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Ok< A Little Bit Of Geky Fun


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#1 croaker260

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Posted 15 December 2011 - 06:35 PM

For those of you who visit other forums, I have posted this on other sites. That said, I thogh it might be a little bit of fun and pseudo science to do here....

Just some of the random stuff I do at work when not running calls...

I was researching some infusion protocols for Mag sulfate and I realized that there was no clear estimates on how fast wide open would be if someone accidentlaly ran in a bag of mag (or any other drug). so, I did this little experiment.

Question: Can 5 GMS mag in 250 cc saline be safely run @ wide open and not exceed common safety parameters (i.e. < 1 gram/minute) in emergency situations?

Methods:
Using a stop watch, time the infusion of 250 cc saline and 10 cc mag using two prosposed infusion methods (noted below).

Experiment #1: 250 cc saline + 10 cc (5 grams) mag elevated 30 inches above distal end, with 15 gtt set and saline extension set (93.5 inches total w/o cath) , run @ wide open, with 16 G 1 1/2 inch at distal end takes 5 minutes 26 seconds to run in. Estimated infusion rate 52 cc/minute

Experiment #2 250 cc saline + 10 cc (5 grams) elevated 30 inches above distal end, with 60gtt set "STAT II PUMPETTE and saline extension set (91.5 inches total w/o cath), run @ "Full OPEN" , with 16 G 1 1/2 inch at distal end takes 15 minutes 03 seconds to run in. Estimated approx 17.3 cc/minute

Methods: Using the commonly used equipment available in my system, simulating the elevation of the bag over the patient on our cot, and using a standard android powerd stop watch, each experiment was prepared in a way typical to EMS care using asepttic/sterile tech. the line was flushed to the distal end without excess wastage. The timer was started and the line clamp was opened to its maximum point.

Limitations: 1) Vascular resistance was not simulated. It is believed that this would create a more conservative estimate and given the limitatons, would be difficult to reproduce. 2) This was done ina station, not a labratory. 3) I am a Paramedic, not a scientist (or a bricklayer, or a doctor on the USS Enterprise) 4) no control, blinding, or IRB oversight was in place.

No paramedics were harmed n the conduction of this experiment. :)

Conclusion: 5 GMS (10 cc) added to 250 cc saline run at the maximal possible infusion rate without a pressure infusion device (AKA wide open) at commonly accepted elevations and normal infusion equipment should not exceed safety parameters for emergency infusion using either commonly accepted infusion sets available in EMS.

Secondary conclusion: I am an EMS GEEK.

My challenge to you: Can you guys reproduce the same experiment with 18 G, 20 G and 14 G? And/or 10 gtt sets? (We dont use 10 gtt sets but some do...) I am sure if everyone takes one part and posts it, it would be very interesting. I am very interesting in the results with 18 and 20 G catheters. (I only had so much expired equipment to use)

DISCLAIMER: I make no observation of the saftey of this practice compared to using an infusion control device.
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"Boldness is like a condom. If you depend on it all the time, no matter how good it is, and no matter how good you are, eventually it will break. " -- Walter SLovotsky

"In crisis we do not rise to the occasion, but sink to the level of our training" -- Lt. Col (ret) Grossman

"Personally, I believe that if we write our CE, text books, and curricula at the physician level instead of the kindergarten level, our medics and EMTs will rise to the occasion and meet the higher standard, maybe with some bitching but they will do it. There are plenty of precedents in every day life and other professions for this. The patients will only benefit, as will our own professions and the level of respect I believe we need and want, but maybe don't yet deserve." Steve Cole

#2 SerendepitySaki

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Posted 15 December 2011 - 07:26 PM

GOOD ON YA! STRONG WORK!

actually, if you eliminate the variable of vascular resistance distal to the catheter tip, and assume that your above results are correct, you can easily derive rates for the remaining gauges/gtt sets...

the only experiments needed are to verify the predictive validity of your calculations and to attempt to define any variability discovered....

perhaps some other interesting questions would be with regards to "common safety parameters...in emergency situations" defined at "(i.e. < 1 gram/minute)"?

is that indeed a "common" safety parameter, and if so,

what is the evidence based rationale, (how is "safe" defined? vasodilatory response? depressed DTRs? respiratory depression?) and

is that evidence based rationale adequately supported by clinical observations?

lies, damn lies, and statistics....

i regularly incorporate both of those topics... determinants of flow and safe magnesium sulfate infusion rates... into my lectures....

here's a little taste/hint for you...

1. look at what serum level of magnesium ion corresponds to what symptomology...both hypomagnesemia and HYPERmagnesemia....

2. use average circulating blood volume, cardiac index/output, and the concentration/rate of your infusing magnesium solution to determine how quickly you are influencing the serum level...

3. that is not the whole story, but, it is a very useful approximation...

if you're feeling really froggy, you can make up a little chart or even a spreadsheet to calculate it for you.... apologies if you've already done all of the above... Joyeux NoŽl, y'all!
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LET THE WILD RUMPUS BEGIN !!!!!!
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#3 croaker260

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Posted 18 December 2011 - 05:41 PM

perhaps some other interesting questions would be with regards to "common safety parameters...in emergency situations" defined at "(i.e. < 1 gram/minute)"? is that indeed a "common" safety parameter, and if so, what is the evidence based rationale, (how is "safe" defined? vasodilatory response? depressed DTRs? respiratory depression?) and

is that evidence based rationale adequately supported by clinical observations?

lies, damn lies, and statistics....



Excellent comments, thank you.

The 1 GM /minute is a common caveat of mag administration in many textbooks and protocols.. (as in" do not exceed 1 GM a minute") though I have heard and seen it pushed much faster than that. As for where THAT parameter originated from, I honestly do not know. Probaly something pushed down through the ages. Its worth looking into.

Any of the other brainey people on this site have any insight? Any old dusty studies? I havent found any (yet).
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"Boldness is like a condom. If you depend on it all the time, no matter how good it is, and no matter how good you are, eventually it will break. " -- Walter SLovotsky

"In crisis we do not rise to the occasion, but sink to the level of our training" -- Lt. Col (ret) Grossman

"Personally, I believe that if we write our CE, text books, and curricula at the physician level instead of the kindergarten level, our medics and EMTs will rise to the occasion and meet the higher standard, maybe with some bitching but they will do it. There are plenty of precedents in every day life and other professions for this. The patients will only benefit, as will our own professions and the level of respect I believe we need and want, but maybe don't yet deserve." Steve Cole

#4 VolandoP

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Posted 12 July 2015 - 10:37 PM

And to those who want to defend Murray....You would be quite confident and happy to put YOURSELF under his care??
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