View Full Version : pH - will anyone be the first penguin in the water?
Browsing eBay, I came across this small pH meter.
http://cgi.ebay.com/New-Great-Portable-ATC-pH-Meter-with-FREE-pH-buffer_W0QQitemZ7555360233QQcategoryZ26237QQcmdZVi ewItem
It doesn't seem like the regular desktop pH meters I recall from my lab days, so there's a part of me that is skeptical of it.
I wouldn't be that interested if all I wanted to do with it was get urine pH's.
But it also occured to me that having a pH meter in a fixed location could be helpful in the preparation of medicine and supplies - particularly if they need to be pH adjusted or buffered - if it's a REALLY long-term predicament, and you're determined to pursue a pretty sophisticated community effort.
I suspect you need to be able to calibrate it with buffers, and probably need to maintain some kind of wet environment on the electrode - presumably at some pH. This would probably also mean having the wherewithal of preparing standard buffer solutions by weight/volume.
http://www.vernier.com/probes/index.html
-t
Vernier carries a pH electrode. You still need something to connect the electrode to, which will operated the electrode and display the pH, etc. The data listed by Vernier for the electrode discuss a range of pre-amplified voltages in the positive to negative range, but a different range of amplified voltages across the pH range. I suspect you could improvise the power supply, as well finding a way to display a useable voltage, if you were able to interpret that voltage into a pH.
They also indicate several different versions of the electrode - to fit pH units which they apparently do not stock. However, they do have some information on ordering it in a configuration to use with common electronic boxes they think purchasers might already own:
http://www.vernier.com/adapters/index.html?bta_connection=none&din_connection=none&photogate_connection=none&other_connection=none&sbi.x=73&sbi.y=8
take a look at the other probes listed...
EKG (in your pocket), temp probe, radiation monitor, etc. Seems like some of the other chem probes might be useful to lab work. Think a CBL / TI calc could be a good addition to a kit... what other probes do you see there that could be pressed into lab work?
vernier and TI also have "open" digital interfaces and provide information so people can create custom probes and sensors - they encourage this.
-t
ps: if you want to go really low tech, there is info on the board about making pH indicators out of cabbage and such...
take a look at the other probes listed...
OK - I didn't fully get the idea of what they feature the first time - I'm with you now. Somehow I mistakenly imagined comparing the price of the Vernier pH electrode to the eBay item that has minimal cost (but is a stand alone). Ergo - my reply did not make that much sense.
EKG (in your pocket), temp probe, radiation monitor, etc. Seems like some of the other chem probes might be useful to lab work. Think a CBL / TI calc could be a good addition to a kit... what other probes do you see there that could be pressed into lab work?
Keep in mind that I'm likely to answer along the lines of what I'd like in a fixed location taking care of a group of people for a long time, more than a 3 day hiking excursion. I'm clearly not insisting that everyone have these sorts of things for all missions.
Going down their list in order:
CO2 sensor - hard to tell how adaptable it is - but if you were ventilating someone during general anesthesia, it would be handy to have exhaled CO2, or a way of seeing end-tidal CO2 - that would allow you to confirm placement of your endotrachial tube in the esophagus, as well as give you a surrogate for blood CO2 levels - ie - a way to adjust your ventilation. ACLS situation? Many of the rescucitation situations I imagine would not have good outcomes far away from definitive care (if you can claim that we have good outcomes that often even when close to definitive care - but I digress). There's also a triage decision to be made about consuming limited supplies in someone who is already down. IOW - I don't picture using exhaled CO2 in a rescucitation situation.
The Colorimeter looks interesting - it gives you 4 wavelengths - 430 nm, 470 nm, 565 nm, 635 nm. The question is whether you can find clinically useful assays which have absorption peaks at or close to those wavelenths AND are also more or less sustainable assays for some period of time. FWIW - the Drabkin hemoglobin method gives an absorption peak at around 530-540nm. The 565nm wavelength *might* miss it enough to prevent it from being used for hemoglobin/Drabkin. OTOH - it might be close enough to get acceptable linear results. You'd either have to try Drabkin hemoglobin at 565nm - or look at how wide the absorption peak at 530/540nm is. If so - I think I'd try to find a way to wrangle the opportunity to do it on someone's lab spectrophotometer before buying this colorimeter (you'd be able to set the wavelenght to 565nm on a real spec). Since it's not essential to get results reliable to 3 digits, I'd settle for a whole number on hemoglobin, even with a +/- 1 margin -- if you could rely on that. That won't meet a QA/proficiency program goal, but it would still be useful. Next, you'd have to think about other assays to be interested in having, and then looking for different assays that operate at/near one of the available wavelengths.
