hypotension and shock Flashcards
what is shock
medical emergency associated with high mortality
underlying causes of shock must be corrected and include the following (3)
haemorrhage, sepsis, myocardial insufficiency
profound hypotension and shock must be treated promptly to prevent (2)
tissue hypoxia and organ failure
Volume replacement is essential to correct the hypovolaemia associated with haemorrhage and sepsis, but may be detrimental in this type of shock
cardiogenic shock
Depending on haemodynamic status, cardiac output may be improved by the use of sympathomimetic inotropes e.g.
adrenaline/epinephrine, dobutamine or dopamine HCl
In septic shock, when fluid replacement and inotropic support fail to maintain BP, what can you consider
vasoconstrictor noradrenaline/norepinephrine may be considered
what is peripheral resistance
the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function
in cardiogenic shock peripheral resistance is freq high (hypertension) and to raise it further can worsen the following (2)
myocardial performance and exacerbate tissue ischaemia
how do vasoconstrictor sympathomimetics work to raise BP
raise BP transiently by acting on alpha adrenergic receptors to constrict peripheral vessels
sometimes used as an emergency method of elevating BP where other measures have failed
what is the danger of vasoconstrictors
although they raise BP, they also reduce perfusion or vital organs such as the kidneys
Spinal and epidural anaesthesia may result in sympathetic block with resultant hypotension .
management may include
IV fluids (usually given prophylactically), oxygen, elevation of legs, injection of a presser drug such as ephedrine hydrochloride
ephederine constricts peripheral vessels but also accelerates HR by acting on
b receptors
As well as constricting peripheral vessels ephedrine also accelerates HR by acting on beta receptors . This dual action is good for managing associated ……… in spinal and epidural anaestheisa which may result in sympathetic block with resultant hypotension
However, IV injection of … can also be used if bradycardia persists
Dual action is useful in managing associated bradycardia, although IV injection of atropine may also be required if bradycardia persists
name 2 ionotropic sympathomimetics used in shock
dobutamine
dopamine
name a sympathomimetic vasocontrictor that is used for severe orthostatic hypotension due to autonomic dysfunction when corrective factors have been ruled out and other forms of treatment are inadequate
midrodrine
