Projects per year
Abstract / Description of output
Abstract Background. Accurate measurement of pulmonary oxygenation is important for classification of disease severity and quantification of outcomes in clinical studies. Currently, tension-based methods such as P/F ratio are in widespread use, but are known to be less accurate than content-based methods. However, content-based methods require invasive measurements or sophisticated equipment that are rarely used in clinical practice. We devised two new methods to infer shunt fraction from a single arterial blood gas sample: (1) a non-invasive effective shunt (ES) fraction calculated using a rearrangement of the indirect Fick equation, standard constants, and a procedural inversion of the relationship between content and tension; and (2) inferred values from a database of outputs from an integrated mathematical model of gas exchange (DB). We compared predictive validity - the accuracy of predictions of PaO2 following changes in FIO2 - of each measure in a retrospective database of 78,159 arterial blood gas (ABG) results from critically ill patients. Results. In a formal test set comprising 9,635 pairs of ABGs, median absolute error (MAE) values for the four measures were: alveolar-arterial difference, 7.30kPa; PaO2/FIO2 ratio, 2.41kPa; DB, 2.13kPa; ES: 1.88kPa. ES performed significantly better than other measures (p<10-10 in all comparisons).Further exploration of the DB method demonstrated that obtaining two blood gas measurements at different FIO2 provides a more precise description of pulmonary oxygenation. Conclusions. Effective shunt can be calculated using a computationally efficient procedure using routinely-collected arterial blood gas data and has better predictive validity than other analytic methods.For practical assessment of oxygenation in clinical research, ES should be used in preference to other indices. ES can be calculated at http://baillielab.net/es.
Keywords / Materials (for Non-textual outputs)
- Shunt fraction
- Arterial blood gas
- respiratory failure
FingerprintDive into the research topics of 'Predictive validity of a novel non-invasive estimation of effective shunt fraction in critically ill patients.'. Together they form a unique fingerprint.
- 2 Finished
1/08/14 → 1/02/20
- MRC Human Genetics Unit
- Deanery of Molecular, Genetic and Population Health Sciences - Senior Clinical Research Fellow in Anaesthetics
Person: Academic: Research Active