CVC tobramycin concentrations
Scenario:
A 15-year-old girl with cystic fibrosis (CF) and needle phobia has recently had a port-a-cath placed to facilitate regular intravenous antibiotic administration. She is admitted to the respiratory ward to receive ceftazidime and tobramycin to treat Pseudomonas aeruginosa. Local guidance requests a blood sample for trough tobramycin concentration to be taken peripherally prior to the second dose. This is due to concerns about the risk of falsely elevated concentrations if sampled from the same line used to give the drug. The patient is anxious and asks, “why can’t you just take it from my port like other blood tests?”
In other departments, such as paediatric oncology, antibiotic concentrations are sampled from the same central line through which the drug is given, prompting us to question could we also spare our respiratory patients the trauma of a peripheral venepuncture to measure tobramycin trough concentrations?
Reference:
Tumelty H, Shenton G, Brodlie M. Are trough tobramycin concentrations taken from a central venous catheter accurate enough to safely use? Arch Dis Child. 2022 Feb 24:archdischild-2022-323836. doi: 10.1136/archdischild-2022-323836. Epub ahead of print. PMID: 35210219.