Temperature logging in medical transport: measuring, recording, calibration and how it differs from validation

Temperature logging is recording the temperature of a shipment at predetermined moments: at pickup, at delivery and, if a data logger travels along, in between. A record is only usable if every measurement states when it was taken, with which instrument, by whom and what the agreed condition was. Without that context a number is just a number.

Why it is the proof: the GDP guidelines require the wholesaler to keep storage conditions during transport within the manufacturer's limits and to give its customer temperature information on request. A laboratory wants to know under which conditions a specimen arrived. In both cases the promise beforehand is not decisive, but what is on paper afterwards. What must be on it at minimum comes further down; who in that chain is responsible for what when transport is outsourced is explained in GDP responsibilities in outsourced transport.

A measured value within the condition is not a release of the product. Whether a medicine or a specimen is still usable after a ride is judged by the owner of the product or the laboratory on the basis of the data; the measurement only supplies the fact. And a single figure at delivery says nothing about what happened on the way: it proves that the condition was met at that moment, not that it was met throughout the ride.

Two measurements, at pickup and at delivery, show the start and the end of the ride. If the temperature is within the condition both times and the ride is short, that is often enough; for the transport of medicines the IGJ accepts risk-based monitoring with spot checks, provided outliers are investigated and reported to the owner of the product. A data logger that travels along shows the course, including a brief peak while reloading or a dip caused by a cooling element lying too close to the product.

Which of the two is needed follows from the risk assessment of the route that chapter 9 requires: duration, outside temperature, packaging, the limits on the outer packaging and the driver's training all weigh in. According to the IGJ, short domestic rides do not always have to be conditioned. For a one-hour ride in an insulated box with endpoint measurements that is a different consideration than for a five-hour ride in summer with a refrigerator product. Anyone using a logger must also know what to do with it: a logger nobody reads out records nothing for the quality department.

Recording captures what actually happened during this ride. Validation shows beforehand that a packaging or a route keeps the condition under defined circumstances, for example that a particular cool box with a particular quantity of cooling elements stays below 8 °C for eight hours at an outside temperature of 30 °C. Qualification shows that equipment is fit for its purpose; chapter 9 requires qualified equipment for temperature-sensitive products. For investigational medicines the European inspectors use exactly that distinction: transport conditions are either validated, or monitored with a temperature logger.

The distinction matters because the three do not replace one another. A validated box without a record says nothing about the ride on which the lid stood open for a quarter of an hour; a record without validation says nothing about the rides on which nobody measured. A carrier that says its boxes are validated must be able to show the test data; a carrier that says it records must be able to show the measurements per ride.

A measurement is only as good as the instrument. The GDP guidelines require measuring equipment used for temperature monitoring to be calibrated at least once a year. In calibration, a calibration laboratory compares the instrument with a reference and records the deviation found in a certificate; if that laboratory works under accreditation to ISO/IEC 17025, the certificate carries the accreditation mark. That standard therefore says something about the laboratory that calibrates, not about the carrier.

Verification is the periodic check by the user itself: does the thermometer still work within its class, for instance when compared with a reference thermometer? There is a European standard for that, EN 13486:2023, aimed at users and verifiers of temperature recorders and thermometers. It is the only one of the standards mentioned here that a carrier can apply itself. What the procedure exactly involves and at which intervals is in the text of the standard, which is only available for a fee and is not reproduced here.

Four standards keep coming up in conversations about temperature logging, and all four concern the instrument or whoever calibrates it, not the ride. EN 12830:2018 describes the characteristics and test methods of temperature recorders for the transport, storage and distribution of temperature-sensitive goods, from -80 to +85 °C, for the whole recording system including external sensors; it is aimed at manufacturers and testers. EN 13485:2023 does the same for thermometers, of every type, for ambient or product temperature; it replaces the 2001 edition, which covered food only. EN 13486:2023 describes the periodic verification of both. ISO/IEC 17025:2017 sets requirements for testing and calibration laboratories.

