Before starting NIV

Signs and symptoms of respiratory insufficiency

Learn more about which signs and symptoms are helpful in identifying people who may have respiratory dysfunction.

Signs and symptoms of early respiratory insufficiency

Early respiratory dysfunction tends to occur when the patient is asleep and presents with symptoms of sleep disturbance and daytime fatigue and sleepiness. MND causes diaphragmatic  and intercostal muscle weakness which is particularly worse when patients are lying flat and in REM-sleep, during which time other skeletal muscles are paralysed.

Diaphragmatic weakness causes a failure to exhale CO₂ resulting in raised arterial CO₂ (hypercapnoea) initially. Later there is a failure of inhalation causing hypoxia. The rise in arterial CO₂ causes patients to wake up disrupting their normal, restorative sleep cycles making sleep unrefreshing. The rise in CO₂ causes early morning headaches and metabolic compensation which can be detected with blood gas sampling and additional testing.

When it is more severe, respiratory dysfunction causes daytime symptoms such as breathlessness which might be initially noticeable only on physical exertion such as on climbing stairs, dressing or (in patients who are less mobile) transferring from bed to chair.

Ideally, monitoring these signs and symptoms over time means respiratory insufficiency can be identified at an early stage allowing plenty of time to commence NIV in a planned manner and avoid ‘urgent’ referrals.

Thinking point

What signs and symptoms do you find most useful for indicating the need for NIV?

Common signs of respiratory insufficiency

Sleep disturbance


Other symptoms

You might wish to have a checklist you use with your patients when you assessment. It can be either a mental checklist or a questionnaire your patients can fill in. The Sheffield MND Care Centre uses a checklist which you can download. It includes a scoring system developed by the Utrecht ALS care centre. Patients who score two or more on this checklist have a high chance of having a forced vital capacity of less than 80%.

“I was waking up feeling very tired with a headache.”

Anne, person living with MND

“I was experiencing a lot of yawning during the day, feeling tired.”

James, person living with MND

Woman coughing

“Often a member of the community team might let us know that a patient is struggling to get comfortable at night. Whilst this might be due to their limb disability it can be a sign that they have respiratory insufficiency at night stopping them sleeping so deeply and causing them to wake up more easily.

When this gets reported we can do a full respiratory assessment but also use it as an opening conversation about the benefits of optimising breathing to help people sleep better. This paints NIV in a really positive light. That early warning from their community team is really helpful to help us gently prepare a patient.”

Esther Hobson, Consultant Neurologist, Sheffield MND Care Centre

Thinking point

What signs or symptoms might indicate that a patient is in severe respiratory failure?

Signs and symptoms of severe respiratory failure

Despite all best monitoring, sometimes patients deteriorate quickly or present with severe respiratory failure. For some patients, respiratory failure can be the presenting problem. 

Clinicians should be aware of the signs and symptoms of severe respiratory failure that suggest the need to consider commencing NIV immediately.

These patients are at high risk of dying in the days before NIV can be established. These include:

These patients are likely to need immediate hospital admission. However, you should also consider the option to palliate their symptoms rather than commence NIV depending on the circumstances and patient preference.

Reflect on your learning

Are there any signs and symptoms listed here that you had not considered as being indicative of respiratory insufficiency?

Clinicians should be aware of situations where signs and symptoms may be subtle, inaccurate or falsely reassuring.

It’s important to remember signs and symptoms can be subtle and patients may have none of these symptoms despite requiring NIV.

Thinking point

In what situations can signs and symptoms be subtle, inaccurate or falsely reassuring?

Examples of patients where monitoring using signs and symptoms may be challenging:

These patients may need more frequent tests to make sure symptoms are not missed, or to see if there is a deterioration which might indicate respiratory insufficiency. More objective measurements such as blood gas measurements should be used and no single measure should be reassuring on its own.  If there is uncertainty, a trial of NIV should be considered.

In the following clip, Rosie Whitehead, a Respiratory Physiotherapist, describes how she monitors patients to check for symptoms of respiratory insufficiency.

Video transcript

Exploring symptoms of respiratory impairment

Rosie Whitehead

“I’m Rosie Whitehead, I’m one of the respiratory physios that looks after the MND patients. I work in clinics, helping screen patients for respiratory failure and then, when patients have respiratory equipment, help troubleshoot with that, setting patients up with NIV and cough assist and supporting them at home.

Ideally, when patients come to clinic to see the neurologist, they will also see myself - a respiratory physio - and we’ll go through a symptom questionnaire to look at if they’ve got any signs of breathlessness or if they’ve started to notice any change in symptoms overnight, which might be a sign that their carbon dioxide levels are going a bit higher.

We’ll have a discussion around if they’re having any strange dreams or if they’re struggling to lie flat - which can be a sign that their diaphragm’s weaker. We’ll also do some spirometry to look at their lung function and how much air they’re able to get out in one breath and also how strong their cough is - thinking about if they then got an infection or if something went down the wrong way when they’re swallowing, if their swallowing is getting weaker, that they would still be able to clear that effectively - and then start to discuss if any of those things are abnormal, what we might want to do and trying to refer them onto respiratory as soon as possible; so they are being seen by them and known by them, starting to have discussions round NIV and cough assist sooner rather than later if possible, if patients will engage in that.”

Good practice points