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Medicine Technology

Know What Time It Is? Your Medical Device Doesn't 290

An anonymous reader writes "A man with one clock knows what time it is, goes the old saw, a man with two is never sure. Imagine the confusion, then, experienced by a doctor with dozens. Julian Goldman is an anaesthetist at Massachusetts General Hospital in Boston. After beginning to administer blood-thinning medication during an urgent neurological procedure in 2005, Mr Goldman noticed that the EMR had recorded him checking the level of clotting 22 minutes earlier. As a result, four hospitals in the northeast had their medical devices checked, and found that on average they were off by 24 minutes. The easy solution that devices could have used since 1985? NTP."
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Know What Time It Is? Your Medical Device Doesn't

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  • It won't help (Score:4, Informative)

    by Gothmolly ( 148874 ) on Wednesday May 23, 2012 @11:26AM (#40089579)

    First, they will use Windows Active Directory for NTP because someone will say "it's authoritative for the whole network". And their clocks will be off.

    Then they will run into config hell, and blaming that for clocks being off - they will load balance the domain controllers. Which is precisely what you're not supposed to do with NTP. And their clocks will be off.

    Then, some small but relevant IT subgroup will secede, claiming that they need "real" NTP. "Network Security" folks are typical suspects here. So their clocks won't match the rest of the gear (which is still off, remember?)

    If you have poor enough technology discipline that your clocks are 24 minutes off already, you're probably screwed.

    • by Nkwe ( 604125 )

      First, they will use Windows Active Directory for NTP because someone will say "it's authoritative for the whole network". And their clocks will be off.

      Then they will run into config hell, and blaming that for clocks being off - they will load balance the domain controllers. Which is precisely what you're not supposed to do with NTP. And their clocks will be off.

      Active Directory time synchronization works properly if you have a competent sysadmin and set it up correctly. If you don't have competent sysadmin it doesn't matter the technology or vendor you are using, you will get it wrong.

      Active Directory domain controllers don't need external load balancing, they automatically distribute work out of the box. When configured correctly they also set up a proper NTP time hierarchy.

      • Active Directory time synchronization works properly if you have a competent sysadmin and set it up correctly.

        Translation: "you are all f&*$ed", cos you KNOW that can't happen.

  • by Animats ( 122034 ) on Wednesday May 23, 2012 @11:27AM (#40089607) Homepage

    Medical devices should not have Internet access.

    Receiving time from a GPS receiver is much safer. That's a broadcast signal with a fixed message format.

    • by King_TJ ( 85913 )

      From my experience in hospital environments, radio reception is often VERY poor. You've got lots of metal in their construction that tends to block signals. Doubtful you'll have any luck receiving a time signal via GPS unless you plan on running antennas all the way up to the roof of the building.

      As I posted already, NTP is a perfectly good way to solve this problem. You simply have ONE system designed to be your time server, which synchronizes over the Internet via NTP, and then all the firewalled off dev

    • by Z00L00K ( 682162 )

      You can always set up a network with trusted only devices. It requires some work but it will pay off in the long run.

    • by AmiMoJo ( 196126 )

      I looked into this last year for a project and it is actually pretty hard to get an accurate time signal cheaply inside a building. NTP works but needs ethernet and TCP/IP, and either a cable or wifi (which means WPA authentication etc.)

      GPS is very accurate but tends not to work well indoors, especially in rooms with no windows like most operating theatres. Around the world there are various low frequency time signals (DCF77, JYY, MSF etc.) but like GPS reception can be a problem. I live in the UK and DCF77

    • by tlhIngan ( 30335 )

      Medical devices should not have Internet access.

      So... don't. NTP works just fine on a private network. And you don't even need a proper time source, either. As long as everything ticks within a narrow boundary of time, it doesn't really matter if the master NTP server clock is off. If it's stable, the offset between it and the real time would be well known.

      NTP's just a way to distribute the time. It doesn't have to be used to distribute exact time. As long as everything's ticking to the same clock, things

    • by Minwee ( 522556 )

      Receiving time from a GPS receiver is much safer. That's a broadcast signal with a fixed message format.

      A fixed what? []

    • Medical devices should not have Internet access.

      That depends entirely on the purpose of the medical device. "Medical devices" covers a lot of products that serve a lot of different purposes. For some devices internet access would be pointless, for others internet access would be dangerous, and for still others internet access makes perfect sense. It depends entirely on what you are doing with it and what the risks are. There is nothing inherently wrong with hooking up a medical device to the internet, provided that the risks of doing so have been ade

  • Most devices dont. In fact it's highly rare for a device to NTP sync.

    Most building lighting control systems do not do a NTP sync. Security systems, etc... all rarely do this.

    It sounds like that someone finally realized that clock drift happens and is shocked about it.

    • by freeze128 ( 544774 ) on Wednesday May 23, 2012 @01:34PM (#40091529)
      Why does clock drift happen? It doesn't need to happen. It can totally be avoided. It only happens because the equipment manufacturers design inaccurate clocks to save money.
      My quartz LCD watch from 1985 was accurate to within 1 second per year. That would WAY outlast the usefulness of the medical device. There should be no way in the world that device was off by 24 minutes.

      Right now, I'm dealing with the same problem in my brand new car. It has a fancy on-board computer with a screen that tells me gas mileage, service info, mp3 and radio interface, etc.... The clock is ridiculously fast (gains 3 minutes a week). My new $20,000 car should have a clock in it at LEAST as accurate as the watch I can get from a happy meal.
  • by jcdr ( 178250 ) on Wednesday May 23, 2012 @11:55AM (#40090127)

    NTP have the problem of discontinuing his UTC timestamp while a leap second occur and NTP do not broadcast the actual UTC-TAI offset (historically because he broadcast UTC directly but this is now more a problem that an advantage). GPS and PTP broadcast (something very closely related to) TAI and a UTC-TAI offset, witch is the right thing to provides the precise actual time without discontinuity.

