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Author
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Topic: GSR Problem
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LSUPoly
Member
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posted 07-25-2005 11:26 AM
  
I ran a test the other day on a subject who was injured in a motorcycle accident last year and has pins in his hip. The first time he came in to be tested I sent him home because he was in pain. He is prescribed Loratab, for pain and takes this medication daily. He went to the doctor after I sent him home and they are going to operate on him in the future.The second time he came in for his test he told me he had taken two Loratab, a total of 20mg at 0730hrs. I began the pre-test at 0845hrs. He had no comprehension problems and appeared focused and alert although relaxed. I ran a ZCT and the first two charts were OK. He showed reaction in all three components. On the third chart the GS reading started to mirror his breathing. I ran a forth chart and the GS did the same thing. I use a Lafayette LX 4000 and have never had this happen. Has anyone had a case where you GS reading mirrored the respiration on your chart? If so do you know why? I checked the finger plates and repositioned them, which helped for about 30 seconds then it started again. The respiration did not change during the test(no deep breaths) except when reacting to a question. Good charts except for the GS. Any opinions or advise is appreciated. Ben IP: Logged |
Capstun
Member
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posted 07-25-2005 01:34 PM
I initially tried the Lafayette instrument when I first became an examiner and quickly abandoned it because of the lousy GSR. I use a Stoelting and have had virtually no GSR problems. Last year I switched to the disposable electrodes and place them on the palm, at the base of the thump and toward the bottom, near the blade of the hand. I can't remember exactly who recommended this placement to me, but I think it was Frank Horvath (the older I get, the more the memory goes). I was advised there are a lot more sweat glands here and the area is less prone to distortions. I have been using them for about one year and have yet to have a plunging GSR or any distortions. It seems to be unaffected by slight movements of the hand. I highly recommend the disposable electrodes. They are not that expensive and make the world of difference.
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Barry C
Member
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posted 07-25-2005 03:03 PM
It's Lortab, a generic form of Vicodin, a narcotic. Oddly, Lafayette's drug reference says it has no effect on EDA.IP: Logged |
LSUPoly
Member
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posted 07-25-2005 03:08 PM
I had lousy GS with the LX 3000 but have had great GS with the LX 4000. I don't think this was related to the hardware, but I don't know. Could be the drugs or something else. I was just hoping someone else had seen this type of recording before.Ben IP: Logged |
J.B. McCloughan
Member
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posted 07-25-2005 10:14 PM
Before I take a stab at this question, I need some more information.1. What were the sensitivity settings for the respiration and EDA channels? 2. What were the ohms readings on the EDA? If you are not already using them, I highly recommend the disposable EDA tabs. You can purchase the lead and disposable tabs from Lafayette. In my opinion, it greatly reduces much of the movement artifacts seen in the permanent tabs.
[This message has been edited by J.B. McCloughan (edited 07-25-2005).] IP: Logged |
LSUPoly
Member
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posted 07-26-2005 09:42 AM
The sensitivity settings for the charts where this occured are #1 P1-1.0, P2-1.5, GS-0.5, ohm avg-365k, min-250k, max-568k#2 P1-1.0, P2-1.5, GS-1.1, avg-455k, min-438k, max-467k Hope this is what you need.
Ben IP: Logged |
J.B. McCloughan
Member
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posted 07-26-2005 11:37 AM
He has average to moderately high resistance or low conductivity in the EDA and, judging from the respiration settings, he was breathing quite deeply. So most likely, the deep breathing was causing a response in the EDA. Just my opinion and I have seen it with both deep breaths and consistently controlled deep breathing.[This message has been edited by J.B. McCloughan (edited 07-26-2005).] IP: Logged |
Bob
Member
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posted 07-27-2005 12:00 PM
Ben;
As J.B. indicated in his post, the low respiratory sensitivity setting of 1.0, suggests the person was engaging in ‘deeper than normal breathing;’ and may have shown compensatory cardiovascular blood volume changes as well (giving the cardio a rolling affect). If the EDA response was consistently occurring following a latency period of about 1.8 (and up to ~4 seconds) after the onset of inhalation, then you can be pretty assured the response was respiratory artifact. EDA responses occurring after that ‘time window’ is a scoreable reaction (up to ~5 seconds after his verabl answer). However, a scoreable EDA reaction maybe superimposed on a respiratory artifact (giving a ‘complex’ or ‘double saddle’ appearance.) The superimposed portion of the ‘complex’ EDA reaction is ‘scoreable’ (however, personally I do not do so unless the respiratory EDA artifact has ‘decayed’ at least 50 %).
The fact you received respiratory induced EDA responses, gives credence that the person has the ‘ability’ to react to posed CQ-RQ questions as well. Curious to know:
[1] what the average respiratory rate and heart rate was? [2] was the EDA recorded in ‘manual mode’ or ‘Auto mode;’ [3] what was the average ‘amplitude’ (in chart divisions) for the EDA / respiratory artifact; considering the EDA sensitivity setting of .05 seems on the rather ‘low’ end too [4] did you inspect both Manual/ Auto mode after 'boosting' the EDA sensitivity level? [5] don’t forget to take a look see at Polyscore Processed ‘EDA Group’ mode— it will give three trace lines: an EDA derivative line, Manual mode line, and Auto mode line all on one display per chart selected and sometimes makes data evaluation\comparison easier. Bob IP: Logged |
Ted Todd
Member
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posted 07-27-2005 08:29 PM
Barry C,Vicodin does not surpress pain, it attaches to the part of the brain that recognises and responds to pain. In other words, it makes you too stupid to know you are in pain.I am wondering how accurate Lafayette's opinion is on this? Any thoughts? LSUpoly, Do a google search on Vicodin and you will see how powerful this stuff is. It is quickly becoming the #1 abused drug in the USA today. It is highly addictive. I don't doubt for a minute that it would invalidate an exam. Ted [This message has been edited by Ted Todd (edited 07-27-2005).] [This message has been edited by Ted Todd (edited 07-27-2005).] IP: Logged |
rnelson
Member
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posted 07-28-2005 03:25 PM
This client is arguably neurologically compromised due to pain and medications.I'm not sure I'd say that the med invalidates the exam. The results might still mean exactly what they appear to mean. However they might compromise his testability or the data quality. I call it a qualifying factor, as the test subject cannot be considered a completely neurologically normal persons, and review the data quality. I've seen a few dampened test charts from pain patients, taking Lortab and other narcotic derivatives. These medications are very abusable (even by radio talk-show hosts). I'll post a picture this evening. I'll also post some recent CM markups. r IP: Logged | |
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