Thermography and Thermoregulation: Do you have cold hands?

Thermography and Thermoregulation: Do you have cold hands?

21/03/2022 By: Ismael Fernández Home

We bring today what we should properly call a “cold” topic. Probably, you or someone you know suffer in some conditions (no need to be extreme cold ones) from cold hands or feet. Norheim and collaborators (2018) showed us that 28% from their sample was unable to recover baseline temperatures of their hands after putting them 1 minute in cold water (20ºC). We explain you why not everyone is showing the same “rewarming” capacity and how thermography can help us to better understand our thermoregulation and pathologies related to it.

Cold injuries are an important issue for people/professionals which are significantly exposed to extreme cold conditions. This is the main reason why Norheim and collaborators (2018) drove a study on the incidence of cold injuries among soldiers in Norway, which has been reported to be around 2% per year (Ervasti et al., 2004).

Besides the most severe cold injuries (Long III et al., 2005) (frostbite, chilblains, foot immersion syndrome, hypothermia or even Raynaud’s disease) there is no need to be a soldier in order to have suffered some of the consequences of being exposed to cold conditions. Regardless of the severity, those issues are mainly related to the blood circulation, which is easily seen using infrared thermography. Therefore Norheim and his colleagues (2018) decided to use thermal imaging to test soldiers and confirm their potential likelihood to suffer cold injuries.

255 soldiers analysed using thermography

Norheim et al. (2018) assessed 260 army conscripts from 2 cohorts: summer (122) and winter (138). All of them underwent the same protocol: they were evaluated using infrared thermography before a mild cold provocation test (hands immersed in 20°C water for 1 minute). Then, soldiers were also assessed immediately after the test and 1, 2, 3 and 4 minutes after the cold exposure. The main aim of this study was to investigate the variability in the ability of skin rewarming of the hands and fingers.

cold water hands
Figure 1. Description of the three main groups identified after mild cold provocation test (adapted from Norheim et al., 2018)

As we can see in figure 1, the results made it possible to distinguish between slow, intermediate and rapid rewarmers after cold provocation test. The majority of them (72%) showed a rapid recovery. However, the intermediate (18%) and slow (10%) rewarmers were unable to recover within 4 minutes to the skin temperature values before the provocation test. The authors focused on the slow group (10%) because they might have a higher likelihood of suffering a frostbite in accordance with another study performed with the Sweedish army (Brändström et al., 2008).

28% of the sample was unable to recover the baseline temperature of their hands within 4 minutes

Norheim et al., 2018

Interestingly, the authors also showed that smokers and users of smokeless tobacco (snuss) belonged to the group of rapid rewarmers, theoretically due to the effect of nicotine (Yun et al., 2005).

In addition to that, Norheim et al (2018) also described that the slow rewarmer group showed significant decreased temperatures before the cold test, which could also be a good indicator of the inability of tolerating cold exposure (see figure 2).

Figure 2. Representation of the hand skin temperature evolution before and after mild cold exposure test of the three groups: rapid (black), intermediate (blue) and slow (green) rewarmers (adapted from Norheim et al., 2018)

Dynamic Thermography

The method used in the publication of Norheim and collaborators (2018) might be described as Dynamic Thermography. It is a very interesting approach to control the external influence factors (using cold water, for instance) and observing the rewarming patterns after the test (as shown in figure 3). In that way, the changes in the skin temperature we observe are certainly coming from the inner factors (vascular, muscles, etc.), which actually are the most interesting ones when we are analysing the thermoregulation and physiology.

dynamic thermography protocol with a football player
Figure 3. Representation of a dynamic thermography protocol with a football player before and after cold water immersion (ThermoHuman)

Thermography applications

As we have already seen thanks to the Lahiri et al (2012) publication, vascular disorders or connective tissue diseases are assessed and even diagnosed using infrared thermography. As Norheim et al (2018) mentioned, the slow rewarmers (10%) might have a higher probability of suffering cold injuries or even Raynaud’s disease. This is a medical condition in which the spasm of small arteries causes episodes of reduced blood flow to end arterioles. Typically, the fingers, and less commonly, the toes, are involved. As we can see in the figure 4, the differences in feet or hands after cold exposure and their skin temperature gradient are totally different if compared to a healthy subject.

cold hands and feet thermography
Figure 4. Thermal images from a Raynaud’s disease patient and a healthy one after cold exposure (on the left side) and the gradient skin temperature description comparison from hand and feet described by Ramirez-GraciaLuna et al. (2022) -right side-

Conclusion

A significant part of the population (28%) might be not able to recover the temperature of their extremities after a cold exposure, which increase the likelihood of suffering cold injuries. This is extremely important for people/professionals that are forced to be exposed to extreme cold conditions. Dynamic thermography assessment seems to be a good technology to assess this predisposition to suffer such inability. The question is: which group do you belong to, rapid, intermediate or slow rewarmer one?


References


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Europa Thermohuman ThermoHuman has had the support of the Funds of the European Union and the Community of Madrid through the Operational Programme on Youth Employment. Likewise, ThermoHuman within the framework of the Export Initiation Program of ICEX NEXT, had the support of ICEX and the co-financing of the European Regional Development Fund (ERDF).

CDTI Thermohuman has received funding from the Centre for the Development of Industrial Technology (CDTI), in participation with the European Regional Development Fund (ERDF), for the R+D activities involved in creating a new tool, based on thermography, for the prediction and prevention of rheumatoid arthritis. See project detail.