Hypothermia

Cold Comfort On A January Morning
http://afludiary.blogspot.com/2010/01/cold-comfort-on-january-morning.html

(snip): Hypothermia, and frost bite, can both be life threatening conditions. And sadly, sometimes ill considered attempts to stay warm can result in house fires or carbon monoxide poisoning.  

So a reminder today about the dangers of winter weather, and the  need to be prepared, no matter what the threat.   ---CONTINUED at LINK---

Cold Weather Survival: 5 Heat Loss Mechanisms
https://gundigest.com/reviews/cold-weather-survival-5-heat-loss-mechanisms

Editor’s Note: Remember that clothing is the first layer of shelter you have available. If you can address three or four of these points, you’ll be much better suited for cold weather survival.

The ways that heat from your body can be transferred to the environment are called heat loss mechanisms. In a hot climate some of these mechanisms can be used to your advantage, but in a cold weather survival scenario they can all be detrimental. ---CONTINUED at LINK---

This is a snip from a larger article:

Hypothermia
http://www.backwoodshome.com/articles/clay60.html

Believe it or not, hypothermia (the condition where the body temperature is lowered below normal) kills more people in survival/stress situations than does gunfire, wild animal attacks, poisonous reptiles and spiders, wounds, or drowning.

Hypothermia has many causes, from shock following an accident to remaining outside in cold weather without adequate clothing or shelter to getting dunked in icy water-even for short periods of time. It is definitely something to watch for in any survival situation.

Identifying hypothermia can be a problem   ---CONTINUED at LINK--- (Scroll down for the part on hypothermia)

Hypothermia - A real winter danger
http://www.backwoodshome.com/hypothermia/

Issue #84 • November/December, 2003

Hypothermia is a deadly enemy. It steals body heat and kills more outdoor enthusiasts every year than anything else.

Hypothermia is the rapid and drastic chilling of the body’s core temperature (normally 98.6 degrees F) during adverse conditions, and begins when the body loses heat faster than it can be replaced. As the body temperature drops because of exposure to cool air and cold water, things begin to happen in a predictable sequence. Left unchecked, it affects one’s mental condition and physical reactions, and can result in unconsciousness. The ultimate result is death.    ---CONTINUED at LINK ---

Don't Know Jack Forst: How to Handle Hypothermia
http://disastermedicine-christine.blogspot.com/2010/01/dont-know-jack-forst-how-to-handle.html

You know I have been debating whether or not to write more about hypothermia. It has no guts, no glory, no raving zombies you have to fight off. It is just Jack Frost taking a chunk out of your hiney then calling it a day. What kind of criminal locks a person in a refrigerator and just leaves whistling like Frosty the Snowman? The boring kind, that's who.

See that's why I like writing about wilderness wound care. Because no bear smacks you upside the head then leaves; they finish you off. Then gnaw on you for a few more days. Now, that's civil.

But mean old Jack, he just sits there on his cold-hearted balloon-knot and ---CONTINUED at LINK---

How to Treat Hypothermia
https://www.artofmanliness.com/articles/how-to-treat-hypothermia/

It’s easy to imagine hypothermia as the type of malady that can only affect people who get trapped in disastrous conditions, like being lost in a frozen Alaskan wilderness or falling into an icy river far. The reality is that hypothermia is fairly easy to get.

Prevent hypothermia by ... ---CONTINUED---

What Every Prepper Needs to Know About Hypothermia
https://survivallife.com/what-every-prepper-needs-to-know-about-hypothermia-backdoor-survival-2/?utm_source=sl&utm_medium=newsletter&utm_campaign=slnl20171231

Unless you live in the tropics, winter is likely to bring uncertain weather, including bone-chilling temperatures, severe winds, freezing rain and significant snowfall.  Needless to say, such conditions are not much fun under the best of circumstances.  If there is no power and no heat, the effects of winter are magnified, especially for those that have failed to prepare for extreme weather events.   ---CONTINUED---

UNITED STATES MARINE CORPS
Field Medical Training Battalion
Camp Lejeune

Manage Environmental Cold Injuries
http://www.operationalmedicine.org/TextbookFiles/FMST_20008/FMST_1404.htm

TERMINAL LEARNING OBJECTIVES

1. Given a casualty in a combat environment and standard field medical equipment and supplies, manage environmental cold injuries, to prevent further injury or death. (FMST-HSS-1404)

