Elevated blood drug levels obtained from indwelling silicon catheters during oral cyclosporine A administration

Correlation Between Tacrolimus Levels in Blood Samples Obtained from Central Catheter and Peripheral Venipuncture in Lung Transplant Patients (Ven-Cat Study)

BACKGROUND

Following lung transplantation (LT), receiving immunosuppressive therapy is crucial. Tacrolimus is considered a drug with a narrow therapeutic range and its use requires constant monitoring. This study aimed to evaluate the correlation between tacrolimus levels obtained from central venous catheter and direct venipuncture in adult patients undergoing LT.

METHODS

This prospective study included LT patients hospitalized in conventional ward carrying a central catheter through which no intravenous tacrolimus was administered. Trough samples were obtained through direct puncture and from the central catheter. Pearson correlation coefficient was calculated to quantify the mean difference between the 2 measures.

RESULTS

A total of 54 sample pairs from 16 LT patients were obtained, mostly male (81.3%) and bilateral transplant recipients (93.8%); the transplant procedure was the primary reason for admission (81.3%). The difference in tacrolimus levels between both samples was 0.3 (0.1-0.6) mcg/L, with the measurement for the samples obtained through venipuncture being mostly higher than that for those obtained from the catheter. A strong correlation was observed between the tacrolimus levels in the samples obtained from the catheter and through venipuncture (Pearson correlation coefficient, 0.991; P < 0.001; R2 = 0.982).

CONCLUSIONS

There is an excellent correlation between tacrolimus levels obtained from venipuncture and those obtained from central venous catheter in LT patients undergoing oral tacrolimus therapy.

Artificially Elevated Tacrolimus Concentrations Obtained From a Venous Catheter Previously Used for Tacrolimus Administration in a Pediatric Patient

Intravenous (IV) administration of calcineurin inhibitors, cyclosporine (CsA) and tacrolimus (TAC), has been associated with spuriously high serum concentrations collected from central venous catheters (CVCs) used for medication administration, secondary to reversible adsorption of medication to the catheter. Thus, therapeutic drug monitoring of IV CsA and TAC via CVCs previously exposed to these agents should be interpreted cautiously and ideally avoided. The duration of this effect is poorly characterized and the risk for extension of this effect to unexposed lumens of the same central catheter remains uncertain. We describe a case of a pediatric patient with artificially elevated serum TAC concentrations obtained from previously exposed and unexposed lumens of a central catheter, 27 days after last IV TAC administration.

Serum Cyclosporine Levels: The Influence of the Time Interval Between Interrupting the Infusion and Obtaining the Samples: A Randomized Clinical Trial

BACKGROUND

There are controversies regarding the best way to collect blood samples for cyclosporine A (CsA) serum levels when this immunosuppressant is administered continuously through a silicone central venous catheter (CVC) to hematopoietic stem cell transplant recipients.

OBJECTIVE

The aim of this study was to verify the effect of the time elapsed between the interruption of a continuous intravenous CsA infusion and the collection of blood samples on CsA serum levels.

METHODS

This randomized 2-group clinical trial involved 32 adults. In group A, blood samples were collected immediately after interrupting the medication from peripheral vein and CVC lines. In group B, the same procedures were performed 5 minutes after interrupting the infusion.

RESULTS

We did not observe influence of the time elapsed between interruption of the infusion and collection of the samples, independent of the collection mode and the volume discarded (P > .05). The line used for the infusion maintained a constant high level when compared with different moments of collection (P > .05), whereas in the other lines, there was a significant increase when compared with the levels obtained at 24 hours and 7 days after CsA start (P = .00).

CONCLUSION

The CVC line free from cyclosporine can safely be used to collect blood. The procedure can be performed immediately after interrupting the infusion, and discarding 5 mL is sufficient to obtain accurate levels.

IMPLICATIONS FOR PRACTICE

The results can help nurses choose how to collect blood samples through the CVC, thus preventing patients from having a painful and stressful procedure such as peripheral venipuncture.

Falsely elevated cyclosporin and tacrolimus concentrations over prolonged periods of time due to reversible adsorption to central venous catheters

Falsely elevated concentrations of immunosuppressants can be caused by reversible adsorption to central venous catheter (CVC) systems. If undetected, this may lead to dose reduction resulting in underdosage which may even entail graft-versus-host disease or organ rejection. We analyzed the adsorption and release for cyclosporine A (CsA) and tacrolimus (Tac) in vitro and in vivo. Four types of CVCs were examined in vitro: two made from polyurethane (PU), one from silicone and one from PU with an incorporated silver ion-based antimicrobial agent. All 26 CVCs analyzed in vitro showed significant reversible adsorption of CsA (n=13; p=0.001) and Tac (n=13; p=0.001, Wilcoxon signed rank test). Immediately after infusing the drugs, the mean concentrations of 6420ng/mL of CsA and 250ng/mL of Tac were measured. Flushing with NaCl lowered the drug release. Besides, blood samples of fifteen patients were taken simultaneously from all lumina of the CVC and via venipuncture. The samples from contaminated lumina showed the mean elevations by a factor of 11 for CsA (n=12) and 89 for Tac (n=3). Blood sampling for immunosuppressant monitoring should thus never be performed from lumina previously used for infusing the drug even after prolonged periods of time and extensive rinsing.

