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Published on 18 August 2010

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Prefilled saline flushes


Prefilled syringes of saline flush solutions save time for nurses and improve patient safety by reducing the risks of medication errors, needle-stick injusry and microbial contamination

Karin Start
Medication Safety Pharmacist
Northampton General Hospital
Northampton, UK

Peripheral intravascular catheters are widely used to provide access for the administration of medicines, fluids and parenteral nutrition. They are also used to provide access for blood sampling for monitoring purposes. Maintaining the patency of such vascular access devices is important to minimise the discomfort, expense and safety risks of replacement. It is common practice to flush the catheters either with physiological saline (0.9% sodium chloride injection) or with a solution of heparin in saline, before and after use (for blood sampling or drug administration), to reduce the risk of clots forming in the lumen.
Although at first sight this appears to be a straightforward procedure, in practice numerous problems have arisen. In part this has been due to the fact flushes were often not prescribed and were therefore not always recorded. The absence of formal policies has also led to widespread use of heparin flushes, although there is little evidence that they are any more effective than saline flushes for peripheral lines.
The risks associated with flushing of vascular access devices are summarised in Box 1.


When saline flushes are prepared at ward level the saline can be drawn up from a single-dose ampoule or from a larger container that is used for multiple doses eg, an infusion bag. One study found that 8% of the saline solutions prepared by nurses for flushes were contaminated with micro-organisms.[1] More recently an outbreak of hepatitis C virus infection in three patients, following percutaneous coronary intervention, at a Swedish hospital was attributed to the use of a vial of saline for multiple saline flushes.[2] A similar episode was reported in a Florida hospital in 2003 and the authors advocated the use of prefilled saline syringes for flushing to reduce the risk of nosocomial transfer of blood-borne pathogens.[3]
Another risk is that when a flush solution is drawn up for immediate use it is rarely labeled. If other injections have also been drawn up there is a danger that mix-ups can occur (see examples in Box 2).


Heparin flush solutions were recognised early on as ‘high-risk, high alert’ medicines by medication safety experts and over recent years reports of incidents have steadily mounted. In April 2008 the National Patient Safety Agency (NPSA) issued a Rapid Response Alert drawing attention to the risks with intravenous heparin flush solutions.[4] This followed the publication of a report reviewing the circumstances of four patient safety incidents where an anaesthetist mis-selected sodium heparin 25,000 units in 5ml (Monoparin) instead of sodium heparin 50 units in 5ml (Hepsal) and administered the more concentrated solution in unlabelled syringes to four children. These incidents were by no means the first of this type. The NPSA received 36 patient safety incident reports concerning heparin flushes between January 2005 and December 2007. Of these, 28 involved mis-selection of heparin and eight involved mix-ups with other injectable medicines, including diamorphine, lidocaine and magnesium. Moreover, similar incidents have been reported in the USA. The most high profile of these was when the newborn twin children of Hollywood actor Dennis Quaid accidentally received thousand-fold overdoses of heparin. In an earlier incident three infants had died in a hospital in Indianapolis as a result of a similar error. Examples of the types of error reported to NPSA are shown in Box 2.
An additional disadvantage of heparin based flushing solutions is that it may be necessary to flush the vascular access device with a separate saline flush before and after administering medicines that are incompatible with heparin.

Heparin or saline for flushing?
The question of whether there is any advantage to using heparin solutions to flush peripheral intravenous catheters to reduce the risk of blockage and the need for replacement has been investigated in detail by the UK Medicines Information Service.[5] The authors also identified other issues that can affect catheter patency including flush technique, patient’s age and site of cannulation. They concluded that there is a reasonable consensus that heparin solutions have no advantage over normal saline for maintaining peripheral intravenous catheters. They were unable to draw any firm conclusions about arterial and central venous catheters and suggested that specific (local) policies may be required depending on the individual devices in use.



