Application of phase angle for evaluation of the nutrition status of patients with anorexia nervosa

The evaluation of the nutrition status of patients has been the subject of interest of many scientific disciplines. Any deviation from normal values is a serious clinical problem. There are multiple nutrition status evaluation methods used including diet history, scales and questionnaires, physical examination, anthropometric measurements, biochemical measurements, function tests, as well as bioelectric impedance analysis or adipometry. Phase angle, obtained by means of bioelectric impedance analysis, is another parameter that is being more and more frequently applied in nutrition status monitoring. It is proportional to body cell mass. Its direct correlation with the cellular nutrition status has been documented. High phase angle values signify well-being, while low phase angle values indicate poor condition of cells. The purpose of this paper was to review the current state of knowledge about the application of phase angle in evaluation and monitoring of the nutrition status of patients with anorexia nervosa on the basis of available literature. It was proven that the phase angle values in patients with anorexia nervosa are much lower compared to healthy people. Detailed observations showed phase angle value increase in the course of treatment. The relevance of the commonly used body mass index (BMI) has been questioned due to significant degree of generalization in the nutrition status evaluation. Thus, there is a need for new, objective parameters for nutrition status evaluation, which will assist in the treatment and monitoring of patients in a more meaningful and reliable way. The existing independent studies equivocally confirm the usefulness of phase angle in the evaluation of nutrition status of patients with anorexia nervosa and its broader application in clinical practice is only a matter of time. However, these are merely attempts and they have not yet found wider application in clinical practice in the treatment of anorexia nervosa.

The mechanism of the silent zone on Lorenz plots in atrial fibrillation

Lorenz plot is an acknowledged method of the evaluation of sequences of ventricular beats in cardiac arrhythmias, particularly in atrial fibrillation. Lorenz plots are scatterplots that show the R-R intervals as a function of the preceding R-R intervals. The authors of this paper conducted studies of 83 cases of atrial fibrillation; histograms of 500 consecutive R-R intervals were made, determining the mean R-R interval, the functional refraction period (FRP) of AV node and Lorenz plots. In 22 cases (26.5%) the presence of the silent zone on a Lorenz plot was observed, similarly to the study of Nakatsu and al. The silent zone appeared only in cases when the statistical distribution of R-R intervals was reflected by a bimodal histogram (less frequently by a trimodal histogram). The silent zone was never observed in cases of monomodal distribution of R-R intervals. The authors discuss Nakatsu's findings and argue that the silent zone in a Lorenz plot is a morphological expression of bimodal distribution of R-R intervals in atrial fibrillation. The silent zone may be caused by pharmacotherapy (e.g. digoxin), increased parasympathetic tension or other factors prolonging FRP. The presence of the silent zone is not a predictor of a spontaneous termination of atrial fibrillation.