hcp measurement in neuropathy

1. 11
Sensitometer for MeasuringSensitometer for Measuring
Heat and Cold PerceptionHeat and Cold Perception
ThresholdThreshold
ANDAND
Heat and Cold PainHeat and Cold Pain
Perception thresholdsPerception thresholds

2. 2
Overview of Neuropathy and LossOverview of Neuropathy and Loss
of Sensationsof Sensations
• The loss of nerve fiber in neuropathy is notThe loss of nerve fiber in neuropathy is not
uniform nor simultaneous, at least in theuniform nor simultaneous, at least in the
beginning.beginning.
• The damage to small thinly myelinatedThe damage to small thinly myelinated
and unmyelinated nerve fiber is usuallyand unmyelinated nerve fiber is usually
the beginning.the beginning.

3. 3
Overview of Neuropathy and LossOverview of Neuropathy and Loss
of Sensationsof Sensations
• This results in diminishing thermal andThis results in diminishing thermal and
pain sensation along with autonomicpain sensation along with autonomic
decline.decline. 11
• Sensitometer HCP helps detecting theSensitometer HCP helps detecting the
early loss of these sensationsearly loss of these sensations
• This is done by finding the raised orThis is done by finding the raised or
lowered thermal thresholdslowered thermal thresholds..
• Diabetic polyneuropathy is thus detectedDiabetic polyneuropathy is thus detected
at an early stage.at an early stage.

4. 4
The Four Thresholds - 1The Four Thresholds - 1
• Threshold for cool sensation:Threshold for cool sensation:
It ranges between 25 to 30 CIt ranges between 25 to 30 C00
i.e. justi.e. just
bellow the neutral zonebellow the neutral zone
• Threshold for warm sensation:Threshold for warm sensation:
It ranges from 34 CIt ranges from 34 C00
up to 45 Cup to 45 C00
ie a little above the neutral zoneie a little above the neutral zone

5. 5
The Four ThresholdsThe Four Thresholds
• Heat Pain Detection Threshold:Heat Pain Detection Threshold:
Ranges between 42 CRanges between 42 C00
to 55 Cto 55 C00
• Cold Pain Detection Threshold:Cold Pain Detection Threshold:
Ranges from 15 CRanges from 15 C00
to 9 Cto 9 C00
• Neutral zone is between 32 CNeutral zone is between 32 C00
to 34 Cto 34 C00

6. 6
The instrumentThe instrument

7. 7
The probeThe probe

8. 8
Features & BenefitsFeatures & Benefits
• Range of applicable temperature:Range of applicable temperature:
1 C1 C00
to 49 Cto 49 C00
• Rate of rise of temperature1 CRate of rise of temperature1 C00
per second to 1per second to 1
CC00
for every 8 secondsfor every 8 seconds
• Resolution for display .1 CResolution for display .1 C00
• Accuracy of application 0.1 CAccuracy of application 0.1 C00
• Auto calibrationAuto calibration
• Separate probe for skin temperatureSeparate probe for skin temperature
measurement at a near pointmeasurement at a near point

9. 9
Features & BenefitsFeatures & Benefits
• 9 User Friendly Programs9 User Friendly Programs
• Easy four key operationEasy four key operation
• No fluids, liquids, filtering etc.No fluids, liquids, filtering etc.
• Stand alone operationStand alone operation
• Can be interfaced with computerCan be interfaced with computer
• Fully controllable through computerFully controllable through computer

10. 10
Features & BenefitsFeatures & Benefits
• Real time graph on the monitorReal time graph on the monitor
• Data storage on Personal Computer (PC)Data storage on Personal Computer (PC)
• Computerized report generationComputerized report generation
• Both tabular or graphical report can beBoth tabular or graphical report can be
seenseen
• Report printing on the clickReport printing on the click

11. 11
ApplicationsApplications
Let us look at the keysLet us look at the keys

12. 12
Key’s functions - 1Key’s functions - 1
• The cool key is used for starting the cool &The cool key is used for starting the cool &
cold pain threshold testing. It is also usedcold pain threshold testing. It is also used
as a reduce key in other settings.as a reduce key in other settings.
• The warm key is used for starting theThe warm key is used for starting the
warm & heat pain threshold testing. It iswarm & heat pain threshold testing. It is
also used as a increase key in otheralso used as a increase key in other
settings.settings.

