Image description

Survival Medic Products, Books and Training

Bookmark and Share

Chapter 22 Shock

Shock (Recognition, Prevention & Treatment)


If you’ve ever injured yourself significantly (or given blood) in addition to the pain you may have experienced being weak,
dizzy, and nauseous, in which case you may have experienced a mild form of shock. In this case, the symptoms appeared immediately after the injury, but
they may not show up for several hours dependant on the speed of the blood or fluid loss. Shock is a condition in which blood circulation is seriously
disturbed. Crushed or fractured bones, burns, prolonged bleeding, asphyxia and dehydration can all cause Shock.

Shock may be slight or it may be severe enough to be fatal. Because all traumatic injuries result in some form of shock, you should learn its symptoms
and know how to treat the casualty.

The best approach to Shock Prevention is to treat all casualties suffering from moderate and severe injuries for shock even if they are no showing immediate
signs or symptoms.

Shock is defined as widespread poor blood supply (hypo-perfusion) of the tissues and cells resulting in not enough oxygen and nutrients arriving at the
various parts of the body and not enough waste products produced in the cells is being removed. The organ that needs the best perfusion is the brain.

Shock is frequently the most serious consequence of an injury

Types of Shock

Shock can be caused by several different processes and a useful analogy is to consider the human vascular system as a houses

heating system consisting of a pump (Heart) and pipes /heating circuit (Vessels) and radiators (Organs):

Hypovolemic shock - (losing the fluid from the pipes)

There are several causes:

· Haemorrhagic – loss of blood due to either internal or external bleeding.

· Intestinal obstruction - results in the movement of large amount of plasma from the blood into the intestine.

· Severe burns - loss of large amounts of plasma from the burned surface.

· Dehydration - results from severe and prolonged shortage of water intake.

· Severe diarrhoea or vomiting - loss of plasma through the intestinal wall.
· Distributive shock: (dilation of the pipes) through either nerves (neurogenic shock) or local chemicals (anaphylactic or septic
shock) causes the blood vessels to dilate or become leaky.

· Neurogenic shock through a spinal cord injury causes rapid loss of contractibility of  blood vessels (Vasomotor Tone) that leads to them expanding (Vasodilatation) to the extent that a severe decrease in blood pressure results. Anaesthesia also decreases the activity of the area of the brain that controls constriction and dilation of blood vessels (medullary vasomotor).

· Anaphylactic shock - results from an allergic response that causes the release of inflammatory substances that increase vasodilatation and amount of leakage (Capillary Permeability).

· Septic shock or "blood poisoning" - results from peritoneal, systemic, and gangrenous infections that cause the release of toxic substances into the circulatory
system, depressing the activity of the heart, leading to vasodilatation, and increasing the amount of leakage (Capillary Permeability). ·
Cardiogenic shock - (the pump itself is broken): Occurs when the heart stops pumping or performance is decreased in response to conditions such as a heart
attack or a very rapid heart rate.

How to recognise Shock
A person who is going into shock may show quite a few different signs or symptoms, some of which are indicated below and are

discussed in the following paragraphs. They reflect the effect of the poor blood supply (perfusion) or the various ways the body has to compensate for
this poor blood flow. Remember that some signs of shock do not always appear at the time of the injury; and, in some very serious cases the symptoms may not
appear until hours later. Shock is caused directly or indirectly, by the disturbance of the circulation of the blood. Symptoms of shock include the

· The pulse is weak and rapid.
·  Breathing is likely to be shallow, rapid, and irregular, because the poor circulation of the blood affects the breathing centre in the brain.
· The temperature near the surface of the body is lowered because of the poor blood flow; so the face, arms, and legs feel cold to the touch.
·  Sweating is likely to be very noticeable.

· A person in shock is usually very pale, but, in some cases, the skin may have a bluish or reddish colour. In the case of victims with dark skin, you may have
to rely primarily on the colour of the mucous membranes on the inside of the mouth or under the eyelid or under the nail bed. A person in or going into
shock has a bluish colour to these membranes instead of a healthy pink.

· The pupils of the eyes are usually dilated (enlarged).

· If the casualty is conscious, they may complain of thirst. They may have a feeling of weakness, faintness, or dizziness, or they may feel nauseous.

· The casualty may be very restless and feel frightened and anxious. As shock deepens, these signs gradually disappear and the victim becomes increasingly
unresponsive to what is going on around them. Even pain may not arouse them. Finally, the victim may become deeply unconscious.You are unlikely to see all
the symptoms of shock in any one case. Some symptoms may appear only in later stages of shock when the disturbance of the blood flow has become so great that the person’s life is in serious danger. Sometimes other signs of the injury may disguise the signs of shock. You must recognise which symptoms indicate the presence of shock, but do not ever wait for symptoms to develop before beginning the treatment for shock.

