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Web-based Hypothermia Information: A Critical Assessment of Internet Resources and a
Comparison to Peer-reviewed Literature
Jeremy M. Spencer, M.S., Department of Geosciences, The University of Akron; Department of
Geography, Kent State University
Scott C. Sheridan, PhD, Department of Geography, Kent State University
Corresponding Author: Jeremy Spencer jspencer@uakron.edu)
Phone: 330-672-2394
This research was not supported by grants.
Part of this work was presented at the American Association of Geographers Joint East/West Lakes
Meeting at Northern Illinois University (DeKalb, IL, USA) on October 26th, 2012
Aims: Hypothermia is a medical condition characterized by a drop in core body temperature, and it
is a considerable source of winter weather-related vulnerability in mid/high latitude areas. Heat
vulnerability research, including assessments of internet-based resources, is more thoroughly
represented in the peer-reviewed literature than cold-related vulnerability research. This study was
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undertaken to summarize available web-based hypothermia information, and then determine its
scientific validity compared to the peer-reviewed literature.
Methods: This research takes a similar approach used by Hajat et al (Hajat, O'Connor, & Kosatky,
2010) for web-based heat vulnerability research, and utilizes this framework to assess hypothermia
information found on the internet. Hypothermia-related search terms were used to obtain websites
containing hypothermia information, and PubMed (medical literature search engine) and Google
Scholar were used to identify peer-reviewed hypothermia literature. The internet information was
aggregated into categories (vulnerable populations, symptoms, prevention), which were then
compared to the hypothermia literature to determine the scientific validity of the web-based
guidance. The internet information was assigned a Strength of Recommendation Taxonomy grade
(SORT, developed by the American Academy of Family Practitioners) of A, B, or C based on the peer-
reviewed evidence.
Overall, 25 different pieces of guidance within the three categories were identified on 49 websites.
Guidance concerning hypothermia symptoms most frequently appeared on websites, with six
symptoms appearing on 50% or greater of websites. No piece of guidance within the vulnerable
population categories appeared on greater than 60% of the websites, and prevention-related
guidance was characterized by varied SORT grades.
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Conclusions: Overall, hypothermia information on the internet was not entirely congruent with the
information within the peer-reviewed medical literature. Several suggestions for improving web-
based hypothermia resources include clearly listing sources for users to see, and eliminating
guidance with lower SORT grades and replacing with evidence-based information.
Keywords: Hypothermia, Wilderness Medicine, Cold Exposure
I. Introduction
Hypothermia is a drop in core body temperature below 35°C caused by exposure to cold
air or immersion in cold water, or from thermoregulation inefficiencies attributable to senescence
or underlying illness (Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006; Epstein & Kiran, 2006;
Mulcahy & Watts, 2009; Ballester & Harchelroad, 1999). Prominent hypothermia symptoms
include shivering, cardiovascular irregularities, and a reduction in mental and physical capabilities
(Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006; Epstein & Kiran, 2006; Connolly & Worthley,
2000; Mulcahy & Watts, 2009; Turk, 2010). Hypothermia progresses through three stages: mild,
moderate, and severe (Table 1). Hypothermia is a significant cause of winter season morbidity and
mortality in middle and high latitude regions (Rango, Exposure-Related Hypothermia Mortality in
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the United States, 1970-1979, 1984; Herity, Daly, Bourke, & Horgan, 1991; Tanaka & Tokudome,
1991; Dixon, et al., 2005; Thacker, Lee, Sabogal, & Anderson, 2008).
There is much hypothermia-related information on the internet, but its scientific validity
has not been assessed. This research took a similar approach to a heat vulnerability review
conducted by (Hajat, O'Connor, & Kosatky, 2010) and analyzed the content of web pages
containing hypothermia-related information. Websites were identified using Google searches and
were reviewed for suitability. The guidance within the websites was aggregated into categories
(vulnerable populations, symptoms, prevention), and the percent of websites that contained
each piece of guidance was calculated. The guidance was then compared to peer-reviewed
hypothermia literature to determine its scientific validity. It should be noted that this study
exclusively assessed direct cold exposure hypothermia, and it did not analyze excess cold
morbidity and mortality-related ailments such as cardiovascular disease.
This research is important for a number of reasons. As hypothermia is a considerable
source of winter time morbidity and mortality, it is imperative that the best information be
available to internet users. Also, medical practitioners can use this research to guide their patients
to additional information that is scientifically sound. Hypothermia guidance sections on websites
can be redeveloped to more accurately reflect the peer-reviewed literature, allowing users to
better prevent hypothermia morbidity and mortality. Evidence-based symptom information will
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allow users to better identify hypothermia in others. Additionally, weather forecast offices that
regularly issue warnings for dangerous cold can include links to websites with valid hypothermia
information to those living within their forecast area.
II. Methods
A search strategy and website selection criteria were applied in a manner similar to Hajat
et al (Hajat, O'Connor, & Kosatky, 2010). The Google search engine was used to search for
websites with hypothermia-related information using several search terms, which were:
“hypothermia”, “hypothermia treatment”, and “hypothermia and public health department”.
Preliminary research using Google Trends indicated these terms were commonly used to search
for hypothermia information. Also, we were trying to emulate the search pattern used by lay
people when searching for hypothermia information. The first ten pages of results were searched
for usable websites; typically, after five pages many repeat results were returned. The redundancy
of the results makes the list of websites robust, so that it accounts for variability in search results.
