5 Basic Vital Signs

Is the casualty "Big Sick" or "Little Sick"?

Examining the casualty's Vital Signs allows us to assess the casualty's state of health accurately and objectively.  The Golden Rule on all of our courses is:

"If it's not normal, it's bad!"

The above statement may sound inaccurate or even childish but whether you are a novice First Aider or a Consultant Anaesthetist, the above statement is always true.  This is what we need to remember when assessing the casualty.

In this article we will look at how we can rapidly assess a casualty's state of health, at a basic level, with no reliance on medical terminology, equipment or numbers.


The Common Mistake

Humans are hardwired to react to the sight of blood and generally judge casualties based on their injury rather than their vital signs.

For example, which would you say are Big Sick or Little Sick?

Most people would gauge the injuries on the right as more severe - Big Sick - and the injuries on the left as minor - Little Sick.  Some injuries can be more serious than others but injuries alone do not tell you if the casualty is Big Sick or Little Sick.  Injuries alone cannot tell you if a person is going to live or die or if so, when.  Injuries can only tell you that someone has an injury.

If we look at the two casualties below, which casualty is Big Sick?

Hopefully most people would recognize the casualty displaying chest pain on the left as being Big Sick.  Even though the casualty on the right has a nasty injury and there is plenty of blood, there is nothing in the photo to suggest that the casualty on the right is going to die any time soon.  He is Little Sick.

This is worth remembering - while we judge injuries based on the amount of blood, the bruising or the shape of the limb, we cannot do the same with casualties:

  • Some injuries can look horrific but be relatively minor. We know that superficial head injuries bleed a lot but the wound may be very small and will easily stop bleeding with direct pressure.

  • Some casualties may have no obvious injuries but the situation can be life threatening.

So how do we judge a casualty who has no visible injury but they tell you the feel 'unwell'?   How do we judge a casualty who is unconscious or uncommunicative?

The answer is to assess their 5 Basic Vital Signs.

Level of Response

One of the first questions you will be asked by either an emergency services call handler or the person stood next you is "Are they conscious?"

This is a polar question' to which our answer is either "Yes" or "No"  and that is too simplistic. Consciousness is a spectrum beyond simply conscious and unconscious.

We want to know about the casualty's Level of Response (LoR)

If you are reading this you are more than conscious, you are fully ALERT - and that is different to simply being conscious:  Someone who is fully ALERT:

  • Knows where they are

  • Knows who they are

  • Knows roughly what time of day it is

  • Knows the date

  • Can speak clearly

  • Can give appropriate answers

Anyone who is not ALERT is unconscious.

But unconsciousness is not like turning off a switch; there are various shades of unconsciousness.  They may be unconscious but they may also still be able to respond to stimuli.

Typically we ask the unconscious casualty "Are you OK?" or "Can you hear me?"    These again are polar questions and it is nonsense asking an unconscious person these questions if you are expecting a "yes" or "no" reply.   An unconscious casualty will never reply with "no" !

  • Start by asking the casualty an open questions such as "Tell me what happened."

    • If the casualty is able to say "I've fallen over, I've really hurt my back" even though they may be laying down with their eyes closed they are in fact ALERT. They know where they are, what has happened and they are speaking clearly and appropriately.

    • If the reply is mumbled or slurred words, they are not Alert, therefore they are UNCONSCIOUS BUT RESPONSIVE TO VOICE.

  • If they don't reply to questioning, shout a strong and simple command like "Open your eyes!"

    • The response you get may be overt - they may actually open their eyes and look at you - or it may be subtle, they may simply groan or flinch. In either case this casualty is still UNCONSCIOUS BUT RESPONSIVE TO VOICE

  • If they do not respond to voice, do they respond to pain? It is at this point on First Aid courses we tell people to pinch the casualty's ear lobe but that is not effective. Unfortunately, to ascertain if your casualty is able to respond to pain, you must administer genuine pain - BUT - it must be appropriate.

    • EITHER - Pinch the trapezius - the muscle along the top of the shoulder, at the fleshiest bit, between your finger and thumb, HARD.

    • OR - Dig a knuckle into the side of their neck and rub it.

    • Look at the casualty's face; any response is a response, be it overt (e.g. eyes open and screaming) or it may be subtle ( a grimace or a flinch). This casualty is UNCONSCIOUS BUT RESPONSIVE TO PAIN
      (Obviously, if your casualty is responding to voice, do not check to see if they respond to pain!)

