BGL-Capillary vs Venous

[Devistat]

My question to everyone. I have yet to test this out or find an answer. When you take a BGL does it matter where the blood comes from. I was told from one paramedic that capillary blood gives a more accurate BGL Level than Venous. Another takes a BGL from the blood from the I.V. And says it doesn't matter. Any input?

Cheers

Alberta EMT

 

[NYMedic828]

My question to everyone. I have yet to test this out or find an answer. When you take a BGL does it matter where the blood comes from. I was told from one paramedic that capillary blood gives a more accurate BGL Level than Venous. Another takes a BGL from the blood from the I.V. And says it doesn't matter. Any input?

Cheers

Alberta EMT

Most newer glucometers are calibrated to accept either.

The difference is usually +/- 10mg/dl. Not really significant for clinical purposes.

 

[Medic Tim]

The glucometers I use are good for capillary and venous blood. I have done a finger stick and used IV blood from the same pts before and there was virtually no difference. The biggest I saw was a 0.2mmol change. I have heard ppl say there can be a big difference, but the number alone means nothing. It is all about pt presentation and your evaluation/assessment.

 

[Shishkabob]

. When you take a BGL does it matter where the blood comes from.

Yes, depending on the glucometer. Some are calibrated for finger capillary only, some can do venous, and some can do forearm capillary.


However, the difference tends to be minimal.

 

[Milla3P]

This seems to be somewhat if a popular topic in the last couple of weeks.
From my understanding... There are supposedly glucometers that are calibrated for both/either. I haven't seen one. I usually use a commercial one (One Step style meters) and they are usually calibrated for capillary blood since laymen check their sugars from finger sticks.
Since venous blood has gone through the capillary beds and made the exchange on the cellular level, the glucose should/would be lower in venous blood than in capillary blood.

Through my ALS education, my instructor regularly noted that 1) Venous BGLs are generally 10-20 points lower and that 2) if you use a meter that needs to be coded and there is a possibility of coding it incorrectly that your meter could be off by 20-60 points. SO of you use venous blood on a device that is coded wrong your BGL could be 10-80 points off... That's a pretty big difference.

Now, just because this is what my instructor taught me that doesn't mean that I only do finger sticks. If laziness was an Olympic sport, I'd at least be in the running. 90% of my BGLs are collected from my IV, but I keep an open mind. If its low, I'll do a capillary stick to confirm. But if it comes out at 104 and my pt is mentating properly, I'll take it and roll with it.

Long, late night rambling short: Know your machine. Use whatever blood you want, but keep an open mind.


On a mildly related note: I've read that BGL is an ALS skill in a lot of states because pricking someone's finger is "invasive." What about somebody with abrasions all over them and capilliary bleeding everywhere? Is that still invasive? Can basics use freely flowing blood?

 

[Medic Tim]

This seems to be somewhat if a popular topic in the last couple of weeks.
From my understanding... There are supposedly glucometers that are calibrated for both/either. I haven't seen one. I usually use a commercial one (One Step style meters) and they are usually calibrated for capillary blood since laymen check their sugars from finger sticks.
Since venous blood has gone through the capillary beds and made the exchange on the cellular level, the glucose should/would be lower in venous blood than in capillary blood.

Through my ALS education, my instructor regularly noted that 1) Venous BGLs are generally 10-20 points lower and that 2) if you use a meter that needs to be coded and there is a possibility of coding it incorrectly that your meter could be off by 20-60 points. SO of you use venous blood on a device that is coded wrong your BGL could be 10-80 points off... That's a pretty big difference.

Now, just because this is what my instructor taught me that doesn't mean that I only do finger sticks. If laziness was an Olympic sport, I'd at least be in the running. 90% of my BGLs are collected from my IV, but I keep an open mind. If its low, I'll do a capillary stick to confirm. But if it comes out at 104 and my pt is mentating properly, I'll take it and roll with it.

Long, late night rambling short: Know your machine. Use whatever blood you want, but keep an open mind.


On a mildly related note: I've read that BGL is an ALS skill in a lot of states because pricking someone's finger is "invasive." What about somebody with abrasions all over them and capilliary bleeding everywhere? Is that still invasive? Can basics use freely flowing blood?

why would a crew carry around a piece of equipment that they couldn't use / was out of theory scope?
In a lot of places it is a bls skill. I have heard in some places first responders can do it.