Several exclusionary criteria were applied to eliminate websites with potentially biased or
unusable information. The first criterion was that the website could not be an advertisement. As
many websites were company web pages dedicated to selling hypothermia prevention products,
with guidance centered on the use of the advertised product, these sites were eliminated from
analysis. The second exclusionary criterion was that the website not be video-centric, such as
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YouTube; many results on these websites were not related to medical hypothermia. The third
criterion was PDF and text document results had to have an associated web page; those not
associated with an active website or broken web links were not assessed because it was
impossible to determine document authorship. The last exclusionary criterion was simply
eliminating results that contained no information relevant to hypothermia. Of 139 websites
identified, 49 met all inclusion criteria (Table 2), and several types of websites were identified in
this process. Popular (n=14) websites were associated with a variety of institutions and wrote
about hypothermia in simpler, less formal terms and were tailored for broader audiences.
Medical (22) websites were associated with medical institutions and public health departments,
and featured more technical discussions on hypothermia. Outdoors (11) websites were written
for audiences engaged in outdoor activities such as hunting, fishing, and hiking, and strongly
focused on preventing hypothermia. Special group (2) websites did not fit into the previous
categories and presented hypothermia information to specialized audiences. The hypothermia
information within the websites was placed into one of the following categories:
Populations of increased hypothermia vulnerability (Vulnerable Populations)
Symptoms of hypothermia (Symptoms)
Hypothermia risk mitigation measures (Prevention)
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The information was coded so the guidance could be tallied, and then the percentage of
websites including the information was calculated. Initially, there were categories for causes and
treatments. The cause category was eliminated because it dealt with the medical definition of
hypothermia, and most websites did not elaborate more than “hypothermia is caused by cold
exposure”. The treatment category was eliminated because of a paucity of peer-reviewed
literature concerning the efficacy of hypothermia field treatment methods, such as use of
blankets, drinking warm liquids, and other hypothermia management methods.
The hypothermia literature was reviewed to determine the stated guidance’s scientific
validity. PubMed, a search engine for medical literature, and Google Scholar were searched for
hypothermia articles using various search terms (Table 3). A larger number of search terms were
utilized here compared to the Google searches so medical articles directly addressing the website
guidance could be identified. Articles were reviewed for suitability, with a total of 58 peer-
reviewed papers identified during this process (Table 4).
The website guidance was then graded using the Strength of Recommendation Taxonomy
(SORT), a criteria scale developed by the American Academy of Family Practitioners. These grades
rated the website guidance’s congruence to the peer-reviewed literature. This ranking method
was employed on a position statement issued by the American College of Sports Medicine in a
report on cold weather injury and exercise (Castellani, et al., 2006; Ebell, et al., 2004). This scale
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utilizes grade rankings of A, B, and C to evaluate the scientific validity of the guidance. An A grade
indicates that the guidance is based on consistent and good patient-based scientific evidence. A B
grade indicates there is some scientific evidence, but it is of limited quantity and lower quality. A
rank of a C indicates that evidence is based on consensus, opinion, or usual practice.
III. Results
Overall, 25 facets of hypothermia guidance from the three categories of web-based
hypothermia information were assessed (Table 5). There are four categories of SORT grades
included in the table: Science, Epidemiology, Usefulness, and Usability. The Science grade reflects
the medical and physiological evidence for a specific piece of guidance. The Epidemiology
category refers to the evidence regarding the vulnerability of specific populations to hypothermia,
and is only applicable to the vulnerable populations category. The Usability grade assesses how
well a specific symptom indicates the presence of hypothermia, while the Usefulness grade
evaluates how early in the course of hypothermia the symptom occurs. The effects of
hypothermia are less reversible later in the course of hypothermia, and symptoms that occur later
are accordingly graded lower.
A. Vulnerable Populations
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For vulnerable populations, two SORT grades are provided: one assessing the medical
evidence and the other assessing epidemiological evidence. The most frequently listed vulnerable
population was the elderly (Science and Epidemiology SORT grade of A), who appeared on 59% of
the websites assessed. Several factors contribute to the high level of elderly hypothermia
vulnerability. First, the cold response mechanism becomes less efficient with age (Ranhoff, 2000;
Mulcahy & Watts, 2009; Pedley, Patterson, & Morrison, 2002). Second, actual temperature
sensation of the cold becomes blunted as people age (Ballester & Harchelroad, 1999; Mallet, 2002;
Dharmarajan & Wijidada, 2007). Therefore, ambient conditions are not perceived to be as cold.
Additionally, many elderly have a smaller BMI than middle-aged adults. Smaller bodies lose
radiative heat more quickly than larger bodies, and many elderly have less subcutaneous fat
providing insulation against the cold because of malnutrition (Dharmarajan & Wijidada, 2007).
However, a study by DeGroot et al (DeGroot, Havenith, & Kenney, 2006) found weak evidence for
body fat as a predictor of elderly hypothermia. Age-related mental decline also contributes to
their vulnerability (Dharmarajan & Wijidada, 2007). Epidemiological data demonstrate that the
elderly have higher rates of both morbidity and mortality compared to other age groups (Rango,
Exposure-Related Hypothermia Mortality in the United States, 1970-1979, 1984; Herity, Daly,
Bourke, & Horgan, 1991; Thacker, Lee, Sabogal, & Anderson, 2008; Rango, The Social Epidemiology
of Accidental Hypothermia Among the Aged, 1985; Taylor & McGwin, 2000). Additionally, there is
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the social confounder of isolated living that contributes to their vulnerability (Dharmarajan &
Wijidada, 2007).
Small children (A, C) were listed as a vulnerable population on 47% of the websites. Small
children and infants can lose much heat to the surrounding environment because of high surface
area relative to their overall mass, which hypothetically increases their hypothermia vulnerability
(Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006; Beim, Koehnke, Classan, & Dosman, 2003).
