The routine replacement of peripheral intravenous catheters has no effect on the incidence of catheter failure, on the basis of a composite measure of phlebitis or infiltration. The result replicates findings from our earlier study, which used narrower inclusion criteria but a broader definition of failure.23
These two studies have increased our confidence in changing intravenous lines according to clinical signs and symptoms, rather than using predetermined time frames.15
Changing our policy would bring the practice in adults in line with recommendations from the Centers for Disease Control and Prevention for changing peripheral intravenous lines in children—that is, to replace catheters only when clinically indicated. Paradoxically, in our hospital peripheral intravenous lines are not routinely changed in premature infants or certain other patients in whom achieving and maintaining venous access is difficult. Such populations are arguably at higher risk of developing catheter related complications than general medical and surgical patients in whom routine changes are mandated.
Our overall combined rate for phlebitis and infiltration was 35%, similar to other reports.27 28
The phlebitis rate in both groups was on the low side of ranges reported in recent studies,29 30
despite our population being elderly and unwell, with almost 75% having at least one comorbidity. Reported rates depend on definitions used, and although we applied a standard definition, interpretation of signs and symptoms could still be affected by subjectivity or omission of reporting. For example, it has been argued that infiltration (easy to diagnose) may result from unrecognised phlebitic changes to the vein wall (hard to diagnose) leading to under-reporting of phlebitis.27
It is perhaps more useful to use the composite measure of infiltration or phlebitis as it avoids any potential for misdiagnosis.
Despite allocation to the control or intervention group, participants showed little difference in dwell times. Two factors contribute to this. Firstly, it is not possible to modify all routinely scheduled changes precisely 72 hours after insertion—for example, some catheters may be left to the next morning rather than waking a patient during the night. Secondly, for various reasons many of the catheters in the intervention group failed before 72 hours—although catheters in the intervention group remained in place longer than those in the control group, the average dwell time was within the 72-96 hours recommended by the Centers for Disease Control and Prevention. This confirms that all catheters fail eventually but that many remain functional for prolonged periods. We found that about 3% remained trouble free for over seven days and some for as long as two weeks. Because of this we believe that routinely changing catheters may be an unnecessary and painful intervention for patients, and costly for the organisation.
Potential cost savings of about 25% for infusion related costs could be made if our policy was to be changed in line with recent evidence. Cost estimates used in our study were conservative, based on a simple intravenous event. Others have suggested that about 2.5% of total drug costs are wasted when preparations are destroyed.31
On the basis of recent data from England this could translate to a cost saving of about £61m per annum.32
The study was not sufficiently powered to show differences in our secondary clinical outcomes. Despite this, non-significant results favoured the control group for lower rates of phlebitis, blockage, and local infection. Numbers were small for these outcomes and confidence intervals wide but with a larger enrolment this risk could reach statistical significance. A large, multicentre trial is needed to confirm our results, using phlebitis or bloodstream infection as the primary outcome. Several serious adverse events were reported during the trial. None of these were related to trial procedures.
Strengths and limitations
The major strengths of the study were the processes used to eliminate selection bias, to ensure allocation concealment, and to ensure that the study was adequately powered to detect differences in our primary outcome. We also included a broad range of participants and did not impose any caveats on how or by whom catheters should be inserted. This was to match normal clinical practice and to ensure that results could be extrapolated to other populations of complex inpatients. We were able to enrol 47% of potentially eligible patients compared with about 25% in the earlier trial. Most of those we were unable to recruit were either too frail or their mental state prevented them from providing informed consent. From the point of randomisation, no losses to follow-up occurred.
The study would have been strengthened if monitoring of outcomes had been more stringent. As it was, we extracted most of the outcome data from medical records. A more standardised approach would have been preferable, using staff trained in the process and data collected in real time. Another potential limitation was that outcome assessment was done by people who were not blinded to group allocation. Although catheters were removed by ward staff or intravenous service staff, part of their normal practice is to record reasons for removal in the patient’s medical record. To falsify such an observation because of group allocation would be unlikely, so we believe our results have not been compromised. Finally, the study was not powered to study differences in the secondary outcomes. Phlebitis alone would have been a more clinically important end point but we were limited by restrictions on funding. For the same reason we did not culture catheter tips. This may have provided additional information to inform practice and future studies.
Replacing peripheral intravenous catheters only when clinically indicated does not reduce the incidence of catheter failure, on the basis of a composite measure of phlebitis or infiltration. Larger trials are needed to test this finding using phlebitis alone as a more clinically meaningful outcome.
What is already known on this topic
- Peripheral intravenous catheterisation is the most common invasive procedure among inpatients
- Changing catheters every three days to prevent infection is standard procedure but the practice has not been rigorously tested
What this study adds
- Catheters may be safely left in place for longer than 72 hours if no contraindications are present
- When catheters are replaced only when clinically indicated 25% of infusion related costs are saved