View as “PDF version

Patient Safety Tip of the Week

October 8, 2019   Another Freezer Accident



In our May 1, 2018 Patient Safety Tip of the Week “Refrigerator Alarms” we discussed incidents at two separate fertility clinics involving loss of tissue when the temperatures in the refrigerating units rose above levels necessary to preserve the specimens. Now, another freezer malfunction resulted in loss of stored stem cells of 56 pediatric cancer patients (Hayes 2019). The stem cells had been harvested from the children before they underwent chemotherapy and radiation treatments. They were in long-term storage in a freezer in case their cancer should return. Apparently, one of the freezer’s sensors failed and there was also failure in the notification process.


In a press release (CHLA 2019), Children’s Hospital Los Angeles stated it sent letters to 56 patients and their families to notify them of a freezer malfunction that resulted in the loss of their child’s blood stem cells. It noted that no child's health was in jeopardy due to this incident. 


According to the press release “The cause was a failure of freezer temperature sensors. Safeguards were in place at the time but were insufficient. Since that time, we have replaced the freezer that malfunctioned, upgraded our sensor monitoring and alert system, double-checked all power supply sources, increased our maintenance schedule and launched training for the engineering team on the new system.”


Your facility may not have stem cells or patient eggs and embryos stored in a freezer, but we bet you have other important items stored in freezers or refrigerators. Such items might be blood products, vaccines, certain other medications, tissue implants, and others.


While we don’t know the details of the failures in the CHLA incident, it is worth repeating some of our observations and recommendations in our Patient Safety Tips of the Week for February 4, 2014 “But What If the Battery Runs Low?” and May 1, 2019 “Refrigerator Alarms”.


In such cases, alarms would be set to trigger when a temperature sensor showed the freezer temperature had risen above a specified level. It should be no surprise that a freezer might fail or that a sensor might fail. So, you have to make sure your alarm will trigger when the freezer fails and that the alarm will trigger if the sensor were to fail or become disconnected. That calls for redundancy and backup systems.


The technology is available to indicate a sensor malfunction or disconnection. We get a “your motion camera has been disconnected” message by email and text message every time our motion detection camera gets disconnected from our WiFi system. We would assume similar capabilities should exist to alert someone when a freezer alarm system has been disconnected (but keep in mind there could also be an event that disables both your refrigerator alarm and your WiFi system).


Since an electrical failure could affect power to both the refrigerator and the alarm system, you probably don’t want both on the same circuit. In many cases, the alarm system is battery-powered. How do you know the alarm is powered and active?  In our February 4, 2014 Patient Safety Tip of the Week “But What If the Battery Runs Low?” we gave the following anecdote: You have an alarm that responds to the temperature in a refrigerator dropping below a set value to protect against loss of the medical products inside. You took great care to make sure the thermometer was not on the same electrical supply as the refrigerator. However, the battery on the thermometer had not been checked recently and had no charge when the refrigerator actually lost power. All the medical products in the refrigerator are lost. The smoke detector or carbon monoxide detector in your home has a button you press that indicates the alarm is functional. Is there a similar capability on these freezer alarms? More importantly, is there a visual indicator of remaining battery capacity on such alarms? And, then, do you have a protocol that requires someone to check that battery level every day?


Then comes your notification and response limbs. You can bet that an event might take place at a time when there is no one physically working near the freezer who might hear an audible alarm. So, you need route the alarm to someone physically able to respond in a timely fashion. In most hospitals, that is probably the on-duty nursing supervisor, though it could also be someone in your 24x7 security department. They might be notified by a text message alert or other means, but you’ll also have to regularly test that such linkage is working. But now you need to make sure the person receiving the alert knows how to respond. There should be a checklist and set of instructions informing the person responding to the alarm what to do. Probably the best place to put this is right on the freezer unit. You don’t want to bury it in a thick policy manual where the respondent may not even find it in a timely fashion.