FWIW - after glucose (by any method), potassium (most likely by selective ion electrode - see below) - the blood chemistry result I'd most like to have after that would be either BUN or creatinine. So I'd think in terms of a glucose assay that could be sustained beyond the life of glucose strips, that would also run at one of the 4 available wavelengths. And then I'd look for a BUN or creatinine assay that would meet the same criteria.
EKG might be worthwhile - it looks as if you'd get rhythm in your 3 limb leads. Since they are talking about this as being for teaching purposes/experiments, you might assume that's all for legal reasons (and to not submit it to the FDA for clearance - hence - reasonable price). However, it's also possible - maybe even likely - that there is not circuitry to isolate the patient from the electronics. Clinical EKGs are usually optically isolated from the patient. In the wrong circumstances, that's a shock hazzard - to the patient AND to the electronics. Is that good enough for thoughtful/careful use in austere circumstances? Everyone needs to make their own decision, but I'd guess it probably is. YMMV - so don't blame me on that one.
pH we're already talking about.
Spirometer might be OK. It wouldn't be at the top of my list. I'd certainly settle for a good old hand-held peak flow meter, but a spirometer for a fixed location with people who have chronic illnesses - could be nice. Especially if it didn't require it's own suitcase.
Turbidity Sensor might be useful - but ONLY if you are aiming for a pretty sophisticated lab. Example - even if you're not trying to do bacterial identification by culturing on differential agars and doing the various steps to differentiate bacteria, it's actually easier to get antibiotic susceptibility results via a bacterial sub-culture on a new plate onto which you drop paper disks of antibiotics. The catch is that you need an approximately standard number of bacteria to suspend in liquid prior to plating the suspension evenly over the agar plate. This is because you are going to measure "zones of inhibition" around each antibiotic disk, and compare them to a table of expected results that allow you to predict the bacteria is sensitive or resistant to the antibiotics. The measurements are invalid if the antibiotic in the disk is not the standard amount, and also if the number of bacteria is WAY off. Making your bacterial suspension is commonly done by having a turbidity standard -- basically a tube that is made to have a specific turbidity. You visually compare your bacterial suspension to the turbidity standard, and that results in having the correct level of bacteria in your suspension. The problem is that the turbidity standards eventually go bad. If you had a turbidity sensor - you could simply vary your bacterial suspension to the correct turbidity. I suppose you could also make up turbidity standards, and conduct trades with other groups of people.
I think I'd personally prefer to use the interface box with a Palm - more things I can do with the Palm, besides whatever sensors are hooked up to the interface box.
vernier and TI also have "open" digital interfaces and provide information so people can create custom probes and sensors - they encourage this.
The "open interfaces" might be appealing. Other than doing flame photometry or selective ion electrodes, it's pretty hard to get serum potassium. A potassium electrode would be like the pH electrode - if you could connect one to the interface box and have the appropriate data conversion in your calculator/computer.
FWIW - there are some reflectance spectrometers (like glucose meters - they operate on strips with a patch of chemical on the strip) that can give potassium measurements. AMES at one point made the Seralyzer (it has not been supported with new reagents or service for 10 or 15 years - organizations that supplied medical missions used to collect them from physician offices), and I'm not sure about the Reflotron. There is a currently produced reflectance spectrophotometer that is being used in soil/water chemistry, brewing and oenology -- http://www.midwestvineyardsupply.com/ProductList.asp?categoryid=23&subcatid=111&cat=Refllectoquant&Type=True
It can measure potassium (giving results in ppm), but has a significant interferance when sodium values are a lot higher than potassium (which is exactly the problem in serum/plasma chemistry - sodium is *much* higher than potassium). I had some experience with the Ames Seralyzer, and the potassium results were OK, but not dead on accurate. Potassium has a narrow range of healthy serum values, so even small uncertainties raise my anxiety level.
The reflectance technology strips also use exotic chemicals to complex potassium. They're not sustainable, and don't have a great shelf-life.
