Parenteral ketamine infusion information sheet

Contact

Pain Medicine, The Children's Hospital at Westmead

Pain Medicine, Sydney Children's Hospital, Randwick

  • (02) 9382 5434

Introduction

Ketamine is a medication commonly used by healthcare professionals for pain relief and sedation. It works very quickly, which makes it especially useful in urgent or emergency situations.

Ketamine is used to treat pain without putting a person to sleep. It is given through a vein (intravenously) or just under the skin (subcutaneously). In smaller amounts, it can help manage both short-term (acute) and long-term (chronic) pain.

Unlike other anaesthetic medications, ketamine allows people to keep breathing on their own and maintain basic protective reflexes, such as the ability to keep their airway open. 

Ketamine is particularly helpful for people who don't respond well to traditional pain medications such as opioids, or who have developed a tolerance to them. It can also be used with these medications to reduce the amount of opioid needed, which can reduce the risk of unwanted side effects.

Administration

When ketamine is given intravenously or subcutaneously it is given as a continuous infusion. 

The dose is calculated on your child’s weight and is introduced at the lowest dose to see how well the medication relieves your child’s pain. The dose may need to be adjusted to effectively manage pain. This can be done by the nurses on the ward or the Acute Pain Service. 

In some cases, a child will require higher doses. In these cases, the Acute Pain Service will work closely with your child’s doctors.

Safety

There are many measures to make sure ketamine is administered safely.

  • The medication delivery device is very accurate and is equipped with safety alarms to make sure it works properly. 
  • Your child will have an oxygen and heart rate monitor. The nurse will check your child's breathing and heart rate every hour. They will also check your child’s level of pain, how sleepy they are, and sometimes their blood pressure.
  • A member of the Acute Pain Service will review your child each day and make any necessary changes. If your child is in oncology or the intensive care unit, medication management is often managed internally.
  • Ketamine does not usually need to be slowly reduced (weaned) before stopping. This is because it is not a medication that commonly causes physical dependence when used for pain relief. In most cases, it can be stopped safely without needing to gradually lower the dose.

You play an important part in caring for your child, as you know your child best and can help measure your child’s pain at and in between nurse checks. If you think that your child’s pain is not being well managed, please tell your nurse.

If your child is asleep, it usually means that their pain is well controlled. You should still be able to wake them easily.

 

Possible side effects

Like all medications, ketamine can cause side effects. Not all children will experience these, and side effects vary depending on the dose given. 

In most cases, reducing the dose of ketamine relieves unwanted side effects.

Psychological effects

These are the most common side effect of ketamine.

Dissociative anaesthesia may occur when ketamine is given at high doses. This means a person may feel completely disconnected from their body and surroundings. During this state, the person does not feel pain and are unlikely to remember what happened.

As the medication wears off, some people may experience what are called 'emergence reactions'. These can include: 

  • dream-like or pleasant sensations 
  • vivid images or hallucinations 
  • confusion or disorientation 
  • agitation or unusual behaviour.

These effects usually only last a few hours and can be mild to more intense. Children under 15 years experience these side effects less often than adolescents. 

At lower doses, severe reactions are unlikely, but children may have vivid dreams or increased sensitivity to light and sound. A calm, quiet environment for recovery (with minimal noise, touch or visual stimulation) can help reduce these effects.

Heart and blood pressure

At higher doses, ketamine sometimes increases heart rate and blood pressure. 

At lower doses, changes are usually mild or minimal.

Breathing

Most people continue to breathe normally while on ketamine. However, in rare cases – especially if a high dose is given quickly through a vein – breathing can slow down or pause for a short period of time.

Eyes

Some people may experience double vision or unusual eye movements. Ketamine can also increase the pressure in the eye.

Nervous system

Some people may develop increased muscle stiffness or jerky movements. These can sometimes resemble seizures, but are not true seizures.

Stomach and digestion

Loss of appetite, nausea and vomiting can occur, but these are less likely compared with opioids.

General side effects

Increased saliva (drooling) and tear production are common, especially at higher doses. Medications can be given alongside ketamine to help reduce these effects.

Pain, redness or irritation can occur at the injection site, especially in small veins. The nurses may change the injection site every few days to avoid skin redness and irritation.

If you have any concerns about any side effects, please raise this with your nurse, doctor, or the Acute Pain Service.