Theoretical Preview


		Theoretical Preview What is Nerve-Express? Nerve-Express is an automatic computer based system that provides a Quantitative Assessment of the state of the Autonomic Nervous System (ANS). Before the development of Nerve-Express, Autonomic Tone (the overall, qualitative state of the ANS) could be assessed only approximately and formulated by three qualitative gradients: 1. Autonomic Balance (Vegetative Homeostasis) 2. Sympathetic Prevalence 3. Parasympathetic Prevalence. Traditionally, the criteria used for evaluating these three gradients were clinical and laboratory findings. Assessment of the Autonomic Tone was thus labor intensive and not always feasible. Nerve-Express solves this problem through a new approach to the recognition and classification of the states of the ANS – analysis of Heart Rate Variability (HRV). In addition, Nerve-Express’s expanded and reproducible capacity of HRV analysis allows for precise recognition and classification of sixty states of the ANS with a corresponding qualitative description for each one. Nerve-Express uses technology that has been extensively researched for over twenty years. However, until the development of the Nerve-Express system, there was no practical way to use this technology outside of a research laboratory, due to the fact that automatic reproducibility proved impossible using any other existing HRV analysis system today. Nerve-Express provides not only a mathematical interpretation of HRV spectral analysis, but also performs a qualitative analysis of the resultant parameters based on principles of artificial intelligence. The algorithms used in Nerve-Express were developed in 1987, and were researched and tested on over fourteen thousand patients. The Nerve-Express test, called the Orthostatic Test, is a simple procedure that takes only a several minutes to administer and allows ANS assessment using a very easy, acceptable, and predictable means of the ANS provocation. The Key Advantage The key advantage is the method’s ability to detect the early signs of development of pathological processes or the presence of a functional disorder, which may not be revealed by the procedures of an ordinary physical examination. Thus, Nerve-Express becomes an objective tool for early physician’s intervention independent of the patient’s reports of his or her own condition. Heart Rate Variability Analysis In the analysis of HRV the Nerve-Express system uses a very effective and easy to interpret visual representation of Heart Rhythm, called Method of Rhythmography ( developed 1967 by Dr. Zhemaitite). Rhythmography draws the time interval between each consecutive heart beat as a straight, vertical line. The longer the interval between each heartbeat (R – R), the longer the vertical lines (Fig. 1).
	When these lines are graphed sequentially they present a curve-specific, wave portrait of heart rhythm (Fig. 2a). Rhythmographic representation allows a great deal of information to be compressed in a single picture. The wave portrait in Fig. 2a is composed of 448 R-R intervals of the ECG. A spectral analysis of this curve allows Nerve-Express to identify two main spectral components (Fig.2b):
	It has been found that there is a high correlation between the power of High-frequency band of the spectrum function and the tone of the Parasympathetic Nervous System (PSNS), and also between the power of Low-frequency band and the tone of the Sympathtic Nervous System (SNS). This finding has been well documented in a number of medical and scientific publications and in conference reports from the American College of Cardiology, The American Heart Association, and others. Nerve-Express uses a unique algorithm, which helps to analyze peak amplitudes in both high and low spectral frequencies, and to graph the quantitative relationship between activities of the Sympathetic and the Parasympathetic tones. Recognition of the ANS States Nerve-Express automatically recognizes sixty states of the ANS that represent different combinations of relationship between levels of SNS and PSNS activities and variations in their balance. Nerve-Express then graphs the Parasympathetic activity on the horizontal or x-axis and the Sympathetic activity on the vertical or y-axis. The intersection point of the Sympathetic and the Parasympathetic system is the point of Autonomic Balance (Fig.3). To the right of and about this balance point, Nerve-Express displays an area of increased Parasympathetic and Sympathetic activities in4 gradation. Decreases in PSNS and SNS activities are shown to the left and below the balance point. Each of the 60 states of the ANS is subdivided into eight categories: Category 1. PSNS prevalence with the average level of SNS activity is shown with 4 points : Point 1 represents a slight PSNS prevalence. Point 2 represents a moderate PSNS prevalence. Point 3 represents a significant PSNS prevalence. Point 4 represents a sharp PSNS prevalence. Category 2. A simultaneous increase in both the PSNS and SNS activity with different relationships is shown with 16 points. Category 3. SNS prevalence is shown with 4 points. Category 4. A PSNS decrease with a SNS increase is shown with 16 points. Category 5. P PSNS decrease the average level of SNS activity represented by 4 points. Category 6. A general decrease in both SNS and PSNS activities. Category 7. A point at zero value on the coordinate system indicates ANS balance. Category 8. SNS decrease with a PSNS increase is shown with 4 points.
