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A quick guide to syringe drivers |
A syringe driver is a portable, battery operated device for mechanically delivering drugs at a predetermined rate by continuous infusion.
The most common indications for their use include:
- Dysphagia
- Persistent nausea and vomiting
- Ineffective pain relief from oral medications or intolerance to oral medications
- Bowel obstruction
- Malabsorption
- Pain and symptom control during terminal care
Given the above indications, the most commonly used medications are opioid analgesics, anti-emetics such as metoclopramide or haloperidol, sedatives such as clonazepam or midazolam, anti-cholinergics such as hyoscine or buscopan.
Syringe drivers are most often used for subcutaneous medications although they can also be used to give epidural or intrathecal medication.
Site selection
The most common site selection for the subcutaneous cannula is the anterior chest wall, anterior abdominal wall and anterior aspects of thighs or upper arms. Unsuitable sites are areas of ascites or oedema, any site over a bony prominence, or previously irradiated skin (within the last eight weeks).
Before a syringe driver is started, it ideally should be discussed with the patient and the family and carers. Often syringe drivers can be interpreted as a last resort but it needs to be stressed that they are an effective method of administering medications to relieve symptoms and are not only reserved for the last few days of life.
Advantages of syringe drivers:
- Increased patient comfort as there is less need for repeated injections.
- Control of multiple symptoms with a combination of drugs in one syringe.
- Round-the-clock comfort because plasma drug concentrations are maintained without peaks and troughs.
- Patient independence with mobility maintained because the device is lightweight and can be worn in a holster either under or over clothes.
- Generally needs to be refilled once daily, usually by community nursing staff if the patient is at home. This can provide security for the family as the patient is being seen daily.
Disadvantages:
- Fear that it is the last resort.
- Occasional technical problems, eg. the syringe pump battery running out over night, which ideally should be anticipated and a spare battery always in place.
- Less independence than taking oral medications. However families can be trained to draw up medications and maintain syringe drivers at home.
- Confusion and safety issues may arise particularly if staff are required to manage a variety of different brands of syringe drivers.
Types of syringe drivers
There are generally two types of syringe drivers in use, the Graseby MS16A (blue syringe driver). It has a rate of millimetres per hour. The Graseby MS26 (green syringe driver) has a rate of millimetres per day.
For both syringe drivers, the medications are drawn up in the syringe with water for injection to achieve a total of 48 MILLIMETRES against the millimetre scale on the front of the syringe driver. It is important to know that the pump delivers millimetres of travel not millilitres. Therefore, a variety of syringe sizes can be used as long as the syringe is always drawn up to 48 millimetres.
In order for the syringe to run over 24 hours:
1. the Graseby MS16A (blue) is set at 2 millimetres per hour
2. the Graseby MS26 (green) is set at 48 millimetres per day.
The first time the syringe driver is set up, the line from the syringe to the subcutaneous site will need to be primed; therefore the first syringe driver will always run through early.
Useful information
The syringe driver should not be placed higher than the infusion site as gravity may contribute to increasing the infusion rate.
The start or boost button on the syringe driver is not to be used to give bolus medication. It is ineffectual for that purpose and is only used as a test mechanism to make sure that the syringe driver is functioning.
If patients need breakthrough analgesia, than this is usually given as a separate subcutaneous injection. The dose is one sixth of the total 24 hour dose.
The site must be changed if there is redness, swelling, tenderness or leakage.
If a patient’s symptoms are becoming uncontrolled, it is always advisable to check the subcutaneous site. An inflamed or oedematous site will impede drug absorption.
The latest circular from NSW Health states that all syringe drivers used in inpatient settings are required to be in locked boxes. Of course this is not practical at home but the locked boxes do give additional protection should the driver be inadvertently dropped.
A Graseby syringe driver currently costs approximately $1,500. Please look after them!
Dr Joanne Doran is the NCAHS director for palliative care and can be contacted via St Vincent's Hospital, Lismore on 6627 9282.
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