1. OurJud
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    OurJud Contributing Member Contributor

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    Human tag / tracker

    Discussion in 'Research' started by OurJud, Aug 15, 2015.

    In my novel, one of the characters has been fitted with a tracker of the 'under-the-skin' variety. This means writing a scene where a DIY operation is performed to remove it.

    On the off chance we have any vets or medical students in the room, can I ask a few questions:

    What might be the procedure for implanting a tracker?

    Where (on the body) ?

    How deep under the skin would it go?

    Thank you in advance.
     
  2. Sifunkle
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    Sifunkle Dis Member

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    From my understanding it's a little more complicated than this, unfortunately. My impending ramble may not immediately help, but perhaps the background is useful. (Grain of salt: I'm no world expert.)

    In animals, GPS trackers are mostly used in wildlife studies. Whether they'd be implanted might depend on the size of the equipment vs the animal, but from what I've seen they're generally affixed externally. For two reasons: anything invasive has questionable ethics (and everything involving science, animals and ethics needs to pass an ethics committee), and surgically implantation is likely to slow the animal as it recovers (as trackers are usually placed for behavioural study, by altering that behaviour you shoot yourself in the foot). Often they use harnesses/glue/whatever to affix the tracker onto the outside somewhere, and it's assumed that at some point it will fall off. If possible, you retrieve your gear before the battery runs out and it can no longer be found.

    They are sometimes surgically implanted. E.g. a captive animal already being anaesthetised/having surgery for something else (perhaps prior to release to the wild). Also, in some animals implanting may be less of a compromise than external fixation (e.g. a shark, where the latter would reduce streamlining). So you assess risks and plan in line with other management.

    I'm not a tech-head so maybe not up-to-date, but from what I've seen trackers are larger than you'd expect - I presume because they're mostly used in wildlife --> there's no money in wildlife --> there's no incentive for companies to develop smaller gear. Perhaps also because they need to be robust to remain functional (also something that could be ironed out with development). I think I recall seeing a tiger (doco, not IRL) have something around the size of a small mango surgically implanted.

    Being this realistic (assuming I'm actually right) may not help your novel much. If it's set in the near future, perhaps you could assume that trackers have shrunk (as most technology does), and can be treated like current microchips (around 12 x 3 mm; although they're shrinking too, and truly miniscule ones might soon be used). I found this article: Human microchipping

    Happy to talk more about how microchips are implanted in animals if you like - there may be some principles applicable to your presumably-unwilling recipient - but this reply is already getting pretty long :)
     
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  3. OurJud
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    OurJud Contributing Member Contributor

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    Yes, sorry, I neglected to mention this. The trackers in my future are very small, pill capsule-size.

    Thing is, although this is future-set, giving me carte blanche, I still like to keep things at least moderately plausible.

    I suppose what I'm trying to find out is would the tracker be implanted just under the skin, using the same kind of chipping gun vets use to insert ID chips into dogs, or would an incision be made?

    Logic tells me the former, to avoid possible infection, but I wanted to make it a little more difficult for my characters to perform the DIY removal.
     
  4. Aaron DC
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    Aaron DC Contributing Member

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    If you want to make it difficult to remove, have it embedded in a bone. Skin deep implants are removed so often in movies it's a given that's what they would do.
     
  5. OurJud
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    OurJud Contributing Member Contributor

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    I said difficult, not impossible :D

    But I see where you're going.
     
  6. Sifunkle
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    Sifunkle Dis Member

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    Ah great, you've already given it a fair bit of thought :)

    My opinion is that you'd want something more secure than under-the-skin (= subcutaneous). It could potentially still be done with a needle (that's all a vet's chipping gun really is), but a surgical implant wouldn't be out of the question.

