Some patients benefit from vancomycin blood level monitoring. The
need to synchronize the blood test with drug administration adds
steps to an already-complex medication process, requires
interdepartmental coordination (nursing, pharmacy and phlebotomy)
and multiplies the likelihood of problems compared to routine
antibiotic administration. Indeed, review of CHPSO’s event
reports database shows recurring errors with vancomycin
Vancomycin accounted for one-fourth of the medication timing
errors reported to CHPSO. Over half the facilities reviewed had
these errors and we have found about 300 events so far. The
reported events generally fall into one of the following
trough drawn while vancomycin was infusing,
trough drawn 30 minutes after administration of vancomycin,
trough drawn prior to next dose after a missed dose,
administration delay due to delay in obtaining trough
administration delay due to delay in blood draw.
The first three are monitoring errors, while the last two are
administration timeliness errors.
Though not reflected in these numbers, trough levels drawn too
early commonly occur. A retrospective study showed this error in
40 percent of all trough level tests (Morrison). We believe that
this particular error is less likely to be identified
contemporaneously than the above five, explaining the dearth
of incident reports we received for early trough level draws.
One of the most powerful ways to make a complex process more
reliable is to simplify it. In the case of vancomycin
administration, a good start is to eliminate monitoring over-use.
Following the consensus recommendations for therapeutic
monitoring of vancomycin in adult patients (Rybak) may reduce
monitoring and, consequently, errors.
According to the consensus recommendations, monitoring is
indicated in patients:
receiving aggressive dosing (i.e., to achieve sustained
trough levels of 15-20 mg/L),
at high risk of nephrotoxicity,
with unstable renal function, or
receiving more than 3-5 days of treatment.
The consensus recommendations also state that frequent monitoring
(more than one trough before the fourth dose) for short course or
lower intensity dosing is not recommended. All patients
on prolonged courses of vancomycin (exceeding three to five days)
should have at least one steady-state trough concentration
obtained no earlier than at steady state (just before
the fourth dose) and then repeated as deemed clinically
Other steps should be taken to improve the coordination of lab
draw and medication administration processes. This may also be a
good time to evaluate the phlebotomy process throughout the
hospital. Redesigning the phlebotomy process system-wide may
provide benefit not only for vancomycin testing but for other
tests as well, as collection timing issues are one of the most
common preanalytic-phase laboratory testing errors (Wagar).
As with any complex systems issue, weak interventions such as
education or reminders are unlikely to provide much benefit.
Several attempts using a weak intervention dramatically increased
nursing knowledge without any gains in trough timing accuracy
Rybak M, Lomaestro B, Rotschafer JC, et al. Therapeutic
monitoring of vancomycin in adult patients: a consensus review of
the American Society of Health-System Pharmacists, the Infectious
Diseases Society of America, and the Society of Infectious
Diseases Pharmacists. Am. J. Health. Syst. Pharm.