Hypothermia is reduced body temperature that happens when a body dissipates more heat than it absorbs. In humans, it is defined as a body core temperature below 35.0 °C (95.0 °F). Symptoms depend on the temperature. In mild hypothermia there is shivering and mental confusion. In moderate hypothermia shivering stops and confusion increases. In severe hypothermia, there may be paradoxical undressing, in which a person removes their clothing, as well as an increased risk of the heart stopping.
Hypothermia has two main types of causes. It classically occurs from exposure to extreme cold. It may also occur from any condition that decreases heat production or increases heat loss. Commonly this includes alcohol intoxication but may also include low blood sugar, anorexia, and advanced age. Body temperature is usually maintained near a constant level of 36.5–37.5 °C (97.7–99.5 °F) through thermoregulation. Efforts to increase body temperature involve shivering, increased voluntary activity, and putting on warmer clothing. Hypothermia may be diagnosed based on either a person's symptoms in the presence of risk factors or by measuring a person's core temperature.
The treatment of mild hypothermia involves warm drinks, warm clothing, and physical activity. In those with moderate hypothermia, heating blankets and warmed intravenous fluids are recommended. People with moderate or severe hypothermia should be moved gently. In severe hypothermia, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass may be useful. In those without a pulse, cardiopulmonary resuscitation (CPR) is indicated along with the above measures. Rewarming is typically continued until a person's temperature is greater than 32 °C (90 °F). If there is no improvement at this point or the blood potassium level is greater than 12 mmol/liter at any time, resuscitation may be discontinued.
Hypothermia is the cause of at least 1,500 deaths a year in the United States. It is more common in older people and males. One of the lowest documented body temperatures from which someone with accidental hypothermia has survived is 13.0 °C (55.4 °F) in a near-drowning of a 7-year-old girl in Sweden. Survival after more than six hours of CPR has been described. For those for whom ECMO or bypass is used, survival is around 50%. Deaths due to hypothermia have played an important role in many wars. The term is from Greek ὑπο, hupo, meaning "under", and θερμία, thermía, meaning "heat". The opposite of hypothermia is hyperthermia, an increased body temperature due to failed thermoregulation.
|During Napoleon Bonaparte's retreat from Russia in the winter of 1812, many troops died from hypothermia.|
|Specialty||Critical care medicine|
|Risk factors||Alcohol intoxication, low blood sugar, anorexia, advanced age|
|Diagnostic method||Based on symptoms or body temperature below 35.0 °C (95.0 °F)|
|Deaths||1,500 per year (US)|
Another classification system, the Swiss staging system, divides hypothermia based on the presenting symptoms which is preferred when it is not possible to determine an accurate core temperature.
Other cold-related injuries that can be present either alone or in combination with hypothermia include:
Signs and symptoms vary depending on the degree of hypothermia, and may be divided by the three stages of severity. Infants with hypothermia may feel cold when touched, with bright red skin and an unusual lack of energy.
Symptoms of mild hypothermia may be vague, with sympathetic nervous system excitation (shivering, high blood pressure, fast heart rate, fast respiratory rate, and contraction of blood vessels). These are all physiological responses to preserve heat. Increased urine production due to cold, mental confusion, and liver dysfunction may also be present. Hyperglycemia may be present, as glucose consumption by cells and insulin secretion both decrease, and tissue sensitivity to insulin may be blunted. Sympathetic activation also releases glucose from the liver. In many cases, however, especially in people with alcoholic, hypoglycemia appears to be a more common. Hypoglycemia is also found in many people with hypothermia, as hypothermia may be a result of hypoglycemia.
As hypothermia progresses, symptoms include: mental status changes such as amnesia, confusion, slurred speech, decreased reflexes, and loss of fine motor skills.
As the temperature decreases, further physiological systems falter and heart rate, respiratory rate, and blood pressure all decrease. This results in an expected heart rate in the 30s at a temperature of 28 °C (82 °F).
There is often no shivering, cold, inflamed skin, hallucinations, lack of reflexes, fixed dilated pupils, low blood pressure, and pulmonary edema. Pulse and respiration rates decrease significantly, but fast heart rates (ventricular tachycardia, atrial fibrillation) can also occur. Atrial fibrillation is not typically a concern in and of itself.
Twenty to fifty percent of hypothermia deaths are associated with paradoxical undressing. This typically occurs during moderate and severe hypothermia, as the person becomes disoriented, confused, and combative. They may begin discarding their clothing, which, in turn, increases the rate of heat loss.