However, epidemiological evidence suggests that this age group is less vulnerable to hypothermia,
with low overall death rates compared to older age groups (Rango, Exposure-Related Hypothermia
Mortality in the United States, 1970-1979, 1984; Taylor A. , et al., 2001; Thacker, Lee, Sabogal, &
Anderson, 2008). Baumgartner et al (Baumgartner, Belson, Rubin, & Patel, 2008) conducted an
analysis of hypothermia morbidity from a small sample of U.S. hospital data, and found that
persons under the age of 15 were approximately 5% of the sample.
Alcohol abusers (A, A) were listed as a vulnerable group on one-third of the websites
analyzed. Ethanol acts as a vasodilator that counteracts the body's vasoconstriction reaction to
cold (Mulcahy & Watts, 2009; Epstein & Kiran, 2006; Kalant & Le, 1984; Teresiski, Buscewicz, &
Madro, 2004). Ethanol can also have a muscle-relaxing effect that hinders shivering
thermogenesis (Kalant & Le, 1984; Huttunen, 1990; Teresiski, Buscewicz, & Madro, 2004; Nixdorff-
Miller, Hunsaker, & Hunsaker III, 2006). Additionally, intoxication can act to inhibit shelter-seeking
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behavior (Mulcahy & Watts, 2009; Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006). Several
retrospective studies have indicated alcoholics have an increased risk for hypothermia morbidity
and mortality (Herity, Daly, Bourke, & Horgan, 1991; Taylor & McGwin, 2000; Kempainen &
Brunette, 2004; Turk, 2010; Gallaher, Fleming, Berger, & Sewel, 1992; Hislop, et al., 1995; Roeggla,
et al., 2001).
Twenty-seven percent of websites stated underlying medical conditions (A, B), or taking
medicine for medical issues, increased an individual’s susceptibility hypothermia. There are many
medical conditions that can potentially increase one’s hypothermia risk (Ballester & Harchelroad,
1999; Kempainen & Brunette, 2004; Brändström, 2012). However, diabetes particularly blunts the
cold response through decreased cold sensation (Kempainen & Brunette, 2004). While many of
the deaths contained in data sets list underlying causes of death, it is not easy to obtain
information about the victim’s medication. Therefore, epidemiologic knowledge of hypothermia
and medical conditions is incomplete.
Approximately one-quarter of the websites investigated stated the homeless (C, B) are
susceptible to hypothermia, as they are dangerously exposed to cold temperatures. Research
suggests that sustained cold exposure can lead to diminished cold response (Castellani, et al.,
2006; Young & Castellani, Exertional Fatigue and Cold Exposure: Mechanisms of Hiker's
Hypothermia, 2007); while it is plausible that the cold response can become blunted in the
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homeless, no studies directly address this. There are also significant confounders with substance
abuse, malnutrition, and mental illness in this population (Fazel, Khosla, Doll, & Geddes, 2008).
Epidemiological data are difficult to obtain for the homeless; however, Hwang (Hwang, 2001)
found that homeless shelter users in Toronto were sometimes afflicted with cold weather
ailments. Homeless hypothermia decedents are sometimes found outdoors with high blood
alcohol concentrations (Tanaka & Tokudome, 1991; Taylor & McGwin, 2000; Roeggla, et al., 2001).
People who spend time outdoors (hikers and workers who willingly spend time outdoors,
distinct from homeless) (A, B) were also listed as vulnerable to hypothermia (24%). The cold
response follows a different course in this population. Initially, core temperature increases with
heavy exertion, compensating for increased heat loss potential due to vasodilatation. However,
when the individual rests, core temperature stops increasing and the cold response does not
immediately begin, which rapidly sends the victim to hypothermia through evaporative cooling
(Ainslee & Riley, 2003; Young & Castellani, Exertional Fatigue and Cold Exposure: Mechanisms of
Hiker's Hypothermia, 2007). Two studies (Taylor A. , et al., 2001; Taylor & McGwin, 2000)
indicated outdoor workers had higher rates of fatalities compared to the average population.
However, their studies had small sample sizes and were geographically limited in scope (Jefferson
County, Alabama). These two studies did not examine hypothermia morbidity.
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Mental illness (C, B) was purported to increase hypothermia vulnerability on 16% of
websites. While mental illnesses do not impact the cold response itself, people with these
conditions incorrectly perceive danger levels, and do not implement behavioral changes to reduce
hypothermia risk. Lack of behavior changes to a stressor does not constitute medical vulnerability.
Additionally, this information is not listed on death certificates and official counts of hypothermia
deaths of mentally-ill people are difficult to obtain. Storm Data is the official source for storm-
related losses in the US, and it contains information on hypothermia-related deaths. While this
publication is known for undercounting storm-related deaths, some hypothermia deaths in this
database contained text describing the context in which the fatality occurred. Some descriptions
mentioned the victim had mental illness and had gone into cold ambient conditions (Spencer,
2009). Overall, few epidemiological data demonstrate the hypothermia vulnerability of the
mentally-ill.
Malnourishment is described in prevention as food and hydration-related guidance (A, C).
No studies have examined the relationship between hypothermia fatalities and nutrition status as
reported on death certificates (Galloway & Maughan, 1998; Galloway, Wooton, Murphy, &
Maughan, 2001; Castellani, et al., 2006).
B. Symptoms
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Overall, hypothermia symptoms were listed on a higher percentage of websites than the
other categories; six of the ten symptoms were identified on 50% or more of the websites.
