Shock Flashcards
define shock
inadequate perfusion to sustain normal organ function
what is hypovolaemic shock and what typically causes it
loss of intravascular volume so loss of forward flow and SBP
vomiting, diarrhoea, third spacing, renal fluid loss, blood loss, severe dehydration
clinical features of mild hypovolaemic shock
normal/raised pulse pressure
tachycardia
sweating
clinical features of large volume hypovolaemic shock
narrow pulse pressure raised CRT hypotension tachycardia anxiety/confusion decreased urine output
describe the action of the baroreceptor reflex in maintaining blood pressure
reduced stretch in carotid sinus and aortic arch
decreased afferent input to the medullar CV centre and increases SNS output and inhibition of PNS from solitary nucleus
what nerve mediates afferent CV centre input from aortic arch
X
what nerve mediates afferent CV centre input from the carotid sinus
IX
describe how starling forces can be of use in hypovolaemic shock
reduced pressure in capillaries reduces capillary hydrostatic pressure, and shifts fluid flow INTO the capillary
describe the action of the SNS to increase blood pressure
release of adrenline and NA to cause chronotropy and inotropy
raised SVR and redirection of blood from periphery
what part of the SNS response to hypovolaemic shock may lead to decompensation
secretion of vasodilators, if left untreated this will decompensate the system and kill the patient
where is renin released from?
juxtaglomerular apparatus
action of renin in low blood pressure
stimulation of AT II to secrete ADH/aldosterone and subsequent vasoconstriction
what is the frank starling law of the heart
greater loading volume of the ventricle in diastole leads to increased ventricular ejection in systole
what is cardiogenic shock and causes
failure of the heart to meet circulatory demand
MI most common
myocarditis, acute mitral prolapse, cardiomyopathy, myocardial contusion
clinical signs of cardiogenic shock
hypotension fatigue syncope raised JVP hepatic congestion pulmonary oedema