Rescuers who are trained in mountain survival techniques are taught to expect this; however, people who die from hypothermia in urban environments are sometimes incorrectly assumed to have been subjected to sexual assault.
One explanation for the effect is a cold-induced malfunction of the hypothalamus, the part of the brain that regulates body temperature. Another explanation is that the muscles contracting peripheral blood vessels become exhausted (known as a loss of vasomotor tone) and relax, leading to a sudden surge of blood (and heat) to the extremities, causing the person to feel overheated.
An apparent self-protective behaviour, known as "terminal burrowing", or "hide-and-die syndrome", occurs in the final stages of hypothermia. The afflicted will enter small, enclosed spaces, such as underneath beds or behind wardrobes. It is often associated with paradoxical undressing. Researchers in Germany claim this is "obviously an autonomous process of the brain stem, which is triggered in the final state of hypothermia and produces a primitive and burrowing-like behavior of protection, as seen in hibernating animals". This happens mostly in cases where temperature drops slowly.
Hypothermia usually occurs from exposure to low temperatures, and is frequently complicated by alcohol consumption. Any condition that decreases heat production, increases heat loss, or impairs thermoregulation, however, may contribute. Thus, hypothermia risk factors include: substance abuse (including alcohol abuse), homelessness, any condition that affects judgment (such as hypoglycemia), the extremes of age, poor clothing, chronic medical conditions (such as hypothyroidism and sepsis), and living in a cold environment. Hypothermia occurs frequently in major trauma, and is also observed in severe cases of anorexia nervosa. Hypothermia is also associated with worse outcomes in people with sepsis. While most people with sepsis develop fevers (elevated body temperature), some develop hypothermia.
In urban areas, hypothermia frequently occurs with chronic cold exposure, such as in cases of homelessness, as well as with immersion accidents involving drugs, alcohol or mental illness. While studies have shown that homeless people are at risk of premature death from hypothermia, the true incidence of hypothermia-related deaths in this population is difficult to determine. In more rural environments, the incidence of hypothermia is higher among people with significant comorbidities and less able to move independently. With rising interest in wilderness exploration, and outdoor and water sports, the incidence of hypothermia secondary to accidental exposure may become more frequent in the general population.
Alcohol consumption increases the risk of hypothermia in two ways: vasodilation and temperature controlling systems in the brain. Vasodilation increases blood flow to the skin, resulting in heat being lost to the environment. This produces the effect of an individual feeling warm, when they are actually losing heat. Alcohol also affects the temperature-regulating system in the brain, decreasing the body's ability to shiver and use energy that would normally aid the body in generating heat. The overall effects of alcohol lead to a decrease in body temperature and a decreased ability to generate body heat in response to cold environments. Alcohol is a common risk factor for death due to hypothermia. Between 33% and 73% of hypothermia cases are complicated by alcohol.
In the UK, 28,354 cases of hypothermia were treated in 2012–13 – an increase of 25% from the previous year. Some cases of hypothermia death, as well as other preventable deaths, happen because poor people cannot easily afford to keep warm. Rising fuel bills have increased the numbers who have difficulty paying for adequate heating in the UK. Some pensioners and disabled people are at risk because they do not work and cannot easily leave their homes. Better heat insulation can help.
Hypothermia continues to be a major limitation to swimming or diving in cold water. The reduction in finger dexterity due to pain or numbness decreases general safety and work capacity, which consequently increases the risk of other injuries.
Other factors predisposing to immersion hypothermia include dehydration, inadequate rewarming between repetitive dives, starting a dive while wearing cold, wet dry suit undergarments, sweating with work, inadequate thermal insulation (for example, thin dry suit undergarment), and poor physical conditioning.
Heat is lost much more quickly in water than in air. Thus, water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia in survivors, although this is not usually the direct clinical cause of death for those who are not rescued. A water temperature of 10 °C (50 °F) can lead to death in as little as one hour, and water temperatures near freezing can cause death in as little as 15 minutes. A notable example of this occurred during the sinking of the Titanic, when most people who entered the −2 °C (28 °F) water died in 15–30 minutes.