Remember, every seriously injured person is likely to develop serious shock!

Prevention and Treatment of Shock

The first priority in the treatment of shock is to stop the underlying cause – stop the blood loss, treat the allergic reaction or

severe infection.You should begin treatment for shock as soon as possible Prompt treatment may prevent the onset of shock or, if it has already
developed, prevent it reaching a critical point. Keep the victim lying down and warm. If conscious, the victim should be encouraged and depending on the
circumstances assure that expert medical help will arrive soon.Keep an injured person warm enough for comfort, but do not let the victim become overheated.

The best position to use to reduce the onset or to help in the treatment of shock is one that encourages the flow of blood to the brain. If possible, place
the injured person on their back on either the floor, a bed, cot, or stretcher. Raise the lower end of the support about 12 inches so that the feet are higher
than the head. If this is not possible, raise the feet and legs enough to help the blood flow to the brain. Sometimes it may be possible to take advantage of
a natural slope and place the victim so that the head is lower than the feet.Of course every case is different and you will have to consider the type of injury
before you can decide on the best position for the patient. Here are some examples:

· If a person has a chest wound, they may have so much trouble breathing that you will have to raise the head slightly.

· If the face is flushed, rather than pale, or if you have any reason to suspect a head injury, do not raise the feet. Instead, you should keep the head level with or
slightly higher than the feet.

· If the person has broken bones, you will have to judge what position would be best both for the fractures and for shock. A fractured spine must be immobilised
before the victim is moved at all, if further injuries are to be avoided.It is often useful to ask the patient to adopt the position which is most comfortable
for them. If you have any doubts about the correct position to use, have the victim lie flat on their back. The basic position for treating shock is one in which
the head is lower than the feet. Do the best you can under the particular circumstances, to get the injured person into this position. NEVER let a
seriously injured person sit, stand, or walk around.No particular harm will be done if you allow the victim to moisten their mouth and lips with cool water,
if it will make them more comfortable. Administer liquids sparingly and not at all if medical attention will be available within a short time. If necessary,
small amounts of warm water, tea, or coffee may be given to a victim who is conscious. Persons having serious burns are an exception. Burn victims require
large amounts of fluids. Water, tea, fruit juices, and sugar water may be given freely to a victim who is conscious, able to swallow, and has no internal
injuries. Slightly salted water is also beneficial. This should be done if they are fully conscious, able to swallow, and you do not suspect that they have
suffered internal injuries. Never give alcohol to a person in shock, as this will cause blood vessels to dilate and reduce blood pressure.An injured person
may or may not be in pain. The amount of pain felt depends in part on the person’s physical condition and the type of injury. Extreme pain, if not
relieved, can increase the degree of shock. Make the victim as comfortable as possible. Fractures should be immobilised and supported. Immobilisation greatly
reduces, and sometimes eliminates, pain.An injured person’s body heat must be conserved. Therefore, warmth is important in the treatment of shock. Exposure
to cold, with resulting loss of body heat, can cause shock to develop or to become worse. You will have to judge the amount of covering to use by
considering the weather and the general circumstances of the accident.Often a light covering will be enough to keep the casualty comfortable. Wet clothing
should be removed and dry covering provided, even on a hot day. Use blankets or any dry material to conserve body heat. Artificial means of warming (hot water bottles, heated bricks, heated sand) should not ordinarily be used. Artificial heat may cause loss of body fluids (by sweating, and it brings the blood closer
to the surface, defeating the body’s own efforts to supply blood to the vital organs and to the brain. Also, the warming agent may burn the victim.The
treatment of Shock. In many emergency situations, is the most helpful thing you can do for an injured person. If shock has not yet developed, the treatment may
actually prevent its occurrence; if it has developed, you may be able to keep it from reaching a critical point.

Emotional Shock

Emotional shock (Faint) – is not shock in the true sense of the work. Sometimes strong emotions can cause strong parasympathetic

stimulation of the heart and results in vasodilatation in skeletal muscles and in the viscera. The impact of this type of shock will vary widely – sometimes
there will be a powerful sympathetic nervous system response or times it may just present and anxiety. Comfort and reassurance coupled with rest and
relaxation after you are clear of immediate dangers is very effective in management of the casualty suffering from emotional shock. It is important to
keep the victim as calm as possible. Try to prevent the victim from seeing their injuries, or others and reassure them that they will be properly cared
for. Keep all unnecessary persons away, as their conversation regarding the victim’s injuries may increase their agitation