13. 13
Key’s functions - 2Key’s functions - 2
• Set key is used to see desiredSet key is used to see desired
temperature. It also starts thetemperature. It also starts the
communication to the computer. Incommunication to the computer. In
combination with cool / warm keys thecombination with cool / warm keys the
settings can be decreased or increased.settings can be decreased or increased.
• Program key is used to see the programProgram key is used to see the program
or change it with cool / warm keys. It alsoor change it with cool / warm keys. It also
aborts the on going test process &aborts the on going test process &
computer communicationcomputer communication

14. 14
Program 0 to 2Program 0 to 2
• In these three programs the probe is inIn these three programs the probe is in
contact with skin at the location to becontact with skin at the location to be
tested.tested.
• The program starts with the baseThe program starts with the base
temperature.temperature.
• For cool side testing generally 34 CFor cool side testing generally 34 C00
isis
default setting. Whereas 30 Cdefault setting. Whereas 30 C00
isis
preferred for warm side testingpreferred for warm side testing

15. 15
Program 0 to 2 – Cool Testing - 1Program 0 to 2 – Cool Testing - 1
• Press the cool key.Press the cool key.
• Temperature reaches the cool base ie 34Temperature reaches the cool base ie 34
degreesdegrees
• Keep pressed the cool button.Keep pressed the cool button.
• The temperature starts dropping.The temperature starts dropping.
• Ask the patient to say yes when he feels coldAsk the patient to say yes when he feels cold
• On receiving “YES” response the key is releasedOn receiving “YES” response the key is released
and then warm key is kept pressed to increaseand then warm key is kept pressed to increase
the temperature.the temperature.

16. 16
Program 0 to 2 – Cool Testing - 2Program 0 to 2 – Cool Testing - 2
• Now ask the patient to say NO when he loosesNow ask the patient to say NO when he looses
the cool sensationthe cool sensation
• On receiving the “NO” response to the stimuliOn receiving the “NO” response to the stimuli
change the direction til you get YES again.change the direction til you get YES again.
• For fine testing test five timesFor fine testing test five times
• It gives five pairs of YES & NOIt gives five pairs of YES & NO
• The average of all is the absolute cool detectionThe average of all is the absolute cool detection
thresholdthreshold

17. 17
Program 0 and 1Program 0 and 1
• In program zero the rate of change ofIn program zero the rate of change of
temperature is fixed to 1 Ctemperature is fixed to 1 C00
per second.per second.
Simple and fast suitable for screening.Simple and fast suitable for screening.
• With program one the rate of change ofWith program one the rate of change of
temperature can be set from 1 Ctemperature can be set from 1 C00
per 1per 1
second to 8 seconds. One can get slowersecond to 8 seconds. One can get slower
but more accurate thresholdsbut more accurate thresholds

18. 18
Program 2Program 2
• Program Two is a combination of previousProgram Two is a combination of previous
programs.programs.
• Here the rate of change of temperatureHere the rate of change of temperature
reduces by half every time there is areduces by half every time there is a
change in direction.change in direction.

19. 19
Program 2Program 2
• One can thus reach near the thresholdOne can thus reach near the threshold
quicker and then detect it accurately withquicker and then detect it accurately with
slower rates of changeslower rates of change
• This allows for adaptation to the effect ofThis allows for adaptation to the effect of
latency of 500 msec of these fibers tolatency of 500 msec of these fibers to
carry sensations.carry sensations.

20. 20
A typical graph of program 2

21. 21
Program 3Program 3
• From program three on words the methodFrom program three on words the method
of testing changesof testing changes
• The desired temperature is presetThe desired temperature is preset
• On reaching that temperature one big LEDOn reaching that temperature one big LED
lights up.lights up.
• The probe is then touched to the skin atThe probe is then touched to the skin at
appropriate locationappropriate location
• Two beeps are heard after Five Seconds.Two beeps are heard after Five Seconds.

22. 22
Program 3Program 3
• After these beeps the response from theAfter these beeps the response from the
person should be elicitedperson should be elicited
• The next temperature setting has to beThe next temperature setting has to be
decided.decided.
• The desired temperature can be set byThe desired temperature can be set by
pressing the “Set” key and “Cool” orpressing the “Set” key and “Cool” or
“Warm” key to decrease or increase the“Warm” key to decrease or increase the
set temperature.set temperature.

23. 23
Merits of Program 3Merits of Program 3
• Suitable for most of the test methods likeSuitable for most of the test methods like
method of limits,method of limits,
constant stimuli,constant stimuli,
adjustment andadjustment and
any other method to be implemented throughany other method to be implemented through
computer.computer.