I mention the reflectance specs for potassium mainly for completeness of discussion - I really think an ion selective electrode is the only way to go -- if you go at all on potassium. Potassium is also very high on my list of desired tests - even though I have believed it would have to be eliminated from a list of tests under auster circumstance. I certainly don't see flame photometry making a comeback under austere circumstances.
Other than being able to measure serum/plasma potassium, you're next bet is probably to look at the T waves in your EKG (for hyperkalemia). I've always found the textbook hypokalemia findings on EKG to be less common, and not as helpful.
if you want to go really low tech, there is info on the board about making pH indicators out of cabbage and such...
I'll have to look for that - I haven't seen it so far.
WolfBrother
10-26-05, 21:44
WB edited for specific sentence
Keep in mind that I'm likely to answer along the lines of what I'd like in a fixed location taking care of a group of people for a long time
DrBaboon,
I've very much appreciated your information. My main concern for lab work is a long term SHTF to possibly TEOTWAWKI situation. Somewhat like the situation in Lucifer's Hammer where the Female Russian Cosmonaut Doctor was having to do xmatch compatibilities by mixing drops of blood from two donors in saline and recording the results on 3x5 cards.
If you've read the book Lucifer's Hammer, you know what I'm talking about.
If not PM/email me and I'll give you a brief book report as to what happened and how the above mentioned Dr got where she was.
Thanks,
WolfBrother
OK - I have not read Lucifer's Hammer - I plead ignorance.
Is a PM enough to clue me in sufficiently to try to post something that is applicable to what you are thinking about? Or is it something where I need to read the book (which I'm willing to do - it'll simply take x-amount-of-time before I'm up to speed)?
Are you looking for a panel of tests for a particular set of circumstances?
WB - before you write too much, look at the fiction section of the Austere med book... what you are talking about may or may not allready be covered.
-t
WolfBrother
10-27-05, 08:22
Tangent,
I had already written the following before reading your post. You're right about it being covered but since I've got this already, I'll include it.
Dr. Baboon:
You wrote:
OK - I have not read Lucifer's Hammer - I plead ignorance.
Is a PM enough to clue me in sufficiently to try to post something that
is applicable to what you are thinking about? Or is it something where
I need to read the book (which I'm willing to do - it'll simply take
x-amount-of-time before I'm up to speed)?
Are you looking for a panel of tests for a particular set of
circumstances?
I am looking for what can reasonably be expected in a 20th century community that has dropped back to a pre-Electric era. With a probable re-supply of pharmaceutical goods not expected for 1 to 2 years.
Or essentially what was found at Senator Jellison’s compound.
Here’s the short version of Lucifer’s Hammer.
A comet calves and hits the Earth. Multiple land and ocean strikes across Asia, Europe, Mediterranean Sea, Atlantic Ocean, US, Pacific Ocean. Millions of tons of sea water is vaporized. Huge Hurricanes are created.
Houston, NY city, Boston, Washington DC are gone due to Tsunami’s. Florida now has the part attached to the US and two new very large islands that used to be middle and lower Florida. The Keys were wiped clean. The San Andreas fault gave way. Rain is filling natural basins like Death Valley.
California Senator Jellison had previously announced a vacation and was at his ranch at higher elevations in California. After it hit and the first set of rains were occurring (HUGE DOWN POURS feet per day). The folks in the area around and in the small town close to the Senators ranch get organized.
Basically a 20th century community has dropped back to a pre-Electric era. The “bigger” town where the regional hospital was – is under water due to dam breaks.
A joint Russian/American science team of Cosmonauts and Astronauts sent up to gather scientific data about the comet manage to return to earth and get to Jellison’s compound. One of the Cosmonauts is a Doctor (in the story – happens to be female).
They gather up lab equipment from the local high school. Includes microscopes with mirrors – candles or sunlight for light. Instead of a centrifuge, She uses a stoppered tube in a sock twirled around. Cross Match compatibilities consists of drops of blood from two donors in saline in the stoppered tube – looks for clumped cells for incompatibility. Compatibilities are kept on 3x5 notecards.
In the story a real rocket scientist – described by other rocket scientists as the smartest guy in the world dies from diabetes because the compound could not spare a sheep a month nor did they have the high speed centrifuges needed to extract the insulin. Pressure cookers for autoclaves.