The actual cause of death in cold water is usually the bodily reactions to heat loss and to freezing water, rather than hypothermia (loss of core temperature) itself. For example, plunged into freezing seas, around 20% of victims die within two minutes from cold shock (uncontrolled rapid breathing, and gasping, causing water inhalation, massive increase in blood pressure and cardiac strain leading to cardiac arrest, and panic); another 50% die within 15–30 minutes from cold incapacitation (inability to use or control limbs and hands for swimming or gripping, as the body "protectively" shuts down the peripheral muscles of the limbs to protect its core). Exhaustion and unconsciousness cause drowning, claiming the rest within a similar time.
Heat is primarily generated in muscle tissue, including the heart, and in the liver, while it is lost through the skin (90%) and lungs (10%). Heat production may be increased two- to four-fold through muscle contractions (i.e. exercise and shivering). The rate of heat loss is determined, as with any object, by convection, conduction, and radiation. The rates of these can be affected by body mass index, body surface area to volume ratios, clothing and other environmental conditions.
Many changes to physiology occur as body temperatures decrease. These occur in the cardiovascular system leading to the Osborn J wave and other dysrhythmias, decreased central nervous system electrical activity, cold diuresis, and non-cardiogenic pulmonary edema.
Research has shown that glomerular filtration rates (GFR) decrease as a result of hypothermia. In essence, hypothermia increases preglomerular vasoconstriction, thus decreasing both renal blood flow (RBF) and GFR.
Accurate determination of core temperature often requires a special low temperature thermometer, as most clinical thermometers do not measure accurately below 34.4 °C (93.9 °F). A low temperature thermometer can be placed in the rectum, esophagus or bladder. Esophageal measurements are the most accurate and are recommended once a person is intubated. Other methods of measurement such as in the mouth, under the arm, or using an infrared ear thermometer are often not accurate.
As a hypothermic person's heart rate may be very slow, prolonged feeling for a pulse could be required before detecting. In 2005, the American Heart Association recommended at least 30–45 seconds to verify the absence of a pulse before initiating CPR. Others recommend a 60-second check.
The classical ECG finding of hypothermia is the Osborn J wave. Also, ventricular fibrillation frequently occurs below 28 °C (82 °F) and asystole below 20 °C (68 °F). The Osborn J may look very similar to those of an acute ST elevation myocardial infarction. Thrombolysis as a reaction to the presence of Osborn J waves is not indicated, as it would only worsen the underlying coagulopathy caused by hypothermia.
Appropriate clothing helps to prevent hypothermia. Synthetic and wool fabrics are superior to cotton as they provide better insulation when wet and dry. Some synthetic fabrics, such as polypropylene and polyester, are used in clothing designed to wick perspiration away from the body, such as liner socks and moisture-wicking undergarments. Clothing should be loose fitting, as tight clothing reduces the circulation of warm blood. In planning outdoor activity, prepare appropriately for possible cold weather. Those who drink alcohol before or during outdoor activity should ensure at least one sober person is present responsible for safety.
Covering the head is effective, but no more effective than covering any other part of the body. While common folklore says that people lose most of their heat through their heads, heat loss from the head is no more significant than that from other uncovered parts of the body. However, heat loss from the head is significant in infants, whose head is larger relative to the rest of the body than in adults. Several studies have shown that for uncovered infants, lined hats significantly reduce heat loss and thermal stress. Children have a larger surface area per unit mass, and other things being equal should have one more layer of clothing than adults in similar conditions, and the time they spend in cold environments should be limited. However children are often more active than adults, and may generate more heat. In both adults and children, overexertion causes sweating and thus increases heat loss.
Building a shelter can aid survival where there is danger of death from exposure. Shelters can be of many different types, metal can conduct heat away from the occupants and is sometimes best avoided. The shelter should not be too big so body warmth stays near the occupants. Good ventilation is essential especially if a fire will be lit in the shelter. Fires should be put out before the occupants sleep to prevent carbon monoxide poisoning. People caught in very cold, snowy conditions can build an igloo or snow cave to shelter.
The United States Coast Guard promotes using life vests to protect against hypothermia through the 50/50/50 rule: If someone is in 50 °F (10 °C) water for 50 minutes, he/she has a 50 percent better chance of survival if wearing a life jacket. A heat escape lessening position can be used to increase survival in cold water.
|Mild (stage 1)||Passive rewarming|
|Moderate (stage 2)||Active external rewarming|
|Severe (stage 3 and 4)||Active internal rewarming|
Aggressiveness of treatment is matched to the degree of hypothermia. Treatment ranges from noninvasive, passive external warming to active external rewarming, to active core rewarming. In severe cases resuscitation begins with simultaneous removal from the cold environment and management of the airway, breathing, and circulation. Rapid rewarming is then commenced. Moving the person as little and as gently as possible is recommended as aggressive handling may increase risks of a dysrhythmia.