    But all of them, NTP, GPS and PTP, have the problem of not broadcasting the historical leap second table, making the client of those protocols alone unable to safely compute a precise date in the past. I hope next NTP protocol will broadcast TAI, and that NTP, GPS and PTP will be able one day to broadcast the leap second table. I am certain that there is still some reserved bits somewhere in those protocol to make that working.

  • "A man with one clock knows what time it is, goes the old saw, a man with two is never sure."

    That's why the sailor's adage is to take one clock or three to sea. With one, well, that's all you've got to go on. With two, you never know which one is right. With three, usually at least two agree.

  • by jklovanc ( 1603149 ) on Wednesday May 23, 2012 @12:17PM (#40090473)

    We are talking about medical equipment that would have to be certified by the FDA. That would mean that every GPS receiver and every implementation of local NTP would have to go through a rigorous and costly certification process. The following issues would have to be certified;
    1. Is the device accurate.
    2. How does the device interact with the software.
    3. How does the device interact with every device receiving data. This is the hard part.

    Secondly, is it even necessary? The issue seems to be that there is an offset between the clock on the equipment and actual time. How about at the beginning of the operation the doctor writes down all the times as stated on the medical equipment. If necessary these offsets can be applied later to normalize the times. This reminds me of the time when the US spent tens of thousands of dollars to build a pen that would work in zero gravity(it was pressurized with gas). When a cosmonaut was asked how they coped he said "In Russia we use pencil". Sometimes high tech just complicates the issue.

  • by ChumpusRex2003 ( 726306 ) on Wednesday May 23, 2012 @12:18PM (#40090481)

    This is often a case of poor administration, perhaps more frequently than poor design.

    For example, I was recently tasked with reviewing the performance of several hospitals in the diagnosis and treatment of stroke. Under national guidelines (UK) a patient with suspected stroke must have had a CT scan within 30 minutes of arrival at hospital, with blood-thinning treatment administered within 60 minutes (if appropriate).

    The problem was that the times on the CT scanners were discrepant by +/- 45 minutes from true time - so the images were tagged with the incorrect time. Further, the CT viewing workstations had times up to 2 hours discrepant. The CT scanners were Windows or Gentoo depending on the manufacturer's preference. Similarly, the CT workstations were windows, and were all bound to the hospital domain.

    The time discrepancies made my assessment very difficult - and I had to correct for each individual scanner, and assume that the clocks hadn't drifted over the 6 month period of the audit.

    I also found several safety issues because of this - e.g. if it was 1am, and a patient had a CT scan, some workstations would be 2 hours slow, so would read 11 pm on the previous day. These workstations would refuse to load the CT scan because the files were filtered by "WHERE [StudyTime] NOW".

    I raised a support issue with the workstation vendor who simply said "These are windows workstations. You should ensure that they are appropriately bound to your domain, and configured to sync with your time server or domain controller". So I called IT to configure this, "No way. These are medical devices, we can't change the configuration - and anyway, what will happen if the clock is fast, and the sync pushes the clock back, so that there are 2 occurrences on the same time. That would cause chaos. Even if the manufacturer supports it, there's no way we'll set it up". Of course, their concern doesn't actually exist, because most time sync algorithms (even on Windows) are clever enough to avoid "double time".

    There was similar obstruction with the CT scanners. The vendors simply said - we support and encourage synchronisation with a time server. IT or the radiology administrators simply stonewalled the ideas. They refused even to correct the clocks on teh scanners - so the clocks are still wrong to this day (even more so, due to accumulated drift).

    Of course, even if the time can be set right - there is disagreement as to how daylight-saving is managed. Some equipment, esp. older embedded kit isn't daylight-saving aware. Do you set it to Summer time or winter time? In most hospitals I've been in, it's been an inconsistent mixture - often with lots of clock drift added, so you can't actually be sure.

  • by rickb928 ( 945187 ) on Wednesday May 23, 2012 @12:25PM (#40090575) Homepage Journal

    When I had a hospital gig, we knew back in 1995 that time would need to be syncronized amongst all the servers etc. We ran a local time server synched to a Tier 1 NTP server which was fortuitiously about 180 miles away. It has since gone to restricted access, but it's nailed to the USNO, and is still a Stratum One server. I bet they still use it as reference.

    But even in 1995, NetWare servers were well behaved and accept NTP, and we set workstation time on login. As other servers came on, we went through the inevitable 'my server is more accurate' and blew them off until the Sun server showed up,and they refused to use our NTP. Fine. Took two weeks to resolve a 300ms difference, and then I watched as they re-fixed the error and synched with the NTP server they initially refused to use. In fariness, it was not SUN engineers involved, but they were arrogant enough to qualify.

    Time is important to networks.

    We did not, however, have any way to manage time on 'devices', such as infusion appliances etc. I do NOT think of an EMR as a 'medical device'. Nor do I think of the EMR sytem that way either. But if time isn't being synched on your network, you got some other problems, I suspect, that are not making your work easier or efficient as a network admin.

  • Once upon a time not so long ago, I wrote EMR software. You have to realize that there's no standard for medical devices and their information reporting; each manufacturer, sometimes each device model, is different. Some of them are quite old, or at least use interfaces that are quite old and haven't been updated in a long time (for compatibility reasons, of course.) Most still use 9-pin serial cables (USB developed: 1994.)

    I would never trust the reported time from any device. Use the time that the recording system receives the data as the time of record (and poll data often.) Who cares what time the device thinks it is, along as it tells you the current data "now" and YOU know when "now" is?

As far as we know, our computer has never had an undetected error. -- Weisert