W26 Pathophysiology of AKI and CKD (SM) Flashcards
What is renal failure?
What are the 2 types of renal failure?
- A reduction in the kidneys ability to sufficiently filter waste products from the blood
- Acute Kidney Injury: A rapid loss of renal/kidney function
- Chronic Kidney Disease: A progressive deterioration of renal/kidney function
Also: Polycystic Kidney Disease: An inherited condition (Kidney are larger than usual due to the gradual growth of masses of cysts in both kidneys)
What is an Acute Kidney Injury?
Features? (6)
What is the diagnosis and staging based upon?
- A rapid loss of renal/kidney functions
-reduced urine output
-large abdomen due to urine retention in the bladder
-fluid overload-raised jugular venous pressure, peripheral and pulmonary oedema - hypertension
- nausea and vomiting or diarrhoea, indicate dehydration (postural hypotension)
- confusion, fatigue and drowsiness
- AKIs diagnosis and staging are based on serum creatinine or urine output (RIFLE, AKIN, KDIGO guidelines)
AKI Incidences and Risk factors:
What are the types of AKI incidences?
Risk factors?
- Community-acquired:
* Poor fluid intake
* Dehydration
* Drugs (ACEIs, ARBs, diuretics, NSAIDs)
* Infection
* Trauma
* Rhabdomyolysis - Hospital-acquired:
* Volume depletion
* Hypotension
* Low cardiac output
* Nephrotoxic drugs - ICU-acquired:
* Sepsis/septic shock
* Major surgery,
* Multiorgan failure,
* Hypotension,
* Low cardiac output,
* Nephrotoxic drugs
What are the 3 categories of AKI causes?
- Prerenal- Impairment in the blood supply to the kidney
- Intrinsic/Intrarenal- Impairments within the kidney’s blood vessels, glomeruli and tubules
- Postrenal- Obstruction of the urinary collecting system
What are the prerenal causes of AKI?
Reduced renal perfusion (blood supply to the kidney) :
- Volume depletion (diarrhoea, vomiting, burns, haemorrhage)
- Decreased effective circulatory blood volume (heart failure, sepsis, anaphylactic shock)
- Altered renal haemodynamic (artery stenosis/ embolism/ thrombosis
- Drugs, such as NSAIDs, ACEis, ARBs
What are the Intrinsic (or intrarenal) causes of AKI?
Pathological damage to glomerular, tubular or interstitial regions
* Glomerulonephritis (due to abnormal immune reaction)
* Nephrotoxic damage/ tubular necrosis (ischaemic or toxic) e.g. heavy metals, ethylene glycol, antibiotics, myoglobin
* Pyelonephritis (assoc with infection)
What are the postrenal causes of AKI?
Obstruction to urine flow-back pressure inhibits filtration:
* Swelling compresses blood vessels leading to ischaemia
* Obstructions (in ureter, bladder, prostate, urethra)
-Urinary tract stones, precipitation of calcium, urates or cystine
-Tumour either within the wall of the tract or outside the wall
What 3 things need to be managed in AKI?
Fluid overload
Metabolic acidosis
Hyperkalemia (clinical emergency)
What is fluid overload in AKI?
Excess fluid accumulation in the body,
including arms and legs (peripheral oedema)
and in lungs (pulmonary oedema)
-swollen ankles, feet and legs
What is metabolic acidosis?
- Decreased Na+ delivery to late DCT & CD is associated with decreased H+ secretion/ loss in the urine (urinary pH becomes alkali and blood pH becomes acidic)
- Nausea, vomiting, drowsiness and breathlessness
What is hyperkalaemia? (clinical emergency)
- Due to impaired potassium homeostasis (excretion/secretion), the level of potassium in
the blood raise. - Cardiac arrythmia (ventricular fibrillation or asystole) and arrest, paralysis and muscle weakness
AKI- Management
What are the underlying causes?
Identify the cause and eliminate the stressors:
infection- antibiotics
obstruction- remove or catheter to empty bladder
toxic drugs- stop taking
How to manage the symptoms of an AKI?
Dehydration/volume depletion
Dehydration/volume depletion: Crystalloids/colloids ? Hartmann’s solution
Fluid resuscitation: To optimise intravascular circulating volume and to decrease cardiac
output and prefusion pressure (improve renal blood flow and filtration)
How to manage the symptoms of an AKI?
Oedema?
Oedema: Loop diuretics (furosemide, only for the management/no proven benefit to prevent
AKI or lower risk of RRTs), direct acting vasodilator infusions (GTN). Restrict salt and fluids intake
How to manage the symptoms of an AKI?
Metabolic acidosis?
Sodium bicarbonate (cautioned for patients with hyperkalaemia or infused under supervision