Physiological Interpretation of ANS Categories 1. PSNS prevalence with the average level of SNS activity: This category represents PSNS dominance. This state is usually noted when a patient is resting or in the first stage of sleep (specifically, dreamless sleep). In the second stage of sleep, SNS activity is generally increased, at times markedly. Thus, this category is differentiated into four grades, dependent on the state of the PSNS. This category is somewhat limited, since it can only be noticed in patients with strictly median values of SNS activity. The ideal points are (3.0) or (4.0) its bicycle corresponds to athletic conditions. 2. Increase in PSNS and SNS activity: This category is subdivided into sixteen different possible combinations of PSNS/SNS activity. It is characteristic of most healthy subjects. 3. SNS Prevalence: This category represents and increase in SNS compared to a median value of the PSNS. From the physiological standpoint, this category represents a transitional stage between the second and the fourth categories. 4. PSNS decrease with SNS increase: This category can apply to both clinically ill and clinically healthy individuals (defined as those not requiring hospitalization). However, the use of the term "healthy" is not always appropriate because functional imbalance, from stress, physical exhaustion, nervous tension, infections, intoxication (drug or alcoholic), exacerbation of chronic conditions, and many other conditions may still be present. In such cases a decrease in PSNS due to depressed PSNS nerve centers can be observed, along with a simultaneous sympathetic adrenergic activation, which is triggered by the struggle of the nervous system to achieve balance. 5. PSNS decrease with an average level SNS: This category, like the third, is transitional. Everything that pertains to the fourth category can be related to it, but here, the SNS activity is within average values. This means that stress, exhaustion, or nervous overload is unlikely. This category may often reflect a depression in the receptors of the PSNS, indicating the possibility of pathology or any chronic situations. 6. SNS and PSNS decrease: The sixth category, especially at points 3 and 4, reflects a general involuntary degeneration of both the SNS and PSNS nervous centers. The majority of cases found in this category are either very old patients of those with diseases, which cause a significant decrease in the sensitivity of the entire receptor system along with a partial degeneration of nervous centers. *NOTE 1:* Point (-1, -1) on the coordinate is an exception to this category. It represents an insignificant, general decrease in ANS and approximates the point of Autonomic Balance. It can be interpreted as a borderline value of Autonomic Balance. *NOTE 2:* Points (-1, -2) or (-1, -3) is characteristic of patients with increased Potassium ions K+ levels (hyperkalemia) 7. Autonomic Balance. This category, although formally just one point, and all points in its vicinity that belong to other categories can be interpreted as borderline values of the Autonomic Balance. 8. SNS decrease with PSNS increase: This category is an exception to all others because the normal physiology of a person gives prevalence to the PSNS with average or increased SNS. A dramatic decrease in the SNS here is unusual. But it is representative of persons with special training, such as scuba divers for whom a depressed SNS level is of foremost importance. Note: Point (o, -1) is and intermediate value between point (1, -1) of group 8 and point (-1, -1) of group 6. Of course, a proper physiological interpretation of these eight categories is only possible within the context of a standard, general assessment of the patient’s overall condition. Method of Evaluation of the State of ANS using Nerve-Express A proper evaluation requires measurements of a patient under at least two different conditions. The method here is to examine a patient both at rest and during ANS activity. This can be accomplished by having a patient engage in some activity where the general response of a healthy person is known. Based on the patients reaction, a more accurate assessment of the ANS is possible. A typical method to provoke an ANS reaction has been the use of beta-blockers or beta-adrenergic agents. Nerve-Express uses a more accessible method of ANS provocation – theOrthostatic Test, which is simply a transition from supine tp standing position. Any dysfunction of the organism will be exhibited as an inadequate reaction of ANS response during the test. Nerve-Express graphs the ANS State and its reaction using SNS and PSNS activities as the coordinate system. The final evaluation point is the center between the points obtained on the SNS/PSNS coordinates (Fig.4). The general approach is to balance the ANS or restore it to homeostasis. However, you can and shuld develop your own methods, based on the needs of specific cases. The Orthostatic Test takes approximately 7 – 9 minutes to administer.
