Cold Chain issues

Issued April 2007

(See initial "Understanding the 'Cold Chain' requirements")

There have been several "cold chain" issues raised at hospital blood bank inspections. This is an area where there appears to be some lack of understanding, despite previous information being provided. It is hoped that this further clarification will unravel some of the areas where compliance as required by the MHRA, is currently not being met.

The current air temperature alarm set at 2 and 8 °C is an ALERT alarm to warn of possible problems. It is allowable for this alarm to have a reasonable time delay built in (e.g. 10 minutes).

A buffered load alarm is required to work on the core temperature of the blood. This alarm must have trigger points of 2 and 6 °C (with acceptable probe calibration tolerances of ± 0.5 °C). This is an ACTION ALARM and must not have a time delay. The thermal mass and position of this probe should be at a position defined by suitable temperature mapping and scientific considerations, as defined in BS 4376 e.g. equivalent temperature capacity to 200 ml water. The time between sampling should be no more than 5 minutes which in real terms equates to the ACTION alarm sounding as soon as the trigger points are reached. This alarm should require a manual acknowledgement and not reset automatically if the temperature returns to within tolerance.

Temperatures recorded from the ACTION ALARM may be chosen as the PRIMARY SYSTEM to replace the temperature records provided by the paper chart recorder.

Temperature mapping

All equipment controlling temperature must be temperature mapped once a year.

The test must have a duration of at least 24 hours and should, for the smallest of storage equipment, include a minimum of 3 points which will normally be at least the centre chamber, top and bottom. The number of probes must be sufficient to comprehensively cover the area being mapped, therefore for equipment such as larger fridges, dual chamber fridges and walk-in cold rooms the number of probes should be increased based on a documented scientific justification. In the case of larger equipment, it is expected that mapping locations will normally be at least the centre chamber, and the 4 corners top and bottom of the parts of the cabinet used for storage. Mapping exercises should include correlation between the routine probe readings and the mapping probes to demonstrate that any condition shown by the routine probes will be representative of any extremes seen i.e. the routine probes must be demonstrated as being in the hot and cold spots of the bank.

The cabinet can be used during the test. The amount and type of product in the cabinet during the test must be recorded with the test results.

The minimum mapping probe calibration tolerance is ± 0.5 °C and the frequency of temperature logging to be no longer than 5 minutes.