Several folks die from infected cuts due to no antibiotics.
There is a very large battle close to the compound with numbers of wounded with a large cannibal group.
The Wikipedia entry for this book is scant:
The story details a cometary impact on Earth, the end of the world, and the battle for the future. It encompasses the discovery of the comet, the LA social scene, and a cast of diverse characters whom fate seems to smile upon and allow to survive the massive cataclysm and the resulting tsunamis, plagues, famines and battles amongst scavengers and cannibals.
As you can tell, the book is a real The End Of The World As We Know It story. It does have a happy ending, they get electricity back in the end.
My question goes to long term planning.
Thanks for sharing your knowledge.
JTFowler AKA WolfBrother
I have been skipping around the Austere Medicine book - and based on the question about your hypothetical situation, I read the 2 fictions included in it today. The 2nd one (Apprentice) has some parellels to to what you envision.
I guess that I find it hard to talk about finding a way to do a lab test as an isolated point. I look at it as a far more integrated bunch of things. It's like a spread-sheet - you might change a value in a cell, and have the calculations shift throughout the spread-sheet matrix. Even though I have been talking about some tests above, whether or not I have said so as I mentioned the test, there was some mental consideration of hypothetical circumstances, my professional abilities, possible availability of treatment, equipment for treatment/intervention, etc.
My own first line of planning would be to evaluate the needs of my family or any other people I set out to care for. That's where I'd look to match some testing capability with treatments. And then build from there.
My sense is that as much as any of us might do the mental exercise of having *nothing* left in a disaster, in a sense, we really do have a number of things going for us. Unfortunately, we might not get it together for each patient fast enough.
What do I mean? Well - taking the "Apprentice" fiction... Alex had been at it for 10 years as the story begins. They had found some books, done some digging around, etc. Sure, light bulbs were pretty much used up.
At what point does cottage industry rise to the occassion?
IOW - what I'm talking about as assets are: 1) time; 2) regaining knowledge and skills; 3) finding tools.
I mean - if Edison could make a lightbulb in the 1800's, why can't someone manage to do the same thing sooner or later?
This stuff goes by bootstrapping - maybe you need some glass to blow and a means to heat it. Maybe you start with finding some old machinery. Maybe sand casting in the old style of the American West makes a comeback with wooden patterns pressed into sand.
I find it hard to imagine *no electricity* - ever again - not even in small amounts, some of the time, anywhere. If it's a burned out generator, rewind it. OK - it might take a long time, and you might have to find wire...
There's gotta be someplace/some way of using water power, wind power, whatever.
Personally, I find it gets overwhelming to think of doing everything yourself - none of us can.
I can picture a 3 month disaster or some other period of time, and collect stock to support needs I expect to encounter (knowing that I will in many cases guess incorrectly!). And after that - who knows.
If you're manufacturing pharmaceuticals, you need to find or make additional tools.
If you're only going to have ketamine, or lidocaine or possibly ether by drop as anesthetic agents - you're not getting into ventilating people for surgery, so even the stab I took at a CO2 detector above is no longer relevant (even if it wasn't a strong consideration when I made it above). However, that also means you're not going to do certain kinds of surgery. How likely would those surgeries be anyhow? Beats me. What I mean is that some surgeries are much easier with (and sometimes even need) neuromuscular blockade for relaxation. Will any of us have such agents available? If we do, we're going to need to ventilate the patient. It would suck to pull off successful surgery, and end up with a patient with an anoxic brain injury because we stuck the endotrachial tube into the esophagus and didn't recognize that we did so. Or is that patient dead anyhow, and not a situation where we would get into surgery for them if it's *that* kind of a problem that can only be addressed with more sophisticated surgery?
How important is blood sugar? Well - I've got it as my #1 blood chemistry. BUT - if you have no means to respond to the blood sugar, how much does having the blood sugar help? If it helps provide information for patient advice and prognosis, that may be a good enough reason to make use of it - even without the means to treat the patient. And perhaps austere times, diet change, weight loss, exercise, etc. ends up improving a type II diabetic - and no medications are needed. Do we have livestock available for meat - if not, then we really might not have a source of pancreas and thyroid for insulin and thyroxine. I don't know. Too many variables.
It's really hard to imagine functioning without a microscope, slides, coverslips, some stains, and a centrifuge and some test tubes (preferably pointy ended urine centrifuge/sediment tubes). And maybe a hemacytometer and the needed accessories. That's a great start.