Hypoglycemia is a frequent complication and needs to be tested for and treated. Intravenous thiamine and glucose is often recommended, as many causes of hypothermia are complicated by Wernicke's encephalopathy.
The UK National Health Service advises against putting a person in a hot bath, massaging their arms and legs, using a heating pad, or giving them alcohol. These measures can cause a rapid fall in blood pressure and potential cardiac arrest.
Rewarming can be done with a number of methods including passive external rewarming, active external rewarming, and active internal rewarming. Passive external rewarming involves the use of a person's own ability to generate heat by providing properly insulated dry clothing and moving to a warm environment. Passive external rewarming is recommended for those with mild hypothermia.
Active external rewarming involves applying warming devices externally, such as a heating blanket. These may function by warmed forced air (Bair Hugger is a commonly used device), chemical reactions, or electricity. In wilderness environments, hypothermia may be helped by placing hot water bottles in both armpits and in the groin. Active external rewarming is recommended for moderate hypothermia. Active core rewarming involves the use of intravenous warmed fluids, irrigation of body cavities with warmed fluids (the chest or abdomen), use of warm humidified inhaled air, or use of extracorporeal rewarming such as via a heart lung machine or extracorporeal membrane oxygenation (ECMO). Extracorporeal rewarming is the fastest method for those with severe hypothermia. When severe hypothermia has led to cardiac arrest, effective extracorporeal warming results in survival with normal mental function about 50% of the time. Chest irrigation is recommended if bypass or ECMO is not possible.
Rewarming shock (or rewarming collapse) is a sudden drop in blood pressure in combination with a low cardiac output which may occur during active treatment of a severely hypothermic person. There was a theoretical concern that external rewarming rather than internal rewarming may increase the risk. These concerns were partly believed to be due to afterdrop, a situation detected during laboratory experiments where there is a continued decrease in core temperature after rewarming has been started. Recent studies have not supported these concerns, and problems are not found with active external rewarming.
For people who are alert and able to swallow, drinking warm sweetened liquids can help raise the temperature. Many recommend alcohol and caffeinated drinks be avoided. As most people are moderately dehydrated due to cold-induced diuresis, warmed intravenous fluids to a temperature of 38–45 °C (100–113 °F) are often recommended.
In those without signs of life, cardiopulmonary resuscitation (CPR) should be continued during active rewarming. For ventricular fibrillation or ventricular tachycardia, a single defibrillation should be attempted. However, people with severe hypothermia may not respond to pacing or defibrillation. It is not known if further defibrillation should be withheld until the core temperature reaches 30 °C (86 °F). In Europe, epinephrine is not recommended until the person's core temperature reaches 30 °C (86 °F), while the American Heart Association recommends up to three doses of epinephrine before a core temperature of 30 °C (86 °F) is reached. Once a temperature of 30 °C (86 °F) has been reached, normal ACLS protocols should be followed.
It is usually recommended not to declare a person dead until their body is warmed to a near normal body temperature of greater than 32 °C (90 °F), since extreme hypothermia can suppress heart and brain function. Exceptions include if there is an obvious fatal injuries or the chest is frozen so that it cannot be compressed. If a person was buried in an avalanche for more than 35 minutes and is found with a mouth packed full of snow without a pulse, stopping early may also be reasonable. This is also the case if a person's blood potassium is greater than 12 mmol/l.
Those who are stiff with pupils that do not move may survive if treated aggressively. Survival with good function also occasionally occurs even after the need for hours of CPR. Children who have near-drowning accidents in water near 0 °C (32 °F) can occasionally be revived, even over an hour after losing consciousness. The cold water lowers the metabolism, allowing the brain to withstand a much longer period of hypoxia. While survival is possible, mortality from severe or profound hypothermia remains high despite optimal treatment. Studies estimate mortality at between 38% and 75%.
In those who have hypothermia due to another underlying health problem, when death occurs it is frequently from that underlying health problem.
Between 1995 and 2004 in the United States, an average of 1560 cold-related emergency department visits occurred per year and in the years 1999 to 2004, an average of 647 people died per year due to hypothermia. Of deaths reported between 1999 and 2002 in the US, 49% of those affected were 65 years or older and two-thirds were male. Most deaths were not work related (63%) and 23% of affected people were at home. Hypothermia was most common during the autumn and winter months of October through March. In the United Kingdom, an estimated 300 deaths per year are due to hypothermia, whereas the annual incidence of hypothermia-related deaths in Canada is 8000.
