@article{
 id = {f805ebb2-9f21-3395-9fd6-f73114aaa1a7},
 title = {Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III.},
 type = {article},
 year = {2009},
 identifiers = {[object Object]},
 keywords = {abstract,background,co 2,dead space,from the 1 department,hospital privado de,lung recruit-,ment,monitoring,of anesthesiology,peep,phase iii slope,volumetric capnography},
 created = {2009-08-17T18:00:51.000Z},
 pages = {197-206},
 volume = {23},
 websites = {http://www.ncbi.nlm.nih.gov/pubmed/19517259},
 month = {8},
 file_attached = {true},
 profile_id = {fe7067eb-58b8-34c6-b8cd-6717fdf7605c},
 group_id = {f87494e7-529d-3e68-b1f1-0e6d57d138db},
 last_modified = {2014-07-19T19:15:34.000Z},
 read = {true},
 starred = {true},
 authored = {false},
 confirmed = {true},
 hidden = {false},
 citation_key = {Tusman2009},
 client_data = {"desktop_id":"4e6295bb-e114-4798-bba2-2078081119f5"},
 abstract = {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).},
 bibtype = {article},
 author = {Tusman, Gerardo and Scandurra, Adriana and Böhm, Stephan H and Suarez-Sipmann, Fernando and Clara, Fernando},
 journal = {Journal of clinical monitoring and computing},
 number = {4}
}

{"_id":"cBQ5A3Y9qfWtGyu3b","authorIDs":[],"author_short":["Tusman, G.","Scandurra, A.","Böhm, S., H.","Suarez-Sipmann, F.","Clara, F."],"bibbaseid":"tusman-scandurra-bhm-suarezsipmann-clara-modelfittingofvolumetriccapnogramsimprovescalculationsofairwaydeadspaceandslopeofphaseiii-2009","bibdata":{"id":"f805ebb2-9f21-3395-9fd6-f73114aaa1a7","title":"Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III.","type":"article","year":"2009","identifiers":"[object Object]","keywords":"abstract,background,co 2,dead space,from the 1 department,hospital privado de,lung recruit-,ment,monitoring,of anesthesiology,peep,phase iii slope,volumetric capnography","created":"2009-08-17T18:00:51.000Z","pages":"197-206","volume":"23","websites":"http://www.ncbi.nlm.nih.gov/pubmed/19517259","month":"8","file_attached":"true","profile_id":"fe7067eb-58b8-34c6-b8cd-6717fdf7605c","group_id":"f87494e7-529d-3e68-b1f1-0e6d57d138db","last_modified":"2014-07-19T19:15:34.000Z","read":"true","starred":"true","authored":"false","confirmed":"true","hidden":"false","citation_key":"Tusman2009","client_data":"\"desktop_id\":\"4e6295bb-e114-4798-bba2-2078081119f5\"","abstract":"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).","bibtype":"article","author":"Tusman, Gerardo and Scandurra, Adriana and Böhm, Stephan H and Suarez-Sipmann, Fernando and Clara, Fernando","journal":"Journal of clinical monitoring and computing","number":"4","bibtex":"@article{\n id = {f805ebb2-9f21-3395-9fd6-f73114aaa1a7},\n title = {Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III.},\n type = {article},\n year = {2009},\n identifiers = {[object Object]},\n keywords = {abstract,background,co 2,dead space,from the 1 department,hospital privado de,lung recruit-,ment,monitoring,of anesthesiology,peep,phase iii slope,volumetric capnography},\n created = {2009-08-17T18:00:51.000Z},\n pages = {197-206},\n volume = {23},\n websites = {http://www.ncbi.nlm.nih.gov/pubmed/19517259},\n month = {8},\n file_attached = {true},\n profile_id = {fe7067eb-58b8-34c6-b8cd-6717fdf7605c},\n group_id = {f87494e7-529d-3e68-b1f1-0e6d57d138db},\n last_modified = {2014-07-19T19:15:34.000Z},\n read = {true},\n starred = {true},\n authored = {false},\n confirmed = {true},\n hidden = {false},\n citation_key = {Tusman2009},\n client_data = {\"desktop_id\":\"4e6295bb-e114-4798-bba2-2078081119f5\"},\n abstract = {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. 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