All Wales evaluation of safety-engineered IV cannula devices
J Ford PhD (R+D Officer, SMTL), P Phillips (Director, SMTL)
2009
Introduction
This report summarises the findings from an All Wales evaluation of 'safety' IV cannula devices, completed in December 2008.
The evaluation process
The aim of the evaluation was to assess safety IV cannula devices available in the UK, in terms of device performance and user acceptability. It was a two stage process involving bench-top assessments/ functionality tests followed by work-place evaluations. The following section describes the process that was undertaken.
- Requested samples of all 'safety' IV cannula devices available in the UK at time of evaluation.
- Bench-top assessment of devices carried out by a group of health care professionals. Nine devices assessed, 7 of them considered appropriate for All Wales evaluations.
- A 'splatter test' was carried out at SMTL. A closed system of tubing was set up, filled with a blood-substitute fluid containing fluorescein dye. Pressure within the tubing was maintained during the test. The safety cannula with needle was inserted into the tubing and the needle withdrawn over a piece of pale blue paper to detect any splatter using UV light.
- List of devices to be evaluated in Trusts finalised. They are BD Venflon Pro, BD Insyte Acuvance, Smiths Medical Protectiv Acuvance, BBraun Vasofix, BBraun Introcan, Terumo Versatus and Vygon Biovalve.
- All Welsh NHS Trusts invited to participate in evaluations. One coordinator and approximately 5 users recruited from each participating Trust. Six hospitals in Wales and the Welsh Ambulance Service took part.
- Device companies provided participants with devices and short training session prior to evaluations.
- Evaluations commenced. Users performed usual tasks using the 'safety' devices instead of conventional devices where appropriate. A minimum of 10 devices were assessed by each user. Each user assessed each model of device in turn (order randomised by SMTL). User filled in a questionnaire after each model of device has been evaluated. Questionnaires designed by SMTL using a scoring system to evaluate device reliability, ease of activation etc
- Once users evaluated all device models, they completed a questionnaire comparing the devices with each other
- SMTL collated, analysed and presented data
- Results were made available to provide advice and recommendations regarding future All Wales purchase contracts
Figure showing a safety IV cannula (the Terumo 'Versatus') before and after activation. Following activation, the tip of the introducer needle is protected by a white plastic guard.
Results
Bench-top assessments
The following table summarises the comments made at the bench-top assessment
|
Device name and company |
General comments |
To be included in hospital evaluations? |
|---|---|---|
|
U-Cannula (Medifix) |
Device flimsy and unsafe, easy to disengage safety feature following activation |
no |
|
Venflon-Pro (Becton Dickinson) |
Assessors generally liked this device |
yes |
|
Nexiva (Becton Dickinson) |
Device possesses extension tubing with dual ports. In addition, the samples that were sent possessed a 3-way tap. Design not considered suitable for use within the Welsh NHS. |
no |
|
InSyte Autogard (Becton Dickinson) |
One of the two non-ported devices in the evaluation, activated by pressing button on device housing device which retracts needle into blind-ending plastic tube via spring-activated mechanism. Winged and non-winged versions exist. Although assessors felt this device would require more training, they generally liked the device. |
yes |
|
Protectiv Acuvance (Smiths Medical) |
Device 'blunts' upon withdrawal from cannula. One concern raised was that the cap could easily be discarded as it is attached to the cannula sheath which would require a change in practice. However, assessors generally liked this device. |
yes |
|
Vasofix (B Braun) |
Assessors generally liked this device. |
yes |
|
Introcan (B Braun) |
Non-ported safety cannula. Assessors generally liked this device. |
yes |
|
Biovalve (Vygon) |
Assessors generally liked this product although they felt that labelling on the packaging was not clear enough as it did not describe it as a 'safety' device. |
yes |
|
Versatus (Terumo) |
There was a mixed response to this device but assessors felt that it was appropriate to include in the evaluation |
yes |
This test was carried out to determine whether the activation of safety mechanisms had the potential to produce fluid splatter. Using this method, the investigator set the pressure at approximately 8 mmHg within the tubing (Dagner et al. 2002) (we chose this value to exert some positive pressure on the system rather than to accurately mimic the clinical situation as peripheral venous pressure can vary considerably between patients) before inserting a safety cannula into the wall of the tubing via the needle. Once this was achieved, the needle was withdrawn over a piece of pale blue paper and the paper analysed under UV light. As a result of this investigation, none of the seven models of safety IV cannula that were to be evaluated produced fluid splatter upon activation.