 

[NYMedic828]

why would a crew carry around a piece of equipment that they couldn't use / was out of theory scope?
In a lot of places it is a bls skill. I have heard in some places first responders can do it.

My grandmother can do it... and she does...

 

[Christopher]

My question to everyone. I have yet to test this out or find an answer. When you take a BGL does it matter where the blood comes from. I was told from one paramedic that capillary blood gives a more accurate BGL Level than Venous. Another takes a BGL from the blood from the I.V. And says it doesn't matter. Any input?

Cheers

Alberta EMT

There is a statistically significant difference in the readings you will get from capillary blood versus venous blood versus arterial blood!

SCARY!

Or is it?

There is not a clinically significant difference in the readings you will get from capillary blood versus venous blood versus arterial blood.

What does this mean for you?

It means that you will get different values but the difference is not going to change your clinical care for the patient. Said another way: it is perfectly safe to use venous blood with modern glucometers which are calibrated for capillary samples.

EMS will likely not be getting arterial samples for BGL (if you are, please put a tourniquet on the limb or remove your misplaced IV catheter...) so we'll ignore that.

As for venous versus capillary samples...if you get a High or Low reading that does not correlate clinically:

• Get another sample from another site

 

[VFlutter]

EMS will likely not be getting arterial samples for BGL

Wait, I'm not supposed to start A-lines in the bus? Oops

 

[Veneficus]

There is a statistically significant difference in the readings you will get from capillary blood versus venous blood versus arterial blood!

SCARY!

Or is it?

There is not a clinically significant difference in the readings you will get from capillary blood versus venous blood versus arterial blood.

What does this mean for you?

It means that you will get different values but the difference is not going to change your clinical care for the patient. Said another way: it is perfectly safe to use venous blood with modern glucometers which are calibrated for capillary samples.

EMS will likely not be getting arterial samples for BGL (if you are, please put a tourniquet on the limb or remove your misplaced IV catheter...) so we'll ignore that.

As for venous versus capillary samples...if you get a High or Low reading that does not correlate clinically:

• Get another sample from another site

I like you.

You can sit by me.

 

[KellyBracket]

For the non-critical patient, I agree with the other posters - whatever the difference is, it isn't relevant clinically.

The issue gets a little more complicated, of course, when the patient is really sick. We see a lot of people working hard to get a finger stick on the cardiac arrest patient, for example. It has been found, however, that such results were often wrong, either falsely high or falsely low. There is also some data out there in the potential errors when checking the FSBG on a septic, hypotensive patient, but I can't find those references anywhere in this cluttered Mac.

I covered some of this in a review I wrote earlier this year, Using Dextrose in Cardiac Arrest.

(For those who don't want to click, here's the summary. Hypoglycemia was added to ACLS as one of the "Hs" in 2005, and then removed in 2010. Both times there was apparently no new evidence for either decision!)

 

[NYMedic828]

For the non-critical patient, I agree with the other posters - whatever the difference is, it isn't relevant clinically.

The issue gets a little more complicated, of course, when the patient is really sick. We see a lot of people working hard to get a finger stick on the cardiac arrest patient, for example. It has been found, however, that such results were often wrong, either falsely high or falsely low. There is also some data out there in the potential errors when checking the FSBG on a septic, hypotensive patient, but I can't find those references anywhere in this cluttered Mac.

I covered some of this in a review I wrote earlier this year, Using Dextrose in Cardiac Arrest.

(For those who don't want to click, here's the summary. Hypoglycemia was added to ACLS as one of the "Hs" in 2005, and then removed in 2010. Both times there was apparently no new evidence for either decision!)

Were supposed to give an amp of D50 to any PEA/Asystole arrest we are working.

I guess its just in there as a "well what else can we do for the heck of it and hope it works"

 

[Veneficus]

Were supposed to give an amp of D50 to any PEA/Asystole arrest we are working.

I guess its just in there as a "well what else can we do for the heck of it and hope it works"

One day I would like to write a protocol that states:

If you don't know what to do, pierce your nose with a bone and then dance around the body waving a dead chicken in your left hand.