Hypothermia has played a major role in the success or failure of many military campaigns, from Hannibal's loss of nearly half his men in the Second Punic War (218 B.C.) to the near destruction of Napoleon's armies in Russia in 1812. Men wandered around confused by hypothermia, some lost consciousness and died, others shivered, later developed torpor, and tended to sleep. Others too weak to walk fell on their knees; some stayed that way some time resisting death. The pulse of some was weak and hard to detect; others groaned; yet others had eyes open and wild with quiet delirium. Loss of life to hypothermia in Russian regions continued through the first and second world wars, especially in the Battle of Stalingrad.
Antarctic explorers developed hypothermia; Ernest Shackleton and his team measured body temperatures "below 94.2°, which spells death at home", though this probably referred to oral temperatures rather than core temperature and corresponded to mild hypothermia. One of Scott's team, Atkinson, became confused through hypothermia.
Nazi human experimentation during World War II amounting to medical torture included hypothermia experiments, which killed many victims. There were 360 to 400 experiments and 280 to 300 subjects, indicating some had more than one experiment performed on them. Various methods of rewarming were attempted, "One assistant later testified that some victims were thrown into boiling water for rewarming".
Water bears (Tardigrade), microscopic multicellular organisms, can survive freezing at low temperatures by replacing most of their internal water with the sugar trehalose, preventing the crystallization that otherwise damages cell membranes.
Dantrolene may also be associated with improved survival and reduced complications, especially in patients with extreme (≥ 42 °C) or severe (≥ 40 °C) hyperpyrexia
Despite the myriad of complications associated with heat illness, an elevation of core temperature above 41.0 °C (often referred to as fever or hyperpyrexia) is the most widely recognized symptom of this syndrome.
Clinical death is the medical term for cessation of blood circulation and breathing, the two necessary criteria to sustain human and many other organisms' lives. It occurs when the heart stops beating, a condition called cardiac arrest. The term is also sometimes used in resuscitation research.
Stopped blood circulation has historically proven irreversible in most cases. Prior to the invention of cardiopulmonary resuscitation (CPR), defibrillation, epinephrine injection, and other treatments in the 20th century, the absence of blood circulation (and vital functions related to blood circulation) was historically considered the official definition of death. With the advent of these strategies, cardiac arrest came to be called clinical death rather than simply death, to reflect the possibility of post-arrest resuscitation.
At the onset of clinical death, consciousness is lost within several seconds. Measurable brain activity stops within 20 to 40 seconds. Irregular gasping may occur during this early time period, and is sometimes mistaken by rescuers as a sign that CPR is not necessary. During clinical death, all tissues and organs in the body steadily accumulate a type of injury called ischemic injury.Fan death
Fan death is a well-known superstition in Korean culture, where it is thought that running an electric fan in a closed room with unopened or no windows will prove fatal. Despite no concrete evidence to support the concept, belief in fan death persists to this day in Korea.Frostbite
Frostbite occurs when exposure to low temperatures causes freezing of the skin or other tissues. The initial symptom is typically numbness. This may be followed by clumsiness with a white or bluish color to the skin. Swelling or blistering may occur following treatment. The hands, feet, and face are most commonly affected. Complications may include hypothermia or compartment syndrome.People who are exposed to low temperatures for prolonged periods, such as winter sports enthusiasts, military personnel, and homeless individuals, are at greatest risk. Other risk factors include drinking alcohol, smoking, mental health problems, certain medications, and prior injuries due to cold. The underlying mechanism involves injury from ice crystals and blood clots in small blood vessels following thawing. Diagnosis is based on symptoms. Severity may be divided into superficial (1st and 2nd degree) or deep (3rd and 4th degree). A bone scan or MRI may help in determining the extent of injury.Prevention is through wearing proper clothing, maintaining hydration and nutrition, avoiding low temperatures, and staying active without becoming exhausted. Treatment is by rewarming. This should be done only when refreezing is not a concern. Rubbing or applying snow to the affected part is not recommended. The use of ibuprofen and tetanus toxoid is typically recommended. For severe injuries iloprost or thrombolytics may be used. Surgery is sometimes necessary. Amputation, however, should generally be delayed for a few months to allow determination of the extent of injury.The number of cases of frostbite is unknown. Rates may be as high as 40% a year among those who mountaineer. The most common age group affected is those 30 to 50 years old. Evidence of frostbite occurring in people dates back 5,000 years. Frostbite has also played an important role in a number of military conflicts. The first formal description of the condition was in 1814 by Dominique Jean Larrey, a physician in Napoleon's army.Gul Rahman