ENABLING LEARNING OBJECTIVES

1. Without the aid of references, given a description or list, identify the predisposing factors associated with cold injuries, per the student handout. (FMST-HSS-1404a)

2. Without the aid of references, given a list of symptoms, identify the types of cold injury, per the student handout. (FMST-HSS-1404b)

3. Without the aid of references, given a list of symptoms, identify the stages of hypothermia, related to decreasing core temperature, per the student handout. (FMST-HSS-1404c)

4. Without the aid of references, given a description or list, identify the proper treatment for cold injuries, per the student handout. (FMST-HSS-1404d)

5. Without the aid of references, given a list, identify preventive measures for cold injuries, per the student handout. (FMST-HSS-1404e)

6. Without the aid of references, given a simulated cold casualty and standard field medical equipment and supplies, manage environmental cold casualties, per the student handout. (FMST-HSS-1404f)   ---CONTINUED---

UNITED STATES MARINE CORPS

From the Marine publication:

THE SHIP'S MEDICINE CHEST AND MEDICAL AID AT SEA DENTAL CARE AND EMERGENCIES- Chapter 10
https://fas.org/irp/doddir/milmed/ships.pdf

IMMERSION HYPOTHERMIA, NEAR-DROWNING AND WATER SURVIVAL
https://fas.org/irp/doddir/milmed/ships.pdf

INTRODUCTION
Immersion in cold water is a hazard for anyone who participates in recreational, commercial or military activities in the oceans, lakes, and streams of all but the tropical regions of the world. For practical purposes, significant risk of immersion hypothermia usually begins in water colder than 77° F. This means that the risk of immersion hypothermia in North America is nearly universal during most of the year. Cold water immersion is associated with two significant medical emergencies: near drowning and hypothermia. The following pages discuss these topics, with emphasis on the body’s response to immersion and on the treatment of hypothermia and near-drowning. The chapter concludes with a brief primer on surviving in cold water.

PHYSIOLOGICAL RESPONSES TO COLD-WATER IMMERSION

Sudden immersion in cold water results in an immediate decline in skin temperature which, in turn, stimulates a cold-shock reflex. This reflex causes an instantaneous gasping for air and sudden increases in heart rate, respiratory rate, blood flow and blood pressure. The cold-shock reflex (see below for a more complete discussion) only lasts for a few minutes, but it can be deadly if the victim’s head is underwater (leading to immediate aspiration and drowning) or if the victim has no flotation assistance and cannot keep his/her head above the water. As body temperature declines, metabolism increases and shivering begins. Also, the muscles of the extremities cool rapidly, leading to a loss of manual dexterity and grip strength. As the body continues to cool, shivering eventually ceases, heart rate and blood pressure decrease, and the victim begins to suffer mental impairment, difficulty in thinking clearly, impaired perception, and finally loss of consciousness. An unconscious victim in the water will drown, oftentimes even if he/she is wearing a personal flotation device. If an immersed unconscious hypothermia victim does not drown, continued body cooling will eventually lead to cardiac arrest.

The following is a simple guide to the levels of hypothermia and their associated signs and symptoms: Note: for accuracy, body temperatures should be measured in the esophagus, if possible, or at the eardrum (but not by infrared sensor), or rectally. Oral temperatures and axillary (armpit) temperatures are not accurate in hypothermia.

Normal: Core body temperature @98.6 ± 1.0° F.

Mild hypothermia: Core body temperature 90-95° F. Shivering; impaired manual dexterity, grip strength and muscle coordination; impaired mental processes.

Moderate hypothermia: Core body temperature 82-90° F. Shivering ceases; loss of consciousness (at body temperatures under 86° F.); increased risk of cardiac irritability and dysrhythmias (irregular or abnormal heart rhythms).

Severe hypothermia: Core body temperature <82° F. Extremity stiffness; vital signs difficult to measure or absent; severe risk of ventricular fibrillation or cardiac arrest from rough handling during rescue or treatment; cardiac arrest or ventricular fibrillation usually occurs spontaneously at body temperatures below 77° F.

The body's responses to cold-water immersion can be divided into three stages: 1) initial immersion and the cold-shock response; 2) short-term immersion and loss of performance; and 3) long-term immersion and the onset of hypothermia. Each phase is accompanied by specific survival hazards for the immersion victim from a variety of physiological mechanisms. Deaths have occurred in all three phases of the immersion response.

