In this episode, I’ll discuss whether patients with antibiotic-impregnated bone cement should receive therapeutic drug monitoring.
Shoutout to Pharmacy Kelsey for inspiring this episode.
When orthopedic surgeons place bone cement in patients, they will often impregnate the cement with antibiotics such as vancomycin and tobramycin. This mixing process occurs in the OR.
There are case reports of patients with such antibiotic-impregnated bone cement developing detectable serum levels of antibiotics and even adverse effects such as acute renal failure.
The amount of antibiotics mixed in the cement can be highly variable, and in my experience OR documentation is not always reliable as to what and how much was mixed.
There are no guideline or consensus recommendations on monitoring antibiotic serum levels in patients who receive antibiotic-impregnated bone cement.
Clinicians at the Department of Orthopaedics, Emory University School of Medicine, Atlanta, GA recommend obtaining a random level of the antibiotics used in the spacer on the first postoperative day. This recommendation is based on their clinical experience of patients with detectable antibiotic levels and adverse events.
A German orthopedic team have noted an apparent correlation in elderly between using antibiotics systemically that are also in the implanted bone cement, and they advise to avoid this practice in the elderly unless there are no other antibiotic options available.
Until more data is available, it is reasonable to follow either or both of these practices in patients who receive antibiotic-impregnated bone cement.
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“Random assessment of serum levels of the antibiotics used in AIC on the first postoperative day to guide subsequent IV antibiotic therapy as the combination of systemic antibiotic exposure with AIC and IV therapy can pose an increased risk of antibiotic associated end organ damage.”
If no postop antibiotic therapy with the AIC drug is ordered then there is no value to the added expense of checking a level. But drug levels do not directly correlate to adverse effects. Perhaps what is more important is responding to minor changes in renal function instead of watchful waiting.