Device Scope-Boundary-Relationships

8.14.1 Scope and Usage 

This is a base resource that tracks individual instances of a device and their location. It is referenced by other resources for recording which device performed an action such as a procedure or an observation, which device was implanted in or explanted from a patient, dispensing a device to a patient for their use, managing inventory, or when requesting a specific device for a patient’s use.  Medical devices include durable (reusable) medical equipment, implantable devices, as well as disposable equipment used for diagnostic, treatment, and research for healthcare and public health. Medical devices may also include some types of software.  Non-medical devices may include items such as a machine, cellphone, computer, software application or algorithm, etc. In short, a Device can range from a tongue depressor to an MRI. The fields in the Device resource must be flexible enough to cover this range.  

The resource may be used to document the Unique Device Identifier (UDI) and information about a device where appropriate or necessary according to local jurisdictions over time. Additional information about UDI is provided in the Unique Device Identifier (UDI) section.

Devices may be categorized and may be associated with one or more categories.  Device category examples include, but are not limited to: active, communicating, durable medical equipment, home use, implantable, InVitro diagnostics, personal health, point-of-care, single use, re-usable, and software.

Active device

'Active device' means any device, the operation of which depends on a source of energy other than that generated by the human body for that purpose, or by gravity, and which acts by changing the density of or converting that energy. Devices intended to transmit energy, substances or other elements between an active device and the patient, without any significant change, shall not be deemed to be active devices. Software shall also be deemed to be an active device. MDR (EU) 2017/745

Active Implantable Medical Devices include the definition for both active devices and implantable devices (see below).  Examples include: Implantable cardiac pacemakers; Implantable defibrillator; Implantable neurostimulator systems; Leads, electrodes, adaptors for implantable pulse generators; Brachytherapy systems; Ventricular Assist Devices (VADs); Cochlear implants; Implantable infusion pumps; Implantable glucose monitors; Micro Electro-Mechanical Systems (MEMS); and their accessories where applicable.

Communicating device

This category of devices communicates electronically to peer information systems or possibly another device. In addition to patient observations for use by clinicians in providing care and for building a health record, the device communicates metadata about its own state and the protocol used to transfer that information.

To support the use and evaluate the reliability of the patient data, it is important to to collect and record data about the identity and operational status of the device that generated the observations. The Device resource is an important locus for such information. The information  it generates for clinical and other purposes goes into other resources such as the Observation or Medication resource depending upon what the device does. To support device-related information about Communicating Medical Devices the Device resource needs to have elements that describe not only the basic information like the serial number, manufacturer name and model number, but information about the protocol, its version, its certification, the properties it has to perform its purposed tasks such as internal clocks, synchronization state, resolution, etc.

Durable Medical Equipment

Equipment and supplies that provides therapeutic benefits to a patient in need because of certain medical conditions and/or illnesses, and which are ordered by a health care provider for everyday or extended use.  

Examples include: oxygen equipment, suction pumps, traction equipment, home infusion services, continuous positive airway pressure (CPAP) devices, hospital beds, wheelchairs, crutches walkers, canes, or blood testing strips and meters for diabetics.

Home Use device

A home use medical device is a medical device intended for users in any environment outside of a professional healthcare facility. This includes devices intended for use in both professional healthcare facilities and homes.

• A user is a patient (care recipient), caregiver, or family member that directly uses the device or provides assistance in using the device.
• A qualified healthcare professional is a licensed or non-licensed healthcare professional with proficient skill and experience with the use of the device so that they can aid or train care recipients and caregivers to use and maintain the device.

US Food and Drug Administration Center for Devices and Radiological Health. Home Use Devices.  Accessed 12 May 2022

Implantable device

Implant means a device that is placed into a surgically or naturally formed cavity of the human body. A device is regarded as an implant for the purpose of this part only if it is intended to remain implanted continuously for a period of 30 days or more, unless the Commissioner determines otherwise to protect human health.  21CFR Part 860.3 Accessed 12 May 2022

‘implantable device’ means any device, including those that are partially or wholly absorbed, which is intended:

• to be totally introduced into the human body, or
• to replace an epithelial surface or the surface of the eye,

by clinical intervention and which is intended to remain in place after the procedure.

Any device intended to be partially introduced into the human body by clinical intervention and intended to remain in place after the procedure for at least 30 days shall also be deemed to be an implantable device; MDR (EU) 2017/745 Accessed 12 May 2022

InVitro Medical device

In vitro diagnostics (IVD) are tests done on samples such as blood or tissue that have been taken from the human body. In vitro diagnostics can detect diseases or other conditions, and can be used to monitor a person’s overall health to help cure, treat, or prevent diseases.

In vitro diagnostics may also be used in precision medicine to identify patients who are likely to benefit from specific treatments or therapies. These in vitro diagnostics can include next generation sequencing tests, which scan a person’s DNA to detect genomic variations.

Some tests are used in laboratory or other health professional settings and other tests are for consumers to use at home.  US Food and Drug Administration Center for Devices and Radiological Health In Vitro Diagnostics and Drug Administration Center for Devices and Radiological Health In Vitro Diagnostics Accessed 12 May 2022

Patient-use device

Patient-use, or home use devices, intended for users in any environment outside of a professional healthcare facility. This includes devices intended for use in both professional healthcare facilities and homes US Food and Drug Administration Center for Devices and Radiological Health. Home Use Devices.  Accessed 13 March 2020. PHDs are the subset of patient-use devices that report their information to a peer via a protocol.

