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Zero-Failure Option

March 23, 2011
by Mark Hagland
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One Tennessee Hospital System Benefits from Creating a Fully Replicated Set of Data Archives


The five-hospital Saint Thomas Health Services, anchored by Middle Tennessee Medical Center in Murfreesboro, Tenn., several years ago became one of the very first multi-hospital systems in the U.S. to create a fully replicated set of data archives, rather than simply a mirrored configuration, to support the continuity of its PACS and other capabilities. That organization's leaders have derived great benefit from their innovation.

When it comes to the storage of diagnostic and other medical images, these days, the race is on to find solutions that make sense for cost-conscious patient care organizations, at a time when the imaging capabilities of MRs, CTs, and other diagnostic imaging modalities are leading to an explosion in study sizes and volumes.

Indeed, healthcare IT leaders at many hospitals, medical groups, and integrated health systems report that their stored caches of diagnostic images are exploding in size, even as the volume of actual diagnostic imaging studies begins to slow. (According to the federal Centers for Medicare and Medicaid Services (CMS), the growth rate for diagnostic imaging services under Medicare was 3.4 percent in 2008 and 2.2 percent in 2009.) This is, of course, because of the increasing sophistication of the modality machines capturing those images, combined with the technological capabilities unleashed by the shift to digital viewing in PACS (picture archiving and communications systems) solutions, meaning that volumes of images can be produced from individual diagnostic imaging studies that would have overwhelmed film-based viewing systems.

Dan West
Dan West

One hospital organization that has blazed a major trail in this area is Middle Tennessee Medical Center, the anchor hospital in the five-hospital Saint Thomas Health Services system, itself a division of the St. Louis-based Ascension Health. Middle Tennessee Medical Center, based in Murfreesboro (located 35 miles southeast of Nashville), and its sister facilities were apparently the first organization in the country to create a fully replicated set of data archives, not simply data centers mirrored to each other.


Dan West, ITS director, Imaging Informatics and EHR Architecture, for the health system, spoke recently with HCI Editor-in-Chief Mark Hagland regarding the storage/connectivity innovation, and the lessons learned from its implementation.

Healthcare Informatics: What exactly have you put in place?

Dan West: It's an integrated platform involving a fully replicated set of data archives, not just mirrored archives. They each have their own set of Oracle running. To explain the difference, what most organizations have is SANs [storage area networks] with mirrored storage at a disk-to-disk level of matching. In our case, what we've created, using enterprise content management (historically known as replicated content management), is at the DICOM [Digital Imaging and Communications in Medicine standard] engine-to-DICOM engine level. In other words, this is actually a DICOM transaction, as opposed a raw-data transaction.

HCI: When did everything get put in place?

West: Our first site went live in January 2004. The five sites we brought up in sequence-the fifth site went live in April 2005.

HCI: What elements of your technology configuration do the different facilities in your organization have?

West: We have five care sites-one pair of two hospitals, the two large hospitals in our chain, and each of those contains one of these nodes. The other three hospital facilities have a merged facility image cache-the same DICOM engine as the larger hospitals, but only 60 days' worth of storage. The maintenance cost for maintaining this configuration is $425,000 a year.

HCI: That sounds relatively reasonable.

West: We think it's quite reasonable.

HCI: What kind of storage volume is involved?

West: Right now, each of our archives has 52 terabytes, and we have 38 terabytes used, and we're burning 1.5 terabytes a month, and 575,000 radiologic studies a year.

HCI: Every one of your four hospitals has imaging?

West: Yes, they all have the same digital imaging engines, but the two big archives are at the two hospitals; the smaller hospitals send their data to the big ones. Merge is PACS; RIS [radiology information system] and EHR are both Cerner.


HCI: What was your strategy in creating this storage innovation?

