Understanding HL7 lies at heart of PACS/RIS replacement

At Doncaster Infirmary, PACS is the most important clinical system for our hospital doctors. As outlined in my previous articles, PACS replacement has been a real success. Similarly, RIS is the most important system for a radiology department, and we have recently replaced our RIS. We have enhanced the clinical value of PACS and RIS by understanding and defining the HL7 fields from a clinical perspective.

For anybody who does not understand HL7, here is my simple definition. HL7 is the language used for communication between healthcare IT systems. It consists of messages, segments, and fields. Updates of information contained in these messages happen by triggers. RIS and PACS are involved in three important HL7 messages: ADT (admission discharge transfer), ORM (order response message), and ORU (observation result).

Dr. Neelam Dugar is a consultant radiologist at Doncaster Royal Infirmary, U.K., and former chair of the Royal College of Radiologists' Imaging Informatics Group.

Dr. Neelam Dugar is a consultant radiologist at Doncaster Royal Infirmary, U.K., and former chair of the Royal College of Radiologists' Imaging Informatics Group.

In the case of our own hospital, understanding clinical processes in the U.K. National Health Service (NHS) is very important when defining informatics flows. A patient may visit an NHS hospital in different ways: by the accident and emergency department, as a hospital admission on the ward, by an appointment for an outpatient clinic, or attending for an investigation (blood test, radiology exam, etc.).

Clerical staff will always register the patient on the patient administration system (PAS), which is on the master patient index (MPI). Registering a patient on PAS includes demographic information (as described below) and also the general practitioner (GP) and the GP practice with which the patient is registered.

When patients are admitted into our hospital, they are taken to a ward and put under a named responsible consultant (i.e., senior doctor), who has the overall responsibility for their care during the stay in hospital. All NHS hospitals work on the same principle. Clerical staff put the information into the PAS. This information then flows from PAS to PACS and RIS via the HL7 ADT message (PV1 segment).

ADT message includes current ward location, and also the name of the responsible consultant. Doctors do not usually access PAS. However, knowing which ward a patient is on and who is responsible for the patient is very important clinical information for doctors.

HL7 ADT messages form the patient banner information on RIS and PACS, and they consist of two main segments of clinical significance, namely the PID (patient ID) and PV1 (patient visit information) segments.

1. PID segment, or patient demographics segment
   The following fields are important for RIS and PACS:

   1. Name (Field 5)
   2. Date of Birth (Field 7)
   3. Gender (Field 8)
   4. Address (Field 11)
   5. PAS ID (Field 3)
   6. NHS No (Field 2)

   Triggers used to update PID: The patient demographics information on RIS and PACS should ONLY be updated by PAS/MPI (NOT by any other system) by the following HL7 ADT triggers:

   A-28 - Inserts a new patient or updates patient demographics
   A-40 - Merge patient data
   A-29 - Deletes patient

   Keeping patient demographics clean and synchronized with PAS is absolutely essential for safe patient care.

2. PV1 segment
   To communicate critical results or call patients down for a test, it is important for users of RIS and PACS to know when patients are admitted to a hospital and in which ward they are located. Hence, the following two fields on the PVI segment are important:

   1. Current Patient Location: Should have ward name and phone extension. (Field 3: Called assigned patient location. NB: Our local PAS, however, uses Field 11-Temporary Location)

   2. Current Responsible Clinician: Include name, GMC number, grade*, main specialty* (Field 9: Consulting doctor)

   *NHS IT systems use the NHS data dictionary for main specialty codes and also use job role position coding for grade of staff.

   PV1 segment triggers: PV1 segment HL7 ADT should only be updated by PAS (not by any other system) by the following ADT message triggers:

   A-01 - Admit patient
   A-02 - Transfer patient
   A-03 - Discharge patient

   PV1 segment: Patient location and current consultant on patient banner will be blank when not in hospital (triggered by A-03 message).

The top left-hand corner of the PACS image display screen consistently displays the patient banner information-demographics and patient location information. On our Zillion RIS from Rogan (Canon), patient banner is the top of the page.

The banner is kept updated by HL7 ADT messages from the PAS/MPI. Following good informatics practices are important for safe patient care because today, patient care is very much dependent on informatics.

The patient banner has the following six pieces of information, which are kept synchronized with PAS/MPI through ADT updates:

1. Name
2. Date of birth
3. Gender
4. Patient ID (we use our local ID for the enterprise)
5. Current patient location (blank when patient is discharged)
6. Current responsible consultant (blank when patient is discharged)

Our surgeons and physicians are now using PACS to get a list of all the inpatients on the wards under their care on PACS; we do not have an electronic patient record (EPR) system. They find that all the patients under their care can be found by a simple PACS search under their name as "current consultant."

As modern medicine is so dependent on imaging diagnostics, they actually find this more useful than a stand-alone EPR. Similarly, when reporting an unexpected finding, radiologists can now see with ease which consultant is responsible for the patient's care by simply glancing at the patient banner information on the RIS and PACS. Radiologists can also make direct contact with the ward or responsible consultant when there are critical or significant results.

By simply improving the visibility of two fields (current patient location and current consultant) in the patient banner on PACS and RIS, massive clinical benefits to patients have occurred. This comes from developing a basic understanding of HL7 ADT messaging.

In my next columns, I will be discussing HL7 ORM and HL7 ORU.

Dr. Neelam Dugar is consultant radiologist at Doncaster Royal Infirmary, U.K., and former chair of the Royal College of Radiologists' Imaging Informatics Group.

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