A&E 140 Collapse Flashcards
(26 cards)
What are the features of SIRS?
Temperature >38 or 90bpm
RR >20bpm
WBC >12x10^9/L <4x10^9/L
What is the definition of Sepsis?
SIRS in the presence of infection
What is severe sepsis?
Sepsis with evidence of organ hypo-perfusion
What are some evidences of organ hypoperfusion?
Hypoxaemia
Oliguria
Lactic acidosis
Altered cerebral function
What is septic shock?
Severe sepsis with hypotension (SYS <90mmHg)
What is one of the reasons for hypovolaemia in septic shock?
Vessels become leaky
Describe how tissue hypoxia can occur in septic shock
Microvascular changes resulting in reduced blood flow to organs, reduced oxygen extraction by tissues, intravascular coagulation
What causes endothelial damage in shock?
Pro-coagulation factors produced in response to cytokines or endotoxins
What is Anaphylaxis?
Severe systemic type 1 hypersensitivity reaction
What must happen prior to anaphylaxis to a particular antigen?
Sensitisation:
Antigen picked up with activation of Th2 cells and B cells which produce the IgE antibodies which bind to Fc receptors on mast cells
What occurs in anaphylaxis when the patient is reexposed to the antigen?
It cross links with IgE on mast cell surface
mast cell degranulation –> release inflammatory mediators
What is the body’s response in anaphylaxis?
Smooth muscle spasm, blood vessel dilatation and increased permeability = oedema
chemotaxis and tissue damage
Where two types of vascular dilators are there?
Arterial and venous dilators
What do venodilators affect?
BP by lowering stroke volume
How do arterial dilators decrease BP?
By decreasing the systemic vascular resistance
What is the common final pathway in the action of vascular dilators?
Nitric oxide/cGMP lowering intracellular calcium = smooth muscle relaxation
What are the main vascular constrictors in the body
Adrenaline and noradrenaline
What adrenergic receptors are there in the body?
alpha and beta receptors
What other non-catecholamine vascular constrictors are there?
vasopressin and angiotensin
Define hypovolaemic shock
Sharp decline in CO due to empty circulation
Describe cardiogenic shock
Failure of the heart e.g. from ischaemic heart disease, pulmonary oedema, inflammation of heart muscle
Describe obstructive shock
When there is blockage to the heart e.g. cardiac tamponade, pulmonary embolism or tension pneumothorax
Describe maldistributive shock
Abnormal dilatation of small artieries
What is the overall pathophysiology of shock?
Critically low oxygen delivery to mitochondria
