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Health professional risk communication

For Health Professionals - Important information concerning unpredictable events in medical equipment due to Daylight Savings Time change

Starting date:
March 7, 2007
Posting date:
March 7, 2007
Type of communication:
Dear Healthcare Professional Letter
Medical Device
Source of recall:
Health Canada
Healthcare Professionals
Identification number:

Notice about Health Canada advisories

Important safety information concerning unpredictable events in medical equipment due to Daylight Savings Time change

March 7, 2007

Health Canada wishes to draw your attention to a Public Health Notification issued on March 1, 2007 by the United States Food and Drug Administration (US FDA) concerning unpredictable events in medical equipment due to new Daylight Savings Time change. This notification has been translated in French by Health Canada for your convenience. Please note that in Canada at the end of DST on the first Sunday in November it will be the 1:00 AM that will repeat in most jurisdictions that use DST; in Newfoundland it will be 12:00 AM that will repeat. Detailed information on time change in Canada can be obtained at

The original posting is available at:

FDA Preliminary Public Health Notification*: Unpredictable Events in Medical Equipment due to New Daylight Savings Time Change

(You are encouraged to copy and distribute this notification.)

Date: March 1, 2007

Dear Healthcare Practitioner, Hospital Director and Safety Manager:

This is to alert you to the possibility that some medical devices (equipment), hospital networks and associated information technology systems may generate adverse events because of the upcoming change in the start and end dates for Daylight Savings Time (DST), and to suggest actions you can take to prevent such occurrences.

While we do not know which specific devices might be affected, FDA is concerned about medical devices or medical device networks that operate together or interact with other networked devices, e.g. where a synchronization of clocks may be necessary.

If a medical device or medical device network is adversely affected by the new DST date changes, a patient treatment or diagnostic result could be:

  • incorrectly prescribed
  • provided at the wrong time
  • missed
  • given more than once
  • given for longer or shorter durations than intended
  • incorrectly recorded

Any of these unpredictable events could harm patients and not be obvious to clinicians responsible for their care.


  • As soon as possible, check with manufacturers for available patches or fixes for medical devices, hospital networks and associated information technology systems.
  • Advise patients who use medical devices in the home to check with manufacturers for available patches or fixes for their devices. You may wish to provide them with a copy of FDA's "Advice for Patients: Change in Daylight Savings Time May Affect Your Medical Equipment in an Unpredictable Way," available at
  • Assess your medical devices, hospital networks and associated information technology systems for the correct time on the four critical DST dates. The four critical dates in 2007 are:
    • March 11 (New date for start of DST)
    • April 1 (Old date for start of DST)
    • October 28 (Old date for end of DST)
    • November 4 (New date for end of DST)
  • Be vigilant with clinical decision-making and use of medical devices during both the New and Old DST dates.
  • Report any unpredictable medical device events or DST medical device-related problems to your biomedical engineer, the device manufacturer and FDA as noted below under Reporting Adverse Events.


DST will now start three weeks earlier and end one week later than in previous years as a result of the Energy Policy Act of 2005, which extended DST in the US to conserve energy. Beginning in 2007, DST will start at 2:00 a.m. on the second Sunday of March (instead of the first Sunday of April) and end at 2:00 a.m. on the first Sunday of November (instead of the last Sunday of October). This means that DST will begin on March 11, 2007 (instead of April 1, 2007) and end on November 4, 2007 (instead of October 28, 2007).

As usual, at the beginning of DST, one hour effectively disappears as 1:59 a.m. is followed by 3 a.m. At the end of DST, a duplicate hour appears as 1:59 a.m. is followed by 1:00 a.m., meaning that the 1:00 a.m. hour happens twice.

Because there are many types of medical devices and systems with clocks and clock-related features such as timers that were sold before the DST rule changes, e.g. they were designed with the old start and end DST dates, it is unknown whether these devices and systems will operate correctly with the new 2007 DST start and end dates.

Internal clocks in devices and systems usually change automatically for DST based on values set internally or interactions with other devices, e.g., servers. Some devices and systems may rely on incorrect values for DST starting and ending dates if the device manufacturers have not patched or fixed their devices to use the new dates.

Reporting Adverse Events

FDA requires hospitals and other user facilities to report deaths and serious injuries associated with the use of medical devices. If you suspect that a reportable adverse event with a medical device was related to the New DST Change, you should follow the reporting procedure established by your facility. Prompt reporting of adverse events can improve FDA's understanding of and ability to communicate the risks associated with devices and assist in the identification of potential future problems associated with the New DST Change.

We also encourage you to report any medical device adverse events related to the New DST Change that do not meet the requirements for mandatory reporting. You can report these directly to the device manufacturer or to MedWatch, the FDA's voluntary reporting program.

This can be done online at, by phone at 1-800-FDA-1088, by FAX at 1-800-FDA-0178; or by mailing FDA form 3500 (download from to MedWatch, 5600 Fishers Lane, Rockville, MD 20857-9787.

Getting More Information

More information about medical devices and the DST change can be found in the ECRI Health Device Alerts publication entitled "Medical Devices and the 2007 DST Changes" at:

If you have questions about this Notification, please contact Julia Marders, Office of Surveillance and Biometrics (HFZ-510), 1350 Piccard Drive, Rockville, Maryland 20850, FAX at 240-276-3356, or by e-mail at You may also leave a voice message at 240-276-3357 and we will return your call as soon as possible.

FDA medical device Public Health Notifications are available on the Internet at You can also be notified through email each time a new Public Health Notification is added to our web page. To subscribe, visit:

Sincerely yours,

Daniel G. Schultz, MD


Center for Devices and Radiological Health

Food and Drug Administration

* CDRH Preliminary Public Health Notifications are intended to quickly share device-related safety information with healthcare providers when the available information and our understanding of an issue are still evolving. We will revise them as new information merits and so encourage you to check this site for updates.

Any suspected adverse incident can also be reported to:

Health Products and Food Branch Inspectorate


Address Locator: 2003D

Ottawa, Ontario K1A 0K9

Tel: The Inspectorate Hotline 1-800-267-9675

The Medical Devices Problem Report Form and Guidelines can be found on the Health Canada web site.

For other inquiries related to this communication, please contact Health Canada at:

Marketed Health Products Directorate (MHPD)


Tel: (613) 954-6522

Fax: (613) 952-7738