    The subcutaneous tissue between the shoulder blades is standard for cats and dogs (in my country anyway), largely because 1. it's not an area that's stressed by the animal's normal motion, and 2. they aren't set up to scratch/chew at that area. However, if chips are injected off-centre or jostled too much prior to scarring in place, a common problem is that they migrate along 'fascial planes', usually ending up somewhere from shoulder --> forelimb --> chest. I.e. they're not held there particularly securely. I think it would be quite easy for a person to dig a subcut one out. But the flipside is that if it's migrated, it might be a bitch to find... (hint: if scanning fails, x-rays).

    Microchips go differently in other species. In horses, they're injected into the muscle in the neck. Shoulder placement probably interferes with saddling, etc. In birds, you generally incise the pectoral muscle (= chest/breast), implant and suture up. Birds move their whole bodies a lot, so implanting into muscle secures it. (I suspect surgical is done because birds are small and delicate, so blindly shoving a big needle in is risky.) Perhaps a muscle implant is the way to go. I'd be pretty reluctant to go digging through one of mine. You could pick an inconvenient muscle: e.g. forearm would limit use of that hand (although those muscles move around a bit, so you'd risk slower healing and/or possibly chip movement if unlucky).

    Whether injected or surgical is fairly moot IMO: aseptic technique would be used either way so infection risk should be minimal, and the principles are the same (= cut through tissue, place microchip +/- suture to close hole). The biggest infection risk might be the character poking and prodding at the wound afterwards, which would happen either way.

    That leads to another point: how long after implantation is the character going to remove it? Subcutaneous probably matters little (unless it migrates), but in muscle it might be easier early on (before the injection tract scars over, or if surgical, while there are convenient sutures that can be pulled out so the wound 'falls open' - but then how does the character close the wound again without raising suspicion?). So you may want removal to be impossible for a few weeks while the implant wound heals. If you wait a long time, the character might not be sure where it is any more (either forgetting, or because it's migrated).

    If you really want to make things difficult, you could come up with something like an 'abdominal wall chip-opexy' (cutting belly open, incising into inner muscle of abdominal wall, suturing chip in place, suturing belly closed). It could probably be done endoscopically, so not necessarily major surgery, but I sure don't know many people who'd be willing to open their abdominal cavity to fish for a chip (... there's a 'fish and chips' joke there somewhere...). But that'd be specialist stuff, so if chipping people is standard I don't think it's realistic.

    Same for @Aaron DC 's bone suggestion. Technical, maybe time-consuming, many major risks, slow to heal up. But it sure as hell wouldn't come out in a hurry (which would be a huge problem if infection were to occur...).

    Anyway, I've been incredibly long-winded (sorry, was having fun). Hopefully somewhere in that stream-of-consciousness mess I might have come within a few miles of being remotely helpful.
     
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  7. AspiringNovelist
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    AspiringNovelist Contributing Member

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    If I were the Sinister Mind (Evil Overlord) -- I wouldn't place any tracker under the skin for two reasons:

    1. It's not visible from a distance,
    2. It could be removed and sat aside.

    In my Sinister Mind -- I'd make a tracker like a choke collar. It can be seen from a distance by my henchmen and if it's removed, an electrical circuit is broken which throws an alarm. Of course, there's always the "off with their heads" tie-in to Queen of Hearts.
     
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  8. OurJud
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    OurJud Contributing Member Contributor

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    That's a great whole bunch of extremely helpful info, Sifunkle. Thanks very much!

    I'm definitely drawn to the incision / muscle implant.

    To answer a few of your questions. The removal would take place maybe 18 months or so after insertion, and the guy would be assisted by a friend when performing the procedure.

    Would a sharp knife, skin glue and surgical wipes be plausible, in order to prevent infection? They have no medical connections or knowledge, so the kind of equipment they could steal / buy from a chemists would be their only option.
    It's a GPS tracker, AN, so no issues with distances.
     
  9. AspiringNovelist
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    AspiringNovelist Contributing Member

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    Right, but the GPS tracker device could be pulled and set aside. So, as an evil overlord I wouldn't put it under the skin. :) And, of course, I would have an awesome evil laugh: Mwahahaha...
     
