MONITORING OF REFRIGERATORS AND FREEZERS continued
continually displays and records the temperature readings. These are typi- cally called data recorders or remote monitoring systems. Probes, which are sensors in rod form, are inserted into the environment being measured and are connected to another device that records the temperature read- ing. A probe can be used with or without a temperature buffer.
Temperature buffers Buffers act as a cushion against temperature fluctuations in a freezer or
refrigerator. A typical buffer (Figure 3) is a bottle filled with glycol solution or glass beads in which a probe or sensor is inserted. Without a buffer, the probe or sensor measures the atmosphere inside the storage unit, which can change rapidly with defrost cycles, door openings or fans circulat- ing the air. The air temperature of the storage unit changes much more quickly than the temperature of vaccines and pharmaceutical products, so a buffered probe reading more accurately represents the temperature of the stored assets.
Continuous vs manual recording of
storage temperatures It is important to keep an ongoing record of temperatures for documenta- tion that items were stored correctly. Data-logging devices have built-in or connected temperature probes and are positioned at the refrigerator or freezer. They continuously measure the temperature in the refrigerator/ freezer and store the data locally on the device. With digital data-loggers, users can set alarms to alert when temperatures go out of range and can re- cord events with far greater accuracy than chart readers or thermometers.
A remote monitoring system includes a data-logger and can automatically store data in a remote location that can be accessed by any desktop, tablet or phone. Laboratory personnel can log data at customizable intervals and log separate intervals when in an alarm state. Data is downloaded re- motely through a website, either via a local network or cloud, where it can be printed or exported in various formats. Remote monitoring systems also have alarms—when a temperature falls outside a preset range, the system sends a telephone call, text or e-mail to the designated contacts.
More advanced systems allow users to log both the highest and lowest temperatures over a set period of time. This provides a snapshot showing whether the temperatures were within range that day, which is especially convenient when the person responsible for temperatures is not the same as the person designated to receive alarm notifications.
CDC recommendations for data-loggers and remote
monitoring systems • Digital display on the outside of the storage unit for reading temperatures without opening the door
• Detachable
• Probe in a bottle filled with a thermal buffer, like glycol, which more closely reflects vaccine temperatures; vaccine temperatures have been found to be more thermo-stable than air temperature, which fluctuates with defrost cycles and opening and closing of the unit door
• Alert for out-of-range temperatures • Accuracy to within ±1 °F (±5 °C) • Low-battery indicator
• Continuous monitoring and recording capabilities to track and record temperatures over time
• Display of current, minimum and maximum temperatures, which indicate the coldest and warmest temperatures recorded since the device was reset.
Calibration The CDC recommends using calibrated temperature monitoring de-
vices with a Certificate of Traceability and Calibration Testing. It is im- portant that calibration testing is performed by a laboratory accredited by an International Laboratory-Accredited Cooperation (ILAC) Mutual Recognition Arrangement (MRA) signatory body.
An alternative is to purchase monitoring equipment from a manufac- turer that provides a Certificate of Calibration. The documentation should show that calibration testing was performed that meets International Organization for Standardization/International Electrotechnical Com- mission (ISO/IEC) 17025 international standards. Once the data-logger is installed, the CDC recommends calibration testing every one to two years to ensure accuracy.
References 1.
www.cdc.gov/mmwr/preview/mmwrhtml/mm5242a6.htm
2. Shafaat, K.; Hussain, A. et al. An overview: storage of pharmaceutical prod- ucts. World J. Pharmacy and Pharmaceutical Sci. 2013, 2.5, 2499–2515.
3.
www.jointcommission.org/standards_information/jcfaqdetails.aspx? StandardsFaqId=1280&ProgramId=46
4.
www.cdc.gov/vaccines/hcp/admin/storage/toolkit/ Figure 3 – Temperature buffer. AMERICAN LABORATORY 16
Rob Fusco is director of Business Development, Sensaphone, 901 Tryens Rd., Aston, Penn. 19014, U.S.A.; tel.: 877-373-2700; e-mail: rfusco@sensaphone. com;
www.sensaphone.com
JANUARY/FEBRUARY 2017
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68