From that follows what is and is not meaningful to say. That a recorder is specified by its manufacturer as conforming to EN 12830 can be true if the datasheet says so. 'EN 12830-compliant transport' means nothing: the standard covers the device. 'Certified to EN 13485' is not an existing certification for a carrier, and EN 13485 has nothing to do with ISO 13485, the standard for quality management of medical devices. Classes, accuracy requirements and procedures from these standards are not reproduced here; anyone wanting to apply them has to buy the texts.

There are two kinds of instrument. A thermometer gives the value at the moment of reading; a recorder or data logger stores values with a time stamp and shows the course afterwards. The standard for recorders, EN 12830, applies according to its public scope to the whole recording system including external sensors and sets requirements for the placement of the sensor per use situation. For a shipment, that last point is the crux: a sensor against a cooling element reads colder than the product, a sensor near the lid reads the air that has just come in. That is why the GDP guidelines say that cooling elements must not touch the product. What a measurement says therefore depends on where the measurement was taken.

Every instrument has an accuracy and a resolution, stated by the manufacturer and tested to the device standard. That specification answers one question: how well does this instrument measure? The product specification answers another: what does this product need, 2 to 8 °C, or below 25 °C? Both are needed and they do not replace one another. A reading close to a limit, taken with an instrument of generous inaccuracy, says nothing about whether the product stayed within the condition; then margin is needed, or a better instrument. Which classes and tolerances the standards use is in the texts of the standards themselves and is not reproduced here.

A measured value can only be compared with others if the instrument is traceable: calibrated against a reference by a laboratory competent to do so, and periodically verified between two calibrations. That is the chain behind a single figure in a report. Anyone assessing a report can therefore ask three things: which instrument was used and how it can be identified, when it was last calibrated or verified and against what, and where the sensor was during the measurement.

That also makes the limits of measurement data clear. A measurement at pickup and delivery is a snapshot in one place; it shows the start and the end, not the course. A logger shows the course, but at the position of its sensor, and usually the air in the packaging, not the core of the product. Neither replaces the validation of a packaging, and neither is a release: a value within the condition is a fact that the owner of the product assesses. What a carrier can say about its own equipment depends on what it can show: a calibration certificate or a verification record, with a date.

If a medicine carries no storage condition, that does not mean, according to the European inspectors, that temperature does not matter: during storage and transport, conditions appropriate to the European climate must then be maintained and monitored. The IGJ translates that to 15 to 25 °C, representative of room temperature. Products that belong in the refrigerator or freezer form the cold chain: according to the IGJ 2 to 8 °C or below -20 °C. Which condition applies and where it comes from is explained in temperature-controlled transport; how medicines move through the chain in medicine transport; what should happen in the event of an excursion in temperature excursion during transport.

In practice a usable report comes down to the following data, per shipment. The most important feature is not a field but an attitude: what was not measured appears as 'not measured', not as 'in order'. A report that colours every ride green is not proof but a promise.

• The shipment: client, ride number, what was transported.
• The agreed condition and where it comes from: label, manufacturer or the client's instruction.
• The measurement moments with time: pickup, delivery and any intermediate measurements or the logger trace.
• The measured values, and with which instrument.
• Who measured.
• Deviations, with what was done and to whom they were reported.
• The client's decision on a shipment with a deviation.

UrgentX measures the temperature at pickup and at delivery and records the value with the time and the driver's name. No data logger travels with the shipment; anyone who needs the course during the ride agrees that in advance. If no measurement was taken at a stop, the file says 'not recorded'; we never show 'in order' without a measurement. In the event of an excursion we report immediately to your contact person and do not deliver without your release; the excursion is recorded in the file of the ride, which you see in the portal. How that works for refrigerated and conditioned transport is described under refrigerated medical transport, and for specimens under transport of laboratory samples.