Personal Health Device Implementation Guide
1.0.0 - STU 1

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## BITs measurement; Device-Sensor status

This example comes from a pulse oximeter when the sensor mechanism is having a set of difficulties. The set of difficulties are reported by setting a bit respresenting the issue in an integer. Since HL7 does not support this kind of measurement, the bit settings are converted to codes for FHIR using the ASN1ToHL7 code system. In this case the codes have value 150604.x where x is the Mder bit representing a given condition and ‘150604’ is the MDC code describing the measurement. ‘150604’ is a device and sensor status measurement. In this case, 5 of the 16 possible flags are set. All of the bits in this measurement are events thus they are only required to be reported when set (values are “Y” in FHIR).

Note there is no logical id in this resource as this resource is being uploaded to the server in a create operation. The server will create the logical id and return it to the sender in the response. There is also no reference to the coincident time stamp since this observation is generated by a device that is streaming data and reporting no time stamp. The time stamp is taken to be the time of reception by the gateway.

    {
    	"resourceType": "Observation",
    	"meta": {
    		"profile": [
    			"http://hl7.org/fhir/uv/phd/StructureDefinition/PhdBitsEnumerationObservation"
    		]
    	},
    	"extension": [
    		{
    			"url": "http://hl7.org/fhir/StructureDefinition/observation-gatewayDevice",
    			"valueReference": {
    				"reference": "Device/ecde3d4e58532d31.000000000000"	// Resource already on the server
    			}
    		}
    	],
    	"status": "final",
    	"code": {
    		"coding": [
    			{
    				"system": "urn:iso:std:iso:11073:10101",
    				"code": "150604"
    			}
    		],
    		"text": "MDC_PULS_OXIM_DEV_STATUS: Measuring process issues"
    	},
    	"subject": {
    		"reference": "Patient/sisansarahId.1.2.3.4.5.6.7.8.10"	// Resource already on the server
    	},
    	"effectiveDateTime": "2018-11-11T19:07:48-05:00",
    	"device": {
    		"reference": "Device/74E8FFFEFF051C00.001C05FFE874"	// Resource already on the server
    	},
    	// The PHD does not send time stamps with its measurements therefore the time stamp is the
    	// time of reception by the PHG and there is no coincident time stamp Observation
    	"component": [
    		{
    			"code": {
    				"coding": [
    					{
    						"system": "http://hl7.org/fhir/uv/phd/CodeSystem/ASN1ToHL7",
    						"code": "150604.2"  // Mder bit 2 is set
    					}
    				],
    				"text": "sensor-displaced"
    				// 'sensor-displayed' is the ASN1 name of the bit setting. The source of the ASN1 names
    				// comes from the IEEE 11073 11404 (pulse Oximeter) specialization standard where this
    				// measurement is described in detail.
    			},
    			"valueCodeableConcept": {
    				"coding": [
    					{
    						"system": "http://terminology.hl7.org/CodeSystem/v2-0136",
    						"code": "Y"
    					}
    				],
    				"text": "Sensor is incorrectly placed on user"
    			}
    		},
    		{
    			"code": {
    				"coding": [
    					{
    						"system": "http://hl7.org/fhir/uv/phd/CodeSystem/ASN1ToHL7",
    						"code": "150604.7" // Mder bit 7 is set
    					}
    				],
    				"text": "signal-pulse-questionable"
    			},
    			"valueCodeableConcept": {
    				"coding": [
    					{
    						"system": "http://terminology.hl7.org/CodeSystem/v2-0136",
    						"code": "Y"
    					}
    				],
    				"text": "Questionable pulse detected"
    			}
    		},
    		{
    			"code": {
    				"coding": [
    					{
    						"system": "http://hl7.org/fhir/uv/phd/CodeSystem/ASN1ToHL7",
    						"code": "150604.10" // Mder bit 10 is set
    					}
    				],
    				"text": "signal-low-perfusion"
    			},
    			"valueCodeableConcept": {
    				"coding": [
    					{
    						"system": "http://terminology.hl7.org/CodeSystem/v2-0136",
    						"code": "Y"
    					}
    				],
    				"text": "Signal experiencing low perfusion"
    			}
    		},
    		{
    			"code": {
    				"coding": [
    					{
    						"system": "http://hl7.org/fhir/uv/phd/CodeSystem/ASN1ToHL7",
    						"code": "150604.11" // Mder bit 11 is set
    					}
    				],
    				"text": "signal-poor"
    			},
    			"valueCodeableConcept": {
    				"coding": [
    					{
    						"system": "http://terminology.hl7.org/CodeSystem/v2-0136",
    						"code": "Y"
    					}
    				],
    				"text": "Signal is poor"
    			}
    		},
    		{
    			"code": {
    				"coding": [
    					{
    						"system": "http://hl7.org/fhir/uv/phd/CodeSystem/ASN1ToHL7",
    						"code": "150604.12" // Mder bit 12 is set
    					}
    				],
    				"text": "signal-inadequate"
    			},
    			"valueCodeableConcept": {
    				"coding": [
    					{
    						"system": "http://terminology.hl7.org/CodeSystem/v2-0136",
    						"code": "Y"
    					}
    				],
    				"text": "Signal is inadequate"
    			}
    		}
    	]
    }