To evaluate serum concentration of antibiotics drawn from a peripherally inserted central catheter (PICC) compared to serum concentration of antibiotic levels drawn from a venipuncture.
A large number of hospitalized patients require PICC line insertion for intravenous (IV) antibiotic treatment targeting respiratory infections, such as cystic fibrosis (CF), pneumonia, and pleural effusions. Often, the antibiotic medications of choice require biweekly surveillance levels before and/or after infusions to assess therapeutic delivery of the drug and renal clearance for the duration of therapy. Our institutional policy for obtaining antibiotic levels does not specify if the specimen should be drawn from a PICC line or venipuncture. Thus, there is varying practice among clinical providers as to the site of specimen collection.
We conducted a prospective study on two inpatient medical units. We screened all subjects ages 1 month to 21 years admitted with a respiratory infection requiring IV vancomycin or tobramycin, and who received a new PICC line insertion for antibiotic treatment. The sample size was comprised of 90 subjects; each subject was eligible for enrollment if he/she required levels within the first 16 days from the date of hospital admission. Subjects required antibiotic levels multiple times throughout their hospital stay. A maximum of two serum antibiotic levels were included for each subject during hospitalization.
Of the 88 subjects enrolled, 80 were patients with CF, admitted for a pulmonary exacerbation and a course of IV antibiotic treatment. Peak tobramycin levels were consistently higher in the peripheral sample than in the same patient's PICC sample. The mean difference was 1.35 ug/ml with standard error 0.29 ug/ml, statistically significant by Student's paired t-test at p<0.0001. Against the mean peak level of approximately 25 ug/ml, this represented a 5% difference. Trough vancomycin levels were likewise consistently higher in the periphery than in the PICC sample, by 0.84 ± 0.15 ug/ml (mean ± standard error), significant at p<0.0001. Against the mean trough level of approximately 11 ug/ml, this was an 8% difference. Trough tobramycin levels were very low (mean 0.15 ug/ml) and did not differ between the peripheral and PICC samples.
The difference between the antibiotic levels from the peripheral and PICC samples was statistically significant for both the peak and trough levels. However, the difference in values was small enough that there was no clinical significance. The evidence would suggest that using our study methods to draw vancomycin and tobramycin levels from PICC lines yields equivalent values for samples drawn from either site. Using PICC lines to draw antibiotic levels would minimize invasive interventions and discomfort for patients. The blood drawing methods and findings from this study may be useful in establishing a formal hospital policy and procedure for drawing tobramycin and vancomycin levels from PICC lines. Thus, decreasing the number of venipunctures and improving the quality of life for those that receive treatment with antibiotics requiring close monitoring of levels.
© 2014 Published by Elsevier Inc.