You also want to make sure that you have an appropriate “escalation” practice (i.e. who to call next if the first person called fails to respond in a timely fashion). While we have such escalation procedures in place for clinical staff, many facilities are less deliberate with regard to non-clinical staff escalation procedures.


It is also worth reiterating that periods around maintenance of equipment are vulnerable times. We discussed this in our August 7, 2007 Patient Safety Tip of the Week “Role of Maintenance in Incidents”, in which we discussed the excellent work of James Reason and Alan Hobbs plus that of Don Norman. In one of the fertility clinic incidents mentioned previously, maintenance issues may have played a role. Also, in our March 5, 2007 Patient Safety Tip of the Week “Disabled Alarms” and several other columns on alarms, we noted instances where the oxygen blender alarms on ventilators had been disabled during maintenance and were not corrected prior to use in patients. When maintenance is done on any equipment we recommend to staff doing maintenance have a checklist they use to remind them of things they must do. And one of those items would be to restore any alarms they might have disabled during the maintenance.


Your facility probably has some refrigerators or freezer units that store important blood or tissue specimens or vaccines. And we know your IT server farm relies on optimal temperature ranges. But how many of you have ever questioned what would happen if there was an alarm malfunction in one of these units? Have you done a FMEA (failure mode and effects analysis) of such alarm systems? Do you look at these alarms when you are doing Patient Safety Walk Rounds? Are the appropriate people alerted when these alarms are triggered? Do those people know how to respond when such alarms trigger? Is there a checklist that helps responders take all necessary steps when such an alarm triggers? Do you know how such alarms are powered and what the impact of a power failure or battery failure might be? Do you have backup systems in place?



So, what should you be doing?



Lastly, a couple comments about the hospital’s response to the patients, family, and the public. Most healthcare incidents involve a single patient (aside from those misidentification incidents that involve pairs of patients). But sometimes incidents, like this one, impact multiple patients and the issues there become much more complex. We refer you to our June 16, 2009 Patient Safety Tip of the Week “Disclosing Errors That Affect Multiple Patients” for recommendations in such cases. The hospital did the right thing in being forthright and honest in letting affected patients know about the error(s) and expressing sincere apology. It also let them know that a proper investigation was being undertaken to address problems so a similar incident does not recur in the future.


It is also important to speak and act with empathy in such situations. CHLA probably made a couple missteps in their response. First, the notification letters were addressed to the children. That fact actually received considerable attention in the media. It certainly might have led to recipient families feeling the hospital had relegated the task of sending out letters to an uninvolved person rather than being supervised by a truly empathetic individual. While letters are the most frequent vehicle used for notification when multiple patients are affected by an incident, one might make the case here that an attempt to first make contact by phone might have been possible with 56 patients rather than several hundred. A phone call offers a better opportunity to convey a heartfelt apology than does a sterile letter. It would also offer the families the opportunity to ask questions immediately. Imagine receiving this letter on a Friday evening and worrying all weekend about what this means. Second, the press release stated no child's health was in jeopardy as a result of the incident. That probably did not sit well with the families or children, who might some day have to face reharvesting of stem cells, which can be quite painful for patients.



Sometimes we learn from incidents that occurred elsewhere. That’s less traumatic than learning from ones that occur at our own facilities. It would be very helpful if CHLA were to publish details of what went wrong in their systems and what specific fixes they put in place. If they don’t want to disseminate that in a publication, they should at least consider sharing the details through a PSO.



Prior Patient Safety Tips of the Week pertaining to alarm-related issues:







Hayes R. Stem cells for dozens of cancer patients destroyed after freezer malfunction at Children's Hospital LA. ABC7 Eyewitness News; September 26, 2019



CHLA (Children’s Hospital Los Angeles). CHLA Apologizes to Patient Families for Freezer Failure. CHLA Published on September 25, 2019





Print “PDF version












Tip of the Week Archive


What’s New in the Patient Safety World Archive