How To Monitor Your Medical Refrigerator Temperature

Published by Emeli Zuno on

Medical facilities implement safe storage of drugs and vaccines to prevent loss of potency from exposure to incorrect temperature ranges.  Once their effectiveness is lost, drugs cannot be restored, and therefore become useless. How to monitor your medical refrigerator temperature. Ensure that efficacy of temperature-sensitive vaccines and pharmaceuticals is maintained

As the medical industry’s demand for vaccines and medicines grows, investment in medical refrigerators also increases.  The medical refrigerator market is expected to grow from US$3.3 billion in 2019 to US$4.2 billion in 2024.  With that amount of money, it would be a waste if those medical-grade refrigeration units were not monitored and maintained properly – which could compromise the quality of the contents.

North America is expected to lead the medical refrigerator market in the next 4 years.
Image source: Markets and Markets
https://www.marketsandmarkets.com/Market-Reports/medical-refrigerator-market-65624174.html

Proper environmental control and maintenance (such as correct temperature, light, and humidity, suitable conditions of sanitation, and appropriate ventilation and segregation systems) of vaccines and pharmaceutical products are important aspects in the cold chain system but unexpected events could still arise if the vaccine refrigerator temperature is not accurately monitored.

The Importance of Temperature Monitoring

Maintaining the entire cold chain process is critical in any medical facility, particularly when it comes to storing temperature-dependent materials.  There are three things that can help in maintaining a functional and effective cold chain: well-trained staff, accurate inventory management, and above all, appropriate temperature monitoring equipment.  A vaccine’s temperature significantly affects its service life and efficacy. If vaccines are exposed to temperatures that are not within their correct temperature range, they will be wasted and patients will have to be vaccinated again.

There is no universally accepted temperature for biological substances and vaccines, as they have different compositions and requirements.  Some need to be frozen, while others demand specific cooling temperatures.  For medical professionals and staff, strict compliance can be quite challenging.  Monitoring samples and vaccines with recording and data logging equipment, such as temperature monitoring devices (TMD), can provide the actual temperature readings on the medicines and vaccines.

TMDs record the minimum and maximum temperature of the items inside the refrigeration units as each workday starts and ends.  If the temperatures reach a range that should not be reached, it will be fast and easy for the medical staff to take necessary actions.  Frequent and manual checking will no longer be needed, and minds will be put more at ease.

The temperature monitoring equipment available in the market today is inexpensive and easily accessible, which removes any obstacles preventing medical facilities from purchasing them.  Even the CDC suggests that these devices serve as insurance for the facility, and possibly provide the best protection for the vaccines and samples.

Temperature Monitoring Recommendations

From using stem and dial thermometers, to equipping 30-day electronic temperature recorders, it is evident that temperature monitoring practices recommended by global health authorities and organizations have continually changed over a number of years.  Due to rapid technological advances, better and more reliable devices continue to be produced, which make the cold chain process more efficient.

chart recorder
Dial thermometer

Temperature Range

A medical refrigerator should have the ability to maintain the temperature between  2° C and 8° C (36° F and 46° F), and a medical freezer should maintain the temperature ranging from -50° C to -15° C (-58° F and +5° F).  Also, refrigeration units and freezer thermostats must be set to the default factory temperature or midpoint temperature, which will reduce the possibility of temperature fluctuations. 

Thermostats are placed in different ways, and generally control levels of coldness rather than just displaying temperatures.  The only way to know the accurate temperature inside the medical refrigerator is to measure and monitor it with a temperature monitoring device or TMD.

Illustration source: CDC
https://www.cdc.gov/vaccines/hcp/admin/storage/downloads/temp-fridge.pdf

Temperature Monitoring Devices (TMD)

Each medical refrigerator should have a TMD.  Accurate temperature records can show the actual temperature of vaccines, drugs, or samples, which is essential for the protection of the contents inside the unit. It is less costly to purchase a reliable device than to replace the vaccines that are wasted due to loss of potency – caused by exposure to out-of-range temperatures  

The World Health Organization (WHO) and CDC recommended the following TMDs for medical refrigerators:

  • 30-Day Electronic Temperature Recorder ( 30 DTR): This is a stand-alone device that is placed with the items inside the medical refrigerator.  Its purpose is to record the refrigerator temperature at intervals of 10 minutes or less, for 30 consecutive days on a running basis.  It also logs and displays a 30-day history of any high temperature or freezing alarm interruptions that occurred.  If the device temperature drops to -0.5°C (31.1°F) or lower within 60 minutes or exceeds +8°C (46.4°F) within a 10-hour rolling time, an alarm will be triggered. Although 30 DTRs are designed for vaccine refrigerators, they are not recommended for vaccine freezers.
Glycol Thermometer
  • Integrated Digital Thermometer: This is a temperature sensor that monitors the coldest point in the refrigeration unit and displays an instant reading on the unit’s control panel.  Also, it overthrew the traditional stem thermometer which can only provide momentary temperature readings and cannot be linked with a programmable electronic temperature sensor and event logger system.  Because of this, the WHO no longer recommends using them as the primary monitoring device in medical refrigerators.  Included with the non-recommended devices for refrigerators are the bimetallic dial thermometers, as these devices gradually lose their calibration over time, especially when they are dropped.
  • Electronic Freeze Indicators:  These devices are not the best option for monitoring the temperatures in medical refrigerators, but can still be used if 30 DTRs are not available.  They are small-sized digital sensors that show if the items in the refrigeration unit have been exposed to freezing temperatures. Once the alarm is activated, the devices cannot be used again, and should be discarded.
freeze tags
  • Digital Data Logger (DDL): Data loggers cost more than standard thermometers, but they offer the advantages of continuous data monitoring and storage.  Unlike manual thermometers (which tend to reflect the air temperature rather than that of the contents of the refrigerator), DDLs have buffered probes that can directly and accurately measure the vaccine temperatures.  They can also indicate how long a unit has been operating outside the correct temperature range (or a temperature excursion).  To ensure that a DDL works accurately, it should have a current and valid Certificate of Calibration testing (or more known as Report of Calibration).
Glycol Thermometer

