What proportion of TBW is intracellular volume?
2/3rds TBW - 70kg man = approx 28 litres
What proportion of the ECF is plasma volume?
20%
What proportion of the ECF is interstitial fluid?
80%
What proportion of TBW is the extracellular fluid?
1/3rd
What is the definition of shock?
Inability of the circulatory system to meet end organ perfusion requirements.
What are the different types of shock?
- Distributive
- Obstructive
- Cardiogenic
- Hypovolaemic
- Neurogenic
How does the body respond to hypovolaemia?
- Tachycardia
- Increased contractility of the heart
- Peripheral vessel constriction - maintain oxygenation to brain and heart
What are the 5 major sites for major haemorrhage?
On the floor and 4 more:
- 3 main central cavities - Chest, abdomen, pelvis
- Long bones
Why are pelvic fractures such a bleeding risk?
There are numerous sources of bleeding in pelvic fractures:
- Bones
- Venous plexus
- Arterial plexus
Why can pelvic fracture cause such a large loss of blood?
Pelvic ring is disturbed, meaning that tamponade of any bleeding does not occur allowing the blood to communicate to the retroperitoneal space (which has a furhter 5L of volume), the thighs and the peritoneum
Therefore pelvic fractures can be considered bleeding into a free space potentially able to hold the entire blood volume
How would you approach assessing circulation in someone in a pre-hospital setting?
- Inspect - major haemorrhage, patient status
- Palpation - CRT, Pulse rate and rhythm, peripheral pulses, skin temp
- GET ACCESS AT THIS POINT - IV/IO
- Auscultate - heart sounds
- Blood pressure measurement
- Assess major bleeding sites
- AVPU - are they cerebrating
What are you looking for when inspecting the patient for circulation?
- Hands/face blue
- Mottled skin
- AVPU - quick cranial perfusion assessment
What does pallor/cyanosis indicate?
Poor perfusion to tissues
What is normal for a Capillary refill time (CRT)?
2 seconds or less
Where can cap refill be performed?
- Peripherally - Nail bed
- Centrally - sternum, forehead
What would tachycardia and hypotension indicate in a patient who is suscpected to be bleeding?
Severe shock
What would a weak/thready pulse indicate?
Hypovolaemia
What is an absent radial pulse indicative of in terms of management?
Begin IV fluids
Is a low BP in isolation indicative of shock?
No - need other clinical signs such as tachycardia, pale skin, decreased consciousness
What is regarded as the minimum BP that a radial pulse is palpable at?
>80 mmHg
If the femoral pulse is palpable but the radial is absent, what would you guess the blood pressure is roughly sitting at?
70-80 mmHg
What is the minimum systolic BP that the carotid pulse is palpable at??
>/= 60 mmHg
Does hypotension usually occur early or late in shock?
Late - occurs with over 25% blood loss
What is the order in which pulses become absent as hypovolaemia worsens?
Radial absent -> femoral absent -> carotid absent
