Trough and Peak levels

Started by wahaha
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wahaha

wahaha

Medical Laboratory Scientist
10+ Year Member
I had an issue where a phlebotomist was drawing a trough level on a patient receiving vancomycin. I was taught that troughs were to be drawn right before the next dose was given. The nurse had already started the IV when the phlebotomist went to collect the sample. I told the phlebotomist not to collect it and performed a trough level on a sample collected two hours before. Just wondering if drawing right before the next dose is a hard and fast rule and if vanc levels are substantially affected?
 
wahaha said:
I had an issue where a phlebotomist was drawing a trough level on a patient receiving vancomycin. I was taught that troughs were to be drawn right before the next dose was given. The nurse had already started the IV when the phlebotomist went to collect the sample. I told the phlebotomist not to collect it and performed a trough level on a sample collected two hours before. Just wondering if drawing right before the next dose is a hard and fast rule and if vanc levels are substantially affected?
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If you draw a vancomycin level while the vanco is infusing the level will be falsely high.
Think about it, the vanco is circulating in the blood while the blood to be tested is withdrawn.

Vanco troughs are always to be drawn between 1hr to right before infusion.
 
awval999 said:
If you draw a vancomycin level while the vanco is infusing the level will be falsely high.
Think about it, the vanco is circulating in the blood while the blood to be tested is withdrawn.

Vanco troughs are always to be drawn between 1hr to right before infusion.
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I know it can't be drawn while being infused. I was wondering if two hours before was too far in advance.
 
Depends on what the level is, if it is already low, you know waiting until a "true" trough it would still be low. Depends on the patient, if the level is at steady state, indication, and trough goal. You can use clinical judgement from that, or ask your pharmacist for help.
 
i remember my first crazy high incorrectly drawn trough. I remember seeing it, freaking out, running to preceptor, only to have them brush it off and give me the "is he stupid" look.
 
thephoenician88 said:
i remember my first crazy high incorrectly drawn trough. I remember seeing it, freaking out, running to preceptor, only to have them brush it off and give me the "is he stupid" look.
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Yaw, vanc dosing. As some already said, drawing a trough during infusion is just a waste of time and money. When I write a trough, I actually specify "draw trough 30 minutes prior to the X dose". And on top of that, I write "hold dose if trough > 20" because you learn very quickly how annoying it is when nurse call your at 10 pm with a "panick" vanc trough of 17. :meanie:
 
to be exact, 30 min before next dose is actually drug as well

You want it to be 30 min before the scheduled dose

there is a clear fine difference in actual practice and we don't live in a perfect world where RN give dose at 0900 and then the next at exactly 2100
 
KARM12 said:
Depends on what the level is, if it is already low, you know waiting until a "true" trough it would still be low. Depends on the patient, if the level is at steady state, indication, and trough goal. You can use clinical judgement from that, or ask your pharmacist for help.
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Thanks. I know there's what you learn in school and how it is actually done. We get a very rough overview of therapeutic drug monitoring.
 
When I first started my PRN staff job, I was told not to get into any dispute with nurses. I was even told that if one of them got snippy with me, not to bite back as I would likely get written up. I said, "bullS**t" I'm prn, if I have a problem with something and they get snippy, I'm getting snippy right back.
 
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