Yet - I hesitate to be enthusiastic about candles as microscope light sources. It's easy enough to use a mirror instead of a light - the problem is how strong the candle light is, and whether it's giving us good "white light" - or if it has limited wavelengths. The reason I say that is that I recall the arguments people have over whether bacteria on the slide are gram positive or gram negative - especially if they are new to looking at slides, or have not gotten in practice doing the stains, or have iffy staining supplies. Change that equation by using weak candle light, that isn't true "white light," and you've got more fun than you want. Sunlight has been mentioned as a better choice by other folks on the board - I'd agree with that. Of course, weather and time of day will have their way with the availability of sunlight.
If such a disaster goes on for a LONG TIME - having apprentices is really important. I'd go so far as to say that some committment to training needs to start as soon as you're into the situation. None of us knows our own future or fate, and how long we'll be able to do our duty, or if we'll be available to teach next year. None of us can do all the healthcare tasks as a one man band.
How does that affect labs? Well - one reason to have more lab capability is to teach it to someone else - and to use it to enhance their apprenticeship.
Using a physician as an example... What I mean by "enhance their apprenticeship" is that there are things a physician can do because they have dissected at least one cadaver, have seen a bunch of x-rays, have made many clinical decisions and then seen the results the next day (or 2, or 3 or whatever). There's a learning curve to it. That also makes us get more efficient as time goes on - we don't need to check as many things to know how things will go. I could probably guess at how much potassium I need to give a patient with a bowel obstruction if they have a naso-gastric tube removing gastric contents. I might even make a decent enough guess without any labs being available. And I still might be unable to avoid a cardiac complication from low potassium. The problem is how do I teach that to 1-2-3 apprentices -- all without potassium measurements.
I can teach - even with nothing. I don't know that I'd demand potassium testing be available simply to teach. And I don't think you could justify using your last supplies for potassium testing simply to make a teaching point.
But that's also where time, manufacturing, digging things up, etc. comes in.
If someone is going to get into this area of healthcare, there's no reason you can't examine your own urine sediment. Or make your own peripheral blood smear and see what you can find in it, and do a differential white blood count. After you've done it 50-100-200+ times, you'll get the hang of it. Repetition matters. Sustaining the skills matters.
WolfBrother
10-28-05, 09:58
DrBaboon,
You're correct about lab studies not being an isolated item but part of a continium.
I did not express the situation as clearly as I should have:
I am looking for what can reasonably be expected in a 20th century community that has dropped back to a pre-Electric era. With a probable re-supply of pharmaceutical goods not expected for 1 to 2 years.
It should have read more like:
I am looking for what can reasonably be expected in a 20th century community that has dropped back to a pre-Electric era with some pockets of electricity (home generators, photovoltaic panels etc) immediately available. But reliable electricity generally available not for a year or two.
Lab materials available are what would normally be expected to be found in a small town high school science lab. If a local hospital/clinic is available, you'll have a small hospital/clinic in the town so much the better in terms of lab equipment/treatment facilities.
The year or two is not completely far fetched. The New Madid fault line in Southern Illinois and the Yellowstone super-volcano are two areas that could cause 1 to 2 year disruptions on a wide scale.
Also
The folks in the area around and in the small town close to the Senators ranch get organized.
This should have been expanded to include - those with skill were identified and assigned to their areas of expertise. Those few nurses and other folks with medical training were set to establishing community health services.
This shows organization and the requirement to NOT have to do everything - like you mentioned.
You wrote:
My own first line of planning would be to evaluate the needs of my family or any other people I set out to care for. That's where I'd look to match some testing capability with treatments. And then build from there.
My wife is a Type2 diabetic, diet controlled. She also had the radiation treatment for Graves. So she has to take thyroid medications. Over the years, I've gotten pretty good at telling when she needs to go back to her Dr and get a TSH done. And pretty good at telling whether the meds will be increased/decreased. In a long term situation, we will be facing some problems due to non-availability of thyroid meds.
What I suspect is a lot of us (including me) are looking for is a generalized "These are the lab tests you reasonably should be able to do" list under austere/3rd world conditions. This will go with the "These are the Medical things you reasonably should be able to do" lists/books we're building/writing/reading.
WB.
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