Wireless IoT Monitors and Alarms

Without needing any physical wire connections, wireless IoT monitoring is effortless to set up.  Each component is powered by batteries, and can be connected directly to the internet.  They can also store data in the cloud, allowing remote and real-time monitoring of temperatures.  In this way, device users can receive immediate alarms in case of temperature abnormalities, via email or SMS.

Temperature Stabilization

The temperature of a newly installed or repaired medical refrigerator normally requires two to seven days to be stabilized.  Before putting the unit into use, it is best to check and record the minimum and maximum temperatures of each workday for two to seven days.  If it’s not possible to record the temperatures digitally, it can be manually checked for a minimum of two times each workday.  Once the temperature for two consecutive days is recorded within the recommended range, the unit will be stable and ready for use.

Handling Temperature Excursions

Temperature excursions refer to any event in which temperature-sensitive products are exposed to temperatures beyond the range recommended for storage.  These events happen rarely, but when they do, they’re a serious matter – which is why they should not be ignored. It is advised to report any temperature excursion to a supervisor or an alternative facility coordinator.

If the refrigerator’s temperature reaches above 2°C (35.6°F), which is too low, the following actions should be taken:

  • Turn the thermostat knob to increase the heat of the unit and make the refrigerator warmer.
  • Check if the seal is damaged, and that the door of the refrigerator closes properly.  If it is broken, repairs should be made immediately.
  • If the temperature falls below 0°C (32°F) for any period of time, check freeze-sensitive items and see if they have been damaged from freezing by using the Shake Test.

If the temperature in the refrigeration unit rises to a level above 8°C (46.4°F), the following corrective measures should be taken:

  • If the overall unit is working, turn the thermostat knob to make the refrigerator cooler.
  • Check if the door of the refrigerator closes properly.  If it does not, then the seal is broken, which will cause the temperature to fluctuate.  Immediately call a technician to make the necessary repairs.
  • Check whether frost is blocking cold air from entering the unit’s compartment.  Some cases require defrosting.
  • If the temperature cannot be maintained between +2°C (35.6°F) and +8°C  (46.4°F), the unit’s content should be stored in another cooling storage equipment that can maintain this temperature range until the medical refrigerator is repaired.

Vaccines, drugs, and other temperature-dependent substances should not remain in a malfunctioning unit for a long period of time.  If a unit is damaged or not functioning properly, initiate the implementation of emergency SOPs.

Conclusion

For the medical and health industry, monitoring of cold storage is a top priority.  It is important that medical facilities have proper storage, but it is more crucial for them to have efficient monitoring equipment that is set up correctly, maintained regularly, and repaired as much as needed.  Failure to do this means that patients will receive compromised and ineffective vaccines, thus, leading to a large number of re-vaccinations – which is expensive and a waste of financial investment.  It may also discourage patients and damage the reputation of vaccine manufacturers. To avoid such incidents, the WHO and CDC have recommended guidelines for the correct monitoring of medical refrigerators’ temperatures.

Advancing from the traditional stem and dial thermometers, TMDs such as DDLs, 30 DTRs, and other current devices have simplified temperature monitoring.  These devices are more expensive than the manual ones, but they offer many advantages, such as accurate and continuous reading, wireless monitoring, active alarm signals, and reduced human errors.  By using the data collected from these temperature monitoring devices, medical facilities will gain better and more critical insights in the storage process, which can improve transparency and output, reduce repeatability, and save time and money.

References :

https://www.cdc.gov/vaccines/pubs/pinkbook/vac-storage.html#:~:text=for%20temporary%20storage.-,Temperature%20Monitoring%20Devices%20(TMDs),use%20a%20buffered%20temperature%20probe.

https://apps.who.int/iris/bitstream/handle/10665/183583/WHO_IVB_15.04_eng.pdf?sequence=1

https://www.who.int/immunization/documents/IIP2015_Module2.pdf

https://www.news-medical.net/whitepaper/20190329/How-Should-Freezer-and-Fridge-Temperatures-be-Monitored-for-Research.aspx

https://www.helmerinc.com/articles/ultimate-guide-vaccine-storage-and-temperature-monitoring

https://k2sci.com/news/a-quick-guide-to-medical-refrigerator-temperature-monitoring


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