Dynamic filling index: a novel parameter to monitor circulatory filling during minimized extracorporeal bypass

Antoine P. Simons, Koen D. Reesink, Marcus D. Lancé, Frederik H. van der Veen, Dick S. de Jong, Patrick W. Weerwind, Jos G. Maessen

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Objective: To evaluate the dynamic filling index, a novel parameter to monitor changes in venous return and drainable volume, in circulatory assisted patients. Minimized extracorporeal bypass systems lack volume buffering capacity, demanding tight control of drainable volume to maintain bypass flow. Therefore, with patients on minimized bypass quantitative assessment of venous drainable volume is crucial. Methods: In seven patients undergoing coronary artery bypass grafting using minimized extracorporeal bypass we utilized luxation of the heart to induce a reduction in venous return. The speed of the centrifugal pump was transiently and periodically reduced to monitor resultant changes in bypass flow. The dynamic filling index, a measure of drainable volume, was calculated as Δflow/Δspeed. Results: With luxation, the dynamic filling index was significantly reduced (from 2.4 ± 0.2 to 2.0 ± 0.2 ml/rotation, p = 0.001; 95% confidence interval of mean difference: 0.23-0.46 ml/rotation), whereas routinely recorded parameters, like bypass flow, pump inlet and arterial line pressure, did not change significantly. The intra-measurement reproducibility for the dynamic filling index was 0.5 ml/rotation (20% of the mean), suggesting good potential for this parameter to monitor on-pump venous return in patients. Conclusion: The dynamic filling index can detect small changes in venous return and drainable volume which remain unrevealed by routinely recorded parameters. This index could be a valuable tool to monitor and control circulatory filling in individual patients supported by minimized extracorporeal bypass.

Original languageEnglish
Pages (from-to)330-334
Number of pages5
JournalEuropean Journal of Cardio-thoracic Surgery
Issue number2
Publication statusPublished - Aug 2009
Externally publishedYes


  • Blood volume
  • Cardiopulmonary bypass
  • Centrifugal pump
  • Minimized extracorporeal bypass
  • Venous drainage
  • Venous return


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