Palliative care: Syringe drivers
A syringe driver is a small portable battery-operated pump that administers drugs subcutaneously by continuous infusion. It is not something that is used by every patient in palliative care, but it can be very useful. Syringe drivers are indicated when other routes become inappropriate or difficult. They are generally programmed to deliver their contents over 24 hours. |
| An empty syringe driver |
Morphine, midazolam and cyclizine are common examples of drugs given in this way, but not all medicines are suitable to be administered via a syringe driver. For example an injection needs to be formulated in a relatively small volume to be given via this route. In addition, products that are irritant (e.g. prochlorperazine, diazepam) are less suitable because of the risk of injection site reactions. Similarly, products that are very acidic or very alkaline may also increase the risk of local irritation.
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| An overhead shot of a syringe driver - the pump pushes the plunger on the left along the barrel of the syringe administering the medicine(s) to the patient |
Most medicines given via continuous subcutaneous infusion are not licensed to be given in this way, and mixing them with other medicines in a syringe driver is also unlicensed. However it is common practice in a palliative care setting, and often several medicines may be given using a single device.
The risk of incompatibility generally increases with the number of drugs, and compatibility information should always be consulted before medicines are mixed in a syringe driver (see Information sources). If you can’t find data for the combination you have been asked about then remember that medicines with a long half-life might not need to go in the syringe driver, and could potentially be given as a once or twice daily direct subcutaneous injection (e.g. dexamethasone, haloperidol). You can also refer back to the Injection Compatibility tutorial on Reducing risk for some more troubleshooting tips.
Water for injection is the preferred diluent in the UK because there are more compatibility data for commonly used medicines. Also it is less likely to cause compatibility problems compared to sodium chloride 0.9% which can produce unpredictable results with cyclizine, and higher doses of diamorphine and haloperidol. However sodium chloride 0.9% is isotonic, and so (in theory) is less likely to cause infusion site reactions than water for injection. In practice though, because the volumes involved are low and the rates of administration are slow, site reactions are not usually a problem with water for injection.
The final volume of a syringe (volume of drug + volume of diluent) may depend upon the brand of syringe driver used and the time over which it is to be administered. Generally the more dilute the contents are, the lower the risk of compatibility problems and injection site reactions. Some centres standardise the volume to be prescribed within different syringe sizes (e.g. 17mL in a 20mL syringe, 22mL in a 30mL syringe). Sometimes the final volume of the syringe may be too large to fit into the device and you may need to consider using more concentrated formulations or splitting the total volume into two equal parts and giving each one over a 12-hour period (e.g. higher doses of levetiracetam).
The risk of incompatibility generally increases with the number of drugs, and compatibility information should always be consulted before medicines are mixed in a syringe driver (see Information sources). If you can’t find data for the combination you have been asked about then remember that medicines with a long half-life might not need to go in the syringe driver, and could potentially be given as a once or twice daily direct subcutaneous injection (e.g. dexamethasone, haloperidol). You can also refer back to the Injection Compatibility tutorial on Reducing risk for some more troubleshooting tips.
Water for injection is the preferred diluent in the UK because there are more compatibility data for commonly used medicines. Also it is less likely to cause compatibility problems compared to sodium chloride 0.9% which can produce unpredictable results with cyclizine, and higher doses of diamorphine and haloperidol. However sodium chloride 0.9% is isotonic, and so (in theory) is less likely to cause infusion site reactions than water for injection. In practice though, because the volumes involved are low and the rates of administration are slow, site reactions are not usually a problem with water for injection.
The final volume of a syringe (volume of drug + volume of diluent) may depend upon the brand of syringe driver used and the time over which it is to be administered. Generally the more dilute the contents are, the lower the risk of compatibility problems and injection site reactions. Some centres standardise the volume to be prescribed within different syringe sizes (e.g. 17mL in a 20mL syringe, 22mL in a 30mL syringe). Sometimes the final volume of the syringe may be too large to fit into the device and you may need to consider using more concentrated formulations or splitting the total volume into two equal parts and giving each one over a 12-hour period (e.g. higher doses of levetiracetam).
Finally, once set up, the infusion should be monitored every four hours to check for precipitation or discolouration and to ensure that the syringe driver is running at the correct rate.
Watch this video, presented by a specialist nurse in Oxfordshire, which shows how the T34 syringe driver is set up. This may not be the brand you use locally, so the detailed instructions may differ in your hospital, but the video does show the range of operational capabilities of a syringe driver.