johan
authors.initials: AB
authors.lastname: Groeneveld
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D001802:Blood Substitutes / Q000627:therapeutic use; D002307:Cardiography, Impedance; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004562:Electrocardiography; D005260:Female; D005440:Fluid Therapy; D006439:Hemodynamics; D006801:Humans; D020896:Hypovolemia / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D018709:Statistics, Nonparametric; D013318:Stroke Volume / Q000502:physiology
chemical_list: D001802:Blood Substitutes
keywords: Fluid responsiveness; Hypovolaemia; Impendance cardiography; Initial systolic time interval; Preejection period