This leaflet answers common questions about a chronic pain infusion. If you would like further information, or have any worries, please do not hesitate to ask your nurse or doctor.

What is a chronic pain infusion

A chronic pain infusion is when medicine (usually lidocaine and/or ketamine) is given to a patient into a vein, through a cannula, using a pump, over approximately 1 to 2 hours. It is given to patients who have chronic pain and have tried various other treatments either without any benefit or not enough benefit.

What does the procedure involve?

The infusions are given at Barnet Hospital MDTU, which is located on the ground floor in the main outpatients area. You will be sent a letter about this. Your infusion time will be either morning or afternoon.

You will be seated in a reclining chair and stay on the unit for the whole session. During the infusion, you will be monitored where your blood pressure, pulse and breathing will be recorded regularly. You will be allowed home when the infusion has ended, and we are confident that you are safe.

What if I can’t make the procedure?

Due to the long waiting lists within the NHS, infusions cannot be rescheduled, and you will unfortunately have to wait until your next scheduled infusion. So, it is important that you attend the session as it will have been saved for you.

If you cannot attend, please cancel the appointment by calling pain admissions on the number above. Failure to cancel will likely result in discharge from the pain service and you will need to be re-referred by your GP if you wish to be seen again.

Before the procedure

  • You must have fasted, so no food (or tea/coffee with milk) for six hours before, and no fluids for two hours before. Patients with specific health needs, such as diabetes or gastrointestinal conditions should be scheduled earlier in the day.
  • Before the infusion, take all your medications as normal. After the infusion, you can continue your medications, including your pain medications.
  • You must inform us if your health has changed since your last appointment. For example, if you are being investigated for any new symptoms, or you have been diagnosed with a new heart problem, please let us know before you turn up. You may be cancelled on the day if you disclose this on the day.
  • If you are pregnant, let us know as it is not recommended to have infusions during pregnancy.
  • You must arrange for someone to take you home after the session. You cannot drive yourself home afterwards due to possible drowsiness. This can include a taxi. You may feel a little tired after, but this should pass within 24 hours.
  • You can return to normal activities within reason. Do not operate heavy machinery or take up any exercise that is new or that you are not used to. Avoid overdoing things too soon.
  • Keep a diary of your pain after the infusion. We recommend using pain apps which you can get mostly for free online. If you need guidance, please discuss with your pain doctor.

Infusion contents

Lidocaine

It is a local anaesthetic. You may have had in injected into your skin or gums if you have ever needed a surgical procedure. It works by decreasing both spontaneous nerve activity and the spread of pain signals in nerve fibres located peripherally and centrally. In other words, it quietens misbehaving nerves in your body.

Ketamine

Ketamine is an anaesthetic medication, which in small doses, controlled by a medical expert, can be used to help control pain that has not responded to standard treatment.

Procedure side effects

Lidocaine

Your consultant will have discussed this with you before the procedure. Fortunately, serious side effects or complications are rare and by being continuously monitored, the chances of problems arising are small.

However, even at the recommended dose, side effects can occur. These include dizziness, headaches, drowsiness, tingling or numbness around your mouth, metallic taste, garbled speech, tunnel vision, ringing in your ears or a tremor, a sense of being drunk and nausea. If any of these side effects do occur, they usually disappear once the infusion is slowed down or stopped.

Recognised potential complications of lidocaine infusions include low or high blood pressure, a slow or fast pulse rate, irregular heartbeats, fainting, seizures, or allergic reactions to lidocaine, which, in extremely rare cases, can lead to death. But again, this is minimised to a small risk by the fact you are being monitored closely throughout.

It is advisable to report any side effects to your doctor.

Ketamine

Side effects of ketamine can include vivid dreams, nightmares, mood swings, hallucinations, feeling restless, overactive bladder, and interstitial cystitis but these are uncommon as you will be having a low dose. High blood pressure and fast pulse rate are also possible but will be picked up through the monitoring.

What to expect from the infusion

Ideally, we hope that your pain will be relieved by this treatment. Sometimes, it is relieved but not fully. Other times, if you have lots of pains, not all may be improved equally. Most of the time, any pain relief will be temporary, with effects of a single infusion lasting for some days to some weeks, occasionally longer. However, you should be able to reduce your normal pain medications within this time, as well as having more function.

Infusion aims

Just like other parts of pain management that are offered, the aim of the infusion is to help get the pain under more control so that you can function daily and learn to cope better with your pain. This involves working with the pain management approaches, learnt through pain physiotherapy and psychology, to improve your everyday life.

You will need to attend your physiotherapy appointments and work with them, using the duration of pain relief from the infusion to help you.

Trial infusions versus regular infusions

What are trial infusions?

Initially, you will be offered the infusion as a trial. If the infusion gives enough benefit, you will be added to the list for regular infusions.

Trial infusions mean that you have three separate infusions, each with a slightly higher dose of medication. The first infusion is to test if you have any significant side effects. The second and third infusions, which will each be two months or so after the last infusion, will test how much benefit you have had and how long the benefit has lasted. You will discuss this with your consultant or physiotherapist in clinic and they will determine if you should proceed with regular infusions.

What are regular infusions?

Regular infusions mean repeating the last infusion dose at a set frequency over a year.

How long can I have the infusions for?

The infusions will be not continued for an indefinite period as the aim is to support you to be able to manage your pain without medical interventions, and with appropriate self-management approaches. The criteria for continuation of the infusions will therefore be defined tightly to ensure that the treatment is needed and not placebo. These are noted below.

Before each infusion, you will be given a questionnaire that is available online (see QR code at the end). If you are unable to access the online version, other options will be made available including paper version. It is important that you fill this in as the information will help guide your consultant in deciding whether to continue the infusions. Please note: failure to fill in the questionnaire could result in you being refused further infusions.

What criteria are required to move from trial to regular infusions?

The questionnaires will measure various outcomes shown below.

  • Pain score before and after the infusions
  • General activity
  • Mood
  • Relationships
  • Sleep
  • Mobility
  • Amount of repeated pain medications
  • Amount of breakthrough pain medications
  • Review and work with a pain physiotherapist
  • Length of benefit

If your results suggest that at least four of these measurements have improved significantly, then the infusions will likely be continued.

How often will I get the regular infusions?

Regular infusions will be offered initially on a two or three-monthly basis. After one year of infusions, you will be reviewed by your pain consultant who will decide whether infusions should continue.

They will use the data from the repeated questionnaires that you fill in, as well as the input from the pain physiotherapy and psychology teams to ensure that you are engaging with these parts of the service (where appropriate). If the decision is to continue, your infusions will be spread out further as described in the table below.

How often will the infusions be if you are engaging with pain management
Year Occurrence
One Two or three monthly – depending on the effect.
Two. Three or four monthly – depending on the effect.
Three. Six-monthly.

Pain infusion questionnaire

Complete the pain infusion questionnaire.