Radiofrequency (RF) Safety Considerations for Wireless Cardiotocography (CTG) Monitoring Systems

The MHRA has conducted a review into the use of wireless cardiotocography (CTG) systems that use radiofrequency (RF) telemetry channels. Signal crossover, erroneous CTG traces and signal dropouts have been identified as patient safety risks associated with these devices. In rare circumstances, signal crossover may result in the fetal heart rate from one CTG monitor being displayed on another CTG monitor operating on the same RF channel. These risks may result in misinterpretation of CTG traces and inappropriate clinical decisions which could lead to adverse consequences.

The risk relates to classic telemetry systems operating within the Industrial, Scientific and Medical (ISM) frequency band where a limited number of channels are available.

Actions for Healthcare Professionals including Clinical and Medical equipment management staff:

Actions for Healthcare Providers:

Procurement:

- it is important that Clinical teams work with local Clinical Engineering teams in procuring the device and extensively assessing the physical environment. Purchasing more devices than the number of available RF channels could lead to signal crossover, irrespective of whether the devices are from the same or different manufacturers

- assess the local RF environment, RF channel availability and the number of wireless CTG devices required before purchasing wireless CTG systems. Examine local infrastructure suitability

Installation:

- ensure installation involves Maternity Services, Clinical Engineering (EBME), Digital Teams (IT Departments), Clinical Safety Officer and manufacturer representatives

- configure RF channels appropriately to minimise interference and crossover risk

Introduce and maintain a register containing:

- wireless CTG systems;

- RF channels;

- frequencies;

- bandwidth allocation;

- deployment locations;

- paired devices

The register should be introduced and maintained by EBME/Clinical Engineering staff.

After installation:

- label transducers;

- label base stations;

- clearly identify paired components;

- place labels on all devices showing the RF channel being used

Environment & Infrastructure:

- monitor the RF environment regularly, particularly when introducing new RF devices, after infrastructure changes and following incidents related to RF CTG signal crossover, erroneous traces and signal dropouts

- consider structural factors such as walls, layout, distance between devices on the same floor and different floors

Governance & Training:

- update local fetal monitoring and training policies to include RF risks and mitigation measures

- ensure competency training includes RF risks and mitigation for all CTG users

Operational Controls:

- ensure that two or more wireless CTG devices are not operating on the same RF channel unless there is sufficient distance between them to prevent signal crossover or interference (consult the Instructions for Use and/or contact the manufacturer)

- ensure equipment is maintained appropriately by EBME/Clinical Engineering