Symptoms have a three-part SORT taxonomy that gauges several aspects of the guidance. First,
the scientific evidence is assessed to determine if the symptom occurs when the victim becomes
hypothermic. The second part of the SORT grade is a usability ranking, or how easy it would be to
use this symptom as a specific indicator of hypothermia. The last part of the SORT grade is a
usefulness rating; i.e., does this symptom occur in the early stages of hypothermia, or does this
occur when the effects of hypothermia are irreversible?
Shivering (Science SORT grade of A, Usability SORT A, Usefulness SORT A) tied with mental
impairment as the most commonly listed symptom on websites (80%). One of the first stages of
the cold response, rapid muscle contractions are capable of raising core body temperature by
nearly 2°C per hour with adequate energy intake (Mallet, 2002; Epstein & Kiran, 2006; Mulcahy &
Watts, 2009). Overall, identifying shivering does not take advanced medical knowledge, and this
symptom is also specific to hypothermia. Shivering occurs early during hypothermia (it stops as
hypothermia becomes more severe) when the effects are largely reversible (Connolly & Worthley,
2000; Mallet, 2002; Ulrich & Rathlev, 2004).
Mental impairment (A, B, B) was also listed on 80% of websites. Successive decreases in
core body temperature overwhelm the cold response and (Poszos & Danzl, 2001). As brain
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temperature decreases, electrical activity begins to slow down due to impaired conduction
(Lansdowne & Scruggs, 1976; Poszos & Danzl, 2001; Mallet, 2002). This has a cascading effect on
brain function- first conscious thought is affected, followed by systems that are not under
conscious control (breathing, heart rate, etc), leading to a wide range of symptoms. Because a
wide range of impacts are involved, mental impairment could be a non-specific symptom based on
context, especially if those involved are not outdoors people or if the ambient conditions are not
perceived to be dangerous . As a wide variety of conditions cause mental impairment, it is not a
clear indicator of hypothermia.
Physical coordination (A, B, B) similarly declines as core temperature decreases, and this
was given as a hypothermia symptom on 76% of websites. This is related to the loss of higher
mental function and the brain’s ability to conduct electrical signals (Poszos & Danzl, 2001). As
higher thought is reduced, the ability to coordinate one's movements decreases and
vasoconstriction reduces blood flow to the extremities. There are other ailments that might cause
a rapid loss of coordination; however, in the absence of mentally-impairing substances, this is a
reasonable indicator of hypothermia. Physical coordination issues can occur from mild to
moderate hypothermia so has limited usefulness (Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006;
Connolly & Worthley, 2000).
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Incoherence (A, B, B), or the inability to communicate thoughts clearly, was listed as a
hypothermia symptom on approximately 60% of the websites. As brain and core temperature
drop, neurons have reduced ability to conduct electricity, with a concurrent loss in conscious
thought that also reduces the ability to communicate clearly (Epstein & Kiran, 2006; Mallet, 2002;
Poszos & Danzl, 2001). While this can indicate the presence of other ailments, the ability to
communicate is also linked to body language and behavior. Early on in hypothermia, behavioral
changes render the victims withdrawn and difficult to communicate with, so it is a reasonable
early indicator of hypothermia (Poszos & Danzl, 2001). If all other factors are known to be equal
(victim is with acquaintances who know the personality of the victim, and it is known no drinking is
involved), this can be a clear indicator of hypothermia. However, it can occur in the moderate
hypothermia stage, so its usefulness is limited (Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006).
Cardio-respiratory problems (A, B, B) were mentioned on 53% of websites. There are
many different manifestations of cardiovascular problems of hypothermia. In the initial stages of
hypothermia, the heart rate and breathing speed up; as hypothermia becomes more severe, the
heart rate begins to slow down, sometimes becoming almost undetectable (Mallet, 2002; Mulcahy
& Watts, 2009; Mustafa, Shaikh, Gowda, & Khan, 2005). Later stages of hypothermia are
associated with electrolyte imbalance; in severe hypothermia the heart can stop completely
(Poszos & Danzl, 2001; Mallet, 2002; Aslam, Aslam, Vasavada, & Khan, 2006; Mulcahy & Watts,
2009). While pulse changes could be detected, heart irregularities are more difficult to judge.
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Also, in the absence of other symptoms, pulse changes would be insufficient for a field diagnosis of
hypothermia. Heart rate changes are well-defined by stage of hypothermia, so they are a strong
indicator of hypothermia severity to knowledgeable people. However, for most of the population,
it is of limited usefulness for determining the presence of hypothermia.
Reduced energy (A, B, C) was listed on 50% of websites. Experiments performed by Young
et al (1998) demonstrated that after long-term exertion fatigue the cold response becomes
compromised. Hypothermia victims have reduced energy levels as hypothermia progresses
(Poszos & Danzl, 2001). However, reduced energy or constant fatigue is an underlying symptom in
a number of ailments (e.g., Cancer, Ischemia, Multiple Sclerosis), limiting its usability in identifying
hypothermia (Stone, Richards, & Hardy, 1998; Murthy, Hargens, Lehman, & Rempel, 2001; Bakshi,
2003). Overall, its usability is limited because clear indications of reduced energy occur during
moderate and severe hypothermia (Poszos & Danzl, 2001) and other, more prominent symptoms
occur during mild hypothermia.
Other symptoms reported on websites include loss of consciousness (43%), pale/icy skin
(29%), and paradoxical undressing (8%). Loss of consciousness occurs in the later stages of
hypothermia (A, C, C) (Nixdorff-Miller, Hunsaker, & Hunsaker III, 2006; Poszos & Danzl, 2001);
however, this symptom is a non-specific diagnostic tool because many other ailments are
associated with unconsciousness, and it occurs when the victim’s survival is less likely. Pale/icy
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skin (A, B, B), or pallor, refers to the loss of skin color that can occur during hypothermia. This can
be concurrent with frostbite and occurs because of reduced blood flow to the extremities and the
top layer of skin, making the skin cold to the touch (Poszos & Danzl, 2001; Ulrich & Rathlev, 2004).