Clinical Signs of Shock




Class 1



Class 2



Class 3



Class 4


Blood Loss

  Volume (mills) in adult






800 - 1500mls



1500 - 2000mls





Blood Loss

  % Circ. blood volume






15 - 30%



30 - 40%






Systolic Blood Pressure



No change









Very low




Diastolic Blood Pressure



No change









Very low / Unrecordable



Pulse (beats /min)



Slight tachycardia



100 - 120



120 (thready)



>120 (very thready)



Capillary Refill






Slow (>2s)



Slow (>2s)






Respiratory Rate









Raised (>20/min)



Raised (>20/min)



Urine Flow (mills/hr)






20 - 30



10 - 20



0 - 10















Pale & cold


















Mental state


Alert, thirsty



Anxious or aggressive, thirsty



Anxious or aggressive or drowsy



Drowsy, confused or unconscious



Giving fluids

The mainstay of treatment in severe shock is the replacement of fluid. In order to safely do this, first there needs to be some

understanding of how fluids behave in the body

Basic homeostasis (how fluid work and move in the body)

Healthy kidneys are very good (better than any doctor) at maintaining a proper balance of salt, water and total volume of your

fluids. With a drop in blood pressure, the kidneys actively absorb more salt and water to correct the balance. Likewise, if the electrolytes such as
potassium are too high or low, the kidneys have mechanisms to correct this. Osmolarity: the amount of electrolyte (sodium, potassium, chloride etc) in the
blood is not just a matter of how much of that electrolyte is there. It also has the effect of how much “saltiness” each electrolytes provides. The
“saltiness” is osmolarity. Normal plasma is about 300 milliosmols per litre (equivalent to 0.9% saline). By comparison, seawater is about 1300 mOsmol/L
(3.5% saline), and the kidneys can concentrate urine up to about 1200 mOsmol/L. Thus, drinking seawater is not an option for most humans, especially as we age and our kidneys become less efficient. “Hypertonic” means extra salty. “Hypotonic” means less salty than normal. A good example of osmolarity: take a
vegetable such as a carrot. Place it in slightly brackish or fresh water and it absorbs water. Even wilting plants can be brought back to a vigorous appearance
this way. Placing a healthy plant in very salty water, on the other hand, causes it to wilt. This is because the water is drawn to the more salty
solution. “Salt sucks” is the simple way to remember this. This becomes of extreme importance when giving IV fluids: red blood cells will burst if plain water is given IV. This can be fatal. “Normal” saline (0.9% sodium chloride – 9gms of salt in 1000mls of water) is so called because it has a “normal” osmolarity, that is, it is saltiness matches plasma. An IV fluid which is too salty will draw water out of the body’s cells, and potentially cause death. A good experiment is to place a
drop of blood into each of 3 test tubes: one tube is filled with water, another with normal saline, and a 3rd with hypertonic saline. The
water-filled tube will lose the turbid cloudy appearance as the red blood cells burst in a few minutes. The 3 samples can be viewed under microscope: the burst
cells will be obvious. The hypertonic (extra-salted) cells will appear shrunken and shrivelled.The concentration of urine takes energy to produce, and the more
concentrated, the harder it is for the kidneys to work. The saltier the water you drink, the more the kidneys have to work “uphill”. Drinking seawater would
be the same as trying to go up too steep a hill: it is just not going to work.

 For an adult, the requirement to rid the body of wastes means a minimum of 500ml of urine per day. This is assuming the kidneys are working as hard as
they can. By drinking extra water, the kidneys can create more dilute urine, but still rid the waste products without working too hard (and at less risk of
kidney stones). The kidneys are essentially like a huge recycling plant: good things are kept and returned to the bloodstream, bad things are tossed out in
the urine. This can be simply due to the concentration of the substance, or by active excretion (e.g. ammonium) or reabsorption (e.g. glucose) of certain
substances. Ant diuretic hormone (ADH) causes water to be reabsorbed in the kidneys. ADH is released in response to low blood pressure of high osmolarity
of the plasma. Alcohol inhibits this ADH from being released, hence the diuresis (lots of urine) as a result of alcohol.

Fluid therapy

There are a number of ways to administer fluid in patients who have shock in an austere or survival situation:

· Orally (by mouth)

· Intravenous (into a vein) / Intraosseously (into a bone)

· Rectally (into the rectum)

These are discussed in more detail below.


The best route to administer fluid to someone (because the gut regulates absorption well) is via the mouth (Orally). The

problem is that in very seriously ill or injured people that the gut stops working and its blood supply is shunted to other parts of the body. This means
the gut is primarily useful in patients mild to moderate shock or dehydration as generally in these cases the gut will be working well enough. In the case of
burns it is possible to rehydrate burns up to approximately 30-35% body surface area.

