PBL 2 Flashcards
what is shock?
circulatory failure of the whole body where blood flow to tissues is dangerously low which leads to cellular injury and possibly damages multiple organs.
what are the 3 types of shock?
hypovolemic
cardiogenic
distributive
what is hypovolemic shock?
induced by low fluid volume of blood.
what is MVO2?
Myocardial Volume Oxygen - approximates the amount of oxygen used by the heart
which types of shock cause a low MVO2?
hypovolemic and cardiogenic
which types of shock cause a high MVO2?
distributive
what are the 2 types of hypovolemic shock?
non-haemorrhagic and haemorrhagic
outline the pathophysiology of hypovolemic shock?
haemorrhagic or non-haemorrhagic causes cause total volume filling the heart to go down so end-diastolic volume goes down which causes a decrease in stroke volume. This means CO goes down and bp will also decrease = decreased tissue perfusion. This leads to catecholamines, ADH and angiotensin 2 to be released to cause vasoconstriction of blood vessels to help increase vascular resistance and HR to increase CO and therefore increase bp.
what is cardiogenic shock?
When something happens to the heart that prevents it from pumping enough blood to the body’s tissues
whats the most common cause of cardiogenic shock?
MI
outline how an MI can cause cardiogenic shock?
when heart muscle cells die they cant contract as heard so stroke volume goes down and so does CO - the body will also release vasoconstrictors to increase vascular resistance and help maintain bp
in which types of shock will the patient feel cool and clammy?
cardiogenic and hypovolemic
in which type of shock will the patient be hit and flushed?
distributive
outline the simple pathology behind distributive shock?
leakiness of blood vessels and excessive arteriole vasodilation = vascular reistance decreases = bp goes down.
what are the 4 types of distributive shock?
septic shock
anaphylactic shock
neurogenic shock
acute adrenal insufficiency
whats the pathophysiology of septic shock?
endotoxins found on outer membrane of gram negative bacteria directly damage endothelial cells and cause them to release vasodilators (e.g. NO). They also activate th complement pathway which stimulates mass cell release of histamine. Immune cells create inflammatory cytokines which also stimulate the endothelial cells to release more inflammatory molecules = increased vascular permeability. Endothelial cells also express tissue factor (pro-coagulant) which increase blood clotting and coaglation which decreases perfusion to tissues further. This widespread vasodilation = very little vascular resistance = blood cant unload as much O2
outline the pathophysiology of anaphylactic shock?
an acute, life-threatening syndrome caused by IgE-mediated release of vasoactive mediators like histamine and bradykinin from mast cells and basophils in response to various allergens.
outline the pathophysiology of neurogenic shock?
Now sympathetic innervation of the heart originates from T1 to T5 spinal cord segments. Injury to these segments may potentially result in loss of the sympathetic innervation, which results in unopposed parasympathetic stimulation, causing hypotension due to peripheral vasodilation and bradycardia.
how can acute adrenal insufficiency cause shock?
rapid decrease in the glucocorticoid cortisol and the mineralocorticoid aldosterone
what is technical efficiency?
the relationship between resource inputs and outputs. It is concerned with achieving maximum outputs with the least cost
what is allocative efficiency?
Refers to how different resoirce inputs are combined to produce a mix of different outputs - whereby all goods and services are optimally distributed among buyers in an economy to maximise the benefits to society.
what are some arguments for using age in allocating resources?
- Treatment and the care of older people is very costly
- Fair innings argument - older people have has a full life already and younger people have not so its much fairer to divert resources from older to younger patients.
- Older peopls have been paying their taxes to finance the healthcare system all their life and just when they need health care the most, the government lets them down. However the NHS is part of a social insurance system not a savings club for individuals health care. Its the lucky ones who dont get their money’s worth out of the system.
- age is relevant at the individual patient level because older people are less likely to be responsive to treatment
- younger people’s rest of life will be longer than the rest of an old person’s life. But you could argue that as the number of years left become smaller and smaller, each year of life becomes more precious.
what are some arguments against using age in resource allocation decision making?