Couldn't hurt. Just might work.

 

[KellyBracket]

It's tough to look at a cardiac arrest and not do anything. If you stop giving lidocaine, sodium bicarb, atropine, amio, and vasopressin, pretty soon you're all just standing around, watching the compressions guy do all the work.

That being said, people have looked at that issue, and I would refer you to points 3 and 4 of my review. An excerpt...

It's the same reason we're trying to cool people down after we get a pulse back - neurologic outcomes. In some studies, they gave dextrose to some cats before they put 'em into cardiac arrest, while other cats they didn't. The cats who didn't get sugar beforehand had better brains afterwards.

Sorry for the digression from the OP's question, but it seems to me that the capillary vs venous issue is both more problematic and clinically relevant in the sick/crashing/crashed patient.

EDIT: Veneficus - some of medics already have elaborate piercings. Not sure what more we could do.

 

[NYMedic828]

One day I would like to write a protocol that states:

If you don't know what to do, pierce your nose with a bone and then dance around the body waving a dead chicken in your left hand.

Couldn't hurt. Just might work.

Our head medical director in NYC (of the 20 or so we have) also does not want us to have CPAP capabilities on our vehicles because it is potentially destructive to the patient.

Its in protocol, but we dont carry it.

 

[Veneficus]

It's tough to look at a cardiac arrest and not do anything. If you stop giving lidocaine, sodium bicarb, atropine, amio, and vasopressin, pretty soon you're all just standing around, watching the compressions guy do all the work.

That being said, people have looked at that issue, and I would refer you to points 3 and 4 of my review. An excerpt...

Sorry for the digression from the OP's question, but it seems to me that the capillary vs venous issue is both more problematic and clinically relevant in the sick/crashing/crashed patient.

EDIT: Veneficus - some of medics already have elaborate piercings. Not sure what more we could do.

very interesting review. In the next review I do I must start out with a picture from Pulp Fiction.

 

[Christopher]

Our head medical director in NYC (of the 20 or so we have) also does not want us to have CPAP capabilities on our vehicles because it is potentially destructive to the patient.

Its in protocol, but we dont carry it.

So instead a BVM would be used, or blind nasotracheal intubation...BVM's generate 2-5 times the pressure of CPAP. Blind nasotracheal intubation...ACK.

Nevermind, too offtopic.

...it seems to me that the capillary vs venous issue is both more problematic and clinically relevant in the sick/crashing/crashed patient.

Yeah, I think the honest answer is you probably are Ok in the field with a reliance on whatever method you choose (venous or capillary) as your decisions and treatments probably won't be negatively affected by any discrepancy.

Consider the case of an unresponsive patient:

1. True low, capillary states normalish: patient will not improve, BGL will be checked again, capillary probably will have caught up, dextrose given.

2. True normal, capillary states low: patient will receive dextrose without improvement. Hopefully somebody will clue in that glucose is not a problem. My worry would be the unresponsive septic patient...

3. True high, capillary states normalish: patient will likely not improve from EMS treatment anyways.

4. True normal, capillary states high: this would be bizarre to see, regardless the Rx for this cause of AMS will remain the same as without; e.g. treating other out of whack vital signs.

 

[medicdan]

Were supposed to give an amp of D50 to any PEA/Asystole arrest we are working.

I guess its just in there as a "well what else can we do for the heck of it and hope it works"

Is that a throwback to the old NYC "coma cocktail"?

 

[46Young]

Is that a throwback to the old NYC "coma cocktail"?

I was a NYC medic just long enough ago (2005-2007) to remember the unresp. D50/narcan/thiamine cocktail. We even had to give that with a high or BGL or suffer the wrath of the QA/QI Nazis

 

[Shishkabob]

It's tough to look at a cardiac arrest and not do anything. If you stop giving lidocaine, sodium bicarb, atropine, amio, and vasopressin, pretty soon you're all just standing around, watching the compressions guy do all the work.

An interesting thought: If we get to the point where it's compressions and shocking (I actually do doubt it will happen) to where 3 people can do an arrest along with a compression device... what excuse will FD have at their response times / levels / etc?


I mean, we won't need them there anymore for manpower...