This symptom can be indicative of other ailments, so is not hypothermia-specific. However, it can
occur in early stages of hypothermia, so it does have some diagnostic utility. Paradoxical
undressing (B, C, C) is when a victim removes their clothes in the late stages of hypothermia. It is
thought that warm blood flowing back to the extremities causes a strong heat sensation, which
compels the victim to take off their clothes. This has limited usability and usefulness because
paradoxical undressing occurs when the victim’s chances of survival are low.
C. Prevention
Similar to vulnerable populations, only some prevention guidance is mentioned on a high
percentage of websites. Approximately three-quarters of websites listed wear appropriate
clothing in layers (Science B) as a preventative measure, with 51% of websites also stating to cover
head/extremities (Science A). Significant heat loss occurs through the skin, and this mitigated by
wearing additional clothing (Young & Castellani, Exertion Induced Fatigue and Thermregulation in
the Cold, 2001; Kempainen & Brunette, 2004). Heat loss through the head deserves a special
explanation, as this specific guidance appeared on many websites. For many years, it was believed
that 50% of heat loss occurs through the head, based on flawed early research and a US Military
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manual (Froese & Burton, 1957; Vreeman & Carroll, 2008). Pretorius et al. (Pretorius, Bristow,
Steinman, & Giesbrecht, 2006) found that heat loss through the head is no greater than in other
parts of the body; uncovered areas lose a proportionally large amount of heat. It is difficult to
ascertain what “appropriate” clothing is, and there are a limited number of scientific studies
testing the efficacy of various clothing types. In an epidemiological study examining mountain
hikers, layered clothing that was alternately removed and added to as activity increased and
decreased was the best way to delay the onset of hypothermia (Ainslee & Riley, 2003; Young &
Castellani, Exertional Fatigue and Cold Exposure: Mechanisms of Hiker's Hypothermia, 2007). A
review of exercise practices in the cold demonstrated that a wind and waterproof outer layer, with
a moisture-wicking layer near the skin and a thicker, water absorbent middle layer, was a good
way to slow hypothermia onset while engaged in physical activity (Castellani, et al., 2006).
However, the authors also admitted that it was difficult to give concrete advice in regard to
clothing, as individual morphology, and fitness level, played some role in how well subjects
resisted the cold. In summary, wearing clothing is paramount to hypothermia prevention, but the
exact type of clothing varies based on individual factors. All areas of the body lose heat and need
to be covered.
Food and hydration-related guidance (A) appeared on 43% of websites. Increased food
intake is needed to fuel the body's cold response and its associated high basal metabolic rate.
Without increased energy intake, the body’s cold response becomes impaired; however, if
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properly clothed and not exercising for long periods, the body’s core temperature would be higher
than resting level and would require only supplementation from small snacks in addition to regular
meals (Galloway & Maughan, 1998; Galloway, Wooton, Murphy, & Maughan, 2001; Castellani, et
al., 2006). Dehydration (C) has no impact on the body's cold response (Castellani, et al., 2006).
No alcohol, smoking, or caffeine was offered as prevention guidance on 31% of websites.
The effects of alcohol (A) were analyzed in vulnerable populations under alcohol abusers. No
research specifically addressed the impacts of smoking (C) on hypothermia. Caffeine (C) has been
noted by several authors (Sterba, 1990; Irwin, 2002) as a beverage ingredient to avoid because of
its diuretic effects. However, as stated earlier, dehydration has no effect on the cold response
(Castellani, et al., 2006).
Stay dry/do not over-exert (A) was listed on 31% of websites. Water immersion can rapidly
cause hypothermia, as water conducts heat 25 times greater than an equivalent volume of air
(Turk, 2010). Moist ambient conditions can also contribute to core temperature drop through
evaporative cooling (Yamane, Oida, Onishi, Matsumoto, & Kitigawa, 2010). Exertion can result in
perspiration and fatigue, which can impact the cold response (see reduced energy and people who
spend time outdoors).
Avoid cold temperatures and high winds (A) were given as preventative guidance on 29%
of the websites assessed. During prolonged exposure to ambient cold temperatures the body
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loses more heat than it produces, and wind exposure lowers core temperature through
evaporative cooling (for perspiring individuals) or the wind creating convection near the skin,
which disrupts the stable warm air near the skin (Pugh, Accidental Hypothermia in Walkers,
Climbers, and Campers: Report to the Medical Commission on Accident Prevention, 1966; Pugh,
Cold Stress and Muscular Exercise, with Special Reference to Accidental Hypothermia, 1967; Young
& Castellani, Exertion Induced Fatigue and Thermregulation in the Cold, 2001; Yamane, Oida,
Onishi, Matsumoto, & Kitigawa, 2010). While not capable of cooling the body temperature
greatly, the concurrent risk of frostbite makes wind exposure a dangerous phenomenon
(Castellani, et al., 2006).
Not wearing cotton garments (C) was guidance given on 14% of websites. Some research
has attempted to determine the thermal properties of garments in different conditions.
