Important Safety Alerts

Medical device manufacturer, Maquet Cardiopulmonary GmbH, has issued a medical device safety alert concerning its Heater-Cooler Unit HCU 40 High Voltage (70104.4054) and Heater-Cooler Unit HCU 40 Low Voltage (70105.4917). All HCU 40 units below serial number 90442012 are affected.

The manufacturer has received complaints in relation to leaking vacuum valves of the HCU 40. The vacuum valve in each water circuit is closed during the HCU 40 operations modes de-airing, warming and cooling as well as cleaning. During the emptying mode, which is regularly performed after surgery, an under pressure is applied to the respective water circuit that opens the vacuum valve. Air is sucked into the circuit in order to prevent the hoses from collapsing to allow the water to be pumped back into the tank.

Based on the manufacturer's engineering testing, it is possible that after performing the emptying mode, the vacuum valve does not fully close. When the HCU 40 is then operated again, water can leak while de-airing, cleaning, but also during regular cooling and warming through the incompletely closed vacuum valve into the inner compartment of the HCU 40.

Depending on the amount of leakage, different consequences can be expected:

• At a minimal water loss, the insulation material will absorb the escaping water and the water will eventually evaporate. In case of a leaking vacuum valve during the cleaning mode, crystalline residues of chloramine T (used for disinfection) and/or citric acid (used for descaling) could remain on the insulation material after evaporating.
• If the water or cleaning/disinfection solution loss is excessive, the insulation material cannot absorb it anymore, and fluid flows onto the floor. If the leakage remains undetected and the HCU 40 is not stopped, the flow sensor of the unit triggers a "water flow too low error" alarm, caused by air sucked into the water circuit due to the vacuum valve being incompletely closed.
• If the leakage is significant and the insulation material of the water circuit cannot absorb the outgoing water or cleaning/disinfection solution from the vacuum valve, the fluid can reach the box of the Printed Circuit Board. This may cause an electrical short circuit and could lead to a shut down of the HCU 40.

A significant leakage of an improperly closed vacuum valve is typically detected already during de-airing (in preparation of the device before surgery) or during the cleaning mode. Therefore, users should check, if during or after performing these operation modes any fluid leaks out of the HCU 40 housing. If this is the case, users should take the unit out of operation and contact the manufacturer for repair.

If the malfunction is not detected prior to use on a patient, critical or catastrophic consequences for a patient are possible, but according to the risk assessment of the manufacturer, it is estimated as unlikely. The manufacturer has not received any complaints of patient harm, serious injuries or deaths caused by a HCU 40 leaking vacuum valve. As a general precautionary measure in the instruction for use for HCU 40, users should always keep a replacement unit on standby in order to ensure continuous full operation in the event of the described vacuum valve leakage. Considering the precautionary measure and based on the associated risk to the leaking vacuum valve, a general decommissioning of the affected HCU 40 systems is therefore not required.

The manufacturer has qualified and verified a new vacuum valve type for HCU 40. Existing vacuum valves in the affected HCU 40 systems will be replaced with proven long-term material compatibility and functional reliability. The vacuum valves in the affected HCU 40 shall be replaced as soon as possible, at the latest during the next annual preventive maintenance.

According to the local supplier, the affected products are distributed in Hong Kong.

If you are in possession of the affected products, please contact your supplier for necessary actions.

Posted on 17 August 2020