Dialysis

In haemodialysis the patient’s blood is rapidly pumped through a dialyser and back to the patient. In the dialyser there is a semi permeable membrane that separates the blood from a dialysis solution, which is also being pumped through the dialyser. The waste materials pass through the membrane due to the difference in osmotic pressure between the blood and the dialysis solution. There can also be a negative pressure gradient across the membrane that causes water and solutes to move from blood to dialysis solution.

In peritoneal dialysis, the patient’s peritoneal membrane (abdominal lining) acts as the semi permeable membrane. A sterile dialysis solution containing minerals and glucose is introduced into the patient’s peritoneal cavity. The dialysis solution is left in the cavity for a period of time to absorb waste materials from the blood and then it is drained out and discarded.

Generic issues
Always be familiar with the instructions for use of the machine you are using
Be aware that different machines sometimes have different set up or menu requirements. For example, the MHRA received a report of a user intending to set an UltraFiltration (UF) volume of 600ml and entering 600. The machine interpreted this as 6000ml and the patient had 4800 ml removed before the error was noticed. This machine was unusual in that it required a leading or leading zeros for values of less than one litre.

Do not override alarms without first checking the cause
Several incidents have been reported to the MHRA where alarms have either been silenced or reset, without first checking the cause, resulting in serious injury or death to patients. For example, the MHRA received a report of the bottom pod of a dialysis filter that was being unloaded on a machine exploding. There was no injury to the patient or to nursing staff. Blood spilt onto the arm of the nurse which could have been serious if there had been broken skin or blood reached the eyes. The user had overridden an alarm without checking the cause and as a result the set ruptured during unloading.

Peritoneal dialysis
Always read the manufacturer's instructions for use for ALL blood glucose measuring devices to ensure that you are familiar with their limitations
The MHRA is aware of several incidents, including one fatality, where systemic patient treatments containing maltose (such as certain peritoneal dialysis fluids and intravenous infusions) have caused overestimation of blood glucose by particular meters. However, food, drinks and oral drugs containing maltose do not cause this problem.
Refer to MDA/2007/058 for further information.

Haemodialysis and haemofiltration
Ensure careful placement and removal of dialysis tubing sets by following the instruction for pre-use checks and disconnection (especially the clamp area and pressure pods)
The MHRA is aware of occurrences of set rupture resulting in blood splatter due to errors in tube placements or removal.

If using a separate compartment bag, ensure that the bag is double checked before use
If using a separated bicarbonate and buffer solution bag ensure the seal is broken and that both solutions are mixed before attaching to the machine. The MHRA is aware of occurrences of inadequate solutions being used because the bag has been inadequately mixed.

Ensure that the correct weight loss is calculated and entered
There have been reports received by the MHRA of miskeyed values of weight loss (e.g. 4kg instead of 0.4kg).

Ensure that syringe pumps that are not part of the haemodialysis machine are not connected to the input side of the blood pump
Stand alone infusion pumps are not designed to infuse into negative pressure systems. The MHRA has had reports of pumps connected to the negative pressure side of the blood pump resulting in:

• syringe pumps having in-line pressure monitoring stopping and indicating a fault when there is none.
• syringe plungers being pulled forward, the pump alarming and stopping. The users restarted it each time this happened resulting in an over infusion due to the extra boluses delivered each time the plunger was pulled forward.
• syringe plungers being incorrectly fitted into pumps resulting in an over infusion of heparin as the plungers were pulled forward by the blood pump.

There is also the possibility that syringe plungers could be pulled from the grippers in some pumps’ carriages and the syringe emptied by the blood pump.

Users should set disconnect alarms to a pressure just below the working pressure in the system. In addition, always ensure that the venous needle is visible and uncovered and regularly check the connection
This ensures that resistance to blood flow through a venous needle is enough to maintain a pressure in the line. Disconnect alarms on dialysis machines have, in some cases, failed to be activated when the patient’s venous needle has inadvertently disconnected as the resulting drop in circuit pressure was not enough to activate the alarm.

Be aware of ECG interference when used in conjunction with dialysis machines
A superimposed pattern on the ECG, which correlates to the rotation of the dialysis blood pump is likely to be due to interference. In some instances, the misunderstanding of the resulting ECG wave forms has led to near medical intervention.

Please report any incidents to the MHRA, retaining any devices involved (including disposables) for investigation.

Contacts for further information
Roopa Prabhakar
Email: roopa.prabhakar@mhra.gsi.gov.uk
Tel: 020 3080 7293

Jim Lefever:
Email: jim.lefever@mhra.gsi.gov.uk
Tel: 020 3080 7262