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Towards goal-directed perfusion - Part I: Developing physiology-inspired mathematical framework using high-resolution

Mansour T A Sharabiani1, Alireza S Mahani2, Richard W Issitt3,4,5

  • 1School of Public Health, Imperial College, London, UK.

Perfusion
|September 10, 2025
PubMed

Insights

A new model, GARIX, accurately predicts oxygen extraction ratio during paediatric cardiopulmonary bypass. This advances understanding of oxygen dynamics and supports intelligent perfusion control in young patients.

Area of Science:

  • Physiology
  • Biomedical Engineering
  • Data Science

Background:

  • Understanding intraoperative oxygen demand during paediatric cardiopulmonary bypass (CPB) is crucial but challenging.
  • Existing models for oxygen demand often oversimplify physiological relationships, particularly temperature dependence.
  • Paediatric populations present unique physiological dynamics during CPB that require specialized modeling.

Purpose of the Study:

  • To develop and validate a novel, high-resolution model (GARIX) for predicting oxygen extraction ratio (OER) minute-by-minute.
  • To capture the complex, dynamic interplay of factors influencing oxygenation during paediatric CPB.
  • To provide a foundation for improved real-time monitoring and perfusion control strategies.

Main Methods:

  • Developed GARIX, a Global AutoRegressive Integrated model with eXogenous variables and an equilibrium force, incorporating autoregressive, exogenous, and equilibrium terms.
  • Utilized high-resolution intraoperative data from 293 paediatric CPB procedures (20,443 minutes).
  • Evaluated model performance using K-fold cross-validation, simulations, and bootstrap confidence intervals, comparing against a baseline model (bGARIX).

Main Results:

  • GARIX accurately reproduced physiologically plausible oxygen extraction ratio dynamics.
  • The model identified significant nonlinear relationships between temperature, age, weight, and oxygen demand.
  • Analysis revealed slower OER adaptation to changes in cardiac index and hemoglobin, but faster adaptation to temperature shifts.

Conclusions:

  • GARIX provides an interpretable, physiology-aligned model for paediatric CPB oxygenation dynamics.
  • The model enables estimation of dynamic responses and latent oxygen demand, enhancing clinical insights.
  • GARIX serves as a foundation for developing advanced real-time monitoring and intelligent perfusion control systems.

Keywords:
cardiopulmonary bypassmathematical modellingoxygen deliveryoxygen extraction ratiosystem dynamicsvan’t Hoff

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