Anecdotal evidence states that cotton is a poor insulator when wet, and that wool retains its
insulation properties. However, research by Holmer (Holmer, 1985) showed that wet wool
garments lost some of their thermal properties when wet, and that wet wool retained thermal
properties more than wet nylon garments. Navy diving experiments also demonstrated that wool
is a poor insulator when wet (Sterba, 1990). Wool has a high heat of sorption, so it is possible this
is perceived as increased warmth by the wearer (Stuart, Schneider, & Turner, 1989). Limited
research exists on cotton and its thermal properties when wet. A study by Bakkevig and Nielsen
(Bakkevig & Nielsen, 1994) showed that wet undergarments (cotton, wool, polypropylene, and a
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wool mix) significantly contributed to cooling; however, the thickness of the garment was more
important than the type of fabric in regards to heat retention. Richards et al (Richards, 2008) also
found that total evaporative heat loss was less for cotton compared to polyester and
polypropylene.
One website mentioned that it was useful to take time to acclimatize to the cold (C).
There are several physiologic mechanisms through which the human body acclimatizes to warm
temperatures; in comparison, the body’s adaptations to cold are much less robust and are difficult
to replicate in a laboratory setting (Castellani, et al., 2006). While some anecdotal evidence
suggests that people can adapt to cold temperatures, there is little scientific evidence that
suggests humans acclimatize to the cold.
IV. Discussion
This paper sought to synthesize available hypothermia information and guidance on the
internet and critically compare it to the peer-reviewed literature. This was done because
hypothermia information on the internet is widespread, and it has not been assessed for its
quality. Overall, 25 pieces of guidance on 49 websites were assessed.
Vulnerable populations were underemphasized on these websites. Additionally, it should
be noted that websites do not differentiate between morbidity and mortality for vulnerable
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populations. The elderly are highly vulnerable to hypothermia, but fewer than 60% of the
websites assessed mentioned this. Also, none of the websites identified listed minorities as
vulnerable populations. In the U.S. in particular, ethnic minority groups such as African Americans
and Hispanics have higher rates of hypothermia deaths than do whites (Thacker, Lee, Sabogal, &
Anderson, 2008). While a review of cold-induced finger vasodilatation demonstrated that blacks
had the smallest response (Daanen, 2003), the primary driver of this vulnerability is socio-
economic disparities (Rango, Exposure-Related Hypothermia Mortality in the United States, 1970-
1979, 1984; Thacker, Lee, Sabogal, & Anderson, 2008).
A considerable portion of the websites focused on stating the symptoms of hypothermia,
and comprehensively listed those that could be identified in the field. Shivering, along with
mental and physical impairment, were stated as hypothermia symptoms on at least three-quarters
of the websites utilized. However, loss of consciousness was stated on 43% of the websites as an
important symptom; this symptom is non-specific to hypothermia and is of limited utility for most
webpage readers.
Prevention guidance reflected widely varied SORT grades; wearing appropriate clothing in
layers was the most frequently stated guidance (76%). While there is a scientific basis to this
advice, it is difficult to give concrete guidance in this regard because individual variation impacts
cold vulnerability. Nearly one-third of the websites stated that consuming caffeine had a negative
24
impact on the cold response, when in fact the diuretic action of this substance has no appreciable
impact on the cold response. In some instances, some guidance based on solid science was not
emphasized enough on these websites. For instance, staying dry and not over-exerting was listed
on 31% of websites. Staying dry prevents evaporative cooling and not over-exerting allows more
of the body’s energy reserves to be used for the cold response.
V. Conclusion
An internet search was conducted to obtain websites with hypothermia guidance, and
then compare them to peer-reviewed literature to determine their scientific validity. A total of 49
websites were analyzed and compared to 58 peer-reviewed articles. While some symptoms were
listed on a high percentage of websites, most other guidance was listed on a smaller percentage of
websites. Several populations were highly vulnerable to hypothermia, but these groups were not
listed on a considerable percentage of websites.
While much of the guidance is based on some research, it was oftentimes not easy to
determine where a website got its information from. The authors suggest that not only do
websites list information sources, but guidance associated with low SORT grades be eliminated.
Additionally, increased mention of vulnerable populations will help users identify people around
them who might be potentially at risk. These suggestions should make web-based hypothermia
information more scientifically sound.
25
Acknowledgements
The authors wish to thank Dr. Thomas Schmidlin and Dr. Lynette Phillips for their
comments on earlier versions of this manuscript. Their insights were valuable and greatly
improved the content and readability of the manuscript. We would also like to thank the
reviewers for their careful review of the manuscript.
This work was not supported by grants, and the authors declare no conflicts of interest.
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32
Table 1. The three stages of hypothermia and the associated ranges in core body temperature, as
well as the symptoms for each stage.
Stage
Core Body Temperature
Symptoms
Mild Hypothermia
35°-33°
Shivering; poor judgment
develops; amnesia and
apathy; increased heart rate;
increased breathing; cold or
pale skin
Moderate Hypothermia
32.9°-27°
Progressively decreasing
levels of consciousness and
stupor; shivering stops;
decreased heart rate and
breathing; decreased reflexes
and no voluntary motion;
paradoxical undressing
Severe Hypothermia
<26.9°
Low blood pressure and
bradycardia; no reflexes; loss
of consciousness; coma; death
Table 2. A list of the 49 websites utilized in this research, including the name of the website, its
web address, and the website’s general category. The medical category represents websites for
medical institutions and public health departments that have more technical discussions on
hypothermia; the popular category is for websites that feature general information on
hypothermia, with a writing style meant to reach a wider audience; outdoors websites were those
with hypothermia information tailored to those engaged in pursuing outdoor recreational
activities, such as hiking; special groups websites were tailored to groups who did not fit into any
of the previous categories (one website was tailored toward military applications, and one website
was written for elderly viewers).
