Systolic time intervals vs invasive predictors of fluid responsiveness after coronary artery bypass surgery

Annemieke Smorenberg, Erik J. Lust, Albertus Beishuizen, Jan H. Meijer, Ruud M. Verdaasdonk, A. B.Johan Groeneveld*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)


OBJECTIVES: 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.

Original languageEnglish
Article numberezt108
Pages (from-to)891-897
Number of pages7
JournalEuropean Journal of Cardio-thoracic Surgery
Issue number5
Publication statusPublished - 1 Nov 2013
Externally publishedYes


  • Fluid responsiveness
  • Hypovolaemia
  • Impendance cardiography
  • Initial systolic time interval
  • Preejection period


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