Safety cannula: Pinpointing safety

Regular monitoring of inoculation injuries at Ashford and St. Peter’s Hospital NHS Trust identified cannulae as commonly involved in percutaneous injuries (where access to inner organs or other tissue is done via needle-puncture of the skin). The approach by a Safer Needle Action Group to introduce a safety cannula device helped prevent injuries using a multi-disciplinary team approach, and involving staff in choosing a new safety cannula device. Staff were involved in selecting a preferred device from the four available companies. A robust business case including key facts and figures regarding cannula-associated injuries and the potential cost to change devices, helped get approval from the trust’s Product and Medical Equipment Group.


The risk of exposure to blood and bodily fluids is an occupational hazard for all healthcare workers. The World Health Organisation (WHO) estimates that 12 billion injections are administered annually worldwide, resulting in two million needlestick exposures for healthcare workers, with one million of these occurring in Europe (WHO 2005).

In 2006, an occupational health adviser (OHA) carried out a study at Ashford and St. Peter’s Hospital NHS Trust entitled Inoculation Injuries; Is poor awareness of reporting procedures leaving staff at risk of developing blood-borne viruses? The report found that percutaneous inoculation injuries such as those sustained from needlesticks and/or sharp objects, were four times more common than mucocutaneous injuries, at 76 (77.6%) and 22 (22.4%) respectively. Within the hospital trust, a Safer Needles Action Group (SNAG) regularly analysed all aspects of inoculation injuries, including the type/nature of injury sustained, specific device in use, and any training needs identified. The multidisciplinary membership of SNAG, which included an OHA who chaired the group, the consultant nurse in infection control, the health and safety adviser, clinical and non-clinical risk managers, the head of supplies and procurement and the clinical skills education manager, helped to ensure that all aspects of inoculation injuries and needle/sharps safety were considered. The discrepancy between the ratio of percutaneous to mucocutaneous injuries was highlighted to SNAG again in the trust’s 2007-08 annual report.

A total of 125 inoculation injuries occurred within Ashford and St. Peter’s Hospital NHS Trust trust during 2007-08: 104 of these were due to percutaneous injuries, and 21 due to mucocutaneous injuries. Five were classified as ‘High Risk’, involving potential exposure to blood-borne viruses (BBV), and as such were reportable under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR). From these, three required a three-day supply of HIV Post Exposure Prophylaxis (PEP), and two required a four-week supply of HIV PEP.

The type of devices causing the percutaneous (needlestick and sharps) injuries varied, but intravenous (IV) cannula were highlighted as being involved in 13% of the innoculation injuries during 2007-08. Of the five high-risk injuries described, one involved an IV cannula. This was significant because, in comparison to other devices, cannulae have a hollow bore, and are likely to have already been in the patient’s vein higher thus increasing the risk of BBV transmission.

The Health Protection Agency’s (HPA) recent Eye of the Needle report (2008) recommends that NHS trusts should be encouraged to adopt safety devices in place of conventional devices, to prevent needlestick injuries among healthcare workers (HPA 2008). Taking into account the higher risk of transmission from BBVs associated with percutaneous injuries (Department of Health 2004, HPA 2008, WHO 2005), and that cannula-associated injuries were one of the most common injuries within the trust during 2007-08, SNAG initiated a review of the market to see what safety cannula were available. The aim of this exercise was to identify a suitable product for use in the trust to reduce the likelihood of cannula-associated inoculation injuries occurring.

Identifying available safety cannula

Although safer devices have been shown to effectively reduce the number of percutaneous injuries (Foley, 2004; Gershon, 1999) it is important that any safety device being considered is evaluated effectively before use. The OH department contacted companies to find out which produced safety cannula and identified BBraun, BD Medical and Vygon. Terumo also confirmed it had a safety cannula device in production, which they anticipated would be available to the market in the near future. Following correspondence, all four companies agreed to attend a safety cannula open day at the trust in March 2008. Each company would present their cannula to staff during the open day, and allow them practical demonstration on dummy arms. With the exception of BD Medical, which had two safety cannula devices available – BD Medical Nexiva and BD Medical Pro Safety – the other companies all presented one device.

The aim of the open day was to gain feedback from staff to help identify two suitable products for further evaluation on selected clinical areas within the trust. A high number of staff from various nursing and medical areas as well as trust directors attended the open day, providing constructive feedback both verbally and through completion of an evaluation questionnaire. The questionnaire asked staff about the functionality of each device – eg, ease of use; effect on cannulation practice; whether or not activation of the safety device was trouble free; disposal safety; whether or not they would use the device again; and the practitioners’ overall preferred choice. Both Vygon and BBraun emerged as the preferred safety devices of those available during the open day.

Before the open day, SNAG was aware that the Vygon safety product was still in production. While it was hoped it would be available for use once the evaluation period had finished, Vygon was unable to give this assurance and as a result was withdrawn from the evaluation process. Consequently the Terumo product, which achieved better results in the initial staff questionnaires, was selected for use in the next stage of evaluation in clinical areas.

