(1371) Therapeutic Drug Monitoring of Aminoglycosides in Medical ICUs

Introduction: Antibiotics are essential for patients in the intensive care unit (ICU) with life-threatening infections. Aminoglycosides (AG) require monitoring of serum concentrations to ensure effectiveness and minimize risk of toxicity. Inappropriately timed AG concentrations (AGc) may lead to dosing errors, excess phlebotomy, and increased cost. Our academic medical center has two medical intensive care units (MICU); one managed by nurse practitioners (NP) and one managed by residents (RES). We sought to compare the appropriateness of AGc in the NP-MICU vs the RES-MICU.

Methods: This was a single center, IRB approved, retrospective chart review that included adult patients (≥ 18 years) admitted between January 2023-December 2023, who received at least one dose of AG (gentamicin or tobramycin) and AGc ordered and resulted ≤ 72 hours of MICU admission. Patients were arranged in a random order and consecutive patients were screened for inclusion. The primary objective was to compare inappropriate AGc between the two MICUs. Inappropriate AGc were defined as two AGc drawn within 4 hrs of each other, AGc without another blood draw, and no AGc for 72 hrs. Descriptive statistics were used to characterize the data. Continuous variables were analyzed with a t-test and categorical variables were analyzed with a chi-square or Fischer’s test.

Results: 72 patients were included; 36 patients in both NP-MIUC and RES-MICU. Between the two groups, there were no statistically significant differences in age, sex, reason for admission, hospital length of stay, or MICU length of stay. Numerically, there were more doses in the NP-MICU compared to the RES-MICU, 64 vs 54; but no difference in the median number of doses per patient (1.5 versus 1; P=0.16). Although there were more AGc in the NP-MICU than the RES-MICU, 46 vs 41, there was no difference in the median number of AGc per patient (1 vs 1; P=0.35). There was no difference in inappropriate AGc between NP-MICU and RES-MICU, 7% (3/46) vs 12% (5/41); p=0.47. Of note, 7% (3/46) (NP-MICU) and 10% (4/41) (RES-MICU) AGc were drawn without another blood draw needed (p=0.7).

Conclusions: Among patients receiving AG ≤ 72 hours of admission, there was no statistical significance in the appropriateness of therapeutic drug monitoring between the MICU-NP and the MICU-R.