  • If they do not respond to pain, they are UNCONSCIOUS AND UNRESPONSIVE.

Your casualty can now be categorised using AVPU:

"Alert" or

"Unconscious but responding to Voice" or

"Unconscious but responding to Pain" or

Unconscious and Unresponsive

REMEMBER:  You do not want to know IF they are unconscious, you want to know HOW RESPONSIVE they are.

This is one of the most complex ideas for us to get our head around.   If you were to ask anyone what an unconscious casualty looks like, most people would say "laying down" and "eyes closed".   Neither of these are anything to do with being unconscious....

What about the drunk, staggering around the town centre at 2am, hugging lamp posts and singing to the moon:  He is upright, his eyes are open.  Is he conscious?

A better question is 'Is he ALERT?'   Does he know where he is?  Does he know what time it is?  Can he give you an appropriate answer?  Is he speaking clearly?

No.  So he must be....Unconscious?

Yes.  When you shout over to him "Hey!  Are you alright?"  And he swings around, almost loosing balance, all he has done is responded to your voice.

This casualty is upright with his eyes open but is UNCONSCIOUS BUT RESPONDING TO VOICE.


In the same way that people tend to simply ask 'Are they conscious?' people will also ask 'Are they breathing?'  This is also a Yes/No question.   Knowing if someone is breathing simply tells you they are alive.   Knowing if someone is not breathing simply tells you they are dead.   It does not tell you if they are Big Sick or Little Sick.  You do not want  to know IF they are breathing, you want to know HOW they are breathing.

RATE -      Is it too fast or too slow?  Normal breathing is between 12 and 20 breaths per minute for adults.

EFFORT - Breathing should require no effort.   

DEPTH -   How much air is moving? Is it shallow / light / weak or is it deep / heavy / strong?

RHYTHM - Is it irregular?

NOISE -   Breathing should be silent.  Are they Wheezing?  Gurgling?  Rasping?

None of these are normal.  All of these are bad.  Anyone whose breathing is not normal is Big Sick.


Isn't all of this a bit pedantic? 

Watch the short clip below and ask yourself, is the casualty Big Sick or Little Sick?

Is the casualty Alert?  No, and that's not normal, that's bad.

Is the casualty Breathing? Yes.  But it's not normal, that's bad.

This is what differentiates Big Sick from Little Sick; because the casualty's Vital Signs aren't normal, that's bad, this casualty is Big Sick.   We don't necessarily know what is wrong with him at this stage but we know he is a serious casualty.

Knowing not just if they are conscious but how responsive they are and not just if they are breathing but how they are breathing also provides information to people who need it.


For the casualty in the clip above it would be reasonable for a lay-person to respond in the following way: 

Call Handler: "Are they conscious?"

You: "Yes."

Call Handler: "Are they breathing?"

You:  "Yes."

So what have you just told the person you are requesting help from?  They are conscious and breathing.  Are they at all concerned?

Better replies would be:

Call Handler:  "Are they conscious?"  

You:  "No, but they are responding to Voice."

Call Handler:  "Are they breathing?"

You:  "Yes, but it is deep and noisy."

These descriptors inform the person you are contacting that the Vital Signs are not normal (and that's bad!) and with this information, professional help will begin to form an opinion of what could be wrong with the casualty.

An experienced emergency services call handler will continue to ask more probing questions but we cannot guarantee that everyone we contact will have that ability.  If we are relaying information to the Emergency Services via a 'runner' we need to ensure the runner can answer these questions appropriately.

Breathing Causes 2.png


Skin colour is another obvious, intuitive Vital Sign; we all judge - consciously or not - an individual's skin colour; we will notice when someone looks pale or flushed.  We can tell which one of the passengers is looking sea sick!

Most changes to skin colour are intuitive:

  • Pale - Blood is moving away from the skin, typically to the core, to protect us when we are cold loosing blood or short of oxygen.

  • Blue - If the cold, blood loss or lack of oxygen is not resolved, we eventually go blue, at the extremities first (peripheral cyanosis) followed by blueness around the mouth and eyelids (central cyanosis). This is not normal. This is Bad!

  • Red - blood is moving towards the skin, usually to help us cool. If the person has a history of exercise and is in a hot climate this would be normal. This would be little sick. If the casualty is sat at their desk in an air conditioned office but is hot and red, this is not normal, this is bad. This is Big Sick.