Further staff evaluation

It was essential to choose clinical areas where a high number of cannulations take place. Therefore the areas chosen were two theatre departments, one surgical and two medical wards. A further questionnaire was also developed for staff to complete after they had used the devices. The answers for each question fell into the categories ‘excellent’, ‘good’, ‘adequate’ or ‘poor’. The questions asked included assessments of: ease of use; skin penetration; visualisation feedback; activation of safety device; perceived patient comfort.

To avoid any confusion about the safety products being evaluated, each product was evaluated over separate two-week periods, with at least one week’s break between each evaluation. The standard cannula in use was replaced with the safety cannula for each assessment period. The clinical skills education manager from SNAG and representatives from both companies were on hand throughout each evaluation period to assist staff and answer any questions. One of the benefits of selecting safety cannula devices was that staff using them did not have to make changes to their working practice. During the evaluation periods it was noted that while staff were happy to give verbal feedback on the products, there was a low response rate from written feedback questionnaires and despite efforts by the OHA, this remained low.

Overall, SNAG received 15 questionnaires for the Terumo evaluation period, and 32 for the BBraun evaluation period. Despite the poor response to the written questionnaires, there was enough verbal feedback to allow SNAG to carry out a meaningful review of the feedback given.

The BBraun safety cannula still achieved far more positive results than the Terumo product. A number of staff commented on the weight of the Terumo cannula, and how that affected their cannulation technique. Others felt the Terumo cannula seemed to ‘stick’ as they withdrew the needle, prompting concern about potentially dislodging a newly inserted cannula.

Taking into account the feedback received from staff, SNAG decided to recommend the BBraun safety cannula device (pictured, right) for use within the trust. Once this result was reached, the next step was to ensure a robust business case was drawn up to support the decision taken, for which the OHA took responsibility.

Business case

When seeking to introduce a new product, the success of a business case is often influenced by cost. The ruling by the Scottish Court of Session (Scottish Courts 2004) in the case of Skinner v Scottish Ambulance Service deemed the cost for safer devices to be irrelevant, and trusts involved could not refuse to implement a safety device on the grounds of cost alone (Kayley et al 2006, Cullen et al 2006, Scottish Courts 2004). Although this ruling is specific to Scottish Law, it sets a good example for the rest of the UK. However, in view of the current economic downturn and financial constraints being placed on the NHS and business as a whole, the focus is on saving money. A change to using more costly safety devices was unlikely to occur without a strong business case to support the decision.

To help identify the figures involved, it was important to determine the cost of a single inoculation injury to the trust. Due to the differing nature of each inoculation injury, they were divided into specific categories with the cost involved increasing in each category:

  • Low-risk injury: source patient known.

  • Low-risk injury: source patient unknown/ no source patient bloods obtained.

  • High-risk injury: Post Exposure Prophylaxis (PEP) required for three days.

  • High-risk injury: PEP required for four weeks.

Other factors taken into account included: actions taken with the member of staff; blood tests both at the time of the incident and any follow-up screening required; vaccinations/immunisations given; consultant specialist intervention/time; laboratory tests and time; lost working time from when the injury is sustained as well as any subsequent sickness absence; OH time spent dealing with the incident. Also included was the cost of any test which the source patient had given informed consent to be carried out, when they were known.

Using the figures identified, OH reviewed each cannula-associated inoculation injury and calculated their overall cost for the trust during the financial year 2007-08 to be £2,821.05. Based on the total number of cannulae used during the previous year, it was also possible to calculate the extra cost for the trust to introduce the BBraun safety cannula as £7,616.63.

However, since this would prevent any cannula-associated inoculation injuries from occurring, in real terms, the cost to the trust to introduce the BBraun device would actually be £4,795.58. In cases where BBV seroconversion takes place, the cost can run into millions (PHLS 1992). But what is not possible to measure is the cost an injury can have on staff both physically and psychologically.

Once completed and agreed by SNAG, the business case was submitted to the trust’s Product and Medical Equipment Group (PMEG) for review and ratification. They agreed that the introduction of a safety cannula device was a very important step for the trust in safeguarding the health of its staff, and the business case was approved in principle. Although implementation of the safety cannula was costly to the trust, the injuries that would be prevented by using the safety cannula were recognised as more important.

Implementation and monitoring

The roll-out of the BBraun safety cannula is currently being co-ordinated by the head of supplies and procurement, the clinical skills education manager, and the BBraun support team. OH will continue to monitor and investigate inoculation injuries which occur within the trust and provide regular reports to SNAG which will identify whether the safety device is achieving its aim of preventing cannula-associated injuries.

Despite the current economic downturn and the financial restraints being felt by all organisations, Ashford and St. Peter’s Hospital NHS Trust has taken a positive proactive step. It also demonstrates to staff the importance the trust places not only on patient/public health and safety, but also that of its staff.

Dwayne Gillane SPCHN – OH, MSc, OH BSc (Hons), RN(Adult) is occupational health specialist adviser at Ashford and St. Peters Hospital NHS Trust. He can be contacted at


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