Oral Rehydration Solution (ORS)

Water is absorbed ok, but oral rehydration solution is absorbed better and is better for the body from a physiological

perspective.There are many recipes, usually differing only in small changes of salt, sugar and other electrolytes. When giving oral rehydration, a small
amount of salt and sugar will help speed up the absorption of the fluid. This may seem counter-intuitive, but the salt and sugar are actively absorbed by the
gut, and so the water is taken up at the same time (“solvent drag”). The following is an easy formula for making an oral rehydration fluid:1/4 Tsp Salt
(Sodium Chloride), 1/4 Tsp Baking Soda1/4 Tsp Lite Salt (Potassium Chloride)21/2 Tbsp SugarCombine ingredients and dissolve in 1000 mills (1liter) of boiled
and cooled water. If only table salt (sodium chloride) and sugar are available, then this is acceptable, but potassium replacement is important if fluid losses
are great, as diarrhoea and vomiting both lose potassium. The minor problem is it does not taste great !


The gold standard for fluid replacement is the intravenous or intra-osseous route. The problem is that it requires sterile

fluid to administer and sterile giving sets and needle to administer (see Clinical Skills Chapter).IV fluids: there is a bewildering array of IV fluids
on the market today. Most are based on the simple principle of 1000mL water and varying amounts of sodium chloride with/without other electrolytes (e.g.
potassium) and sometimes glucose.










Osmolarity (approximate)






“normal” saline



0.9% saline or 9 grams NaCl per litre.



300 mOsmol



Too much will dilute potassium



Hartmann’s solution (compound sodium lactate)



Almost as much sodium chloride as normal
  saline.Normal level of potassium (slightly higher than body, but not
  dangerously so).



274 mOsmol



Too much will result in low sodium levels (this
  is especially dangerous in head injuries)



3% dextrose and 1/3rd normal saline
  (“3 and a third”)



1/3rd of normal saline (0.3%) plus



283 mOsmol



As per Hartmann’s+



4% dextrose and 1/5th normal saline
  (“4 and a fifth”)



1/5th of normal saline (0.18%) plus



282 mOsmol



As per Hartmann’s ++



5% dextrose



ZERO sodium or other salts. Just sugar and water.



278 mOsmol



As per Hartmann’s +++


 In a trauma situation, either normal saline or Hartmann’s will do for the first litre (adults). Subsequent volumes of fluids mean more interference is being
done to the body’s normal state, and more caution is required. For head injuries, it is often better to start (if required) with normal saline. It is
worth noting that a quantity of cold (room temperature) fluid can lower the body’s core temperature, as well as making the blood more acidic, both of which
can interfere with blood clotting. Large volumes also dilute the natural clotting factors, which also impairs the body’s ability to stop bleeding. This
leads to the “Lethal Triad” of cold, acidosis (acid produced in cells not being cleared), and poor coagulation (clotting factors are used up).As always, the
correct amount is “enough but not too much”. Give a small amount (10-20 ml per kilo of body weight) and reassess if any more is actually needed. The modern
trend is towards “minimum volume resuscitation”, where enough fluid is given to maintain blood pressure, but then only given more if required. “Enough” in this
case means: Blood pressure of about 100mmHg systolic (the patient has a radial pulse)Blood pressure enough to keep patient awake and not drowsy.


It is possible to drown a patient if too much fluid is given too quickly. The heart gets overloaded with fluid, and a backlog of pressure can cause oedema

(fluid build-up) in the lungs. This is more likely in patients with some heart problems, the elderly, or very small (e.g. Children). It is also more likely in
the types of fluids easily obtained (e.g. Saline, Hartmann’s) than in the more specialised fluids such as plasma or plasma substitutes. An similar example of
this situation is peripheral oedema, seen where heart failure patients have “puffy” legs, which can be dimpled with finger pressure, like pressing on an
orange. A long bus trip can cause this in some people, as the fluid accumulates in the lower limbs. If this happens to a patient, they may experience shortness
of breath, and they may have pink frothy sputum when they cough. Listening to their chest with a stethoscope leads to a crackling sound (like wringing out a
wet sponge), worse over the lower part of the lungs than the top. Treatment involves sitting the patient up, ceasing fluids, or even giving diuretic drugs
(makes them pass urine), such as Furosemide (“Lasix”). Oxygen helps if available.


This is a much underutilised and neglected route of fluid administration. The rectum and lower large bowel is very well adapted to absorbing water. Water can be administered at a rate on up to 150-200ml an hr – all that is needed for administration is a smallish diameter (1/2 to 1cm plastic tubing) 1m piece of

tubing, the end gently inserted 15-20 cm in the rectum and a funnel. Equally commercial enema sets are perfected set for the sort of fluid administration,
the main limiting factor is it needs to be given slowly.