Evaluation results
As a result of the bench-top assessment, the functionality tests, it was decided that seven devices : the BD Venflon Pro, BD Insyte Autoguard, Smiths Medical Protectiv Acuvance, BBraun Vasofix, BBraun Introcan, Terumo Versatus and Vygon Biovalve would be evaluated in Trusts. Following the evaluation of each model, users were asked to fill in the following form by circling their response to each statement. Responses ranged from 'Strongly agree' to 'Strongly disagree'. Responses were ranked and the median response is shown in the following tables.
|
Statement/question
|
Venflon Pro (n=29) |
Insyte Autoguard (n=10) |
Protectiv Acuvance (n=27) |
Introcan (n=13) |
Vasofix (n=27) |
Biovalve (n=20) |
Versatus (n=25) |
|---|---|---|---|---|---|---|---|
|
The action required to engage the safety feature is clear when observing the device |
Agree |
Agree |
Agree |
Neither agree nor disagree |
Agree |
Agree |
Agree |
|
The device is easy to activate |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
Disagree |
|
There is a clear view of the sharp tip prior to use Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
|
The device can be activated using one hand only |
Neither agree nor disagree |
Disagree |
Neither agree nor disagree |
Disagree |
Agree |
Neither agree nor disagree |
Disagree |
|
The safety feature does not interfere with the normal use of the device |
Agree |
Agree |
Neither agree nor disagree |
Agree |
Agree |
Agree |
Disagree |
|
The device is compatible with current practice |
Agree |
Neither agree nor disagree |
Agree |
Neither agree nor disagree |
Agree |
Agree |
Neither agree nor disagree |
|
It is obvious when the safety feature has been activated |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
|
The device will require no more training than for conventional device |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
Agree |
|
The device is reliable
|
Agree |
Agree |
Neither agree nor disagree |
Neither agree nor disagree |
Agree |
Agree |
Neither agree nor disagree |
|
I do not think this device increased patient pain/trauma |
Agree |
Agree |
Agree |
Neither agree nor disagree |
Agree |
Agree |
Neither agree nor disagree |
|
I would be happy using this instead of the conventional device |
Agree |
Disagree |
Disagree |
Disagree |
Agree |
Neither agree nor disagree |
Disagree |
|
This device should be considered for use within the Welsh NHS |
Agree |
Disagree |
Disagree |
Strongly disagree |
Agree |
Neither agree nor disagree |
Disagree |
|
How many times did you use the device until you felt comfortable using it? |
5-10
|
5-10
|
5-10
|
5-10
|
5-10
|
5-10
|
10-15
|
|
Did you sustain any injuries whilst using the product? |
No |
No |
No |
No |
No |
No |
No |
Comparing devices
Twenty users from six NHS Trusts/areas completed comparison forms where users were asked to compare safety IV cannula devices they evaluated with each other. Most users did not evaluate all device models included in the evaluations (as they were divided between two groups of users in each Trust/area). The following table summarises some of the main findings when devices were compared.
Result summary
Venflon Pro and Vasofix - These were the most preferred devices of those evaluated. Most users were happy to use either of these devices instead of a conventional and thought they should be considered for use in the NHS.
Biovalve - had similar scores to the Venflon Pro and Vasofix in most areas, although less users would use it instead of a conventional device or felt that it should be considered for use in the NHS.
Versatus, Insyte Autoguard, Protectiv Acuvance and Introcan - These devices were considered unfavourable by most users.
No injuries were reported when using any of the safety devices during this evaluation.
