Medical City · Device Lab 23 of 69
Peritoneal Dialysis
An extracorporeal blood circuit exchanges across a hollow-fibre membrane against a separate prepared dialysate stream. Access, blood handling, fluid preparation and protective sensing are different parts of the same treatment system.
- 10 parts
- 2 configurations in the Device Lab
- Also called: Pd Cycler, Apd Cycler
Configurations
The versions in the Device Lab.
Hemodialysis
An extracorporeal blood circuit exchanges across a hollow-fibre membrane against a separate prepared dialysate stream. Access, blood handling, fluid preparation and protective sensing are different parts of the same treatment system.
Automated peritoneal dialysis
A pneumatic cycler moves dialysis solution through a disposable cassette and a single patient catheter. Fill, dwell and drain are separate phases; the peritoneum provides the exchange surface and blood remains inside the body.
Manual peritoneal dialysis
A gravity exchange set connects fresh solution, a patient transfer set and a drain bag. There is no powered cycler. The patient connection, bag heights, clamp states and clean connection workflow determine what can happen.
The parts
Part by part.
Housing
This machine lives in a bedroom and runs while somebody sleeps next to it. That single fact drives more of its design than any clinical requirement.
Display
This screen is reporting on a treatment happening inside a body cavity that neither you nor the machine can see. That is a genuinely different problem from a hemodialysis display, which at least reports on fluid passing through its own hardware.
Heater
Two litres of fluid at room temperature is about to go into somebody's abdominal cavity. Cold fluid there hurts, and the discomfort is severe enough that patients stop treatment over it.
Cassette
Here is the idea that makes this whole machine work, and it is worth stopping on. The cycler never touches dialysis solution.
Actuator
The actuation plate is where air becomes fluid movement, and it is the most easily misunderstood surface in this machine. Nothing crosses it.
Pneumatic source
This is an air pump, and everything about the treatment depends on it while nothing about the treatment passes through it. Understanding that sentence is understanding the architecture.
Reservoirs
These hold air, and knowing that immediately rules out an entire category of wrong hypothesis. When something in this machine loses pressure, the question is never whether the patient is losing fluid.
Manifold
If the pump is the muscle and the reservoirs are the store, the manifold is the decision. It is a block of passages and electrically operated valves that decides, several times a second, which part of the cassette gets pressure and which gets vacuum.
Heater assembly
The plate is the part you can test, and that is exactly why it gets tested wrongly. An empty heater plate reaching temperature is an easy measurement, a satisfying number, and evidence of very little.
Electronics
This assembly is running an unattended medical treatment for eight hours while its operator is asleep. It cannot ask anybody anything.
Next