West: We were the first replicated content management that had been deployed by what was once Emageon. They are now a part of [the Chicago-based] Merge Healthcare. There were two parts of our strategy. One, we determined that, implementing this strategy, if we lost one of the nodes at the large hospital during any kind of disaster or failure, then we could fail over to the node at the other hospital. Our claim to fame, if you will, is that we've never had a ‘severity 1′ downtime at either hospital, since we've never had two failures at the same time, which would be unlikely.

HCI: Was it expensive to do this?

West: It was less expensive than the alternative, which is having your second copy spooled off to tape. Now, they're putting that second copy of the images on a SAN. This is a live copy, you can log into an application. To explain how this works by analogy, it's like having two laptops sitting next to each other, and whatever file you created on laptop A would immediately be sent over to laptop B. So each has its own operating system and its own Oracle database, but the transaction is taking place at the DICOM engine level. It's truly replicated. The other way, with mirrored sites, you still have a down system, just with a second copy of images.

Middle Tennessee Medical Center

Middle Tennessee Medical Center, Murfreesboro, Tenn., is a 286-bed community hospital, the anchor in the five-hospital Saint Thomas Health Services regional health system; Saint Thomas Health Services is itself one of the divisions of the St. Louis-based Ascension Health system, the largest not-for-profit health system in the U.S.

The Saint Thomas Health Services system encompasses more than 1,450 beds. Altogether, more than 575,000 diagnostic imaging studies are performed in the system every year. Murfreesboro has a population of about 100,000, and is located 35 miles southeast of Nashville.

The other aspect of how we created this was that our strategy for purchasing what was the Emageon solution at the time was because of its adherence to open DICOM connectivity; as a result, we have no proprietary DICOM studies at all. And there are no studies that have not been worklisted via HL-7 from the Cerner EHR, as opposed to having a technologist enter in from a piece of paper the patient's name, date of birth, etc. Instead, all of that data is fed into the modalities, CTs, MRs, whatever, into the worklists, so all the header information is now correct.


HCI: The doctors have liked this?

West: Yes, very much so.

HCI: As far as you know, are there other multi-hospital systems that have done this?

West: Since we went live, four hospital systems within Ascension Health have done this. This architecture would not fit well if you were a single hospital; it would just be too darned expensive. We were the reference site for Emageon, and Johns Hopkins visited us, and duplicated what we had done.


HCI: What lessons has your organization learned from creating this innovation?

West: The lesson learned is that there is a distinct advantage to having the capability to fail over.

HCI: Have you had situations where you would have been down otherwise?

West: Yes, two years ago, one of the archives was located in an offsite data center in downtown Nashville; there was a major failure of the power grid, which meant we lost connectivity to one of the hospitals, so that hospital centrally pointed all its imaging devices to the other node, and the radiologists were instructed to read from the second node. There is a bit of a manual process to it; there are some things like document scanners, for example, that won't automatically take a second destination. But in the case of CTs and MRs, you can put in multiple destinations, and we simply put out a notice saying the one PACS was down, redirect.

And the beauty is, when the second node comes back up, DICOM matching automatically takes place, so the replication is automatic. So in other words, it catches up with itself. It's almost like having side-by-side DVRs watching cable TV, and if you lose one of those boxes, you simply watch the other television.

HCI: What would your advice be for CIOs thinking about these storage and continuity issues?

West: The first thing would be for any CIO to determine if the scope of what they want to do with their imaging warrants this kind of configuration. This is not the sort of thing you would do with a 200-bed single community hospital.

HCI: It's somewhat surprising that more multi-hospital organizations haven't done this yet.

West: More and more have. But there's a geographic factor involved that we call the Goldilocks Syndrome, because everything has to be just right; if the two nodes are too far apart, as we discovered in one Ascension system, then creating the connectivity can be prohibitive.

HCI: So you have to be within the same community or region?

West: Yes, at least virtually. If you can afford the connectivity-and it's a minimum of a gigabit of connectivity-if you can put the two nodes within 100 miles apart, you could do this.

Healthcare Informatics 2011 April;28(4):32-36

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