Results of comparison
Only 20 users completed 'comparison' questionnaires where they directly compared the devices they had used with each other and as most users did not evaluate all seven devices, comparisons were limited. When either the Vasofix or Venflon Pro were compared with one of the other devices, there was a clear preference for those two devices. When Venflon Pro or Vasofix were compared to another device they were considered to be the 'most liked' device in over 50% of the cases. No user considered the Vasofix to be the 'least liked' whereas a small number (6%) considered the Venflon Pro to fit this description, indicating that at least a small minority did not like using this device. However, nearly 70% of users who completed the comparison forms stated that they would use the Venflon Pro instead of a conventional, whereas the number was less for the Vasofix (55%).
Results from the individual questionnaires for Vasofix and Venflon Pro were so similar and fewer users directly compared the two devices than completed individual questionnaires, there is not enough evidence to identify a clear favourite between the Venflon Pro and the Vasofix.
Discussion
Evaluations - practical issues
The evaluations took longer than anticipated because of issues with recruiting users in some cases and the logistics of carrying out training and evaluations of up to seven devices per Trust/area. As evaluations could take a long time, there was the potential for 'evaluation fatigue' to set in. As a result, individual users were not expected to evaluate all seven devices. In most cases, up to 10 users in a Trust were divided into two groups that evaluated approximately half of the device models each as directed by the project coordinator. The benchtop assessors (who decided what should be included in the full evaluation programme) felt that all devices that were considered to be potentially suitable should be evaluated, rather than picking a selection, which could introduce bias and leave out potentially good devices.
Also, because this exercise was designed to assess user acceptability of devices, other issues such as cost or provision of company support were not considered here.
Device issues
Comments from participants provided some very interesting insights although by their nature, most comments tended to be negative. An interesting observation is that no device in this evaluation escaped criticism.
Some of the frequent comments made about some/most of the devices are shown below:
- flashback of blood (too slow or lack of)
- blood splash from back of device
- resistance experienced when withdrawing needle from cannula
An interesting point about these comments is that they all (at least to some degree) could be related to the presence of the safety mechanism. However, this is conjecture and would require investigation to establish. For example, some of the needles were longer than usual (another complaint made by some users) which could be due to the requirement for needle length to accommodate the safety mechanism. A longer needle may lead to a slower flashback which users find disconcerting as it is used to indicate when the cannula is in position and lack of flashback can cause vein injury. Blood splatter from the back of the device may be a result of the safety feature as it is removed from the device hub. Finally, the safety feature within the device which engages as the needle tip passes (in most cases) could lead to an increase in resistance. This certainly appeared to be the case with a number of the devices evaluated. In some cases, the force required to withdraw the needle was considered to cause additional patient pain, required extra hands and also re-positioned the cannula.
In hindsight, it would have been informative to include questions on flashback, blood splatter and needle-withdrawal resistance within the questionnaire.
What these issues highlight is that a 'safety' device may introduce new concerns and even new safety issues and it is necessary to balance the advantages (in terms of reduction in injury) against the disadvantages.
Most safety IV cannulae are 'passive' devices. This means that the device is 'made safe' during normal procedure and no special action is required make the device 'safe'. In the case of most safety IV cannulae, the safety feature engages automatically as the user withdraws the needle from the cannula during normal use. This represents a potential advantage over 'active' safety devices because users do not have to remember to activate the device following use. Studies auditing the contents of sharps bins following the use of safety devices have indicated that large numbers of devices are not activated prior to being disposed of. An example of this is a study of a safety syringe that was activated by pushing a button, where over 40% of the devices had not been activated prior to disposal (Mulherin et al., 1996). In our evaluations, with the exception of the Insyte Autoguard (which also required the pushing of a button for activation) the devices possessed 'passive' safety mechanisms.
During this evaluation, size 18G and 22G needles were used. Needle size may have an effect on flashback speed, pain levels, flexing of needles etc., but we did not evaluate the impact of needle size during this project.
