When should a sink test be performed on an ECG input?

Performing a sink test on an ECG input is a critical procedure conducted to ensure that the device functions correctly and safely after any repairs have been made to the input component. This testing confirms that the signal received from the patient does not create any feedback or interference, which is crucial for maintaining accurate readings and patient safety. After repairs, a sink test assesses whether the modifications have successfully restored or improved the device's operational integrity.

While the other scenarios mentioned, such as design validation, incoming inspections, or annual quality assurance checks, are important for the overall maintenance and reliability of medical equipment, the specific need for a sink test arises directly as a follow-up to repairs. This immediate testing ensures that any changes or fixes applied to the ECG input do not introduce issues that could compromise performance or patient safety. Therefore, the most relevant time to conduct a sink test is indeed after any repairs to the input have been made.