Suppression of heparinization of central venous catheters between cycles of chemotherapy. Results of a phase I study

The Management of Totally Implanted Venous Ports in the Ambulatory Oncologic Patient

Totally implanted venous access devices (ports) are widely used in all oncology units, because of the many advantages that they offer if compared to external central venous catheters, particularly in terms of safety. Nonetheless, infection, lumen occlusion and venous thrombosis may still occur, and they are often caused or facilitated by inappropriate insertion or inappropriate management. Reviewing the management protocols of ports in ambulatory patients of 50 Italian oncology units, we have been able to detect the lack of common standardized behavior regarding the technical management of these devices: in addition, some aspects of management differ significantly from what suggested by international guidelines.

Central venous catheter sampling of low molecular heparin levels: an approach to increasing result reliability

BACKGROUND

The low molecular weight heparin effect in children is monitored using the anti-factor Xa level. Venipuncture is recommended; however, central venous catheter blood sampling is often necessary. Heparin infused through central venous catheters may contaminate central venous catheter blood samples, preventing reliable anti-factor Xa level measurement. Simultaneous anti-factor Xa/partial thromboplastin time measurement with central venous catheter blood sampling may predict anti-factor Xa reliability.

OBJECTIVES

To determine the prevalence of heparin contamination as measured by the partial thromboplastin time/anti-factor Xa in central venous catheter blood samples and whether careful sampling could minimize heparin contamination of anti-factor Xa levels from central venous catheter blood sampling.

METHODS

Simultaneous partial thromboplastin time/anti-factor Xa measurements from central venous catheter blood sampling determined the prevalence of heparin contamination of central venous catheter blood samples. In phase II, children receiving low molecular weight heparin had routine central venous catheter blood sampling to measure the peak anti-factor Xa and the simultaneous partial thromboplastin time. Anti-factor Xa levels with a partial thromboplastin time of >40 secs (pair 1) were identified; there was no low molecular weight heparin dose change, and the paired sample was repeated using a careful sampling technique (pair 2). Pairs 1 and 2 were compared to determine the efficiency of the sampling technique in removing heparin from the central venous catheter blood samples.

RESULTS

In phase I, 100 children had 485 paired anti-factor Xa/partial thromboplastin time central venous catheter blood samples with 29% ± 4.1% (95% confidence interval 25% to 33%) anti-factor Xa with partial thromboplastin times of >40 secs. In phase II, 43 children had 129 paired anti-factor Xa/partial thromboplastin time samples with partial thromboplastin times of >40 secs. The pair 1 mean partial thromboplastin times/anti-factor Xa levels were 109.8 secs (SD 53.1, range 34.0 to >200 secs) and 1.03 units/mL (SD 0.56, range 0.26-4.2 units/mL). Repeated partial thromboplastin times/anti-factor Xa levels (pair 2) were significantly decreased from those of pair 1 (p < .001) with means of 58.5 secs (SD 21.2, range 22-152 secs) vs. 109.8 secs (SD 53.1, range 34.0 to > 200 secs, p < .001) and 0.63 unit/mL (SD 0.30, range 0.02-1.77 units/mL) vs. 1.03 units/mL (SD 0.56, range 0.26-4.2 units/mL), respectively.

CONCLUSIONS

Measurement of the partial thromboplastin time performed in combination with that of the anti-factor Xa level can be used to assist health practitioners to identify unfractionated heparin contamination of anti-factor Xa levels drawn from central venous catheters. A careful sampling technique may minimize heparin contamination in central venous catheter blood samples.

Heparin flushing and other interventions to maintain patency of central venous catheters: a systematic review

AIM

This paper is a report of a review to assess clinical studies comparing the effectiveness of different means of maintaining central venous catheter patency.

BACKGROUND

Flushing with heparin is a routine part of central venous catheter maintenance, but it presents risks, including heparin-induced thrombocytopenia. Other techniques used to prevent occlusion of catheters include saline flushes, heparin-bonded catheters and pressure caps.

DATA SOURCES

A search was conducted using the MEDLINE, CINAHL, EMBASE, Cochrane, National Guideline Clearinghouse and University Healthsystem Consortium databases.

METHODS

A systematic review of effectiveness was conducted, using GRADE criteria to assess the strength of evidence for each intervention. The review period covered 1982 or earlier to January 2008.

RESULTS

There is weak evidence that heparin flushing reduces occlusion of catheters, but no evidence that it reduces bloodstream infections. Results from clinical trials of pressure caps are inconsistent regarding their ability to maintain catheter patency, but provide moderate evidence that at least some varieties of caps are associated with increased bloodstream infections.

CONCLUSION

The evidence base on heparin flushing and other interventions to prevent catheter occlusion is small, and published studies are of low quality. There is insufficient evidence on which to conclude that flushing catheters with heparin is more effective than flushing with saline solution.

Prophylaxis of port system-associated thromboses in advanced oncology patients using heparin flushing

PURPOSE

Thromboses occur in connection with the use of venous port systems. Valid data on the instillation of heparin-based solutions in the lumen of the port system are lacking.

METHODS

One hundred and seventy-three patients with malignancy from 19 centres who had participated in an observation study of subcutaneous thromboprophylaxis with dalteparin-Na (Fragmin P/-Forte) were analysed with a view to flushing the port systems and investigating any related influence on the occurrence of catheter-associated thromboses.

RESULTS

All catheter-associated thromboses were seen in centres which used either no UFH, or UFH concentrations of up to 250 IU/ml (8/108; 7.4%). The rate of thrombosis rose to 10% (6/60) if no high-risk dose of dalteparin was applied subcutaneously. On the other hand, the rate of catheter-associated thromboses under the high-risk dose of dalteparin and/or a more highly concentrated instillation fluid, at 0.9% (1/113), was much lower. One haemorrhage from gastric ulcer occurred under the highest UFH concentration in the instillation fluid (2,500 IU UFH/ml).

CONCLUSION

The results indicate that a concentration between 500 IU UFH/ml and 1,000 IU UFH/ml in the instillation solution, at the same time as high-risk prophylaxis with subcutaneous dalteparin for prevention of catheter-associated thromboses, is effective in patients with manifest tumour disease. The instillation of LMWH-based solutions at a concentration of approx 500 anti-Xa units/ml should be discussed as a pending issue.