hypovolaemic and distributive shock Flashcards
what is shock? What is it due to in general terms?
Tissue Hypoxia (low oxygen), which can be due to:
* Reduced oxygen delivery to tissues
* Excessive oxygen demand/usage by tissues
* Inadequate utilisation of oxygen by tissues
Clinically, we usually care about the first of these (reduced delivery) and categorising which type is causing this.
what is metabolic shock?
hypoglycemic shock (not enough glucose therefore can’t combine with oxygen to make energy)
what is hypovolaemic shock
volume loss and therefore inability of body to get enough blood round the body
what are the causes of hypovolaemic shock?
Traumatic – blood extravasation or plasma and blood with severe bruising/third space loss.
Haemorrhage for other causes e.g. coagulopathy
Fluid loss e.g. severe vomiting and diarrhoea, or marked polyuria.
what is the clinical sign of hypovolaemic shock?
Clinical signs all relate to the body’s compensatory mechanisms to try and restore blood pressure:
Increase cardiac output – Tachycardia
Prioritise vital organs – peripheral vasoconstriction – pale mms, prolonged CRT, poor pulse quality.
When these mechs fail leads to shock - > reduced mentation due to reduced cerebral oxygen supply
needs to have reduced metatino inorder for it to be shock and not just hypovlaemic
what are the diagnostic markers for hypovolaemic shock?
Clinical signs and history plus:
Low blood pressure.
Elevated Lactate.
Point of care ultrasound:
Collapsing caudal vena cava (flat)
Poorly filling heart
what is the treatment for hypovolaemic shock?
Treatment depends on the cause but fundamentally is the same – restore the volume.
Fluid loss - > Isotonic Fluids
Blood/plasma loss - > Transfusion
In the real world we start with isotonic fluids in all circumstances, and then transfusion if necessary.
Speed is of the essence – hypoxia leads to brain death rapidly – so bolus fluids.
what is distributive shock?
(relavtive hypovolaemia) -
is a state of relative hypovolemia resulting from pathological redistribution of the absolute intravascular volume.
dilation of vessles
what are the causes of distributive shock?
Primarily as result of inappropriate vasodilation, however ‘leaky vessels’ also plays a role.
Sepsis/SIRS is probably the most common version you will see, the inflammatory cascade releasing pro-inflammatory cytokines that promote vasodilation and permeability.
what are the clinical signs of distributive shock?
Vasodilation - > injected mucous membranes, shortened CRT (pooling of blood in membrane capillaries), bounding/hyperdynamic pulse. Tachycardia due to hypotension.
Permeability - > peripheral oedema (sepsis causes leaky vessles), pulmonary oedema, cavitatory effusions.
what is the diagnosis of distributive shock?
Clinical signs and history plus:
Low blood pressure.
Elevated Lactate.
Point of care ultrasound:
* Collapsing caudal vena cava (flat)
* Poorly filling heart
* Septic focus e.g. septic abdomen (free fluid)
* Evidence of vascular leak e.g. pulmonary oedema, small effusions.
* Gall bladder halo sign (oedema of the wall)
what is the most common cause of systemic odema?
spesis - it causes leaking vessels and because it is a systemic disease it affects everywhere and therefore there is odema everywhere
what is systolic pressure?
measure of ventricular (pump) function
what is diastolic pressure?
the tone in the vessles (pipes)
why does boundign/hyperdymanic pluse occur with vasodilation? how do you test for a boundign pulse?
vassular tone is lost and therefore the heart has to work harder to maintian the the circulation - large systolic pressure and small diastolic (can be affected with adrenaline)
low MAP or press harder and will occlude the vein (bounding can be occulded)
pumps obviously but weakly as often hypovolaemic aswell
