If you work with vaccines, medicines or other medical supplies requiring refrigeration, you know the significant financial, safety, and human costs if they’re not kept at the right temperatures. Here are 4 ways to prevent excursions and ensure the safety of refrigerated content.
- Use a Digital Data Logger (DDL)
A simple thermometer can’t make you aware of an excursion unless it happens to be occurring at the time your staff is completing a temperature check. A min/max thermometer lets you know an excursion happened, but not if, or how long medicine was out of range.
In contrast, a DDL automatically records your refrigerator temperature every few minutes and builds a detailed, downloadable data set of timestamped temperature readings. In addition to eliminating the task of manual temperature recording, the digital record clearly shows when an excursion occurred, the temperatures reached and length of time medicines were out of range – all the necessary details needed to confirm with the product manufacturer whether your refrigerated content is still viable.
Reviewing DDL logs also offers clues and provides actionable information for preventing future excursions. For example, perhaps you notice a concerning pattern of high temperatures during peak times of the day, during off-hours or seasonally. When you know an excursion-prone time period exists, you can develop an effective prevention or mitigation strategy to improve safety and save money. The state of Massachusetts realized a 30% reduction in annual cost of vaccine waste within 2 years of adopting DDLs.1
- Measure Medicine Temperature
If you’ve ever wanted to go for a swim in spring only to find the water disappointingly cold, you know water takes longer to warm up than air. The same thing happens in a refrigerator. Just as the thermal mass of pool or lake water causes it to warm more slowly than the surrounding air, so does the thermal mass of refrigerated content cause it to warm more slowly than the refrigerator air when a door is opened.
Standard thermometers reflect the air temperature inside a refrigerator, not the temperature of your stored contents. If only air temperature is monitored, an open door could even lead you to think an excursion happened when your medicines actually stayed within acceptable ranges.
Instead of just measuring air temperature, augment your system with a buffered thermometer. These work by utilizing a temperature probe inserted into a bottle containing a “buffer”, which is a substance having a similar viscosity to that of the actual stored content. The buffer’s thermal mass makes it less sensitive to air temperature changes, resulting in temperature readings more accurately representative of the contents being monitored. Buffered thermometers are readily available as DDLs.
- Use calibrated thermometers
Regardless of the type of monitoring device used, look for one calibrated and traceable to NIST. NIST stands for National Institute of Standards and Technology and is the governmental organization that maintains the US standards for temperature. Calibration and traceability to NIST ensures that your thermometer has been tested and demonstrated to be accurate. Recalibration will be required at certain intervals, typically annually, to ensure continued accuracy. Click here for an overview of NIST calibration and traceability.
- Correctly position your thermometer
Where your monitoring device sits inside your refrigerator is key to getting an accurate temperature reading. You want to keep the thermometer under the same conditions as your refrigerated content. Therefore, it should always sit in the same type of bin or basket used to store your medicine. Aim to position the device where it is less likely to be jarred or bumped. And as with medicines, avoid potential cold spots – commonly the bottom storage shelf or next to a fan. In household grade refrigerators, the center of a center shelf is often the best location; avoid areas next to refrigerator walls or directly on a glass shelf.
1 https://www.nist.gov/industry-impacts/reliable-vaccine-storage