Gul Rahman (Pashto: ګل رحمان; died 20 November 2002) was an Afghan man, suspected by the United States of being a militant, who was a victim of torture. He died in a secret CIA prison, or black site, located in northern Kabul, Afghanistan and known as the Salt Pit. He had been captured October 29, 2002.His name was kept secret by the United States for more than seven years although his death was announced. In 2010 the Associated Press reported that before his death he was left half-stripped and chained against a concrete wall on a night when the temperature was close to freezing. The United States government did not notify his family (wife and four daughters) of his death, according to the report.Human body temperature
Normal human body temperature, also known as normothermia or euthermia, is the typical temperature range found in humans. The normal human body temperature range is typically stated as 36.5–37.5 °C (97.7–99.5 °F).Individual body temperature depends upon the age, exertion, infection, sex, and reproductive status of the subject, the time of day, the place in the body at which the measurement is made, and the subject's state of consciousness (waking, sleeping or sedated), activity level, and emotional state. It is typically maintained within this range by thermoregulation.Hyperthermia
Hyperthermia is elevated body temperature due to failed thermoregulation that occurs when a body produces or absorbs more heat than it dissipates. Extreme temperature elevation then becomes a medical emergency requiring immediate treatment to prevent disability or death.
The most common causes include heat stroke and adverse reactions to drugs. The former is an acute temperature elevation caused by exposure to excessive heat, or combination of heat and humidity, that overwhelms the heat-regulating mechanisms. The latter is a relatively rare side effect of many drugs, particularly those that affect the central nervous system. Malignant hyperthermia is a rare complication of some types of general anesthesia.
Hyperthermia differs from fever in that the body's temperature set point remains unchanged. The opposite is hypothermia, which occurs when the temperature drops below that required to maintain normal metabolism. The term is from Greek ὑπέρ, hyper, meaning "above" or "over", and θέρμος, thermos, meaning "hot".Hypothermia cap
A hypothermia cap (also referred to as cold cap or cooling cap) is a therapeutic device used to cool the human scalp. Its most prominent medical applications are in preventing or reducing alopecia in chemotherapy, and for preventing cerebral palsy in babies born with neonatal encephalopathy caused by hypoxic-ischemic encephalopathy (HIE). It can also be used to provide neuroprotection after cardiac arrest, to inhibit stroke paralysis, and as cryotherapy for migraine headaches.
Worn tight on the head, hypothermia caps are typically made of a synthetic such as neoprene, silicone or polyurethane, and filled with a coolant agent such as ice or gel which is either frozen to a very cold temperature (−25 °C to −30 °C, or −13 °F to −22 °F) before application or continuously cooled by an auxiliary control unit.
In the United States a course of treatment may cost 1,500 to 3,000 USD.J wave
A J wave — also known as Osborn wave, camel-hump sign, late delta wave, hathook junction, hypothermic wave, K wave, H wave or current of injury — is an abnormal electrocardiogram finding.
J waves are positive deflections occurring at the junction between the QRS complex and the ST segment, where the S point, also known as the J point, has a myocardial infarction-like elevation.James Kim
James Kim (August 9, 1971 – December 4, 2006) was an American television personality and technology analyst for the former TechTV international cable television network, reviewing products for shows including The Screen Savers, Call for Help, and Fresh Gear. At the time of his death he was working as a senior editor of MP3 and Digital Audio for CNET, where he wrote more than 400 product reviews. He also co-hosted a weekly video podcast for CNET's gadget blog, Crave, and a weekly audio podcast, The MP3 Insider (both podcasts were co-hosted with Veronica Belmont).
His disappearance and death, and his family's ordeal, made them the subject of a brief but intense period of news coverage in December 2006.Neil MacCallum
Neil R. MacCallum (15 May 1954 – 9 November 2002) was a Scottish nationalist political activist and poet.