Personal Health device

One class of communicating devices is the Personal Health Device or PHD.  PHDs are medical devices that can be used by patients or others who are typically not medical professions, to gather patient observations and information. These devices can often be purchased in department stores or online by anyone. They may be regulated as medical devices, or not.

PHDs include the popular fitness trackers often combined with heart rate monitors, but also blood pressure monitors, weight scales, pulse oximeters, thermometers, and, for those that require them, glucose meters. Over time more sophisticated devices such as continuous glucose monitors, insulin pumps, vital signs monitors including ECGs, and even spirometers are entering the PHD consumer market. These devices communicate measurement data and data about themselves via a digital transport protocol to some peer entity, often a mobile phone or tablet. The protocol may follow a standard but most protocols are proprietary. In either case, it is common practice for manufacturers to provide free applications that run on these mobile platforms for the purpose of communicating with their devices.

The fields populated in the Device resource by PHDs, typically via a gateway, is the information a PHD reports about itself electronically. There is no input by the patient except for information the patient may enter on the device through some UI. This device reporting capability distinguishes communicating PHDs from the general set of patient-use devices. 

Point-of-Care device

PoCDs are of another level of complexity compared to PHDs: they include devices like multi-parameter physiological patient monitors, anesthesia workstations, infusion pumps and numerous other kinds of devices that provide near-real-time information about patient condition or therapy, potentially including dozens or hundreds of variables coming from a single device system. They may be structurally complex, involving multiple subsystems that are themselves complex, such as a ventilator or gas analyzer functioning within an anesthesia workstation, or pluggable modules in a patient monitor controlling invasive blood pressure or gathering EEG data.

Information systems using such data need to be able to understand the structure and dynamic state of the devices originating them, generally requiring access to what is in effect a dynamically changing model of the device and its subsystems and measuring capabilities. This requires more than a single Device resource - a hierarchy of Device resources is constructed carrying data about the top-level containing device (for example a monitor), and a hierarchy of contained Device resources representing subsystems (in the monitor, builtin and attached modular measurement capabilities), channels, and DeviceMetric resources representing individual measurements or computations.

Single-Use device

A device that is intended to be used on one individual during a single procedure; MDR (EU) 2017/745 Accessed 12 May 2022

Reusable device

Reusable medical devices are devices that health care providers can reuse to diagnose and treat one or multiple patients. Examples of reusable medical devices include surgical forceps, endoscopes and laryngoscopes. US Food and Drug Administration Center for Devices and Radiological Health Reusable Medical Devices

Software 

A software item like a data transformer or converter, or a clinical support algorithm, may be an independently deployed, managed and configured entity that contributes to patient care and needs to be documented just a surely as, say, a physical cardiac monitor. The FHIR Device resource can contain instance data such as version information and operational attributes. It can also represent the relationship of the software item to other device and information system components through reference linkages.  This category includes software regardless of whether or not is regulated.  Device resource instances documenting software items are important to traceability of data and analyzing adverse events, and so have important patient safety roles.

8.14.2 Boundaries and Relationships 

These are the device related resources

• Device (this resource)
• DeviceDefinition - Describes a "kind" of device - not a physical instance. A kind of device is frequently defined and documented by the manufacturer, reseller, or regulatory. Documentation would include general information any information that applies to any instance of a device, and may be published through a catalog. For example, the characteristics of a test analyzer, x-ray machine, or wheelchair.
• DeviceMetric - Describes a measurement, calculation or setting capability of a device. A Device may include multiple device metrics, each yielding a different observation.
• DeviceRequest/DeviceDispense
• SupplyRequest/SupplyDelivery
• DeviceUsage
• NutritionOrder - An order for nutrition can request to a specific device to administer enteral feeding.
• Observation - A measurement can be generated by many types of devices. It may be linked to and supplemented by data about the current structure and status of the device itself in one or more Device or DeviceMetric resources.
• Procedure - A procedure can be performed using a variety of devices, or a device can be implanted or otherwise associated with a patient.
• MedicationAdministration - A medication administration can be performed using a variety of devices.

In FHIR, the Device represents either the device in total, or a component of an encapsulating device when there is a need for individual tracking of a component. A Device as a component then points to the parent device it is part of. The top-level Device captures the actual data about the instance of the device and the instances of all its children that either provides identifying characteristics of the Device (including applicable UDI – unique device identification) and data that can vary dynamically by device, e.g., specific settings at a particular point in time.

The DeviceMetric models the properties of the Observations generated by the device, such as whether or not the Observation is a setting.

Devices differ from medications because they are not "used up" - they remain active in or for a patient for a longer duration. They also may be re-used, particularly non-implanted devices and those used for diagnostics and procedures. Frequently, when a device is packaged with a medication, the ordering, dispense, and administration processes typically focus on the medication aspects and reference the device.

In the case of an infusion pump, while some actions are focused on the device (e.g., ordering to a room or maintaining the pump), the focus is as well on the medication while the device is used for administration. However, that separation is not always as clear and may be impacted by specific implementations. Regardless, the Medication resource should not be used to represent (implanted) devices, rather reference the relationship where an actual device needs to be tracked in addition to the medication. In some sense the Medication is analogous to the Observation generated by a Blood Pressure personal health device. The Observation resource contains the blood pressure values, units and the time stamp while the Device resource contains the manufacturer name, model number, serial number, firmware and hardware versions, exchange protocol information, any clock capabilities, etc.