The purpose of this study was to validate a single bioelectrical impedance analysis (BIA) equation in healthy Indian subjects aged 22-59 years with a body mass index (BMI) between 16.8 and 47.3 kg m⁻². Healthy subjects (34 men and 30 women) were measured by two methods: bone mineral content (BMC) was measured by a commercial body composition analyser and bioelectrical impedance at various frequencies was measured by a newly developed bioelectrical impedance measurement system. As correlations were high and prediction error was low, a single equation was developed using all subjects as follows: BMC = -3.5268 + (0.0279  x  h) + (0.0145  x  w) + (184  x  (h²/Z(body50)))-(1.08  x  (w x  h²/Z(body6.25)))-(0.0032  x  (age))-(0.103  x  (sex); men = 1, women = 0). BMC measured from commercial instrument InBody720 was 2.552 ± 0.457 kg. BMC predicted by equation was 2.554 ± 0.447 kg (R = 0.976, adjusted R² = 0.948, standard error of estimate = 0.104 kg, total error = 0.09987 kg). The results of this study show that the newly developed multi-frequency bioelectrical impedance measurement system with the single prediction BIA equation can be used in screening the subjects suspected with osteoporosis and for follow-up study of the patient under the therapy for osteoporosis. For validation of commercial instrument InBody720, BMC of 22 healthy subjects was measured by InBody720 and dual-energy X-ray absorptiometry. High correlation (R = 0.9531) and low error (total error = 0.0913 kg) was found between these two methods.

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In this paper, the limitations of the conventional formula for the computation of peripheral blood flow from impedance plethysmograms are highlighted, and a correction to the formula is suggested. A conductivity cell experiment is described to show the dependence of the value of the blood flow index (BFI), obtained from the conventional formula, on the mean resistivity of the cell. It is also shown that the value of the corrected BFI is independent of the mean resistivity. Anomalies observed in the amplitude of systolic waves in impedance plethysmograms of patients with oedema are explained.

Impedance Plethysmographic (IP) observations from the arterial pulse forms a powerful tool for deciphering various cardiovascular diseases. However, a major bottleneck for applying this technique effectively is the assignment of variable waveform morphology to its respective diseases. Rationale of this work is to investigate Non linear and Dynamic Time Warping (DTW) approaches for classifying Impedance Plethysmographic (IP) waveforms. Our adaptation is two fold, firstly, where we establish the IP waveforms as a dynamic system using embedding dimension. Analysis of IP waveforms reveal the existence of eight different patterns corresponding to normal subjects and those suffering from diseases of heart, liver and lungs. Secondly we take up the task of classification of these patterns with template matching using DTW technique. Parametric evaluations reveal that IP waveforms exhibit dynamical nature in a three dimensional attractor. This observation is further validated by exhibition of determinism in reccurrence plots and by parameters determined using recurrence quantification analysis. Classification of the IP patterns by DTW on 1200 samples selected meticulously from 5628 patterns shows an average accuracy of 94%, 95% sensitivity, high statistical predictive values and kappa value of 0.9314 for the eight different classes.