- Much of this burden relates not to age per se but to the costs of illness and incapacity in the last years or months of life (i.e. the costly bit is about end of life care not age)
- Fair innings - someone who has said to have suffered a lifetime of pain and disability cannot be said to have had a fair innings even if they did live to 80 (should it be more about whos experience the most QUALYs). Also palliative care can be more expensive than therapeutic care so the only way this argument would work would be if you made euthanasia compulsory at the end of the innings.
- Even if treatment were more costly is this a price worth paying for a society that treats its members equally and with respect and compassion.
- age alone is not a good predictor of prognosis or likelihood of developing complications (its biological rather than chronological age that predicts prognosis**)
- older people appreciate the smaller imporvements more than younger people appreciate the bigger improvements. But should the young sacrafine the large benefits so that the old can enjoy the small ones?
- making treatment decisions on the basis of age masks discrimination - discrimination is against the law and the Equality Act 2010 states that protection must be offered for age, race, sex, gender reassignment status, disability, sexual orientation, marriage/partnership status and pregnancy/maternity.
what are some arguments for using QUALYs in resource distribution?
- Addresses the primary purpose of healthcare which is about maximising healthcare and the net benefit - utilitarian theory
- Also might seem to be motivated at the individual patient level i.e. often for patients quantitiy and quality of life are what matter most to them
- They have been used widely by NICE
what are some arguments againt using QUALYs in resource distribution?
• Difficulties relating to measurement and bias
• Measurements of output in units based on life years puts different values on individuals according to their life ecpectancy and thus citizens are no longer equal and older people are particularly disadvantaged - ageist
• It assumes that the value of life is determined by its length but the only person who can put a true value on life, is the person living it.They presume that given the choice a patient would prefer a shorter healthier life to a longer period of survival in a state of severe discomfort.
• some object QUALY based assessments are unjust
◦ double jeopardy objection - those patients with pre-existing medical conditions will be treated much worse as it will reduce their overall quality of life
◦ does end of life care lose out? because people at the end of life have a lot shorter life expectancy
what is the fair innings argument?
older people have has a full life already and younger people have not so its much fairer to divert resources from older to younger patients.
what is the double jeopardy objection?
those patients with pre-existing medical conditions will be treated much worse as it will reduce their overall quality of life
whats the aim of economic evaluations?
to aid decision makers to make efficient, equitable decisions by comparing the costs and benefits of healthcare interventions
what are the 4 techniques of economic evaluation?
cost-benefit, cost-effectiveness, cost-utility and cost-minimization
what is a cost-benefit analysis
compares all the costs and benefits of a given intervention both measured in the same metric (usually money) to determine whether the outcomes are worth achieveing given the costs
what are the pros and cons of cost-benefit analysis?
◦ Allows comparison across programmes with different health outcomes and non-healthcare interventions.
◦ how can we assign money values to health outcomes? how much is a life worth? ethical issues
what is a cost-effectiveness analysis?
compares across different interventions that achieve an outcome measured in a common metric to identify the one that is least costly per unit outcome. The outcome is usually measured in ‘natural’ units and presents results in terms of cost per unit of effect
what are the pros and cons of cost-effectiveness?
◦ starightforward and simple to carry out and easily understoof as we use clinical units
◦ narrow, uni-dimensional measures of effect so we can only compare altrnatives measured in the same units
what is a cost-utility analysis?
compares across different interventions that achieve an outcome measured in a common metric, to identify the one that is least costly per unit outcome. It combines life years gained with some judgement on the quality of those life years. The outcome is usually measured in QUALYs
what are the pros and cons of cost-utility analysis?
◦ enables us to make comparators between interventions that would be measured using different clinical outcomes (useful when effects of intervention are multi-dimension). QUALYS show health benefits in terms of quantitiy and quality of life
◦ QOL measures tend to be more subjective than clinical measures. Does not capture non-health effects. QUALYs get criticism for being insensitive to mental health outcomes so these patients become disadvantaged for healthcare resources.
what is a cost minimisation analysis?
compares across interventions to achieve a fixed outcome, to identify the least costly option.
what are the cons of cost-minimization analysis?
This technique is only valid if it can be shown that the alternatives achieve identical outcomes -rare in practice as there is always uncertainty.
In the UK, what is the preferred choice for economic evaluation?
cost utility analysis
