|
Procedure |
|
Rationale |
|
| 1. |
Draw
blood samples as per "Procedure for Withdrawal of Blood Samples From an
Indwelling Line."
Draw
pre and post levels with the THIRD dose of aminoglycoside (obtain order). |
1. |
Levels
are indicated to determine if the correct dose is being administered,
as per the patient's weight and volume of distribution, and if the dosing
interval is appropriate for the patient's renal function. These agents
have signficant renal toxicity, particularly when serum concentrations
are excessive. Inadequate levels provide inadequate gram negative coverage. |
|
| 2. |
Draw
"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). |
2. |
This
will reflect the lowest serum concentration. |
|
| 3. |
Administer
the drug by IV infusion over precisely 60 minutes
(e.g., infuse from 0800-0900 hours).
Upon
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. |
3. |
Steady
infusion over 60 minutes prevents high peak serum concentrations.
- Backflushing
may leave a small amount of drug within the "Y" connection.
- Any
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.
|
|
| 4. |
Draw
"post" aminoglycoside level precisely 30 minutes post completion of
infusion (eg. at 0930 hours). | 4. |
The
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. |
|
| 5. |
When ordering
the lab test, enter the infusion start time and end time (discontinue
time).
Under comments
section at the bottom of the screen (NOT under "label"), make
a notation of the actual time that the level was drawn.
If
unable to draw levels at these times, ensure exact times are recorded
on biochemistry requisition. |
5. |
If
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.
NOTE:
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. |
|
| 6. |
Communicate
results to physician and pharmacist. |
6. |
To
ensure appropriate dose adjustments are made.
Pre-dose
levels are used to determine the appropriate dosing interval. Post-dose
levels are used to determine the appropriate dose. |
|
Print
Handheld
Contrast
