Comparison of closed-loop and open-loop model in the assessment of cardiopulmonary and baroreflex gains

Reijo Takalo, J. Philip Saul, Ilkka Korhonen

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)


Objectives: Both open- and closed-loop models of beat-to-beat cardiovascular control have been suggested. We tested whether the modelling yields different results with real data while assessing cardiopulmonary and baroreflex gains.

Methods: Two autoregressive models are described to resolve causal relationships between systolic blood pressure (SBP), RR-interval (RRI) and instantaneous lung volume (ILV): a closed-loop model which takes into account both the RRI changes induced by changes in SBP and the SBP changes mediated by changes in RRI, and an open-loop model which does not have a link from RRI to SBP. The performance of the models was compared in 14 healthy men in supine and standing positions under control conditions and under conditions of β-sympathetic and parasympathetic pharmacological blockades. Transfer function gains were computed from ILV to RRI (cardiopulmonary gain) and from SBP to RRI (baroreflex gain). The measurements were done under controlled random-interval breathing.

Results: The gains identified by the open-loop model tended to be higher than those from the closed-loop model, but the differences did not reach statistical significance. Importantly, the two models discriminated the changes in transfer gains between different interventions equally well.

Conclusions: Because the interactions between SBP and RRI occur physiologically in a closed-loop condition, the closed-loop model provides a theoretical advantage over the open-loop model. However, in practise, it seems to be little reason to select one over the other due to methodological errors when estimating cardiopulmonary or baroreflex transfer gains.

Original languageEnglish
Pages (from-to)296-301
JournalMethods of Information in Medicine
Issue number3
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed


  • Multivariate
  • Modelling
  • Baroreceptors
  • Blood pressure
  • Heart rate


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