Double-lumen central venous port catheters: simultaneous application for chemotherapy and parenteral nutrition in cancer patients

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Impact of blood collection devices on clinical chemistry assays

Blood collection devices interact with blood to alter blood composition, serum, or plasma fractions and in some cases adversely affect laboratory tests. Vascular access devices may release coating substances and exert shear forces that lyse cells. Blood-dissolving tube additives can affect blood constituent stability and analytical systems. Blood tube stoppers, stopper lubricants, tube walls, surfactants, clot activators, and separator gels may add materials, adsorb blood components, or interact with protein and cellular components. Thus, collection devices can be a major source of preanalytical error in laboratory testing. Device manufacturers, laboratory test vendors, and clinical laboratory personnel must understand these interactions as potential sources of error during preanalytical laboratory testing. Although the effects of endogenous blood substances have received attention, the effects of exogenous substances on assay results have not been well described. This review will identify sources of exogenous substances in blood specimens and propose methods to minimize their impact on clinical chemistry assays.

A Comparison of Peripheral and Centrally Collected Cyclosporine A Blood Levels in Pediatric Patients Undergoing Stem Cell Transplant

PURPOSE/OBJECTIVES

To measure differences in cyclosporine A (CSA) trough concentrations from blood collected as a peripheral sample and from a CSA-uncontaminated (naive) lumen of a double-lumen central line.

DESIGN

Prospective, comparative study.

SETTING

Pediatric university teaching hospital in metropolitan Australia.

SAMPLE

71 paired central and peripheral CSA blood samples from a convenience sample of 14 pediatric allogeneic stem cell transplant recipients receiving IV CSA as prophylaxis or treatment for graft-versus-host disease. Ages ranged from 2 months to 14 years, 5 months.

METHODS

Comparing blood samples collected from a peripheral site and a CSA-naive lumen of a double-lumen central line. Data were analyzed using a paired student t test and calculation of the 95% confidence interval of the concentration ratio from different sampling sites.

MAIN RESEARCH VARIABLES

Site of blood sampling and CSA trough concentrations.

FINDINGS

No significant difference existed between CSA concentration in samples collected from the different sites in children receiving intermittent infusions of CSA (p = 0.13). The 95% confidence interval of the CSA concentration ratio was 0.92 1.04.

CONCLUSIONS

When CSA is administered on an intermittent dosing schedule, comparable CSA trough concentrations can be determined from blood collected via the CSA-naive lumen of a double-lumen central line or at a peripheral sampling site.

IMPLICATIONS FOR NURSING

Pediatric allogeneic stem cell transplant recipients who require regular CSA trough concentrations no longer will require peripheral blood samples when receiving an intermittent dosing schedule.

O cuidado de enfermagem e o cateter de Hickman: a busca de evidências

INTRODUÇÃO: Os pacientes submetidos ao transplante de medula óssea (TMO) necessitam de um acesso venoso seguro para a infusão da medula óssea. A implantação de um cateter venoso central é parte da terapêutica, sendo o de Hickman o mais utilizado atualmente; entretanto, sua presença impõe riscos, sendo a infecção, o mais preocupante. OBJETIVO: Revisão integrativa da literatura, que teve como objetivo buscar e avaliar as evidências sobre os cuidados de enfermagem relacionados ao cateter de Hickman. MÉTODO: Para a seleção dos artigos utilizamos as bases de dados Lilacs, Medline, Cinahl e o periódico Bone Marrow Transplantation, e a amostra constituiu-se de 18 artigos. RESULTADOS: O curativo recomendado é o de poliuretano trocado a cada 7 dias. O método de coleta de sangue observado foi o de descarte, sendo que a dosagem de ciclosporina não deve ser coletada da mesma via onde foi infundida. A redução do número de manipulações do cateter é considerada uma medida eficaz na prevenção e no controle de infecção. CONSIDERAÇÕES FINAIS: As evidências extraídas dos estudos analisados podem auxiliar a implementação de cuidados de enfermagem eficazes relacionados ao cateter de Hickman.