Dynamic functional residual capacity can be estimated using a stress-strain approach

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dc.contributor.authorSundaresan, A.
dc.contributor.authorChase, Geoff
dc.contributor.authorHann, C.E.
dc.contributor.authorShaw, Geoff
dc.date.accessioned2012-02-22T23:10:06Z
dc.date.available2012-02-22T23:10:06Z
dc.date.issued2011en
dc.descriptionInvited. Available online 9 June 2010.en
dc.description.abstractBackground Acute Respiratory Distress Syndrome (ARDS) results in collapse of alveolar units and loss of lung volume at the end of expiration. Mechanical ventilation is used to treat patients with ARDS or Acute Lung Injury (ALI), with the end objective being to increase the dynamic functional residual capacity (dFRC), and thus increasing overall functional residual capacity (FRC). Simple methods to estimate dFRC at a given positive end expiratory pressure (PEEP) level in patients with ARDS/ALI currently does not exist. Current viable methods are time-consuming and relatively invasive. Methods Previous studies have found a constant linear relationship between the global stress and strain in the lung independent of lung condition. This study utilizes the constant stress–strain ratio and an individual patient's volume responsiveness to PEEP to estimate dFRC at any level of PEEP. The estimation model identifies two global parameters to estimate a patient specific dFRC, ß and mß. The parameter ß captures physiological parameters of FRC, lung and respiratory elastance and varies depending on the PEEP level used, and mß is the gradient of ß vs. PEEP. Results dFRC was estimated at different PEEP values and compared to the measured dFRC using retrospective data from 12 different patients with different levels of lung injury. The median percentage error is 18% (IQR: 6.49) for PEEP = 5 cm H2O, 10% (IQR: 9.18) for PEEP = 7 cm H2O, 28% (IQR: 12.33) for PEEP = 10 cm H2O, 3% (IQR: 2.10) for PEEP = 12 cm H2O and 10% (IQR: 9.11) for PEEP = 15 cm H2O. The results were further validated using a cross-correlation (N = 100,000). Linear regression between the estimated and measured dFRC with a median R2 of 0.948 (IQR: 0.915, 0.968; 90% CI: 0.814, 0.984) over the N = 100,000 cross-validation tests. Conclusions The results suggest that a model based approach to estimating dFRC may be viable in a clinical scenario without any interruption to ventilation and can thus provide an alternative to measuring dFRC by disconnecting the patient from the ventilator or by using advanced ventilators. The overall results provide a means of estimating dFRC at any PEEP levels. Although reasonable clinical accuracy is limited to the linear region of the static PV curve, the model can evaluate the impact of changes in PEEP or other mechanical ventilation settings.en
dc.identifier.citationSundaresan, A., Chase, J.G., Hann, C.E., Shaw, G.M. (2011) Dynamic functional residual capacity can be estimated using a stress-strain approach. Computer Methods and Programs in Biomedicine, 101(2), pp. 135-143.en
dc.identifier.doihttps://doi.org/10.1016/j.cmpb.2010.05.005
dc.identifier.issn0169-2607
dc.identifier.urihttp://hdl.handle.net/10092/6313
dc.language.isoen
dc.publisherUniversity of Canterbury. Electrical and Computer Engineeringen
dc.publisherUniversity of Canterbury. Mechanical Engineeringen
dc.rights.urihttps://hdl.handle.net/10092/17651en
dc.subjectMechanical ventilationen
dc.subjectFunctional residual capacityen
dc.subjectMechanical stressen
dc.subjectPEEPen
dc.subjectModel based methodsen
dc.subject.anzsrcField of Research::09 - Engineering::0913 - Mechanical Engineeringen
dc.subject.anzsrcField of Research::11 - Medical and Health Sciences::1102 - Cardiovascular Medicine and Haematologyen
dc.titleDynamic functional residual capacity can be estimated using a stress-strain approachen
dc.typeJournal Article
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