10. Drugs used in radiology I: emergency drugs Flashcards
what are medical emergencies
any clinical situation that requires immediate medical attention to prevent harm or loss of life
what are sympathomimetics
mimic sympathetic nervous system
what are antiarrhytmics in terms of what they do
restore cardiac rhythm
what is the goal in prescribing emergency drugs
restore normal physiology
what is normal physiology
any physiology that allows you to maintain homeostasis and allows perfusion of vital organs and respiration
what is DRABC
D = remove from danger R = check for response A = check airways are open B = if patient is attempting to breathe C = circulatory refill, check blood pressure and pulse and see if capillary refill is normal
what are the determinants to blood pressure
cardiac output and total peripheral resistance
what is CO determined by
stroke volume and heart rate
what is SV determined by
venous return/preload
what is the determinants of systemic resistance
arteriolar constriction
what 3 aspects of blood pressure does SNS affect
Heart rate, arteriolar constriction and veno-constriction,
what does IV fluids affect in terms of blood pressure
blood volume -> preload -> stroke volume
what does the autonomic nervous system allow the body to do
maintain homeostasis by determining individual end organ homeostasis
what response is determined by the SNS and PSNS
SNS = fight or flight PSNS = rest and digest
what are the SNS and PSNS in relation to each other in homeostasis
SNS and PSNS are in balance
what does SNS do to the heart rate and contraction
increases both
how does the SNS impact contraction of the heart
arteries constrict as want to move blood from periphery to central compartments for heart to pump more and get better contraction
when SNS is activated, veins constricting do what to the TPR and BP
increase total peripheral resistance and BP
what effect does BP and TPR increase due to venous constriction have on perfusion (when SNS is activated)
how is the bronchus involved
improves perfusion to end organs and dilation of bronchus to get more air into the lung so more air transfers
what happens to the gut and liver when the SNS is activated
Decrease gut and liver and constrict to get blood out of reservoir and vasoconstrict in lungs to get more blood circulating
how is the SNS used to manipulate blood pressure and what receptors are involved
using drugs that act on adrenoreceptors that are receptors associated with SNS to mimic flight or fight situation
in hypotension what does heart rate needed to do
Heart rate want to increase and want to increase contractility and reduction of conduction velocity as want heart to repolarise quicker
what does veins constriction do to SV
increase preload so increases SV
what are the 2 types of adrenoreceptors
alpha and beta
what does alpha 1 adrenoreceptors work on
vascular smooth muscle to increase vasoconstriction
what does beta adrenoreceptors work on
acts on heart for positive ionotropic to increase force of contraction and chronotropic to increase heart rate
how do direct catecholamines act
direct interact with A and B receptors
how do naturally indirect catecholamines act
indirect = affect presynaptic preterminal to release adrenaline and noradrenaline to produce effect
what are 2 naturally occuring catecholamines
adrenaline
noradrenaline
what are 2 synthetic catecholamines
alpha 1 and B2 antagonists
what is metaraminol and how does it work
synthetic indirect mixed a and b receptor antagonist, release adrenaline and noradrenaline across synaptic terminal to cross synapse and interact with alpha and beta
why do you need to raise the legs or give fluid bolus for someone who has collapsed to the ground
Raise legs for someone collapsed to shift blood from legs to central compartment to increase blood volume to increase SV and preload
give fluid bolus rapidly to make heart think its got a lot of blood transfused and act as pump
Increases SV
what is the bronchospasm mechanism
Only affect one organ with anaphylaxis
Narrowing and constriction of airways
what are symptoms of a bronchospasm
Cant get air in or out (easier to get air in than out)
Cough wheeze, shortness of breath, severe can have silent chest (no air in or out) and in this case need to help them expel air by pushing on chest mechanically or by using drugs
what are the anatomic mechanisms of bronchospasm
Airway inflammation and mucous secretion, smooth muscle constriction, swelling of membrane in acute phase
what is salbutamol similar to and how do they work
Salbutamol is similar to adrenaline structurally and act mainly on Beta 2 receptors so don’t get cardiac effects, works more on smooth muscles of lungs
What do anticholinergics do and how do they work
Anticholinergic as PSNS relies on acetylcholine as a neurotransmitter and by giving anticholan blocks acetylcholine from work so don’t have PSNS working against us to relax the smooth muscle
how do nebulizers work and what do they do
Nebulizers deliver drug to site of action - bronchial smooth muscle - relaxes smooth muscle by B2 effect and anticholinergic effect
what are the 2 types of medications to treat acute bronchospasm
sympathomimetics and anticholanergic
For someone who goes through a anaphylatic shock reaction what happens to their blood pressure and why
low blood pressure as the trigger goes systemically and all blood vessels don’t know what it is so it has peripheral relaxation, not going to get venous return and SV low so increase HR to compensate - and systemic vascular resistance is going to be low so BP is low as well
how does adrenaline treat anaphylatic shocks
Give adrenaline as it treats/stabilises mast cell degranulation makes vessels bronchi leaky and peripheral vasodilation
Stops mast cells from producing histamine
how is adrenaline administered to treat anaphylactic shocks
Bolus of adrenaline into muscle via epipen or injection
Muscles are vascular rich and can repeat administration every 5 min
Can also give intravenous bolus
what is a con of using adrenaline to treat anaphylactic shock
Problem with adrenaline is that it pushes patient into fight flight, muscles in body get charged metabolically and release hydrogen ions and get acidotic and potassium release so hyperbulemic (not good in long term)
what are the 2 types of shockable rhythms
ventricular tachycardia and ventricular fibrillation
how does amiodarone treat anaphylactic shock
antiarrythmic
blocks potassium channels in the heart and slows rate of repolarisation
how does amiodarone block potassium channels in the heart and slows rate of repolarisation - 2 ways
increases duration of action potential
increases refractory period
what is predisone
corticosteroid that acts as anti-inflammatory and stabilize mast cells and inflammation that leads to anaphylaxis
what is loratidine
antihistamine, histamine acts of histamine receptor and loratadine drug blocks receptor so reduces chance of having allergy reaction
