Kidney Flashcards
What is renal blood flow
20% of CO
What are proximal tubular cells susceptible to
Hypotension and hypoxia
Where is erthropoietin produced
Kidneys (px can be anaemic if CKD)
What are the functions of the kidneys
Excretion of electrolytes Clearance of waste products Receptor sites for hormones: ADH, aldosterone, ANP, PTH Gluconeogenesis Production of hormone: renin, vitamin D, erythropoietin, prostaglandins
What are pre-renal causes of AKI
Hypoperfusion - anything that causes shock, cardiac output
Renal artery stenosis
What are renal causes of AKI
Glomerulonephritis
Diabetes
PKD
Toxins - gentamycin, NSAIDs (reduce prostaglandin production, which reduce renal perfusion)
What are post renal causes of AKI
Anything in urinary tract
Takes 2 weeks for damage
Swollen kidney with no urine output is a medical emergency
What are the effects of AKI
Fluid overload
Oedema (pulmonary - breathlessness lying flat, pleural effusion, peripheral, sacral, ascites)
What investigations should be undertaken for AKI
Chest X-Ray
GFR
ECG for heart failure
Weight change
How is hyperkalameia treated
Hyperkalaemia: Treat with calcium gluconate, then insulin (pushes potassium into cells), or calcium resonium for long term treatment. Dialysis.
What are the ECG signs for different hyperkalameia
K 5.5-6.5 - Peaked T waves, prolonged PR segment
K 6.5-8 - Loss of P wave, prolonged QRS complex, ST segment elevation, ectopic beats and escape rhythms
K > 8 - Progressive widening of QRS complex, sine wave, VF, asystole, axis deviations, bundle branch block, fascicular blocks
What are signs of metabolic acidosis
Metabolic acidosis: exacerbates potassium issues Typical ABGs pH > 7.3 pCO2 Low pO2 normal to high HCO3 low
What is uraemia
Retention of metabolic waste products (sulphate, urea, ammonia, creatinine, phosphate)
What are the symptoms of metabolic acidosis
breathless, tachypnoeic, nausea, non-specifically unwell
What are the effects of uraemia
Pericarditis, pleurisy, encephalopathy
How is AKI diagnosed
Serum creatinine (only rises after losing more than 50% of kidney function) >26.5 in less than 48 hours or rises to 1.5 fold from baseline in the preceding 7 days Urine output less than 0.5ml/kg/h for 6 hours
What are life threatening complications of AKI
Life threatening pulmonary oedema Severe metabolic acidosis Severe hyperkalaemia Uraemic pericarditis Uraemic encephalopathy
Where are the insertion sites for dual lumen catheters for RRT
Insertion sites:
Internal jugular vein
Femoral vein
Subclavian vein
What is ideal body water composition
TBW = 60% ideal
40% intracellular
20% extracellular (15 interstitial fluid and 5 intravascular)
What is thirst stimualated by
Increases in plasma osmolality of 1-2% (normally between 280-300)
Decline in plasma volume of 10-15%
Baroreceptor input, angiotensin II
What is ADH and what does it co
Binds to V2 receptors on basolateral membrane of principle membrane along distal convoluted tubules and increases AQP2 expression of luminal membrane
Leads to arteriole vasoconstriction
What is ANP
Primarily released from atria - in response to volume expansion
What is BNP
Released by ventricles - in response to stretch
What do ANP and BNP promote
Dilatation of afferent arterioles and constrict the efferent arterioles (higher pressure in glomerulus and increase GF)
Reduce Na reabsorption in the DCT
Inhibit renin secretion
inhibit renal sympathetic tone
What is hyponatremia
Na<135 mmol