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Senior Clinical Pharmacist
Marie Curie Palliative Care Institute
The Cardiothoracic Centre
Continuous subcutaneous infusion (CSCI) is an effective method of drug administration that is commonly encountered in palliative care. When the oral route is no longer available, the use of a CSCI is the preferred method of drug administration to maintain symptom control. A syringe driver, or pump, is used to deliver a CSCI. Such portable battery-operated devices were first described in 1978 when they were used to deliver desferrioxamine for the treatment of thalassaemia in children. Shortly after this, the use of CSCIs in the context of palliative care was soon described.
The Medicines and Healthcare products Regulatory Agency (MHRA) has received reports of incidents involving syringe drivers and pumps, which have resulted in patient harm or death. In an attempt to reduce these incidents, the MHRA issued guidance on infusion devices, which included recommendations on important safety features (see Table 1).
There are also International Standards, issued by the IEC (International Electrotechnical Commission) and adopted into British Standards to which infusion devices should attain. One such standard that is pertinent to syringe drivers, or pumps, is IEC 60601-2-24, which includes particular requirements for the safety of infusion pumps and controllers.
This article describes four devices that are presently used to deliver CSCIs in the UK.
They each have an array of advantages and disadvantages.
Smiths Medical MS26 and MS16A
The Smiths Medical (formerly SIMS Graseby) MS26 and MS16A are presently the most commonly encountered syringe drivers used for the delivery of CSCIs in the UK.
Until recently, these were the only devices available and pre-date the MHRA recommendations and International Standards. It is therefore of no surprise that these devices fail to meet these requirements. Nonetheless, they are simple to use but are very similar in appearance (see Figure 1) and fatal errors, due to incorrect identification have been reported to the MHRA. Although the devices are coloured differently, and are clearly labelled on the front, the most commonly encountered issue relates to confusion between model and delivery rates.
The flow rate is determined in the same way on both devices, that is, in millimetres of syringe travel over time (MS16A delivers at a rate of millimetres/hour; MS26 delivers at a rate of millimetres/24hours); it is the length of liquid within the syringe, not the volume, that determines the rate of delivery with these syringe drivers. The rate is set by simply turning two screws on the front of the device.
Since the rate of infusion is determined by length, it allows for greater flexibility in the choice of brand and size of syringe. The maximum length than can be infused is 60 mm, but syringes of varying sizes can be attached with 35 ml being the largest; this equates to a maximum volume of approximately 25 ml.
Many palliative care services have adopted one syringe driver (commonly the MS26) in order to reduce the risk of error.
The T34 syringe pump (see Figure 3) differs from the previously mentioned syringe drivers in that the delivery rate is based on volume, rather than length. It potentially has a larger application than the above syringe drivers given the additional safety features discussed below. It is more sophisticated and complicated than the other syringe drivers, but it is inherently safer. A 50 ml syringe will fit comfortably on the device, allowing a volume of up to 38 ml to be infused, dependent upon brand.
The Micrel MP Daily offers a simple and safer alternative to the MS26/MS16A syringe drivers. However, it fails to meet all the MHRA safety features, or satisfy IEC 60601-2-24.
However, the McKinley T34 fulfils all of the MHRA specifications and also satisfies the requirements of IEC 60601-2-24.
1. Wilcock A, Jacob JK, Charlesworth S, et al. Drugs given by a syringe driver. Palliat Med 2006;20(7):661-4.
2. Graham F, Clark D. The syringe driver and the subcutaneous route in palliative care. J Pain Symptom Manage 2005;29:32-40.
3. Russell PS. Analgesia in terminal malignant disease. Br Med J 1979;1(6177):1561.
4. DoH. Hazard MDA HN9506: Graseby Medical MS16, MS16A and MS26 ambulatory pumps. London: Department of Health; 1995.