Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III.
Background: This study assessed the performance of a Functional Approximation based on a Levenberg-Marquardt Algorithm (FA-LMA) to calculate airway dead space (VD(aw)) and the slope of phase III (S(III)) from capnograms.Methods: We performed mathematical simulations to test the effect of noises on t...
| Published in: | Journal of Clinical Monitoring & Computing Vol. 23; no. 4; pp. 197 - 207 |
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| Main Authors: | , , , , , , , , , |
| Format: | research Journal Article |
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Springer Nature
Aug2009
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| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=105392674&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 105392674 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 13871307 OHC jtl: Journal of Clinical Monitoring & Computing issn: 13871307 maglogo: N pubinfo: dt: Aug2009 vid: 23 iid: 4 pid: 237 pub: Springer Nature place: New York, New York artinfo: ui: 105392674 NLM19517259 2010355804 10.1007/s10877-009-9182-z NLM19517259 105392674 ppf: 197 ppct: 10 formats: fmt: @attributes: type: P tig: atl: Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III. aug: au: Tusman G Scandurra A Böhm SH Suarez-Sipmann F Clara F Tusman, Gerardo Scandurra, Adriana Böhm, Stephan H Suarez-Sipmann, Fernando Clara, Fernando affil: Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Argentina sug: subj: Airway Resistance Physiology Capnography Methods Positive End-Expiratory Pressure Methods Pulmonary Alveoli Physiopathology Respiratory Dead Space Algorithms Carbon Dioxide Computer Simulation Equipment Design Models, Statistical Models, Theoretical Pulmonary Gas Exchange Reproducibility of Results Respiratory Airflow Software Human ab: Background: This study assessed the performance of a Functional Approximation based on a Levenberg-Marquardt Algorithm (FA-LMA) to calculate airway dead space (VD(aw)) and the slope of phase III (S(III)) from capnograms.Methods: We performed mathematical simulations to test the effect of noises on the calculation of VD(aw) and S(III). Data from ten mechanically ventilated patients at 0, 5 and 10 cmH(2)O of PEEP were also studied. FA-LMA was compared with the traditional Fowler's method (FM).Results: Simulations showed that: (1) The FM determined VD(aw) with accuracy only if the capnogram approximated a symmetrical curve (S(III) = 0). When capnograms became asymmetrical (S(III) > 0), the FM underestimated VD(aw) (-3.1% to -0.9%). (2) When adding noises on 800 capnograms, VD(aw) was underestimated whenever the FM was used thereby creating a bias between -5.54 and -1.28 ml at standard deviations (SD) of 0.1-1.8 ml (P < 0.0001). FA-LMA calculations of VD(aw) were close to the simulated values with the bias ranging from -0.21 to 0.16 ml at SD from 0.1 to 0.4 ml. The FM overestimated S(III) and showed more bias (0.0041-0.0078 mmHg/ml, P < 0.0001) than the FA-LMA (0.0002-0.0030 mmHg/ml). When calculating VD(aw) from patients, variability was less with the FA-LMA leading to mean variation coefficients of 0.0102, 0.0111 and 0.0123 compared to the FM (0.0243, 0.0247 and 0.0262, P < 0.001) for 0, 5 and 10 cmH(2)O of PEEP, respectively. The FA-LMA also showed less variability in S(III) with mean variation coefficients of 0.0739, 0.0662 and 0.0730 compared to the FM (0.1379, 0.1208 and 0.1246, P < 0.001) for 0, 5 and 10 cmH(2)O of PEEP, respectively.Conclusions: The Functional Approximation based on a Levenberg-Marquardt Algorithm showed less bias and dispersion compared to the traditional Fowler's method when calculating VD(aw) and S(III). pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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