Teaspoon of Salt
A patient with septic shock becomes oliguric. MAP is 55 mmHg despite fluids.Creatinine rises over 24 hours. What type of AKI is most likely initially?
Pre renal injury from hypo perfusion
What are the two primary mechanisms of solute clearance in HDF?
Diffusion + convection
Why is documenting pressures hourly important?
Identifies trends before circuit failure.
Rising venous pressure usually indicates what?
Clotting or obstruction in the return line.
What is the normal urine output target in critically ill adults?
0.5 mL/kg/hr
What is the primary driver of hyperkalaemia in acute kidney injury?
Reduced renal excretion of potassium.
What is the primary mechanism of solute removal in intermittent HD?
Diffusion.
In SCUF/ISO what principles of filtration are occuring?
Ultrafiltration - hydrostatic pressure forces water through semi permieable membrane
Perhaps minimal convection but unlikely to be enough to significantly remove solutes.
No dialysate is used - NO DIFFUSION !!
Highly negative arterial pressure suggests?
Poor access flow (kink, obstruction, malposition, hypovolaemia)
What measured value on the filter might indicate slow progressive clotting?
Gradual rise in venous pressure and TMP.
Why do AKI patients often develop metabolic acidosis?
Inability to excrete hydrogen ions and regenerate bicarbonate
In pre-dilution HDF, how does substitution fluid effect the blood entering the filter?
It dilutes the blood before it reaches the membrane, reducing haemoconcentration and filtration fraction but slightly reducing solute clearance efficiency.
You notice rising venous pressure and dark streaking in the dialyser. What is happening physiologically?
Progressive fibre clotting increasing resistance → risk of full circuit loss.
Escalate and consider returning blood early prior to clotting.
Patient on HDF becomes hypotensive 40 minutes into treatment. What in the prescription might need to change?
UltraFiltration Goal - Fluid removal might need to be turned down or off
Blood flow - although reducing will reduce efficicacy of treatment
(In discussion with medical team)
Why are septic patients at higher clotting risk in dialysis circuits?
Hypercoagulable inflammatory state.
Why can aggressive bicarbonate correction worsen intracellular acidosis?
CO₂ diffuses into cells, generating intracellular acidosis
Ensure adequate ventilation to eliminate CO2 produced
It is generally better to correct underlying cause of acidosis and give supportive care than to give sodium bicarbonate
Septic patient on norad 20 mcg/min with pulmonary oedema and K+ 6.5. Why might HDF be chosen over SCUF?
Requires solute clearance + fluid removal
If the conductivity alarm triggers, what are you concerned about?
Dialysate concentration error.
Conductivity reflects the concentration of electrolytes (Na+, K+, HC03-) in dialysate.
Check the Acid & bicarb canisters.
Why can aggressive ultrafiltration worsen lactate?
Reduced preload → reduced cardiac output → tissue hypoperfusion.
What is the primary stimulus for renin release from the juxtaglomerular cells?
Decreased renal perfusion pressure
Which hormone increases water reabsorption in the collecting ducts
Antidiuretic hormone (ADH)
What is the primary mechanism of solute removal in haemofiltration (HF)?
Convection.
Replacement fluid used to control fluid removal from Ultra filtration.
In SCUF (slow continuous ultrafiltration), the primary goal is:
Fluid removal only
Patient becomes acutely dyspnoeic mid-dialysis. What rare but serious cause must you consider?
Air embolism.
Explain how the renin–angiotensin–aldosterone system (RAAS) increases blood pressure (2–3 key mechanisms).
Angiotensin II causes vasoconstriction
Aldosterone increases sodium and water reabsorption
ADH release increases water reabsorption
Overall → increased circulating volume and systemic vascular resistance