			The Rythmographic Strip (Fig.4) correlates to number 1 – 192 in the supine position and to 225-448 in the upright. The R-R intervals from 192-256 are dedicated to the transition between the supine and upright states. Potential Applications • Individuals who wish o monitor their own Autonomic State. • Physicians, including specialists in rehabilitation, who want an objective means to monitor their patients’s Autonomic reaction. • Corporations that periodically test employee work force for personnel and insurance purposes. • Sports organizations that monitor the Autonomic Tone of their athletes. • Health club operators who want to monitor the well-being and progress of their clientele • Public health investigators who need an efficient way of assessing the general health status of large populations. The Nerve Express Test The data for evaluation is gathered through computer monitoring of the R-R intervals using a chest strap sensor applied to the subject’s body (Figure 5). First, the patient lies down (supine position) for several minutes. Then, after a computer-generated signal (beep), the subject stands up and remains standing (upright position) until the second computer-generated cue comes on. This concludes the test. During the test the monitoring device downloads the test data into the computer, where results are calculated by the Nerve-Express system. Nerve-Express can test up to four patients simultaneously, with special devices. The time required to complete the testing is seven to ten minutes, and the results are sent immediately either to a disk, the screen, or a printer
				Fig.5 Sample placement of the electrode chest strap and clip on receiver Technical Guide to the System’s output The rhythmogram strip is shown in the upper left corner of the screen. Two tables under the rhythmogram strip represent the test parameters of the supine (left) and orthostatic (right) positions. 1. The tables include the following data: HR [beats per minute] – Heart Rate HF [msec2] – the Power of Spectral Function of Low Frequency range 0.5-0.15 [Hz] (This is the index of the Parasympathetic Tone). LF1 [msec2]—the Power of Spectral Function of Low Frequency range 0.07-0.15 [Hz]. LF1 is an index of Sympathetic and Parasympathetic Tone activities, corresponding the baroreflex influences on the Heart Rate Variability (waves of Traube-Gearing). LF1 [msec2]—the Power of Spectral Function of Low Frequency range 0.033-0.07 [Hz]. LF2 [msec2]—the index of Sympathetic Tone (waves of Mayer). TP [msec2]—This is the Total Power of Spectral Function of all the frequencies 0.033-0.5 [Hz]. This is a combined index of the ANS activity. 2. If you do not see the statement:"Extrasystoles not recognized" under the described chart that means that there were extrasystoles detected. In this case appropriate diagnostic referral or testing should be considered. Note: this feature is necessary for proper Spectral Analysis of the data. However, we make no representation or claims as to any diagnostic capabilities of the Nerve-Express System. 3. The left lower part of the printout is dedicated to the conclusion about the Tone of the ANS (supine) and the reactivity of the ANS (upright). All conclusions represent a qualitative description of the ANS state that is represented graphically by a point in a system of two coordinates (PSNS and SNS). Each point is composed of two corresponding components. For example, the point in Fig. 6 has a value of 3 on PSNS (the x-axis} representing a significant Parasympathetic increase, and a value of 2 on SNS (the y-axis) representing a moderate Sympathetic increase.