24. 24
Probe is away from the locationProbe is away from the location

25. 25
Now the probe is touched to the footNow the probe is touched to the foot

26. 26
Program 4Program 4
• Program 4 is same as 3 with an addition ofProgram 4 is same as 3 with an addition of
step temperature.step temperature.
• On pressing both “Set” & “Prg” keysOn pressing both “Set” & “Prg” keys
simultaneously the step is displayed.simultaneously the step is displayed.
• It can be increased or decreased byIt can be increased or decreased by
pressing “Warm” or “Cool” key additionallypressing “Warm” or “Cool” key additionally

27. 27
Program 4Program 4
• To start the test - Press the “Cool” key for coolTo start the test - Press the “Cool” key for cool
side testing as before and release.side testing as before and release.
• The set temperature will reduce by one step. I.e.The set temperature will reduce by one step. I.e.
if the step is 1 Cif the step is 1 C00
and set temp. is 34 Cand set temp. is 34 C00
then thethen the
temp. will become 33 Ctemp. will become 33 C00
• It will reduce by 1 degree every time we pressIt will reduce by 1 degree every time we press
the “Cool” keythe “Cool” key
• Pressing “Warm” key the temperatures will risePressing “Warm” key the temperatures will rise
in the same manner.in the same manner.
• Most suitable method for method of limits. AndMost suitable method for method of limits. And
method of adjustmentsmethod of adjustments

28. 28
Program 5 & 6Program 5 & 6
• These programs are designed for theThese programs are designed for the
most popular and trusted method themost popular and trusted method the
successive approximation or 4,2,1 methodsuccessive approximation or 4,2,1 method
• Program 5 is for cool or warm thresholdsProgram 5 is for cool or warm thresholds
• Program 6 is for cold or heat pain.Program 6 is for cold or heat pain.
• Therefore in prg 5 the starting step is 2 CTherefore in prg 5 the starting step is 2 C00
• It is 8 CIt is 8 C00
in program 6.in program 6.

29. 29
Program 5 & 6Program 5 & 6
• On pressing the “Cool” key the temperatureOn pressing the “Cool” key the temperature
drops by 8 Cdrops by 8 C00
• If the response is YES for cool press “Cool” keyIf the response is YES for cool press “Cool” key
• The temperature will rise by 4 CThe temperature will rise by 4 C00
• If the response now is warm then on pressingIf the response now is warm then on pressing
the cool key again it will decrease further by 2 Cthe cool key again it will decrease further by 2 C00
• For every reversal the step will reduce by halfFor every reversal the step will reduce by half
and zero in on the threshold.and zero in on the threshold.

30. 30
A typical plot of prg 6A typical plot of prg 6

31. 31
Program 7 & 8Program 7 & 8
• In program 7&8 theIn program 7&8 the
skin temperature isskin temperature is
displayed when thedisplayed when the
skin probe isskin probe is
attached to theattached to the
connector in the frontconnector in the front
and then touched toand then touched to
the appropriate skinthe appropriate skin
area.area.

32. 32
Base temperaturesBase temperatures
• One can change the cool base and HeatOne can change the cool base and Heat
base temperature in program 7&8base temperature in program 7&8
respectively.respectively.
• It is done in the same way as one changesIt is done in the same way as one changes
the set temperature in earlier programs.the set temperature in earlier programs.

33. 33
The report -1The report -1
• When the computer is connected theWhen the computer is connected the
report can be generated through it.report can be generated through it.
• When the tab is in appropriate locationWhen the tab is in appropriate location
even by double clicking on the temp theeven by double clicking on the temp the
data is transferreddata is transferred

34. 34
The report - 2The report - 2
• By clicking “report” one can see theBy clicking “report” one can see the
tabular reporttabular report
• By clicking “show graph” one can see theBy clicking “show graph” one can see the
graphical format.graphical format.
• Any of the reports can be printed byAny of the reports can be printed by
clicking on print buttonclicking on print button

35. 35
On double clicking the probe temperature the data is transferred to bigOn double clicking the probe temperature the data is transferred to big
toe field. No typingtoe field. No typing

36. 36
Click on report button and see the reportClick on report button and see the report

37. 37
Show graph will show graphShow graph will show graph

38. 38
AverageAverage
• The total and average is automaticallyThe total and average is automatically
done.done.
• But for individual point if you need to takeBut for individual point if you need to take
the averages one needs to do it manuallythe averages one needs to do it manually

39. 39
We have developed similarWe have developed similar
report format for VPT asreport format for VPT as
wellwell

40. 40
Sensitometer VPTSensitometer VPT