Method and device for measuring of oedema
A method and apparatus for measurement and distinguishing between brawny and pitting oedema comprises a measurement head including a tactile sensor to measure a first characteristic of the oedema and a force decay sensor mounted adjacent the tactile sensor, to measure a second characteristic of the oedema so as to distinguish brawny oedema from pitting oedema. The tactile sensor may be a resonance oscillating sensor which may determine frequency shift, and the forced decay sensor may provide information regarding the degree of displaced fluid as a measure of pitting oedema through measurement of decay of force.
1. A method of measuring oedema in a patient, the method comprising:
pressing a surface of an oscillating resonance sensor against the skin surface of the patient to a certain depth;
simultaneously reading with a force sensor a force required to depress the skin surface to the certain depth and a frequency of the oscillating resonance sensor over a period of time;
determining a difference Δf between the oscillating resonance sensor frequency reading and a known resonance frequency of the oscillating resonance sensor that occurs when the oscillating resonance sensor freely oscillates as a measure of brawny oedema; and
determining a decay in the force F required to depress the skin surface to the certain depth as a measure of pitting oedema.
2. A method according to claim 1 , further comprising:
presenting the frequency readings and the force readings.
3. A method according to claim 1 , further comprising:
calculating a parameter Δf/F that describes a relative relationship between pitting oedema and brawny oedema.
4. A method according to claim 3 , wherein simultaneously reading the force and the frequency comprises continuously reading the force and the frequency, and the method further comprises:
plotting a curve corresponding to the parameter Δf/F, wherein an inclination of the curve corresponds to a measure of the relative relationship between pitting oedema and brawny oedema.
5. A method according to claim 1 , wherein the oscillating resonance sensor surface has a circular cross section.
6. A method according to claim 5 , wherein the oscillating resonance sensor surface has a diameter of 15 mm.
7. A method according to claim 1 , wherein the period of time comprises 20 seconds.
8. A method according to claim 1 , wherein the certain depth comprises 4 mm.
9. A method according to claim 1 , wherein the surface of the oscillating resonance sensor is parallel to the skin surface when pressed.
10. A device for measuring oedema in a patient, comprising:
a measuring head, the measuring head comprising
an oscillating resonance sensor, the oscillating resonance sensor comprising a surface configured to be pressed against a skin surface of the patient, and
a force sensor, wherein the oscillating resonance sensor is connected to the force sensor so that the oscillating resonance sensor is operable to oscillate without interference from the force sensor; and
an adjustable stand that adjustably supports the measuring head.
11. A device according to claim 10 , wherein the control is further configured to calculate a parameter Δf/F that describes a relative relationship between pitting oedema and brawny oedema.
12. A device according to claim 11 , wherein control is configured to continuously simultaneously read the force and the frequency, and plot a curve corresponding to the parameter Δf/F, and an inclination of the curve corresponds to a measure of the relative relationship between pitting oedema and brawny oedema.
13. A device according to claim 10 , further comprising means for adjusting the measuring head.
14. A device according to claim 13 , wherein the adjusting means comprises a stepping motor.
15. A device according to claim 10 , further comprising means for presenting the oscillating resonance sensor readings and the force sensor readings.
16. A device according to claim 15 , wherein the presenting means comprises a computer.