  • Yellow - Jaundice, for example, can have an effect of skin colour due to a build up of bilirubin which stains the blood an orangey colour, which appears yellow through the skin.

  • Green - Do people go green? Who knows, but you can quite accurately tell when someone is going to be sick just by the look of them.


Changes in skin colour are most noticeable in Caucasian skin because the skin is contains less pigmentation making it almost translucent, a bit like grease proof paper (if you have ever peeled off the flap of skin left over from a blister).  We are able to see blood through the skin and how it is changing - whether it is moving close to the surface, further away or if there is a stain to it.

In casualties with strong ethnicities, this becomes more difficult as the greater amount of pigmentation in the skin masks the changes we would otherwise see.

Whilst it can be difficult to notice changes in skin colour when dealing with people of different ethnicities, it is not impossible:

We are all pale in the same places; everyone has pink conjunctiva (behind the lower eyelid) and finger nails which will go pale or blue.

Colour is closely associated with temperate - blue is cold, red is hot.  This is a universal.

Jaundice will also reveal itself in staining the sclera, the 'white' of the eye.

While it can be harder to notice abnormal skin colours in strangers because you do not have a normal baseline reference, we are able to notice changes in the skin colour of people we know because, regardless of ethnicity, we know what normal is for them.


Casting you're mind back to when you were a little boy or little girl, you Mum would usually measure your temperature by feeling your forehead with her hand.  And we know that Mums are always right.

If your casualty feels hot, they are hot.  If your casualty feels cold, they are cold.  All we have to ask is "Is it normal?"

Is it normal for:

  • The environmental temperature

  • Their levels of activity

  • Their clothing

This is simple enough for an initial assessment.

For long term monitoring you will need a thermometer.   If the casualty is getting cold/hot due to the environment, your hands will be getting cold/hot.   Checking the casualty's temperature every 5 minutes you will have forgotten what it felt like last time you checked.

The most accurate thermometers are tympanic (ear) thermometers but they are bulk and expensive; ideal for parents at home not ideal for remote or industrial first aid kits.   Infra-red forehead thermometers are smaller and cheaper.   Digital Fridge thermometers are tiny and dirt cheap.   These are also ideal for monitoring a packaged casualty.  Bin your old fashioned glass thermometer.

Tympanic Thermometer

Tympanic Thermometer

Infra-red Forehead Thermometer

Infra-red Forehead Thermometer

Digital Fridge Thermometer

Digital Fridge Thermometer


Monitoring a casualty's temperature is essential for managing the casualty with infection, illness, heat stroke or hypothermia.

Capillary Refill

Taking a pulse manually is time consuming, requires regular practice and rarely accurate.   A quicker, easier and more reliable test is Capillary Refill.

Pressing on the casualty's forehead or sternum for 5 seconds will push blood from that area.   When you remove your thumb the pale patch you have created will refill with blood as colour returns.   This should happen within 2 seconds.   Capillary Refill only happens if the casualty has enough circulating blood.

  • If the casualty does not have enough blood they will be pale and the pale patch will not be apparent. This could indicate hypovolaemic shock.

  • If the casualty does not have circulating blood, the pale patch will take longer to refill, if at all.

  • If the colour refills almost instantaneously, there is too much peripheral perfusion, vasodilation is sending blood to the skin which could indicate head injury, anaphlayxis or sepsis.


Capillary Refill does not work on non-Caucasian skin.   In this instance test for capillary refill on the casualty's finger nail:

  • Expect the refill to take longer than 2 seconds.

  • Capillary Refill at the finger nail is affected by the cold more than the forehead.



  • It is the Vital Signs that tell us if the casualty is Big Sick or Little Sick and all we have to ask is "Are they normal?"

  • The 5 basic Vital Signs are

    • Level of Response

    • Breathing

    • Colour

    • Temperature

    • Capillary Refill

  • A casualty may have horrific injuries but if they are Alert, breathing normally, with normal skin colour and at a normal temperature, they are Little Sick. They are not going to die any time soon. And that is reassuring because while the injuries may be disturbing we know we have plenty of time.

  • A casualty may have no injuries at all but if they have a reduced level of consciousness, their breathing is not normal, their skin colour has changed or they are not a normal temperature, they are Big Sick. And this is important because it prompts us to act even though there is no obvious injury.

  • If we monitor the Vital Signs over time we will notice changes. This may reveal if the casualty is improving, deteriorating or stable.

Next Article - Pulse and Pulse Oximetry

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