Current Solutions

Companies are using different approaches to minimise the number of NSI’s and protect the end user. The following is C-Major Medical’s analysis. 

There are two broad approaches to reducing NSI’s:  either cover up the needle after use (protective shields) or retract it so that it is no longer accessible.  

Protective Shields

These are the simplest solutions and the lowest cost point of the range of safety syringes.  However their approach is so simplistic that on many occasions the safety mechanism does not work and most types do not meet the guidelines that will be described below.  Issues with this approach are:-

Sheath

  1. These have limited use and tend to be targeted toward diabetics.
  2. Many of these require two hands to operate.
  3. With the needle partially covered, it is sometimes difficult to see and position the needle correctly, so they are often used only for intra-muscular injections.

Clip: A Plastic Cover is provided with and Pre-Attached to the Syringe or Needle

  1. It is a two handed process to cover the needle after use.  This is not ideal when the first priority of the clinician is to use one hand to cover the injected area on the patient with a plaster or gauze and to stem any bleeding.  More often than not the clinician puts the syringe down first and then picks it up again later to cover the needle. This can leave unprotected contaminated needles on a tray or other work surface, and can be a source of NSI’s.
  2. To cover the needle you have to move your hand toward the contaminated end and swing the already attached cover over and attach it with a click. This is something that is not recommended as hands should always be behind the contaminated needle.
  3. Some companies issue guidelines in an attempt to get over the two-handed approach by recommending that the needle is lined up with the cover and sharply tapped onto a hard surface. This however can produce an issue with splutter  where the act of moving the syringe quickly can cause blood droplets to be ejected from the needle.  The RCN’s guidance to comply with the UK Health and Safety Sharp Instruments in Healthcare (2013) mandates that a safety device must not create other safety hazards or sources of blood exposure (such as splutter).
  4. The cover is already attached to the syringe and can get in the way of the injection site, the cover often flops around as the needle is being inserted.

Syringe with retractable needle

These are the preferred mechanism as the needle is retracted back into the syringe, ensuring no possibility of a NSI post retraction.   There are two types of mechanism, manual and automatic:-

Manual

  1. Unpopular as it requires a two handed process to enable the retraction.
  2. The two handed process is fiddly and could in itself cause an NSI or some other form of blood contamination to the user.
  3. Research has shown that because of the need for the two handed process the safety feature is frequently not activated by the practitioner before disposal

Automatic

This type of product is currently the preferred format, and even though more expensive, the designs start to address some of the user requirements for a safety syringe. However current designs do have significant shortcomings:-

  1. Cannot be used for aspiration (withdrawing fluid from a patient including blood collection) All current designs retract the needle into the fluid chamber and thus cannot be used for blood collection or taking of other samples from the body, further limiting their use.
  2. Retraction is triggered ‘automatically’ (hence the name) at the end of the injection stroke which could be while the needle is still in the patient. If the needle is in a vein and either the patient or the practitioner moves during the retraction process, or the needle is bent during insertion then there is a risk of injury to the patient. The current devices therefore are not approved for intravenous procedures, again limiting their use.
  3. Some require additional pressure on the plunger to engage the retraction mechanism and so can cause extra pain and risk of injury to patients.
  4. One handed trigger is possible, but with all current devices this occurs only at the end of the dispensing stroke.   This means that retraction cannot occur if only a partial injection is made until the remaning injectant is disposed of in some other way.
  5. Standard syringes are provided without needles and clinicians select and fit the gauge/size of standard needle to suit the application/patient. However, many existing auto-retracting devices incorporate needles as an integral fixed part, so many combinations of syringe size and needle gauge need to be stocked – increasing cost.  In addition the inability to change needles after charging the syringe makes them incompatible with some current clinical practices.