Contrast-Induced Acute Kidney Injury Flashcards
what is the function of the kidneys - 5 points
fluid, electrolyte and acid-base balance
blood pressure regulator
vitamin D activator and calcium absorption for bone metabolism
hormone production - erythroprotein
removes waste products from the blood - INCLUDING CONTRAST MEDIA
what can injecting contrast media do to the kidneys
possibility of upsetting the balance of all the functions and/or cause direct damage to the kidney tissues impairing function
how do we assess renal function
what additional way can be used to assess renal function
by measuring the renal output (how well the kidneys are filtering waste products) - estimates how much blood passes through the glomeruli each minute
identified using the glomerular filtrate rate (GFR)
normal GFR = 130ml/min/1.73m2 for men and 120ml/min/1.73m2 for women
can also measure serum creatinine levels in the blood where the kidneys break down creatinine phosphate generated in the muscles to create creatinine
when is there contrast induced kidney injury? - 4 points
when serum creatinine rises by greater than or equal to 26 micro moles within 48 hours post contrast admin
serum creatinine level is greater than or equal to 1.5 times higher than the baseline within a week post contrast admin
urine output is less than 0.5ml/kg/hour for more than 6 consecutive hours post contrast admin
a combo of above
how can the eGFR be accurately calculated
usually with a 24 hour urine collection sample but also without using serum creatinine and some/all of the following variables - sex, age, race and weight
who is at risk of AKI following iodinated contrast media
existing chronic kidney disease (eGFR < 60)
diabetic nephropathy (damage to the kidneys due to diabetes) & advanced heart failure
hypovolaemia (decreased volume of blood circulating body) & dehydration
presence of multiple myeloma - can cause excess protein and calcium in the blood putting strain on kidneys to remove excess materials
nephrotoxic drugs - meds already affecting kidney function
high doses of contrast or contrast media that collects in the kidney tissues
repetitive use of contrast media
prevention in high risk patients - 6 points
use of different form of imaging - US or MR w/o contrast
minimised doses of contrast and avoid repeats within 48-72 hrs of each other
hydration therapy prior to contrast admin - IV fluids - increase sodium and fluid levels that protect the kidneys as contrast agent is diluted with blood serum, 6 hrs prior and 6-24 hrs post
use of low or iso-osmolar contrast media - exact same osmolality (rate fluids are absorbed across tissue membranes) as blood serum so less likely to cause damage to kidneys, low osmolar agents have higher osmolality but only marginally higher and so risk to kidneys is reduced
administration of N-acetylcysteine - reduces level of serum creatinine in blood h/e some studies show it only acts on creatinine in blood not necessarily on kidney GFR
withhold nephron-toxins such as ACE inhibitors, diuretics, metformin - no need to stop metformin post with serum creatinine within normal range and or >60 ml/min/1.73m2
what is the preparation before the exam - 4 points
eGFR should be available for all non-emergency patients so patients are in a stable condition with satisfactory eGFR within previous 3 months
particular care given to severely ill patients - hypotension/hypovolaemia
early involvement of nephrology team advised
insufficient evidence for use of pharmaceuticals to reduce incidence of CI-AKI
prognosis for CI-AKI - 3 points
symptoms can be from minor issues affecting urinary output to severe renal failure requiring dialysis
ultimately death
shown to increase morbidity, mortality and length of stay in hospital