Born in Edinburgh, MacCallum studied at Firrhill High School and Napier College before working for the Lothian Health Board. In this role, he joined the NALGO trade union and served for a while as a shop steward. He joined the Scottish National Party (SNP) while young, and attended the 1972 Plaid Cymru conference with a group of friends from the SNP, drawing attention by playing the bagpipes at the event.MacCallum was elected to Edinburgh City Council in 1977, representing Wester Hailes. He lost his seat in 1980, but was elected as Assistant National Secretary of the SNP, then National Secretary the following year. While Secretary, he chaired the SNP Commission of Inquiry into the party's structures, and it was he who convinced party leader Gordon Wilson to include Alex Salmond as a member. He also stood as a candidate in the 1983 general election in Edinburgh South, taking fourth place with 5.0% of the vote. He stood down in 1986, following ill health, and was succeeded by his assistant, John Swinney.MacCallum also wrote poetry in Lowland Scots, his work first appearing in "Out of Charity" in 1973, and from the late 1980s, he published compilations of other poetry in the language. In the 1990s, he became active in the Scots Language Society and served on the board of the Scottish Poetry Library, and acted as arts correspondent for the Scots Independent newspaper.In later life, MacCallum suffered with depression and problematic drinking, and went missing on several occasions. In November 2002, he fell into the Union Canal and died later the same day from hypothermia.Nuciferine
Nuciferine is an alkaloid found within the plants Nymphaea caerulea and Nelumbo nucifera. It has a profile of action associated with dopamine receptor blockade. It induces sedation, hypothermia, ptosis, and (in higher doses) catalepsy; it inhibits spontaneous motor activity, conditioned avoidance response, amphetamine toxicity and stereotypy. Nuciferine may also potentiate morphine analgesia. The median lethal dose in mice is 289 mg/kg. It is structurally related to apomorphine.PB-22
PB-22 (QUPIC or 1-pentyl-1H-indole-3-carboxylic acid 8-quinolinyl ester) is a designer drug offered by online vendors as a cannabimimetic agent, and detected being sold in synthetic cannabis products in Japan in 2013. The structure of PB-22 appears to use an understanding of structure-activity relationships within the indole class of cannabimimetics, although its design origins are unclear. PB-22 represents a structurally unique synthetic cannabinoid chemotype, since it contains an ester linker at the indole 3-position, rather than the precedented ketone of JWH-018 and its analogs, or the amide of APICA and its analogs.
PB-22 has an EC50 of 5.1 nM for human CB1 receptors, and 37 nM for human CB2 receptors. PB-22 produces bradycardia and hypothermia in rats at doses of 0.3–3 mg/kg, suggesting potent cannabinoid-like activity. The magnitude and duration of hypothermia induced in rats by PB-22 was notably greater than JWH-018, AM-2201, UR-144, XLR-11, APICA, or STS-135, with a reduction of body temperature still observable six hours after dosing. One clinical toxicology study found PB-22 to be the cause of seizures in a human and his dog.Poltpalingada Booboorowie
Poltpalingada Booboorowie (born c. 1830 – died 4 July 1901) was a Ngarrindjeri Aboriginal of the Thooree clan prominent among the community of Fringe dwellers in Adelaide, South Australia during the 1890s. He was better known to the Adelaide residents as Tommy Walker. He was the subject of several portraits by the Adelaide artist Oscar Friström.Reperfusion injury
Reperfusion injury or reperfusion insult, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue (re- + perfusion) after a period of ischemia or lack of oxygen (anoxia or hypoxia). The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than (or along with) restoration of normal function.Saskatoon freezing deaths
The Saskatoon freezing deaths were a series of deaths of Canadian Aboriginal people in Saskatoon, Saskatchewan in the 2000s. Their deaths were caused by members of the Saskatoon Police Service, officers of which arrested Aboriginal men (usually for drunkenness and/or disorderly behavior), drove them out of the city in the dead of winter, and abandoned them there. The practice was known as taking Aboriginal people for starlight tours.Targeted temperature management
Targeted temperature management (TTM) previously known as therapeutic hypothermia or protective hypothermia is an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an effort to improve health outcomes during recovery after a period of stopped blood flow to the brain. This is done in an attempt to reduce the risk of tissue injury following lack of blood flow. Periods of poor blood flow may be due to cardiac arrest or the blockage of an artery by a clot as in the case of a stroke.Targeted temperature management improves survival and brain function following resuscitation from cardiac arrest. Evidence supports its use following certain types of cardiac arrest in which an individual does not regain consciousness. Both 33 °C (91 °F) and 36 °C (97 °F) appear to result in similar outcomes. Targeted temperature management following traumatic brain injury has shown mixed results with some studies showing benefits in survival and brain function while others show no clear benefit. While