AKI Flashcards
name three things the kidney regulates?
pH via recreation and reabsorption of HCO3-
Osmolarity
Blood presssure
what does the kidney maintain?
ion balence
Na+ K+ ca2+ and HCl
what does the kidney excrete?
urea , creatinine, drugs , urobilinogen and hormones
what hormones does the kidney produce?
vitamin D3 and erythropoetin
how do you calculate the amount of solute excreted?
amount filtered - ( amount absorbed + amount secreted )
why is creating a useful indicator of eGFR?
It undergoes glomerular filtration in the kidneys and very little is reabsorbed. mainly excreted so useful indicator
what are two advantages of the Cockcroft and gault calc ?
- easy to calculate on practise
- used for many years and so used in spa as a refernece
what are two disadvantages of the Cockcroft and gault calc ?
- body weight isn’t an accurate measure of muscle mass so it cannot be used if a patient is obese
- the calc is used on variable limits
what is an advantage of the MRDR equation?
a better estimation than cockcraft and Gault
what is an disadvantage of the MRDR equation?
Harder to calculate in practise
docent take into account the patients body mass
what is a negative of the CKD-EPI?
very complex to calculate
how does an AKI affect fluid balance?
oedema ( swollen legs) and pulmonary oedema can develop
diuretics may be needed
how does an AKI affect acid balance?
when a patient has pulmonary oedema and respiratory compensation acidity in the blood increases which can lead to hyper ventilation
Sodium retention increases leading to seizures and thirst
how does an AKI affect electrolyte balance?
electrolyte balance becomes disturbed which can cause arrithhymias , muscle weakness and paralyis.
what happens to endocrine function in an AKI
erythropoetin production can be reduced leading to anemia this is more common in CKD than an AKI
vitamin d activation is reduced leading to an increased risk of fractures
renin agiotensin system is reduced leading to calcification in blood vessles and an increased cardiovascular risk
how does an AKI affect excretion?
patient has reduced excretion of
- water soluble substances leading to pruritus , itching cramping and restless leg syndrome
- waste products leading to nausea and toxicity and due to increased acidity ulcers
- medication leading to drug toxicity
what is an AKI?
a sudden decline in kidney function over hours or days , not a disease or a physical injury
why does acidosis happen during an AKI ?
as there is disruption of acid base balance
why doses oedema happen during an AKI?
disruption of the fluid balance
why do cardiac arrhythmias , muscle weakness and paralysis occur during an AKI?
disruption go the regulation of electrolytes which causes hyperkalemia
what are the pre renal causes of an AKI ?
hypo-perfusion
kidney cells being killed
acute tubular necrosis
blood going into the kidney and having a low bp
what are the renal causes of an AKI ?
intrinsic renal disease
what are the post renal causes of an AKI?
obstruction something is blocking urine output
what are the causes of kidney failure?
pyelonephritis , hypertension, diabetes mellitus , nephrotoxic drugs ,hypoyvelemia and nephroallergens
how can phylonephriitis cause an AKI?
it is inflammation and detonation of the phenols due to infection antigens
how can hypertension cause an AKI?
chronic overloading of the kidney with fluid and electrolytes may lead to kidney insufficiency and failure.
how can diabetes cause an AKI?
disturbance of sugar and the acid base balance may lead to renal disease
how can nephrotoxic drugs cause an AKI?
some dugs taken chronically can cause irreversible kidney damage
how can hypovelemia cause an AKI?
reduction in renal blood flow will lead to schema and damage
how can nephroloallergens cause an AKI?
some compounds produce an immune reaction type of sensitivity reaction with nephritic syndrome
which drugs in particular are nephrotoxic ?
ahminoglycosides , phenacetin and heavy metals.
what is uraemia?
it is chronic or acute kidney failure causing impaired glomerular filtration caused by disease or trauma
what are the pharmacokinetic considerations ?
oral bioavalibility elimination volume of distribution dose considerations total body clearance
how is oral bioavailability affected in the pk considerations of a uraemia patient?
oral bioavalibility may decrease but drugs with a high first pass effect increase bioavalibility
how is elimination affected in the pk considerations of a uraemia patient?
elimination clearance increases which reduces glomerular filtration
how is total body clearance affected in the pk considerations of a uraemia patient?
it is reduced
how is volume of distribution affected in the pk considerations of a uraemia patient?
-protein binding decreases so the amount of free unbound drug increases
- accumulation of metabolites decreases especially weak bases
-changes in total body water
Overall Vd increases
what is dialysis?
the diffusion of molecules from the patients blood into the dialysis fluid through a membrane until an equilibrium, can be reached
what are the factors affecting dialyisis?
protein binding
molecular weight
volume of distributon
water soluble
how does water solubility affect dialysis ?
drugs that are fat soluble are not dialysis
what is peritoneal dialysis?
filters through the patients own peritoneal membrane in there abdomen
what is haemodialysis ?
uses an artificial membrane to filter through
how does molecular weight affect dialysis ?
drugs under 500 MW are dialysed easily
how does protein binding affect dialysis ?
drugs that are tightly bound to proteins aren’t dialyses easily as dialysis is a passive process
how does volume of distribution affect dialysis ?
drugs that have a volume of distribution take longer to be hydrolysed
what is hemoperfusion?
when the blood passes through an absorbent material and goes back into the patients body
what is haemofiltration
when fluids electrolytes , small molecules are removed from the body by low pressure flow through hollow artificial fibres
