Single versus double occlusive dressing technique to minimize infusion thrombophlebitis: Vialon and Teflon cannulae reassessed

Peripheral venous catheters: an under-evaluated problem

Peripheral venous catheters (PVC) are the most frequently used invasive devices in hospitals. Up to 70% of patients require a peripheral venous line during their hospital stay, and conservative estimates suggest that PVC days account for 15-20% of total patient days in acute care hospitals. Most published studies focus on thrombophlebitis and address the issue of scheduled catheter change, but there is still no consensus on the optimal time point for PVC change, or whether catheter replacement is required at all. Although PVC-associated catheter-related bloodstream infections (PVC-BSI) are far more serious than thrombophlebitis, few studies address this issue, and a large multicentre trial is lacking. Some studies on thrombophlebitis mention that no, or only a few, PVC-BSIs were identified, but such results must be interpreted with caution. Current data available on PVC-BSI suggest incidence density rates of 0.2-0.7 episodes per 1000 device days, which appear low when compared with other catheters. However, some studies report absolute PVC-BSI numbers in the range of central line-associated infections. It remains unclear whether PVC-BSI should be considered a serious healthcare problem or simply a very rare event. More research is needed both to capture the dimension of the problem and to provide efficient control measures.

Evidence for elective replacement of peripheral intravenous catheter to prevent thrombophlebitis: a systematic review

AIM

This paper reports a review of the scientific evidence for elective replacement of peripheral intravenous catheters in adults in the absence of any clinical complications, with the aim being to reduce the incidence and severity of thrombophlebitis.

BACKGROUND

The incidence of thrombophlebitis associated with peripheral intravenous catheters has been reported to range from 5.3% to 77.5%. Many factors that increase the risk for thrombophlebitis have been reported, of which time in situ is one. In Sweden, the recommended guideline is elective replacement of peripheral intravenous catheters every 12-24 hours.

METHOD

A systematic literature review was carried out in 2005 using the Cochrane Library, OvidMedline and CINAHL databases and hand searching of reference lists and with keywords catheterization, peripheral, thrombophlebitis and parenteral nutrition. The review included randomized controlled trials of elective replacement of peripheral intravenous catheters in adults. Three reviewers assessed the data found according to predetermined criteria.

FINDING

Three randomized control trials met the inclusion criteria and were retrieved for critical appraisal. The samples in two of the trials included patients requiring total parenteral nutrition. Patients in the third trial were receiving crystalloid and drugs. Time intervals for elective replacement varied. Study quality and relevance were rated as 'medium' in two of the trials and as 'low' in the third trial.

CONCLUSION

Limited scientific evidence suggests that elective replacement of peripheral intravenous catheters reduces the incidence and severity of thrombophlebitis.

Different kinetics of the respiratory burst response in granulocytes, induced by serum from blood coagulated in contact with polymer materials

Tubes of different polymer materials were filled with blood collected by venous puncture. The blood was allowed to clot for 10 min, and the serum was collected. Complement activation was demonstrated through assessment of the C3-level by radial immunodiffusion. Phospholipid fingerprints were made after lipid extraction of serum and separation by thin-layer chromatography. The granulocyte fraction of venous blood was separated on a Percoll gradient and the cells were either loaded with a calcium probe, or incubated with luminol. These cells were used as a biological test for inflammatory mediators. Serum from blood coagulated in contact with different materials was added to the test cells. The intracellular calcium level was recorded by Calcium Green-1 fluorescence and the respiratory burst of the test cells was recorded by luminol-amplified chemiluminescence. Serum from blood coagulated in contact with glass tubes, methylised glass tubes and teflon (PTFE) tubes induced a transient increase of the cellular calcium level, indicating a G protein-coupled activation of the test cells. Serum from blood coagulated in contact with glass tubes, methylised glass tubes, and PTFE tubes primed the test cells for a subsequent f-MLP response. Serum from blood coagulated in contact with polyurethane and polypropylene induced a direct biphasic respiratory burst response in the test cells and serum from blood coagulated in contact with methylised glass induced a direct monophasic respiratory burst response in the test cells. Complement activation was demonstrated after blood contact with hydrophobic glass and PTFE. Different fingerprints of phospholipid content were found in sera after blood contact with different materials. The data show that different inflammatory mediators are released during blood coagulation in contact with different materials. The method may be valuable as a screening test for blood compatibility of materials.

Subcutaneous, catheter-related inflammation in a rabbit model correlates with peripheral vein phlebitis in human volunteers

In the development of a polyurethane vascular catheter with anti-infective properties, it became desirable to develop a measure of tissue inflammation. This was investigated in a rabbit model by implanting uncoated catheters and catheters coated with heparin (HEP), chlorhexidine (CH), or CH/HEP in the subcutaneous space with or without 10(4) Staphylococcus aureus. At intervals of 2, 4, and 7 days after implantation, animals were sacrificed; tissue blocks containing catheters were removed and preserved with formaldehyde; and sections were stained with hematoxylin and eosin. Using a histologic index, 240 sections (10 for each experimental condition) were evaluated by two investigators blinded to experimental conditions. Uncoated catheters or catheters coated with CH alone had a lower histologic index (less inflammation) than catheters coated with HEP alone or CH/HEP (P < .05). When catheters were inoculated with S. aureus, those coated with CH, with or without HEP, had a lower histologic index than uncoated catheters (P < .05). Next, 30 volunteers had a control catheter inserted in a vein in one forearm and a catheter coated with either CH alone or CH/HEP in a vein in the other forearm. After 96 h of observation there was a greater risk of phlebitis associated with CH/HEP catheters than control catheters (P < .05), and no difference in the risk of phlebitis between CH catheters and control catheters (P = 0.43). Thus, the amount of inflammation around the catheter in the subcutaneous space of rabbit correlated with the risk of peripheral vein phlebitis.