Novel Method for Reducing Temperature of i-STAT1 Analyzer in Extreme Environments

A fit-looking 23-year-old male participant in a summer mountain trail run collapses 3 km from the end of the 25 km race. Despite the altitude, ambient temperatures are warm, and the participants have been exposed to the full sun for several hours. On your first assessment, he is very confused, with a weak, rapid pulse (160 beats per minute). His skin is wet and cool. A passing member of the same running club alleges that he is not known to have any medical conditions. You notice that his water bottles are both empty. As fellow runners help you carry him to the nearby medical-aid station, a rapidly expanding differential diagnosis fills your thoughts. BackgroundWilderness heat-related illnesses span a continuum of medical problems caused by the generation of, and/or exposure to, excessive heat in the wilderness environment. They can range from minor annoyances to life-threatening conditions. Endogenous heat production is directly dependent on the sum of that from inescapable sources, such as basal cellular metabolism and cardiorespiratory work, and heat generated by physical exertion. All heat exchange (gain or loss) occurs through four mechanisms: conduction, convection, radiation and evaporation. Conduction refers to the direct transfer of heat from one object to another through contact. Convection is heat gain or loss due to movement of a fluid (such as air); a convection oven or wind chill from an Antarctic breeze are similar examples. Radiation describes transfer of heat through electromagnetic waves, epitomised by the heat of the sun on skin. Evaporation is the loss of heat induced by the phase change from liquid to gas, which is dramatically affected by ambient vapour pressure or relative humidity.Many animals have developed ingenious strategies to adapt their physiology to control heat gain or loss. Indeed, it is hypothesised that particular human traits -our upright stance, complex bony structure of the foot, nuchal ligament, relatively hairless skin and copious capacity for perspiration -evolved to give us an advantage in chasing down prey in the prehistorical African heat.[1] Today, however, humans are unique in their ability to adapt the environment to control their physiology through behaviour and material means: use of clothing, shelter, and devices such as heaters and air conditioners. Despite this, we cannot alter the laws of thermodynamics, and people in the wilderness are subject to the same exposure and thermal exchange mechanisms as our primitive ancestors. Fortunately, the development of modern science, clothing technology, and an understanding of physiology allow us to function successfully in environments of extreme heat under many adverse circumstances (Fig. 1).Risk factors traditionally considered to increase our susceptibility to the deleterious effects of heat stress include obesity, lack of acclimatisation to hot environments, poor physical fitness, extremes of age, underlying illness (e.g. cardiac conditions, hyperthyroidism), dehydration, certain medications (e.g. beta blockers, anti...

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“…16 -30°C for the i-STAT [14] ), and the device may have to be kept cool in the field to guarantee function when required. [15] …”

Section: Field Managementmentioning

confidence: 99%

Heat-related illness in the African wilderness

Hofmeyr

Dalton

2017

S Afr Med J

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“…POC BD testing is available, with good correlation with lab tests 100 101. Nevertheless, as other POC testing, such devices cannot work in extreme temperatures 102 103. Outside the required temperature range of 16–30°C, the unit ceases to operate and displays a message indicating the unit’ s temperature is out of range.…”

Section: Protocol Proposalmentioning

confidence: 99%

Tactical damage control resuscitation in austere military environments

Daniel¹,

Habas²,

Malan³

et al. 2016

J R Army Med Corps

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In tactical situations, in association with haemostatic procedures (tourniquet, suture, etc), tranexamic acid should be the first medication used according to the current guidelines. The use of fibrinogen concentrate should also be considered for patients in haemorrhagic shock, especially if point-of-care (POC) testing of haemostasis or shock severity is available. If POC evaluation is not available, it seems reasonable to still administer this treatment after clinical assessment, particularly if the evacuation is delayed. In this situation, lyophilised plasma may also be given as a resuscitation fluid while respecting permissive hypotension. Whole blood transfusion in the field deserves special attention. In addition to the aforementioned treatments, if the field care is prolonged, whole blood transfusion must be considered if it does not delay the evacuation.

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“…As these events typically occur throughout the night in diverse and often challenging conditions, such improvisation may be necessary to ensure that diagnostic equipment is functional. Like the recently reported cooling of i-STAT analyzers, 3 these techniques described may lead to malfunction of the equipment. And although further testing is required before applying these methods to increase the temperature of an i-STAT analyzer and cartridges in cold temperatures to patient care, the alternative may be to have no diagnostic testing equipment at all.…”

mentioning

confidence: 99%