The ‘dead space’ is the void space in the syringe that contains blood after it has been used.
Low dead space injecting equipment has less space between the tip of the needle and the plunger after injecting. Blood and drug(s) remain in this space, so if syringes and needles are shared the risk of spreading blood borne viruses such as HIV and Hepatitis C may be lower when there’s less space for blood to be left in the equipment.
Previous research has found that low dead-space syringes could reduce the chance of spreading infections, such as HIV and Hepatitis C, if they are re-used or shared because there is less blood and therefore less virus.
Some needles and syringes have a greater dead-space than others.
Below are some examples of syringe and needle combinations available on the market.
The first image is a conventional syringe and needle combination with full dead-space between needle and plunger, this is classed as a high dead-space needle and syringe combination.
The second image is an example of a syringe with a modified plunger to reduce the dead-space between plunger and needle, this is classed as a reduced dead-space needle and syringe combination. It has about half the dead-space of a high dead space syringe.
The third image is a needle that has a modified hub to reduce the dead space between the plunger and needle, this is classed as a low dead-space needle and syringe combination. It has less than half the dead-space of a reduced dead-space syringe.
The fourth image is a 1ml fixed needle syringe. This has the lowest dead-space and can be called a ‘low dead space syringe’.
If the dead-space between a syringe and a needle is reduced:
Though it is always highly recommended to use a new syringe and needle each time a person injects, we know that some people do re-use equipment. It is believed that if low dead-space syringes are cleaned and re-used then this lowers the risks involved. It is important to know that low dead-space syringes can still contain viruses, therefore there are still risks present.
There are many reasons a person may re-use drug injecting equipment. People affected by homelessness may not have easy access to Needle and Syringe Programmes and may not have places to store a stock of injecting equipment. People who have purchased drugs late at night and have no stock of sterile equipment at home might also be at risk of re-using equipment.
The project to develop this animation included Bristol Drugs Project service users as co-designers. The project was overseen by a steering group that included Bristol Drugs Project, Exchange Supplies, Public Health England, NIHR CLAHRC West and NIHR Health Protection Research Unit (HPRU) in Evaluation of Interventions.