Website
Web Address
Type of
Website
33
AARP Below
Normal Body
Temp
http://healthtools.aarp.org/galecontent/hypothermia/1
Special
Group
About.com
(Marine)
http://maritime.about.com/od/Safety/a/Hypothermia-Prevention-
And-Treatment.htm
Popular
About.com
(Sports
Medicine)
http://sportsmedicine.about.com/od/enviromentalissues/a/extrem
ecold.htm
Popular
Alaska DNR
http://dnr.alaska.gov/parks/safety/hypother.htm
Popular
Boise Health
http://www.boisehealth.com/what-is-hypothermia.php
Medical
Camping
Advice Blog
http://www.campingadviceblog.com/hypothermia-prevention-for-
backpackers/
Outdoors
CDC
Hypothermia
http://emergency.cdc.gov/disasters/winter/staysafe/hypothermia.
asp
Medical
City of
Columbia,
Missouri
Department of
Health and
Human
Services
http://www.gocolumbiamo.com/Health/hypothermia.php
Medical
City of
Stamford,
Connecticut,
Health
Department
http://www.ci.stamford.ct.us/content/25/52/140/214/364/402/43
5/4805.aspx
Medical
emedicine
http://www.emedicinehealth.com/hypothermia/article_em.htm#H
ypothermia%20Overview
Popular
Enter
http://www.enter.net/~skimmer/coldwater.html
Outdoors
Examiner
http://www.examiner.com/article/hypothermia-prevention-begins-
before-leaving-the-house
Popular
Family
Camping and
Hiking
http://www.family-camping-and-hiking.com/hypothermia-
symptoms.html
Outdoors
34
Free MD
http://www.freemd.com/hypothermia/overview.htm
Popular
Get Outdoors
http://www.getoutdoors.com/go/golearn/128
Outdoors
Google Docs
https://docs.google.com/presentation/d/1-hj0F5bG-
CiQg059FsDLSuqyKgpBXw3piKYNaE8JTuo/edit?pli=1#slide=id.p
Popular
High Country
Explorations
http://highcountryexplorations.com/Preventing_Hypothermia.html
Outdoors
HowStuffWork
s
http://adventure.howstuffworks.com/survival/wilderness/how-to-
avoid-hypothermia2.htm
Popular
Hypothermia
http://en.wikipedia.org/wiki/Hypothermia
Popular
Illinois
Department of
Public Health
http://www.idph.state.il.us/public/hb/hbwinter.htm
Medical
Jefferson
County,
Kansas Health
Department
http://www.jfcountyks.com/index.aspx?NID=279
Medical
Kayak Lake
Mead
http://kayak-skills.kayaklakemead.com/hypothermia-definition-
cause-prevention.html
Outdoors
King County
Public Health
(Seattle)
http://www.kingcounty.gov/healthservices/health/preparedness/di
saster/hypothermia-english.aspx
Medical
MacScouter
http://www.macscouter.com/keepwarm/hypotherm.asp
Outdoors
Mayo Clinic
http://www.mayoclinic.com/health/hypothermia/DS00333/DSECTI
ON=prevention-
Medical
Medicine Net
http://www.medicinenet.com/hypothermia/article.htm
Popular
Medline
http://www.nlm.nih.gov/medlineplus/ency/article/000038.htm
Medical
Minnesota Sea
Grant
http://www.seagrant.umn.edu/coastal_communities/hypothermia
Medical
35
Missouri
Department of
Health and
Senior
Services
http://health.mo.gov/living/healthcondiseases/hypothermia/survei
llance.php
Medical
Montana
Department of
Public Health
and Human
Services
http://www.dphhs.mt.gov/newsevents/newsreleases2005/january
/extremecold.shtml
Medical
Nature Skills
http://www.natureskills.com/outdoor-safety/hypothermia-
prevention/
Outdoors
New South
Wales
Department of
Health
http://www.health.nsw.gov.au/factsheets/environmental/hypothe
rmia.html
Medical
New York
Times
http://health.nytimes.com/health/guides/injury/hypothermia/over
view.html
Popular
NHS Choices
http://www.nhs.uk/Conditions/Hypothermia/Pages/Introduction.as
px
Medical
Princeton.edu
http://www.princeton.edu/~oa/safety/hypocold.shtml
Medical
Red Cross
http://www.redcross.org/www-
files/Documents/Preparing/Frostbite_and_Hypothermia.pdf
Medical
Scubadoc's
Diving
Medicine
http://www.scuba-doc.com/hypoth.htm
Outdoors
Seattle
Backpacker's
Magazine
http://seattlebackpackersmagazine.com/2011/04/01/hypothermia-
prevention-identification-and-treatment/
Outdoors
Sherman
Health
http://www.shermanhealth.com/blog/tipsadvice/its-cold-outside-
tips-on-frostbite-hypothermia-prevention
Medical
36
State of Ohio:
Committee for
Severe
Weather
Awareness
http://www.weathersafety.ohio.gov/WinterHealthSafetyTips.aspx
Medical
The Free
Dictionary
(Medical
Dictionary)
http://medical-dictionary.thefreedictionary.com/hypothermia
Popular
Third Age
http://www.thirdage.com/hc/c/hypothermia
Popular
Three Rivers
District
(Nebraska)
Health
Department
http://threeriverspublichealth.org/heatlth_topics/hypothermia.ht
m
Medical
University of
Maryland
Medical
Center
http://www.umm.edu/altmed/articles/hypothermia-000092.htm
Medical
US Army
Public Health
Command
http://phc.amedd.army.mil/topics/discond/cip/Pages/ColdCasualti
esInjuries.aspx
Special
Group
Virginia
Department of
Public Health
http://www.vdh.virginia.gov/weather/ColdWeatherSafety.htm
Medical
Washington
State
Department of
Health
http://www.doh.wa.gov/Emergencies/EmergencyPreparednessand
Response/Factsheets/Hypothermia.aspx
Medical
Weather.com
http://www.weather.com/activities/recreation/ski/articles/snowbo
arding_frostbite.html
Popular
Wilderness
Utah
http://www.wildernessutah.com/learn/hypothermia.html
Outdoors
37
Table 3. The search terms utilized to identify peer-reviewed hypothermia publications.
