A 68-year-old man is evaluated in the intensive care unit on day 4 of treatment for ventil… — USMLE Step 3

A 68-year-old man is evaluated in the intensive care unit on day 4 of treatment for ventilator-associated pneumonia. He was extubated yesterday and is currently breathing comfortably on room air. His empiric antibiotic regimen consists of intravenous vancomycin and cefepime. Sputum cultures are pending. On admission, his serum creatinine was $0.9 \text{ mg/dL}$ . Today, laboratory studies show:

Laboratory Test	Result
Blood urea nitrogen	$48 \text{ mg/dL}$
Serum creatinine	$2.2 \text{ mg/dL}$

A vancomycin trough level drawn 30 minutes prior to the 7th scheduled dose is $28 \text{ \mu g/mL}$ (therapeutic range for severe infections: $15$ - $20 \text{ \mu g/mL}$ ). The patient's vital signs are temperature $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure $120/75 \text{ mmHg}$ , and heart rate $82\text{/min}$ . Physical examination reveals clear lungs bilaterally and no peripheral edema.

Which of the following is the most appropriate next step in the management of this patient's pharmacotherapy?

Hold the vancomycin infusion and recheck the trough serum level in 24 hoursAnswer
B
Discontinue vancomycin and initiate intravenous daptomycin
C
Administer the scheduled vancomycin dose and obtain a peak serum level
D
Decrease the vancomycin dose and administer the medication immediately
E
Continue the current antibiotic regimen and order a renal ultrasound

Answer

Hold the vancomycin infusion and recheck the trough serum level in 24 hours

The correct answer is to hold the vancomycin infusion and recheck the trough serum level in 24 hours. This patient has developed acute kidney injury (AKI), evidenced by a rise in serum creatinine from

0.9 \text{ mg/dL}

2.2 \text{ mg/dL}

. This is directly correlated with a supratherapeutic vancomycin trough level of

28 \text{ \mu g/mL}

. The standard of care for vancomycin-induced nephrotoxicity with a high trough level is to withhold the medication and monitor serum levels sequentially. Once the level falls within the acceptable therapeutic target (typically

15

20 \text{ \mu g/mL}

for severe, complicated infections like VAP), vancomycin may be restarted using a renally adjusted regimen (e.g., lower dose or extended interval).

Step-by-Step Solution

Evaluate the patient's laboratory results in the context of their medication regimen.

The patient's serum creatinine has increased from

0.9 \text{ mg/dL}

2.2 \text{ mg/dL}

, and the vancomycin trough is supratherapeutic at

28 \text{ \mu g/mL}

Identifying the etiology of the acute kidney injury (AKI) dictates the next management steps.

Determine the therapeutic safety protocols for the offending agent.

Vancomycin is notoriously nephrotoxic, especially at sustained elevated trough levels above

20 \text{ \mu g/mL}

Proper pharmacotherapeutic monitoring requires ceasing the administration of drugs that are actively causing end-organ damage.

Formulate a treatment modification plan.

The current dose must be held. The trough level should be monitored daily (e.g., rechecked in 24 hours) until it falls back into the therapeutic range (

15

20 \text{ \mu g/mL}

), after which vancomycin can be restarted at a lower dose or extended interval.

Giving further doses or immediately adjusting the dose without waiting for drug clearance will prolong the toxic state.

Key Concept

In patients who develop acute kidney injury accompanied by supratherapeutic vancomycin trough levels, the most appropriate management is to withhold the medication until levels return to the therapeutic target, followed by a dosage or frequency adjustment.

Estimated Time:1m 30s

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