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Critchley, Lester A. H.; Critchley, J. A. J. H.

doi:10.1023/a:1009982611386

Cited by 1,172 publications

(353 citation statements)

References 32 publications

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“…Limits of agreement were calculated arbitrarily as ±1.96 SD of the bias. The percentage error (1.96 SD/mean CO) was calculated according to Critchley and Critchley [10] for comparison of CO values. The precision of the reference PAC derived CO was measured within the study according to Cecconi et al [11] Data are given as mean and the 95% confidence interval of the mean or the SD as appropriate.…”

Section: Discussionmentioning

confidence: 99%

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Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Rajput¹,

Das²,

Chauhan³

et al. 2014

WJCS

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Objective: This study was conducted to compare the cardiac output by using Electrical Cardiometry (EC), a noninvasive method of continuous cardiac output monitoring during cardiac surgery with pulmonary artery catheter (PAC) derived cardiac output. Design: Prospective observational clinical study. Setting: Cardiac surgery operating room of a tertiary care cardiac center. Participants: Twenty five patients undergoing coronary artery bypass surgery with cardiopulmonary bypass. Measurements and Main Results: A total of 150 double data of cardiac output were compared with Thermodilution Cardiac Output (TDCO) and Thoracic Electrical Bioimpedance (TEBCO). The TDCO value ranges from 1.8 -6.9 litre·min −1 with a mean of 4.39 ± 1.16 litre·min −1 and TEBCO ranges from 1.8 -7.1 litre·min −1 with a mean of 4.21 ± 1.16 litre·min −1 . The averaged Bland-Altman analysis for TDCO and TEBCO revealed that a mean bias was 0.18 and limit of agreement was −1.25 -0.89 litre·min −1 and the percentage error (PE) ranged from 22% -32%. The precision for the TDCO was measured to be ±16.2% and the precision for TEBCO was ±19.6%. Receiver Operating Characteristic (ROC) curve analysis between TDCO and TEBCO with a cutoff of 15% shows a sensitivity of 84% and specificity of 63 and area under ROC curve of 0.80. Mountain plot between TDCO and TEBCO shows that a median percentile is 0.25 and value of 97.5 percentile is 1.525. R. S. Rajput et al. 124Conclusions: The present study indicates that the electric cardiometry device yields numerically comparable results to cardiac outputs derived from the PAC during the cardiac surgery. Therefore, electrical cardiometry can be used to evaluate haemodynamic variables with clinically acceptable accuracy, when invasive methods are to be avoided or not available.

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Section: Discussionmentioning

confidence: 99%

“…In a meta-analysis of studies using bias and precision statistics to compare CO measurement techniques, Critchley and colleagues [10] reported an overall mean CO of 4.86 L·min −1 from the 23 bioimpedance studies. The bioimpedance method was compared with thermodilution, dye dilution or the Fick method which was used mainly in children.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Rajput¹,

Das²,

Chauhan³

et al. 2014

WJCS

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“…To detect potential sources of inaccuracy, we compared the demographic and functional characteristics of two patient groups with better and worse agreement, respectively. A threshold CO bias of 1.5 liters/min (30% of the mean CO) was set to separate a group of outliers according to previous recommendations [27]. The univariate analysis revealed a significant influence of male gender, CO as measured by CMR, systolic blood pressure and body weight.…”

Section: Discussionmentioning

confidence: 99%

“…Application requires the difference to be independent of the mean, which had been tested using regression analysis in advance. For objective evaluation of the comparability, we used the approach of Critchley und Critchley [27], whereupon two methods for measurement of CO can be considered equivalent if the limits of agreement do not exceed ±30%. Outlier analysis was performed by Student’s t test, Mann-Whitney test and stepwise multiple regression.…”

Section: Methods and Subjectsmentioning

confidence: 99%

Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging

Saur¹,

Fluechter²,

Trinkmann³

et al. 2009

Cardiology

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Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained by IGR in 305 consecutive patients as compared to the noninvasive gold standard, cardiovascular magnetic resonance (CMR) imaging. Results: Bland-Altman analysis showed a good correspondence of the two methods for CO measurement with an average deviation of 0.2 ± 1.0 liters/min (mean ± SD) and a good reproducibility with a mean bias of 0.2 ± 0.5 liters/min. The accuracy of the present measurements at rest was significantly better in the physiological range than in higher or lower CO ranges. The error levels set forth by current recommendations were exceeded. Conclusion: The data show that IGR measurements are easy to perform and show good agreement with CMR; however, the technique appears to be less accurate in extreme CO ranges at rest. The clinical importance of the IGR method remains to be proven by further studies.

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“…This 95% confidence limit is just over 25% of the range [0, 4], which, being less than 30%, is considered an acceptable percentage value when introducing a new measurement technique in cardiology. 55 …”

Section: E Comparison Of Updrs and Dde Scores For Groups I And Ii Comentioning

confidence: 99%

Finger tapping movements of Parkinson’s disease patients automatically rated using nonlinear delay differential equations

Lainscsek

Rowat

Schettino

et al. 2012

Chaos: An Interdisciplinary Journal of Nonlinear Science

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Parkinson's disease is a degenerative condition whose severity is assessed by clinical observations of motor behaviors. These are performed by a neurological specialist through subjective ratings of a variety of movements including 10-s bouts of repetitive finger-tapping movements. We present here an algorithmic rating of these movements which may be beneficial for uniformly assessing the progression of the disease. Finger-tapping movements were digitally recorded from Parkinson's patients and controls, obtaining one time series for every 10 s bout. A nonlinear delay differential equation, whose structure was selected using a genetic algorithm, was fitted to each time series and its coefficients were used as a six-dimensional numerical descriptor. The algorithm was applied to time-series from two different groups of Parkinson's patients and controls. The algorithmic scores compared favorably with the unified Parkinson's disease rating scale scores, at least when the latter adequately matched with ratings from the Hoehn and Yahr scale. Moreover, when the two sets of mean scores for all patients are compared, there is a strong (r ¼ 0.785) and significant (p < 0:0015) correlation between them. Parkinson's disease (PD) is a common disease affecting tens of millions of people worldwide. Its cardinal signs are resting tremor, bradykinesia (slowness clumsiness of movement), rigidity, and loss of postural reflexes. The disease evolves slowly and, to adjust medications to the severity of the disease, there is a need for automatic and objective evaluation of movements. Such objective movement assessments would supplement subjective clinical ratings, which are ordinal rather than metric and often show large inter-rater variability. Rather than using a spectral based technique, we rated dynamical features of each individuals' finger-tapping-one of the items from the unified Parkinson's disease rating scale (UPDRS) used for rating the severity of the disease-by using data models based on nonlinear delay differential equations (DDEs). The coefficients of the DDEs are then used to assess the severity of the disease.

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Abstract: When using bias and precision statistics, cardiac output, bias, limits of agreement, and percentage error should be presented. Using current reference methods, acceptance of a new technique should rely on limits of agreement of up to +/-30%.

Cited by 1,172 publications

References 32 publications

Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging

Finger tapping movements of Parkinson’s disease patients automatically rated using nonlinear delay differential equations

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