using

BIA multi-frequency technology
impedance values
at 5 kHz and 200 kHz ONLY

and

independent of weight, age and sex.

The Bodystat^® QuadScan 4000 multi-frequency device measures Impedance values at 5, 50, 100 and 200 kHz.

The QuadScan 4000 is designed more for hospitalised patients (or trained athletes to check their hydration status) where a higher degree of measurement sensitivity is required (hence using 200 kHz) in tracking CHANGE of fluid shifts and cellular health. The Bodystat 1500MDD with its Wellness Marker only measures up to 50 kHz and would not be suitable for these subject groups.

Impedance is the resistance to the flow of the current in a given body. Hence the greater the resistance, the higher the Impedance measurement value.

In a healthy subject, at a low frequency of 5 kHz, the Impedance or resistance will be HIGH because the current cannot penetrate the cell membrane - it measures therefore only the extra-cellular space (ECW). A HIGH Impedance value is registered on the device.

However, at a higher frequency of 200 kHz, the current is sufficient to penetrate the cell membrane wall; the Impedance is then LOWER and measures both inside and outside the cells - total body water (TBW).

The greater the variance between these two values, the healthier the body cell.

Hence, if these two values are tracked over time (days, weeks) and the variance becomes smaller, this may indicate that the cell is becoming less healthy.

With the two impedance values expressed as a ratio of 200 kHz / 5 kHz, then the closer to 1.00, the less healthy the body cell.

NOTE: Some users express the ratio as 5 kHz divided by 200 kHz producing values greater than 1; this method still produces the same evidence, namely the closer to 1.00, the less healthy the body cell.

It appears from data analysis that for healthy people with good cellular nutritional status, we find this Marker or Indicator to be around 0.75 and for very fit people, even lower. In the case of critically ill subjects, with poor and deteriorating cellular status, this "Illness Marker" may increase to around 0.86 and higher.

As a subject approaches death, the ratio would therefore become even closer to 1.00.

Some investigators calculate the ratio as 5 kHz / 200 kHz (Refer VAL 29 below) and may use this Index as a PREDICTOR OF OUTCOME in seriously ill patients.

Healthy Male 51 yrs

Frequency	Impedance in Ohms	"Illness Marker"	Phase Angle at 50 kHz	Reactance at 50 kHz
5 kHz	573
50 kHz	480		7.3°	61
100 kHz	450
200 kHz	433	0.756
Variance between 5 and 200 kHz	140

"Dying" Male 58 yrs

Frequency	Impedance in Ohms	"Illness Marker"	Phase Angle at 50 kHz	Reactance at 50 kHz
5 kHz	568
50 kHz	530		2.9°	27
100 kHz	515
200 kHz	504	0.887
Variance between 5 and 200 kHz	64

TO EXPLAIN MORE FULLY

Expansion of ECW and loss of ICW are typical features of systemic illness and arises from protein leakage into the extra-cellular space and loss of intra-cellular protein in the case of critical illness.

Loss of intra-cellular potassium and extra-cellular accumulation of sodium result in an increased whole-body exchangeable Na⁺-K⁺ ratio, which is a strong predictor of mortality in surgical patients.

The resistance of the cell membrane at 5 kHz, is therefore significantly reduced in the case of critical illness and the difference between the Impedance values at 5 kHz and 200 kHz is markedly closer to each other, indicating cellular deterioration.

In the past, there have been many publications claiming that Phase Angle (PA) could be used as an indicator of survival times; the lower the PA, the shorter the survival time. It seems that healthy subjects have PA values of at least 6° and higher; subjects with 5° have lower survival times and below 4.4°, even lower survival times.

The phase angle is defined as the relation between the two vector components of impedance: resistance and reactance. It may be interpreted as an indicator of water distribution between the extra- and intra-cellular spaces.

However, it is not easy to explain nor to understand the concept of Phase Angle. Furthermore, BMI does not reflect nutritional status in ill patients, as the decrease in body cell mass is obscured by an expansion of extra-cellular water.

We have instead adopted the Bodystat "Illness Marker" approach using the index between Impedance values at the two above-mentioned frequencies. This approach therefore uses only factual raw data measurement and does require the use of the latest in multi-frequency electronic technology, hence the use of our Bodystat^® QuadScan 4000 device. This approach is also easier to explain to clinicians and for others to understand.

Note that neither subject weight, gender, age, height nor race group, is required as input data. Either whole body or segmental analysis is possible. The test is furthermore, quick and easy to perform.

ADVANTAGES

• Potential opportunity for use:
  Predictor of Outcome or "Illness Marker"^TM
  Effectiveness of Rehabilitation recovery
  Body Cell fitness
  and
  Hydrational Status assessment
• No subject weight is required - often a problem in areas such as ICU
• Independent of age and sex
• Uses RAW IMPEDANCE DATA only - no predictive equations are required
• Suitable for WHOLE BODY and SEGMENTAL analysis
• Applies to ANY:
  disease state or physical fitness state
  age group
  population group
• Uses only the latest in Multi-Frequency BIA electronic equipment
  
• Quick to perform the test requiring little or no skills
• Inexpensive technology
• Non-invasive
• Cost effective

Supporting evidence can be found under the RESEARCH DIGEST.
Refer to:

VAL 4
Nutrition index determined by a portable multifrequency bioelectrical impedance analysis machine. (Keller W et al.)
GUT 1998; 42 (suppl 1).

VAL 39
Impedance Ratio: new multi-frequency electrical Bio-impedance functional assessment parameter.. (Barbosa e Silva et al)
Presented as an Abstract at the FELANPE Nutrition Congress in Montevideo, Uruguay on 7th November, 2005.

GRAPHIC PRESENTATION

From the graphic presentation below, the curve of the "dying" male is much flatter than the healthy male; the steeper the curve the healthier the body cell.

Copyright © 2005, Bodystat Limited.