Validation of XXXX volume and cardiac output by electrical interrogation of the brachial artery in normals: assessment of strengths, limitations, and sources of error.

@entity1 @entity64 @entity339 @entity27921 @entity299
UNASSIGNED: The goal of this study is to validate a new, continuous, noninvasive @entity64 volume (SV) method, known as transbrachial electrical bioimpedance velocimetry ( @entity27921 ). @entity27921 SV was compared to SV obtained by cardiac magnetic resonance imaging (cMRI) in normal @entity1 devoid of clinically apparent @entity299 . Thirty-two (32) volunteers were enrolled in the study. Each subject was evaluated by echocardiography to assure that no aortic or @entity339 was present. Subsequently, each subject underwent electrical interrogation of the brachial artery by means of a high frequency, low amplitude alternating current. A first @entity27921 SV estimate was obtained. Immediately after the initial @entity27921 study, subjects underwent cMRI, using steady-state precession imaging to obtain a volumetric estimate of SV. Following cMRI, the @entity27921 SV study was repeated. Comparing the cMRI-derived SV to that of @entity27921 , the two @entity27921 estimates were averaged and compared to the cMRI standard. CO was computed as the product of SV and heart rate. Statistical methods consisted of Bland-Altman and linear regression analysis. @entity27921 SV and CO estimates were obtained in 30 of the 32 subjects enrolled. Bland-Altman analysis of pre- and post-cMRI @entity27921 SV showed a mean bias of 2.87 % (2.05  mL), precision of 13.59  % (11.99  mL) and 95  % limits of agreement (LOA) of +29.51  % (25.55  mL) and -23.77  % (-21.45  mL). Regression analysis for pre- and post-cMRI @entity27921 SV values yielded y  =  0.76x  +  25.1 and r(2)  =  0.71 (r  =  0.84). Bland-Altman analysis comparing cMRI SV with averaged @entity27921 SV showed a mean bias of -1.56  % (-1.53  mL), precision of 13.47  % (12.84  mL), 95  % LOA of +24.85  % (+23.64  mL) and -27.97  % (-26.7  mL) and percent error  =  26.2  %. For correlation analysis, the regression equation was y  =  0.82x  +  19.1 and correlation coefficient r(2)  =  0.61 (r  =  0.78). Bland-Altman analysis of averaged pre- and post-cMRI @entity27921 CO versus cMRI CO yielded a mean bias of 5.01  % (0.32  L  min(-1)), precision of 12.85  % (0.77  L  min(-1)), 95  % LOA of +30.20  % (+0.1.83  L  min(-1)) and -20.7  % (-1.19  L  min(-1)) and percent error  =  24.8  %. Regression analysis yielded y  =  0.92x  +  0.78, correlation coefficient r(2)  =  0.74 (r  =  0.86). @entity27921 is a novel, noninvasive method, which provides satisfactory estimates of SV and CO in normal @entity1 .
