A comparison of aminoglycoside antibiotic serum concentrations collected by peripheral veins and peripherally inserted central catheters in adults with cystic fibrosis

Background: People with cystic fibrosis (PwCF) are frequently hospitalized for treatment of pulmonary exacerbation. The Cystic Fibrosis Foundation Pulmonary Guidelines support the use of intravenous aminoglycosides with therapeutic drug monitoring for the treatment of pulmonary exacerbation due to Pseudomonas aeruginosa. Serum intravenous tobramycin concentrations are commonly collected by peripheral venipuncture (PV). Discomfort associated with collection of samples by PV prompts collection via PICC, but the accuracy of intravenous tobramycin serum levels collected by PICC has not been documented in adult PwCF. The primary study objective was to evaluate the difference between intravenous tobramycin serum levels collected by PV and PICC in adult PwCF. Methods: The authors conducted a prospective case-control study of adult PwCF admitted to University of Utah Health for a pulmonary exacerbation receiving tobramycin by a single lumen PICC. The authors compared tobramycin peak and random serum levels collected by PV and PICC using a detailed flush and waste protocol. Results: The authors analyzed a total of 19 patients with peripheral and PICC samples. The mean tobramycin peak collected by PV (27.2 mcg/mL) was similar to the mean peak collected by PICC (26.9 mcg/mL) (paired samples Wilcoxon signed-rank test, p = .94). The correlation coefficient was 0.88 (95% CI = 0.85-0.91, p < .001). Conclusion: Tobramycin serum samples collected by PICC appear to be similar in value to PV collections. Collecting aminoglycoside levels by PICC rather than PV may reduce patient discomfort and improve quality of life. Additional multicenter studies are needed to confirm these results.