A study to determine the minimum volume of blood necessary to be discarded from a central venous catheter before a valid sample is obtained in children with cancer
ABSTRACT The objective of this study was to determine the minimum volume of blood that should be discarded from a range of different types of central venous catheter (CVC), such that the subsequent blood sample was not diluted or contaminated by the residual intra-luminal fluid.
Seventy children aged 1-19 years with central venous access inserted as part of their standard clinical treatment were recruited to this prospective study. Statistical comparison of the extent of variation in biochemical and haematological parameters observed between two blood samples taken following routine 5 ml discard blood volumes, as compared to the extent of variation between samples drawn following a 5 ml discard volume and <5 ml volumes, was carried out.
Data indicate that the measurement error in a clinical sample obtained following a 3 ml discard volume is no different to the measurement error obtained when using a standard 5 ml discard volume. Comparable results were obtained from patients with various different types of CVC or portacath access.
The withdrawal of a 3 ml discard volume is sufficient to ensure that the subsequent blood sample is not diluted or contaminated by residual intra-luminal fluid. This may have a significant clinical impact in paediatric oncology, where patients frequently require blood transfusions due to the haematological toxicities associated with chemotherapy. It is hoped that these results will impact on hospital policies concerning specified discard volumes taken from CVCs prior to the withdrawal of blood samples for research purposes and routine clinical analysis.
- SourceAvailable from: Carina Ritzmo
- [Show abstract] [Hide abstract]
ABSTRACT: This study was designed to evaluate the clinical benefit of low-profile double-lumen port catheters in patients receiving simultaneous chemotherapy and parenteral nutrition (PN). Potential advantages, complications, and the durations of simultaneous and single use of the catheter were assessed. At a university teaching hospital, 10 patients received a double-lumen port catheter (5 men, 5 women; mean age 61.5 ± 12 years). All port implantations were performed under ultrasonographic and fluoroscopic guidance in the radiologic interventional suite. Procedure-related immediate, early, and late complications were recorded until removal of the device, patient's death, or completion of follow-up period. Application times and durations for chemotherapy or PN were determined. No immediate complications were observed. First use of the port system for chemotherapy was within 12 days (± 25 days, range 0-84 days) and within 17 hours (± 22 hours, range 0-72 hours) for PN on average. During the application of PN, no delay or interruption of chemotherapy was observed. The port catheter was used for the simultaneous application of chemotherapy and PN for a total of 1,216 hours. One port catheter was removed after 30 days due to suspected port infection. Central venous double-lumen port systems as a therapeutic option in patients requiring chemotherapy and PN can increase safety during those simultaneous applications, while offering improved patient comfort.The journal of vascular access 10/2010; 11(4):335-41. DOI:10.5301/JVA.2010.5812 · 0.85 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: There are many sources of variability in plasma samples drawn for pharmacokinetic analyses or therapeutic drug monitoring. In this article, methods are proposed on how to prevent sample dilution (Part I) and contamination effects (Part II) in plasma samples, using doxorubicin as an example. Experiments were performed in the laboratory setting to identify factors that could influence plasma samples in clinical practice. In part I, it was hypothesized that saline solution left in a catheter could lead to a dilution of samples drawn through this catheter. The impact of 2 different sampling techniques, the "discard method" and the "push-pull method", was examined. In part II, an infusion system was filled with a 1 mg/mL solution of doxorubicin. After rinsing the system with increasing volumes of saline solution, the drug concentration of the fluid left in the system was analyzed. Furthermore, plasma samples were drawn through the drug administration catheter, and the contamination of these samples with doxorubicin left in the catheter was measured. In part I, a discard volume of plasma equal to 4 dead volumes of the sampling line was necessary to avoid dilution of a sample taken from a port or double-lumen catheter filled with saline solution ("discard method"). Pulling up and down the same volume through the catheter 5 times ("push-pull method") was proved to be an alternative with no need to discard blood. In part II, after rinsing the infusion system with a volume of saline solution corresponding to 4 dead volumes of the system and after discarding a volume of plasma corresponding to 4 sampling line volumes, the doxorubicin contamination in the samples was negligibly small. Under the described conditions, the push-pull method delivered the same results as the discard method to prevent sample dilution. To avoid contamination in plasma samples, development of standardized sampling procedures seems to be essential and feasible.Therapeutic drug monitoring 12/2011; 33(6):766-71. DOI:10.1097/FTD.0b013e31823aa8ab · 2.38 Impact Factor