The HD Machine Flashcards
Name the TWO (2) distinct sections of the extracorporeal.
The ‘arterial’ portion, always signified by a red motif.
The ‘venous’ portion, signified by a blue motif.
Recite the steps involved in set-up of a HD machine.
- Disinfection (cleaning the dialysate fluid pathway)
- Connecting dialysate and bicarbonate to achieve appropriate conductivity
- Mandatory machine self-test of operating and safety systems
- Attaching the extracorporeal circuit (blood lines and dialyser) to the haemodialysis machine
- Connect dialysate lines (the lines that deliver the dialysate to the dialyser) to the dialysate side of the dialyser
- Prime the extracorporeal circuit using normal saline or online fluid supplied by the haemodialysis machine
What fluid is used to prime the extracorporeal circuit?
Saline or online fluid.
This process expels air from the lines and dialyser. It also flushes the sterilant ethylene oxide from the lines.
Why is saline vital during dialysis?
To treat hypovolaemia induced by ultrafiltration.
What does the blood pump allow and how is this achieved?
The blood pump allows you to set a required Blood Flow Rate (BFR). This is achieved via a roller pump compressing the soft, pliable segment of the dialysis lines inserted into the pump.
As it does this, blood is removed from the patient under a negative pressure and once past the pump the blood is under positive pressure.
Blood pump speed is sometimes represented as what?
Qb
When increasing the BFR, what should you always be watching?
Arterial and venous pressures.
Why is artierial pressure represented as a negative pressure?
It is represented as a negative pressure as the speed of the blood pump exerts a pulling force on the access blood flow.
Name TWO (2) reasons for an increased negative pressure can be triggered by.
- inadequate access flow either from stenosis or hypotension
- kinking/occlusion of the lines
- vascular access issues including poorly placed (or infiltrated) arterial needle, ‘sucking’ arterial line in central venous catheters
- clotting
Name TWO (2) reasons for an decreased negative pressure.
- a wet arterial transducer
- the saline line being left open in circuits that use saline for prime
- vascular access with high blood flow
- arterial line becoming disconnected from the patient
How is the venous pressure measured?
After the dialyser by a pressure sensor that measures the pressure of the blood in the extracorporeal circuit before it returns to the patient.
Name TWO (2) reasons for an increased venous pressure.
- needle infiltration or poor placement
- high blood pump speeds
- clots in the bubble trap or cannula
- occlusion of the lines by clamps or kinks
Name the reasons for low venous pressue alarms.
Line disconnection or if the needle becomes dislodged.
However the alarm may not always be triggered as the pressure does not fall below the lower limit. This can result in exsanguination (bleeding out).
Explain the function of the venous bubble trap.
Allows for the collection and possible removal of air that may enter the circuit.
Explain the function of the air detector and clamp.
The air detector plays and essential role in maintaining patient safety and will be triggered by a decrease in the blood level in the venous bubble trap or by microbubbles that can present ad foam. Whatever the cause of the alarm may be, when it is triggered, the blood pump is stopped and a clamp is applied across the line to ensure that air is not delivered to the patient.
