Accounting for respiration is necessary to reliably infer granger causality from cardiovascular variability series

Alberto Porta, Tito Bassani, Vlasta Bari, Gian D. Pinna, Roberto Maestri, Stefano Guzzetti

Research output: Contribution to journalArticlepeer-review


This study was designed to demonstrate the need of accounting for respiration (R) when causality between heart period (HP) and systolic arterial pressure (SAP) is under scrutiny. Simulations generated according to a bivariate autoregressive closed-loop model were utilized to assess how causality changes as a function of the model parameters. An exogenous (X) signal was added to the bivariate autoregressive closed-loop model to evaluate the bias on causality induced when the X source was disregarded. Causality was assessed in the time domain according to a predictability improvement approach (i.e., Granger causality). HP and SAP variability series were recorded with R in 19 healthy subjects during spontaneous and controlled breathing at 10, 15, and 20 breaths/min. Simulations proved the importance of accounting for X signals. During spontaneous breathing, assessing causality without taking into consideration R leads to a significantly larger percentage of closed-loop interactions and a smaller fraction of unidirectional causality from HP to SAP. This finding was confirmed during paced breathing and it was independent of the breathing rate. These results suggest that the role of baroreflex cannot be correctly assessed without accounting for R.

Original languageEnglish
Article number6108354
Pages (from-to)832-841
Number of pages10
JournalIEEE Transactions on Biomedical Engineering
Issue number3
Publication statusPublished - Mar 2012


  • Arterial pressure variability
  • autonomic nervous system
  • baroreflex
  • cardiovascular control
  • Granger causality
  • heart rate variability
  • respiratory sinus arrhythmia

ASJC Scopus subject areas

  • Biomedical Engineering

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