The first search term was “hypothermia”, and the terms listed in these tables comprise the second
phrase used in the internet search.
Acclimatization
Homeless
Moisture
Alcohol consumption
Hunger/nausea
Mountain climbers/hikers
Blankets
Inactivity
Move out of cold weather
Cardiovascular problems
Inadequate clothing
No direct heat/bath
Cold exposure
Inadequate food/hydration
Pale/icy skin
Cold weather clothing
Incoherence
Paradoxical undressing
Cover extremities/head
Infants/children
Reduced energy
Drug use
Insulate from the ground
Remove wet clothes
Elderly
Loss of body heat
Sharing body heat
Ethanol
Loss of consciousness
Warm compresses
Exertion
Malnourishment
Warm liquids
Handle victim gently
Medical conditions
Water immersion
Heart conditions
Mental illness
Wind exposure/wind chill
Table 4. The references that were utilized to critically assess the hypothermia information found
on web pages (references used in background not listed; full list is in the bibliography).
1
Ranhoff A. Accidental Hypothermia in the Elderly.
Int J Circumpolar Health. 2000; 59(3-4): p. 255-259.
2
Mulcahy AR, Watts MR. Accidental Hypothermia: An
Evidence-Based Approach. Emerg Med Pract. 2009;
11(1): p. 1-26.
3
Pedley D, Patterson B, Morrison W. Hypothermia in
Elderly Patients Presenting to Accident and
Emergency during the Onset of Winter. SMJ. 2002;
47(1): p. 10-11.
38
4
Ballester JM, Harchelroad FP. Hypothermia: An
Easy-to-Miss, Dangerous Disorder in Winter
Weather. Geriatrics. 1999; 54(2): p. 51-57.
5
Mallet M. Pathophysiology of Accidental
Hypothermia. QJ Med. 2002; 95: p. 775-785.
6
Dharmarajan T, Wijidada D. Hypothermia in the
Geriatric Population. Aging health. 2007; 3(6): p.
735-741.
7
DeGroot D, Havenith G, Kenney LW. Responses to
Mild Cold Stress are Predicted by Different
Individual Characteristics in Younger and Older
Subjects. J Appl Physiol. 2006; 101: p. 1607-1615.
8
Rango N. Exposure-Related Hypothermia Mortality
in the United States, 1970-1979. Am J Public Health.
1984; 74: p. 1159-1160.
9
Herity B, Daly L, Bourke GJ, Horgan JM.
Hypothermia Mortality and Morbidity: An
Epidemiologic Analysis. J Epidemiol Community
Health. 1991; 45: p. 19-23.
10
Thacker MT, Lee R, Sabogal RI, Anderson A.
Overview of Deaths Associated with Natural Events,
United States, 1979-2004. Disasters. 2008; 32(2): p.
305-315.
11
Rango N. The Social Epidemiology of Accidental
Hypothermia Among the Aged. Gerontologist. 1985;
25(4): p. 424-430.
12
Taylor AJ, McGwin G. Temperature-Related Deaths
in Alabama. 2000; 93(8): p. 787-792.
13
Nixdorff-Miller A, Hunsaker DM, Hunsaker III JC.
Hypothermia and Hypothermia Medicolegal
Investigation of Morbidity and Mortality from
Exposure to Environmental Temperature Extremes.
Arch Pathol Lab Med. 2006; 130: p. 1297-1304.
14
Beim J, Koehnke N, Classan D, Dosman J. Out of the
Cold: Management of Hypothermia and Frostbite.
CMAJ. 2003; 168(3): p. 305-311.
39
15
Taylor A, McGwin GJ, Davis G, Brissie R, Holley T,
Rue III LW. Hypothermia Deaths in Jefferson County,
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42
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43
Table 5. The information content of the 49 websites analyzed in this study, with the number (N)
and the percentage of websites that the guidance appeared on, along with the SORT grade
analysis.
Category
N
%
SORT
Science
SORT
Epidemiology
SORT
Usability
SORT
Usefulness
Vulnerable Populations
Elderly
29
59%
A
A
Infants/children
23
47%
A
C
Alcohol abusers
16
33%
A
A
Medical conditions
13
27%
A
B
Homeless
12
24%
B
B
Spend time outdoors
12
24%
A
B
Mental illness
8
16%
C
B
Malnourished
3
6%
A
C
Symptoms
Shivering
39
80%
A
A
A
Mental impairment
39
80%
A
B
B
Physical/coordination
impairment
37
76%
A
A
A
Incoherence
30
61%
A
B
B
Cardio-respiratory
problems
26
53%
A
B
B
44
Reduced energy
25
51%
A
B
C
Loss of consciousness
21
43%
A
C
C
Pale/icy skin
14
29%
A
B
B
Paradoxical undressing
4
8%
B
C
C
Prevention
Wear appropriate clothing
in layers
37
76%
B
Cover extremities/head
25
51%
A
Adequate nutrition and
drink
21
43%
A
No
alcohol/smoke/caffeine
15
31%
C
Stay dry/do not over-exert
15
31%
A
Avoid cold
temperatures/high wind
14
29%
A
Do not wear cotton
7
14%
C
Take time to acclimatize
1
2%
C
