What needs temperature monitoring?
Any environment or equipment that uses temperature to maintain the stability of testing samples, reactions or materials should be monitored. Examples are: instruments, incubators, refrigerators, freezers and rooms that contain specimens, reagents or active testing. These must be monitored for temperature control on a daily basis at a minimum, including weekends and holidays. By monitoring temperature in accordance with the manufacturer’s instructions the laboratory protects the integrity of the materials. If temperature control is not maintained for reagents and specimens, then the laboratory can not have confidence in the results obtained. Great expense and patient harm can occur.
Exceptions
If the environment or equipment does not contain reagents or samples and testing is not done on certain days, then monitoring is not required for those times. Enter a notation of “not in use” on the recording chart for that day. An example would be a warm water incubator not used for testing during a particular day.
For refrigerators and freezers only, but not for devices containing specimens or repository samples, a case-by-case exemption can be determined by DAIDS to use a continuous recording device or a min/max thermometer over weekends or short holidays. This practice is not recommended due to the expense and time involved in verifying materials suspected of possible spoilage or loss of materials from temperature range failure. Any time that the temperature is outside the appropriate range and there is a suspected violation of the manufacturer’s recommendations, corrective action must be undertaken to verify the integrity of the materials stored.
How to measure
A constant recording graph or computer monitoring system is ideal. A minimum/maximum thermometer is also a good measuring device, because it will alert the laboratory to temperature variance between monitoring. Otherwise, a thermometer that covers the expected range of temperature can be used. Each measuring device should be uniquely labeled for easy identification. The temperature measuring sensor is often placed in a small sealed tube of glycerin inside a refrigerator or freezer to dampen the effect of opening the door from time to time.
Calibration records
All temperature measuring devices must have calibration verified when placed in service and at least once a year thereafter. These devices should be calibrated against a current National Institute of Standards and Technology (NIST) traceable thermometer or equivalent certified instrument. Temperature readings from the two measuring devices are taken at the same time under the same conditions and compared. The two measurements should be within laboratory established criteria. Each measuring device should have a continuous calibration record for the life of the device. The calibration record should contain: an identifier unique to the thermometer, the certified and test thermometer temperature readings, criteria of acceptance, result of the calibration, date performed, initials of the person performing the testing and a comments section for any additional information. This record should be reviewed, at least annually, then signed and dated for completeness by the lab director or designee. Those thermometers failing calibration should be removed from service. After the device is no longer used, then this calibration record should be preserved in accordance with study or laboratory guidelines.
Range
The range limitations are determined by the most limiting of the manufacturer’s recommendations for the materials stored or in use in that environment or equipment. An example would be a refrigerator that contained two reagents: one must be stored between 3-8 degrees and the other between 2-6 degrees Centigrade. The acceptable range would be 3-6 degrees Centigrade for this refrigerator.
Recording
A separate recording sheet should be maintained for each device. The record should contain: temperature, date, monitor’s initials, space for comments and any corrective actions. The recording sheet must also specify the temperature range permitted. To help ensure that temperatures are recorded, temperature records must be kept near where the monitoring is done and assessable to all pertinent personnel.
Corrective Actions
If the temperature is outside of the acceptable range, then corrective action should be taken. It is important to insure the integrity of the materials and determine if product deterioration has occurred. The length of time, the degree of variance in temperature and the manufacturer’s recommendations for material storage stability are used to determine what actions are necessary. The effected materials should be marked to indicate possible quality problems and moved, or in some way restored, to the correct temperature range. Corrective actions for those materials should at least include parallel testing as done when new materials are received in the laboratory.