Timing of Pre Drug Level
pre and post levels with the THIRD dose of aminoglycoside (or as per order).
"pre" level within 30 minutes prior to the next scheduled drug dose. (eg.,
if drug is due at 0800 hours, "pre" level is drawn between 0730-0800 hours).
will reflect the lowest serum concentration.
Drug Administration Time
the drug by IV infusion over precisely 60 minutes
(e.g., infuse from 0800-0900 hours).
completion, hang a bag of saline and administer a 20 ml piggyback bolus.
DO NOT back flush the piggyback line as a method
of drug clearance.
infusion over 60 minutes prevents high peak serum concentrations.
may leave a small amount of drug within the "Y" connection.
aminoglycoside that remains in the tubing would be administered with
subsequent IV infusions. If an infusion is started just prior
to drawing the post level, falsely high peak serum concentrations
may be obtained.
Timing of Post Drug Level
"post" aminoglycoside level precisely 30 minutes post completion of
infusion (eg. at 0930 hours).
distribution phase is completed by this time. Waiting any longer to obtain
post level would miss the true maximal serum concentration, resulting
in a falsely low level. Drawing the level too soon would measure
within the distribution phase, resulting in a falsely high level.
the lab test, enter the infusion start time and end time (discontinue
section at the bottom of the screen (NOT under "label"), make
a notation of the actual time that the level was drawn.
unable to draw levels at these times, ensure exact times are recorded
on lab requisition.
exact times are recorded, pharmacokinetic calculations can be done to
calculate true levels.
The lab will
assume that the sample was drawn at the time the label was printed.
This can lead to interpretation error. Comments entered in the "label"
section are not saved in the lab system; these comments only appear
on the label to facilitate correct tube placement.
If the drug infused over a different time period (e.g., 30 minutes)
or was measured at a different time in relation to completion of the
drug administration (e.g., 1 hour post), accurate interpretation depends
upon correct recording of the method of collection. It is more important
to accurately document the time of the measurement , than to obtain
at 30 minutes.