Question

The nurse is preparing a patient care plan for Deshawna, a 20-year-old college student who has been diagnosed with bacterial meningitis. Her symptoms before admission included a significant headache, photophobia, nausea, a stiff neck, and vertigo. A spinal tap was performed, and culture and sensitivity was ordered. While waiting for the results, the physician has ordered gentamicin intravenous piggyback (IVPB) 120 mg every 8 hours. Gentamicin trough levels are ordered every 8 hours, to be taken 30 minutes before administration of the next dose. 1. What is the purpose of obtaining the trough level? 2. What trough level would be considered a normal concentration? 3. What adverse effects of gentamicin will the nurse monitor for in Deshawna?

Answer 1

ANSWER 1. Pre-dose (trough) gentamicin levels should be taken four hours before the next dose is due in order to minimise toxicity. If the trough level is above 1mg/L the dose must be omitted until the level falls below 1mg/L.

2. less than 1 mg/ dl

3. ADVERSE EFFECTS

Nephrotoxicity

Adverse renal effects, as demonstrated by the presence of casts, cells, or protein in the urine or by rising BUN, NPN, serum creatinine or oliguria, have been reported. They occur more frequently in patients treated for longer periods or with larger dosages than recommended.

Neurotoxicity

Serious adverse effects on both vestibular and auditory branches of the eighth nerve have been reported, primarily in patients with renal impairment (especially if dialysis is required), and in patients on high doses and/or prolonged therapy. Symptoms include dizziness, vertigo, tinnitus, roaring in the ears and hearing loss, which, as with other aminoglycosides, maybeirreversible. Hearing loss is usually manifested initially by diminution of high-tone acuity. Other factors which may increase the risk of toxicity include excessive dosage, dehydration and previous exposure to other ototoxic drugs.

Peripheral neuropathy or encephalopathy, including numbness, skintingling, muscletwitching, convulsions and a myasthenia gravis-like syndrome, have been reported.

Other reported adverse reactions possibly related to gentamicin include: respiratory depression, lethargy, confusion, depression, visual disturbances, decreased appetite, weightloss, hypotension and hypertension; rash, itching, urticaria, generalized burning, laryngeal edema, anaphylactoid reactions, fever and headache; nausea, vomiting, increased salivation and stomatitis; purpura, pseudotum or cerebri, acute organic brain syndrome, pulmonary fibrosis, alopecia, joint pain, transient hepatomegaly and splenomegaly.