Notes for the SimpleAlerting Extension

The SimpleAlerting extension is used to define the behavior and configuration of simple alerting systems for PHD Devices. Below is a description of the original IEEE 11073-20601 attributes, including their MDC code and the corresponding element in the extension. In IEEE 11073-10206 / ACOM simple alerting can be modeled as an extension to a numeric observation with the same attributes as this FHIR extension.

Alert Type

In some cases there can be multiple types of alerts defined for a monitored value. For example in a continuous glucose monitor there can be a patient normal range low and high value and a critical hypo and hyper value. In IEEE 11073-20601 these are reported as numeric settings with MDC codes MDC_CONC_GLU_PATIENT_THRESHOLDS_LOW_HIGH and MDC_CONC_GLU_THRESHOLDS_HYPO_HYPER that reports the monitored low and high limits.

Current Limits

The IEEE 11073 Current-Limits attribute specifies the lower and upper threshold limits of the monitored parameter. The MDC code of the attribute is MDC_ATTR_LIMIT_CURR.

The currentLimits element specifies the acceptable range for the monitored parameter. It is represented as a valueRange with the following sub-elements:

• low: The lower limit of the acceptable range. If the monitored value falls below this limit, an alert may be triggered.
• high: The upper limit of the acceptable range. If the monitored value exceeds this limit, an alert may be triggered.
• Units: The limits are expressed in a specific unit (e.g., % for percentages) using the Unified Code for Units of Measure (UCUM) and should match the unit of the monitored parameter.

Alert Operational State

The IEEE 11073 Alert Operational State attribute uses an ASN1-BITs field to indicate whether the alerts on a given limit (upper or lower) are on or off. When SET, the alerts are off. This is a state-type measurement, and when this attribute is present, both the set and cleared states are reported. The MDC code of the attribute is MDC_ATTR_AL_OP_STAT.

The alertOperationalState element indicates the current operational state of the alerting system. It is represented as a valueCodeableConcept with codes from the SimpleAlertOperationalStates CodeSystem. Examples of operational states include:

• On: The alerting system is active and monitoring the parameter.
• LowLimitOff: The lower limit monitoring is disabled.
• HighLimitOff: The upper limit monitoring is disabled.
• LimitsOff: Both upper and lower limit monitoring are disabled.

Alert Operational Text

The IEEE 11073 Alert Operational Text attribute consists of a pair of strings that describe the operational state of the lower and upper threshold monitoring.

The alertOperationalText element provides a single human-readable string describing the operational state of the lower and upper threshold monitoring.

Threshold Notification Text

The IEEE 11073 Threshold-Notification-Text-String attribute provides a human-readable string notifying the user of a value outside the current limits. It may include details about the condition that triggered the alert or instructions for responding to it. The MDC code is MDC_ATTR_THRES_NOTIF_TEXT_STRING

The thresholdNotificationText element provides this notification text, ensuring that users are informed about the specific condition that caused the alert.

These elements collectively define the configuration and behavior of the SimpleAlerting extension, enabling systems to monitor and respond to specific conditions effectively.