Differences in practice can affect people's experience of a device. For example, if participants are used to a ported cannula, they may be less positive about a non-ported variety. Also, an issue raised by a couple of users was that the needles on most of the safety devices could not be re-introduced into the cannula after they had been withdrawn (something which is possible with conventional devices). Although this practice is discouraged, it is sometimes carried out and in an emergency situation, it could cause problems and users should therefore be aware of this.
Another issue is user perception of a device. This was apparent with the Protectiv Acuvance, where a couple of users felt that it could still cause an injury even after it was 'blunted'. This was a 'perception' and only further investigation would clarify this.
Literature review
Relevant published studies were identified by searching the Pub Med database using keywords (list available on request). Searches for literature published up to the January 2009 were included. Only those papers which assessed devices that we have evaluated have been included in this article.
Device evaluations
One study compared the BD InSyte AutoGuard with a conventional cannula (Asai et al., 1999). Patients were randomly allocated into two groups, and the success of IV cannulation using either the conventional or safety device was recorded. No difference in the success of insertion was detected between the two devices. Blood was seen in the tray following needle removal with the conventional device but not with the InSyte AutoGuard, which they considered a safer device. In a similar study (Asai et al., 2002), the BD InSyte AutoGuard and the (then) Medex Protectiv Acuvance safety cannulae were compared to a conventional cannula. For IV cannulation, the AutoGuard was considered much more difficult to insert but safer than the Protectiv Acuvance in terms of blood contamination. The authors stated that further improvements to these types of devices were required before they could be used 'reliably and routinely'. In another American study investigating the the factors involved in nurses' acceptance of a safety product, the J+J Protectiv Plus safety catheter was fully implemented throughout a large teaching Hospital in Texas (Rivers et al., 2003) and data collected a year after its introduction. Most nurses were generally satisfied with the device and comfortable with the training they had received, although acceptance was not universal.
A recently published evaluation comparing user experience of the BD Venflon (a standard cannula) with the B Braun Vasofix was carried out in a London Hospital (Crocker et al., 2008). A total of 105 patients were cannulated by 23 anaesthetists, randomised to either the Vasofix or the Venflon. The Vasofix was found to be more difficult to site and thread, and produced a slower flashback than the Venflon, although pain, blood splatter and use of injection port were similar between devices. However, the authors stated they discovered that the Vasofix devices provided by Braun for the evaluation had become obsolete, with a new version of the Vasofix now on the market that addressed some of the issues raised. We raised this issue with B Braun they confirmed that our users evaluated the new Vasofix and that the old version has not been available in the UK for approximately 12 months. The authors stressed the importance of fully evaluating devices such as these before implementing them in clinical areas.
Flashback and blood splatter
A quick flashback is desired by most users because it indicates successful cannula placement into a vein. If the flashback is slow, users are less confident of correct placement of the cannula and risk piercing the opposite wall of the vein (Strauss e al., 2008).
A recent letter published by a medic in a US hospital raised this concern regarding the BD Insyte Autoguard device (Mychaskiw and Mayhew 2009). They cannulated 100 patients with the device and activated half of them in the vein (as recommended by the manufacturer) and half of them outside of the patient's vein following cannulation. They recorded blood splatter by placing filter paper behind the cannula during activation. They reported that 32% of devices produced blood splatter following activation in the vein whereas only 8% produced it if the device was removed first. They raised the issue that consideration must made to balance the advantage of fewer injuries with the concern of blood splatter.
Our laboratory test did not demonstrate fluid splatter upon activation of any safety IV cannula tested. However, it is clear from studies such as this and user comments in our evaluation that it does occur. This indicates that the method we used to study fluid splatter needs to be investigated and improved if it is to be useful in the future.
Conclusion
A range of mostly 'passive' safety IV cannula exist but some appear to be more acceptable to users than others. The authors of this article recommend that devices are evaluated by users before being introduced into workplaces.
In addition, it should be emphasised that the introduction of safety devices alone will not eliminate occupational sharps injuries and this should be accompanied by other measures such as education and appropriate changes in work procedures as part of an overall sharp safety strategy.
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