Modelling mixing within the dead space of the lung improves predictions of functional residual capacity

Chris D. Harrison, Phi Anh Phan, Cathy Zhang, Daniel Geer, Andrew D. Farmery

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Routine estimation of functional residual capacity (FRC) in ventilated patients has been a long held goal, with many methods previously proposed, but none have been used in routine clinical practice. This paper proposes three models for determining FRC using the nitrous oxide concentration from the entire expired breath in order to improve the precision of the estimate. Of the three models proposed, a dead space with two mixing compartments provided the best results, reducing the mean limits of agreement with the FRC measured by whole body plethysmography by up to 41%. This moves away from traditional lung models, which do not account for mixing within the dead space. Compared to literature values for FRC, the results are similar to those obtained using helium dilution and better than the LUFU device (Dräger Medical, Lubeck, Germany), with significantly better limits of agreement compared to plethysmography.
LanguageEnglish
JournalRespiratory Physiology and Neurobiology
Early online date18 Mar 2017
DOIs
Publication statusPublished - 31 Aug 2017

Fingerprint

Functional Residual Capacity
Lung
Plethysmography
Prediction
Modeling
Whole Body Plethysmography
Helium
Dilution
Nitrous Oxide
Germany
Oxides
Entire
Model
Equipment and Supplies
Estimate

Keywords

  • lung function
  • functional residual capacity
  • mathematical modeling
  • parameter estimation
  • alveolar volume
  • airway dead space
  • nitrous oxide
  • mechanical ventilation

Cite this

Harrison, Chris D. ; Phan, Phi Anh ; Zhang, Cathy ; Geer, Daniel ; Farmery, Andrew D. / Modelling mixing within the dead space of the lung improves predictions of functional residual capacity. In: Respiratory Physiology and Neurobiology. 2017.
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abstract = "Routine estimation of functional residual capacity (FRC) in ventilated patients has been a long held goal, with many methods previously proposed, but none have been used in routine clinical practice. This paper proposes three models for determining FRC using the nitrous oxide concentration from the entire expired breath in order to improve the precision of the estimate. Of the three models proposed, a dead space with two mixing compartments provided the best results, reducing the mean limits of agreement with the FRC measured by whole body plethysmography by up to 41{\%}. This moves away from traditional lung models, which do not account for mixing within the dead space. Compared to literature values for FRC, the results are similar to those obtained using helium dilution and better than the LUFU device (Dr{\"a}ger Medical, Lubeck, Germany), with significantly better limits of agreement compared to plethysmography.",
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author = "Harrison, {Chris D.} and Phan, {Phi Anh} and Cathy Zhang and Daniel Geer and Farmery, {Andrew D.}",
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Modelling mixing within the dead space of the lung improves predictions of functional residual capacity. / Harrison, Chris D.; Phan, Phi Anh; Zhang, Cathy; Geer, Daniel; Farmery, Andrew D.

In: Respiratory Physiology and Neurobiology, 31.08.2017.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Modelling mixing within the dead space of the lung improves predictions of functional residual capacity

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AU - Phan, Phi Anh

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AU - Geer, Daniel

AU - Farmery, Andrew D.

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