title: A mathematical model approach quantifying patients' response to changes in mechanical ventilation: Evaluation in pressure support.
abstract: OBJECTIVE
  This article evaluates how mathematical models of gas exchange, blood acid-base status, chemical respiratory drive, and muscle function can describe the respiratory response of spontaneously breathing patients to different levels of pressure support.
  
  
  METHODS
  The models were evaluated with data from 12 patients ventilated in pressure support ventilation. Models were tuned with clinical data (arterial blood gas measurement, ventilation, and respiratory gas fractions of O2 and CO2) to describe each patient at the clinical level of pressure support. Patients were ventilated up to 5 different pressure support levels, for 15 minutes at each level to achieve steady-state conditions. Model-simulated values of respiratory frequency (fR), arterial pH (pHa), and end-tidal CO2 (FeCO2) were compared to measured values at each pressure support level.
  
  
  RESULTS
  Model simulations compared well to measured data with Bland-Altman bias and limits of agreement of fR of 0.7 ± 2.2 per minute, pHa of -0.0007 ± 0.019, and FeCO2 of -0.001 ± 0.003.
  
  
  CONCLUSIONS
  The models describe patients' fR, pHa, and FeCO2 response to changes in pressure support with low bias and narrow limits of agreement.
authors.affiliation: Respiratory and Critical Care Group (RCARE), Center for Model-based Medical Decision Support, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Larraza
authors.affiliation: Department of Anaesthesia and Intensive Care, Regions Hospital Herning, Herning, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Dey
authors.affiliation: Respiratory and Critical Care Group (RCARE), Center for Model-based Medical Decision Support, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: D S
authors.initials: DS
authors.lastname: Karbing
authors.affiliation: Mermaid Care A/S, Nørresundby, Denmark.
authors.forename: J B
authors.initials: JB
authors.lastname: Jensen
authors.affiliation: Department of Anaesthesia and Intensive Care, Regions Hospital Herning, Herning, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Nygaard
authors.affiliation: Department of Anaesthesia and Intensive Care, Regions Hospital Herning, Herning, Denmark.
authors.forename: R
authors.initials: R
authors.lastname: Winding
authors.affiliation: Respiratory and Critical Care Group (RCARE), Center for Model-based Medical Decision Support, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark. Electronic address: sr@hst.aau.dk.
authors.forename: S E
authors.initials: SE
authors.lastname: Rees
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000379:methods; D016638:Critical Illness / Q000628:therapy*; D006801:Humans; D008875:Middle Aged; D008962:Models, Theoretical; D011175:Positive-Pressure Respiration; D011659:Pulmonary Gas Exchange; D015203:Reproducibility of Results; D012119:Respiration; D012121:Respiration, Artificial; D015656:Respiratory Mechanics; D012132:Respiratory Muscles / Q000503:physiopathology*
keywords: Blood acid-base status; Chemoreflex respiratory control; Pressure-support ventilation; Pulmonary gas-exchange; Spontaneous breathing