Prefilled saline flushes
The use of prefilled saline syringes eliminates the risks of microbial contamination that arise when doses are drawn up at ward level. Moreover, because prefilled syringes are fully labelled, the risk of mis-selection is reduced. An additional factor to take into consideration is the time saving for nurses – the costs (including disposable items and nurse time) of ad hoc preparation of intravenous doses are often overlooked but they can be significant in a busy ward. One study showed the total nursing time input with prefilled syringes was 42% lower than with conventional injection systems.[6]
At Northampton General Hospital, we introduced prefilled saline syringes earlier this year as part of a comprehensive campaign to minimise the use of heparin flushes, in line with the NPSA advice. The starting point was NPSA Alert 20, Promoting Safer use of Injectable Medicines, that listed a number of action points and recommended measures to improve the safety of injectable medicines.[7] Amongst the action points hospitals were asked to:

  • Ensure there are up-to-date protocols and procedures for prescribing, preparing and administering injectable medicines in all clinical areas.
  • Ensure essential technical information on injectable medicines is available and accessible to healthcare staff in clinical areas at the point of use.
  • Implement a ‘purchasing for safety’ policy to promote procurement of injectable medicines with inherent safety features.
  • Provide training for, and supervision of, all healthcare staff involved in prescribing, administering and monitoring injectable medicines.

In addition, a key recommendation was that all syringes and infusions containing injectable medicines that leave the hands of practitioners during use should be labelled. Discussions with ward and theatre staff suggested that this would be difficult to achieve in practice for flushing solutions because of the numbers involved. However, the safety principle was understood and all staff were keen to find a solution. Prefilled, ready-to-use syringes containing 0.9% sodium chloride injection were the ideal solution to this problem. The key advantages are that they are clearly labelled and because they do not require additional manipulation the risk of microbial contamination is minimised. Furthermore, the risk of needle-stick injuries is reduced because no ‘drawing up’ is required. The hospital now uses needle-free systems wherever possible.
This initiative provided the opportunity to examine critically the use of saline and heparin flushes in the hospital and to draft guidance on best practice. We identified all the types of vascular access devices that were in use in the hospital and, in discussion with clinicians in the relevant directorates we agreed on the appropriate flushing procedures. In line with the NPSA guidance, saline flushes are recommended for all peripheral lines and heparin flushes are used for some arterial lines and central venous catheters according to local policy. A table was constructed to serve as an aide mémoire for staff in clinical areas (see Box 4).
We chose the 3ml prefilled saline syringes because this was the volume most suitable for flushing peripheral lines. The paediatric department initially had concerns about the possibility of high pressures being generated in the flushing syringe and the potential for catheter damage as a result. However, the PosiFlush prefilled syringes that we selected have the same diameter as a standard 10ml syringe and generate significantly lower pressures than smaller diameter syringes and are therefore safe for paediatric use.
The prefilled saline syringes were introduced throughout the hospital using a poster campaign, to ensure that only saline flushes were used to flush peripheral lines, and in-service training in the use of the prefilled syringes. One big advantage of having trainers visit the wards was that they were able to reinforce the key messages in the NPSA guidance and emphasise the importance of labelling of injectable products.
Another critical part of the campaign was to organise appropriate distribution of the prefilled syringes to the wards and units. At Northampton General Hospital the prefilled saline syringes are handled by the stores (along with dressings and other medical devices) and not through the pharmacy. A top-up scheme operates and this ensures that adequate supplies are always available.
Although no formal evaluation has been undertaken there is general agreement that the flushes have been an immensely helpful addition to the trust. Both doctors and nurses value them as they support safer administration of injectable medicines – they are easy to use and reduce the work burden involved in preparing flushes at the bedside.
BD PosiFlush has been well received by all staff and the introduction of the pre-filled flushes across the trust has been supported by Safer Patients In Northamptonshire (SPIN) – a group of doctors, nurses, healthcare professionals, managers, patient representatives and board members that works together to put patient safety first. SPIN recognised that BD PosiFlush could reduce the risk of infection to the patient by reducing the number of manipulations required to prepare them for treatment.

1. Calop J, Bosson JL, et al. J Hosp Infection 2000;46:161–162.
2. Lagging LM, Aneman C, et al. J Infect Disease 2002;34(8):580–2.
3. Krause, Trepka G, et al. The Official Journal Of The Society Of Hospital Epidemiologists Of America; vol24,issue 2,February 2003,122–127.
4. Risks with intravenous heparin flush solutions. NPSA Rapid Response Alert NPSA/2008/RRR002. April 2008.
5. Medicines Q&As – April 2008:
6. Detournay B, Aden G, et al. European Hospital Pharmacy 1998;4:109–13.
7. Promoting Safer use of Injectable Medicines, NPSA/2007/20, March 2007.

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