associated with some complications, these are generally mild.Targeted temperature management is thought to prevent brain injury by several methods including decreasing the brain's oxygen demand, reducing the production of neurotransmitters like glutamate, as well as reducing free radicals that might damage the brain. The lowering of body temperature may be accomplished by many means including the use of cooling blankets, cooling helmets, cooling catheters, ice packs and ice water lavage.Thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation. The internal thermoregulation process is one aspect of homeostasis: a state of dynamic stability in an organism's internal conditions, maintained far from thermal equilibrium with its environment (the study of such processes in zoology has been called physiological ecology). If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. For humans, this occurs when the body is exposed to constant temperatures of approximately 55 °C (131 °F), and with prolonged exposure (longer than a few hours) at this temperature and up to around 75 °C (167 °F) death is almost inevitable. Humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above 35 °C (95 °F) for six hours. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. It results when the homeostatic control mechanisms of heat within the body malfunction, causing the body to lose heat faster than producing it. Normal body temperature is around 37 °C (99 °F), and hypothermia sets in when the core body temperature gets lower than 35 °C (95 °F). Usually caused by prolonged exposure to cold temperatures, hypothermia is usually treated by methods that attempt to raise the body temperature back to a normal range.It was not until the introduction of thermometers that any exact data on the temperature of animals could be obtained. It was then found that local differences were present, since heat production and heat loss vary considerably in different parts of the body, although the circulation of the blood tends to bring about a mean temperature of the internal parts. Hence it is important to identify the parts of the body that most closely reflect the temperature of the internal organs. Also, for such results to be comparable, the measurements must be conducted under comparable conditions. The rectum has traditionally been considered to reflect most accurately the temperature of internal parts, or in some cases of sex or species, the vagina, uterus or bladder.Occasionally the temperature of the urine as it leaves the urethra may be of use in measuring body temperature. More often the temperature is taken in the mouth, axilla, ear or groin.Some animals undergo one of various forms of dormancy where the thermoregulation process temporarily allows the body temperature to drop, thereby conserving energy. Examples include hibernating bears and torpor in bats.Trauma triad of death
The trauma triad of death is a medical term describing the combination of hypothermia, acidosis and coagulopathy. This combination is commonly seen in patients who have sustained severe traumatic injuries and results in a significant rise in the mortality rate. Commonly, when someone presents with these signs, damage control surgery is employed to reverse the effects.
The three conditions share a complex relationship; each factor can compound the others, resulting in high mortality if this positive feedback loop continues uninterrupted.
Severe haemorrhage in trauma diminishes oxygen delivery, and may lead to hypothermia. This in turn can halt the coagulation cascade, preventing blood from clotting. In the absence of blood-bound oxygen and nutrients (hypoperfusion), the body's cells burn glucose anaerobically for energy, causing the release of lactic acid, ketone bodies, and other acidic compounds into the blood stream, which lower the blood's pH, leading to metabolic acidosis. Such an increase in acidity damages the tissues and organs of the body and can reduce myocardial performance, further reducing the oxygen delivery.Wilfred Gordon Bigelow
Wilfred Gordon "Bill" Bigelow, (June 18, 1913 – March 27, 2005) was a Canadian heart surgeon known for his role in developing the artificial pacemaker and the use of hypothermia in open heart surgery.Born in Brandon, Manitoba, the son of Dr. Wilfred Abram Bigelow, founder of the first private medical clinic in Canada, and Grace Ann Gordon, nurse and midwife, he gained his MD from the University of Toronto in 1938. He served during World War II as a captain in the Royal Canadian Medical Army Corps, performing battle surgery on the frontlines. He was appointed to the surgical staff of Toronto General Hospital in 1947, after spending a year at Johns Hopkins Medical School, and to the Department of Surgery at the University of Toronto in 1948.
In the 1950s, Bigelow developed the idea of using hypothermia as a medical procedure. This involves reducing a patient's body temperature prior to an operation in order to reduce the amount of oxygen needed, making heart operations safer.He wrote two books, Cold Hearts and Mysterious Heparin. He served as a director of the Audubon Society and the Nature Conservancy of Canada.
In 1981 he was made an Officer of the Order of Canada. He was inducted into the Canadian Medical Hall of Fame in 1997.
He was married to Ruth Jennings for almost 60 years. They had four children; Pixie, John, Dan and Bill.