  10. OurJud
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    Agreed. That's why I'm so drawn to the alternative offered by @Sifunkle - incision / muscle implant.
     
  11. OurJud
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    In addition to these, Sifunkle, where would be a likely place for the implant? And would there be lots of blood during removal?
     
  12. Sifunkle
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    If you go the muscle route, I think the site is largely up to you. It might depend on the character's physique a bit, but you probably want a muscle that doesn't move heaps when used, or where use can be avoided in daily life. Have a poke around your own body. I kinda like the pectoral option (as per birds) if it's a male character, although there are also decent muscles on the neck (as per horses). Maybe even buttock? Sitting might hurt...

    18 months after implantation, muscle would have healed as much as it's going to. Muscles have a structure like a rope: a bundle of parallel fibres, except not twisted. If implantation is surgical, they'd cut parallel to the fibres to split them apart rather than actually severing them. Conversely, jabbing a big needle in will sever fibres. Severed fibres heal by breaching gaps with scar tissue (less functional than the original muscle tissue, so healing is never optimal). So once your characters get through the skin/subcut tissue and see muscle, there might be an obvious discoloured blemish (if injected), or the muscle may appear mostly normal (if surgical with good technique).

    I suspect if faced with an obvious muscle scar (i.e. needle tract) most would dig through it to find the chip. The better approach would probably be to part fibres by cutting parallel to them (ditto if no needle tract). They'd want a fine blade to give better precision/less collateral damage. Assuming your characters can't suture... hmm... perhaps a nice tight bandage going perpendicular to the incision line would hold the muscle together and wound shut. Keep as immobile as possible for a good long while, probably need to change bandage regularly as the wound discharges. Skin glue can be fairly inflammatory in other tissues, but whether your characters know this... A thought: would it be possible for them to get professional help once they've disposed of the chip? ("I appear to have hurt myself entirely innocently: stitch me up Doc!")

    It will be a fairly bloody process, so gauze swabs should be on the shopping list (mostly for dabbing away blood to see what you're doing; also to apply pressure on haemorrhages). Muscle has a big blood supply, but the vessels are mostly tiny capillaries, so you tend to get ongoing ooze rather than gushing haemorrhage. There are always other vessels around though, so 'squirters' do happen. If they're cautious, they'd be unlikely to cut a major artery.

    In terms of minimising infection risk (aseptic technique), I reckon shave away hair, scrub thoroughly with some kind of soap/detergent to get rid of dirt, then skin swab (prepackaged wipes would probably be appealing to a layperson? but they could also use cotton wool + a disinfectant - chlorhexidine or iodine probably most commonly available). They'd also want to treat the blade prior to using it - boiling isn't the best, but probably reasonable for a metal blade; or if they bought a bottle of disinfectant (e.g. chlorhex solution) they could soak it in that for a while. It should be thoroughly scrubbed prior.

    Long hair should be tied back. Doubt they'd bother with cap or mask, but they might be available... They should scrub their own hands/arms with disinfectant (including picking out crud from under nails, which are hopefully short) immediately before they start. Sterile gloves ideal, but maybe not available.

    I think painkillers would be on the shopping list. Most over-the-counter stuff probably wouldn't be remotely strong enough. Are local anaesthetic sprays available in chemists? They could try spraying as they go, but it won't kick in immediately. Alcohol might reduce capability somewhat (not sure it's a fantastic painkiller anyway), as would heroin... but there's always post-operative pain to consider. Plenty of oxycontin, etc gets scammed from pharmacies, so maybe that's an option too. Or maybe they just go old-school with no pain relief (how to characterise a badass).

    I've tried to think 'best practice given the circumstances', although I certainly wouldn't expect laypeople to cover everything I've mentioned. I might not be the best person to judge what would or wouldn't occur. Anyway, my bedtime - happy to answer further questions, but it will have to be a bit later on. Good luck!
     
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  13. OurJud
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    OurJud Contributing Member Contributor

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    Excellent stuff! Thanks, Doc!
     

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