The first step is a 24hour ECG Holter recording by means of a compatible ECG recording system (Nevrokard OSAS is at present compatible with Cardiac Science Burdick^{®}, Mortara^{®}, Rozinn^{®}, Philips Zymed^{®}, Forest Medical^{®}, DelMar Reynolds^{®} and Mini Mitter^{®} systems, further compatibilities to be added later at customers' request). During the second step the RRI file derived from the Holter recording is submitted to analysis by the Nevrokard OSAS software. The AWAKE and SLEEP sections of each recording are separately analyzed and directly compared in the same screen. A set of quantitative parameters describing the patient's heart rate variability in both time and frequency domains is obtained and easily compared. Differences between some of these parameters are proportional to the probability that the patient has sleep apnea.Nevrokard OSAS consists of two software modules:

An ECG file recorded by any compatible acquisition system or an RR interval file recorded by a compatible Holter system (see above and Data Formats) is required. 
AWAKE and SLEEP sections are clearly colorcoded (see below). 
Recordings can be displayed and analyzed either in the RRI (below left) or HR mode (below right). 
TIME DOMAIN ANALYSIS  
All timedomain displays and calculations will be done either in the RR or HR mode.  
Statistics: Max., Min., Max./Min., Range, Mean NN, Mean dNN (MSD), Median, 95% Conf. Interval, 99% Conf. Interval, lnHRV, Coef. of Variance, Variance, SDNN, SENN, SDSD, RMSSD, NN50 Count, pNN50, SDANN, SDNN Index, SDASD. The AWAKE and SLEEP results are directly compared in the table. 

Segmented statistics: SDANN, SDNN Index, SDASD, ttest between segments; Mean, STD, SE, 95% Confidence Interval and 99 % Confidence Interval for each segment. 

Histogram: Mean, SD, Median, Modus, Dispersion, Upper F(X), Uncertainty, Skeweness, Kurtosis and Variability Index (HRV Triangular Index with a freely adjustable Class Interval (bin value)). 

Poincare Analysis: SD1, SD2 in both absolute and normalized units, SD1/SD2 Ratio, CSI (Cardiac Sympathetic Index), CVI (Cardiac Vagal Index), dRRt, dRRr in both absolute and normalized units, dRRt/dRRr, Centroid, Ellipse Area, R^{2} and SEE. 
FREQUENCY DOMAIN ANALYSIS 




RESULTS OF ANALYSIS 
