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Non invasive ventilation (NIV)

Patient information A-Z

Key messages

  • NIV helps remove waste gas (Carbon Dioxide) from your lungs by helping support your breathing
  • Blood tests will monitor your response to the treatment whilst in hospital and help direct treatment decisions
  • NIV masks need to be fairly tight fitting to the face to work effectively but should still be relatively comfortable
  • Initially you may need to wear the NIV for the majority of the day. This will then be reduced as you get better

Who is this leaflet for? What is its aim?

This leaflet is intended to provide information on NIV for patients who may need to start or have started on treatment. It may also be of use for their relatives and or carers.

What is NIV?

NIV is a method of supporting your breathing when you are in respiratory failure.

What is respiratory failure?

Respiratory failure is used to describe a problem with the lungs and breathing. It occurs in two parts:

  • not enough oxygen in the blood
  • too much waste gas (carbon dioxide) which turns the blood acid and acts like a poison

Too much carbon dioxide can cause a variety of symptoms, including:

  • headaches
  • twitching
  • confusion
  • drowsiness – nodding off mid conversation
  • In severe cases – loss of consciousness

Poor levels of oxygen can be treated by providing extra oxygen. However, if there is a problem with high carbon dioxide levels then treatment by oxygen alone will usually not be enough and NIV is required.

How does NIV help?

NIV machines blow a mix of oxygen and air into your lungs via a snugly fitting mask. It does this on each of your breaths, blowing when you take a breath in and a weaker blow when you breathe out. It does not stop blowing but alternates between two pressures during breathing. This helps you to take bigger breaths and helps to rest your tired respiratory muscles. As a result the balance of your oxygen and carbon dioxide will be restored.

How do you know if I need NIV?

You will have an arterial blood gas (ABG) test which is a blood test usually taken from your wrist. This is the best way of measuring carbon dioxide levels. If the carbon dioxide levels are high then it may be decided that a NIV should be trialled.

How do I use NIV?

You will be fitted with a mask over your nose and mouth with a head strap that keeps the mask in place. Because the machine blows air under pressure the mask needs to be quite tight to prevent leaks. A small dressing will be placed on the bridge of your nose to reduce the chances of it becoming sore. Each machine is set up specifically for the patient it is being used on so the amount of oxygen and strength of support you will receive may vary.

If you find either the mask or settings uncomfortable, please tell the nurse looking after you or the Specialist Physiotherapists. Adjustments can usually be made to the NIV settings to improve comfort and effectiveness.

How long do I need to use NIV for?

For the first 24 hours you will be required to wear the NIV mask for as long as possible. As your condition improves the specialist team would look to reduce how often in the day you need to wear the mask, with the goal to remove it completely. The rate at which it is reduce depends on your own recovery, this may be days to weeks. During this time ABG tests will be used to monitor your progress.

Sometimes, after stopping NIV, the respiratory failure may return. If this is the case then the NIV may be restarted. In some cases it may be recommended that you have a NIV machine at home to help prevent further episodes. If so you will be referred to Papworth Hospital’s Respiratory Support and Sleep Centre (RSSC).

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Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151