The following extract is taken from the information provided by Louise O’Dwyer in the Nurses Club webinar ‘Shock – How to Treat it and What it Means for Our Patients’.
The most common type of shock seen in veterinary practice is hypovolaemic shock. Here there is hypoperfusion and hypovolaemia because the circulating blood volume has been lost. That volume can be lost in several ways:
- haemorrhage – internal or external
- fluid and solute loss in excess of intake, eg severe, chronic vomiting/diarrhoea, polyuria
- ‘third spacing’ of fluids, eg parvo puppies get third spacing of fluids into the stomach
The intravascular fluid compartment is only small – only 4% of our fluid is here. So when a patient loses fluid from that 4% it has a profound effect on their body.
What you do need to bear in mind, is that hypovolaemia is very, very different to dehydration and we treat them very differently.
Hypovolaemia refers to loss of intravascular fluid. It does not take into include extravascular (ie intracellular and interstitial) fluid.
Dehydration refers to the loss of water from the whole body (a global loss), assessed by measuring parameters that assess hydration, ie skin turgor/moistness of mucous membranes/eye sunkeness. These all assess interstitial fluid; they are not measuring hypovolaemia. If you are dehydrated you are thirsty, you are not hypovolaemic. Think of the water deprivation test – 5% lost, no ill effects, no change in pulse.
If dehydration persisted, it could eventually cause hypovolaemia, but the two are not interchangeable.
Become confident in dealing with shocked patients in your clinic and learn how you can target treatment in order to gain a successful outcome in August’s Nurses Club webinar.