Stage 1: Initial Immersion: the Cold Shock Response: The cold shock response occurs within the first 1-4 minutes of cold water immersion and is dependent on the extent and rate of skin cooling. The responses are generally those affecting the respiratory system and those affecting the heart and the body's metabolism. Rapid skin cooling initiates an immediate gasp response, the inability to breath-hold, and hyperventilation. The gasp response may cause drowning if the head is submersed during the initial entry into cold water. The significant lessening of breath holding time makes it more difficult to escape underwater from a capsized vessel, and it further increases the risk drowning in high seas. Finally, hyperventilation may cause a low level of blood carbon dioxide, which can lead to decreased brain blood flow and oxygen supply. This may lead to disorientation, loss of consciousness and drowning.

Skin cooling also initiates peripheral vasoconstriction (the constriction of small blood vessels in the skin and superficial tissues) as well as increased cardiac output, heart rate and blood pressure. The increased workload on the heart may lead to myocardial ischemia (low blood oxygen levels in the heart muscle) and arrhythmias (abnormal heart rhythm), including ventricular fibrillation. Thus, sudden death can occur either immediately or within a matter of minutes after immersion in susceptible individuals (i.e., victims with pre-existing heart disease or high blood pressure.

Stage 2: Short-Term Immersion: Impaired Performance: For those surviving the cold shock response, significant cooling of muscles and other soft tissue, especially in the extremities, continues with most of the effect occurring over the first 30 minutes of immersion. This cooling has a direct negative effect on neuromuscular activity (nerve and muscle control). This effect is especially significant in the hands, where blood circulation is negligible, leading to finger stiffness, poor coordination of gross and fine motor activity, and loss of power. It has been shown that this effect is primarily due to peripheral and not central cooling. The loss of motor control makes it difficult, if not impossible, to execute survival procedures such as grasping a rescue line or hoist, operating a radio, using signaling devices, etc. Thus the ultimate cause of death is drowning, either through a failure to initiate or maintain survival performance (i.e., keeping afloat, swimming, grasping onto a liferaft, etc.) or excessive inhalation of water under turbulent sea conditions.

These phenomena have obvious survival implications. It is, of course, advisable to avoid cold water exposure completely. If cold-water immersion does occur however, it is best to quickly determine and execute a plan of action: 1) try to enter the water without submersing the head; 2) escape (i.e., pull oneself out of the water, inflate and board a liferaft); 3) minimize exposure (i.e., get as much of one’s body as possible out of the water and onto a floating object); 4) ensure flotation if one must remain in the water (i.e., don or inflate a personal flotation device); and 5) call for assistance (i.e. activate signaling devices). It may be difficult to execute these actions while the cold shock is active. However, once the respiratory effects have subsided, immediate action should be taken. If self-rescue is not possible, actions to minimize heat loss should be initiated by remaining as still as possible, curling up in a fetal position. This posture is often called the “Heat Escape Lessening Posture”, or HELP, but it requires the use of personal flotation device (PFD) – see Figure (1)), or huddling with other survivors. Drawstrings should be tightened in clothing to decrease the flow of cold water within clothing layers.

Stage 3: Long-term immersion: hypothermia: Many cold-water deaths likely result from drowning during the first two stages of cold-water immersion. In general, true hypothermia usually only becomes a significant contributor to death if immersion lasts more than 30 minutes. The individual who survives the immediate and short term stages of cold-water immersion faces the possible onset of hypothermia as continuous heat loss from the body eventually decreases core body temperature.

Figure 1

The rate of body core cooling during cold-water immersion depends on the following variables: water temperature and sea state; clothing; body morphology; amount of the body immersed in water; behavior (e.g. excessive movement) and posture (e.g. fetal position, huddling, etc.) of the body in the water; amount of shivering; and other non-thermal factors.

RESCUE AND MANAGEMENT OF HYPOTHERMIA

The primary goals in pre-hospital management of victims of accidental immersion hypothermia are prevention of cardiopulmonary arrest, prevention of continued cooling, moderate core rewarming if practicable, and transportation to a site of definitive medical care. Aggressive rewarming in moderate or severe hypothermia is usually ill-advised, since the means to either diagnose or manage the many potential complications are often unavailable outside the hospital. However, when transportation to a site of definitive care is impossible, as is often the case aboard a vessel, rewarming the patient using the principles and techniques of management described in the following paragraphs, is appropriate.

Retrieval of a victim from cold water immersion must be performed with caution. Sudden reduction of the “hydrostatic squeeze” applied to tissues below the water’s surface may worsen low blood pressure. Since a hypothermic patient’s normal cardiovascular defenses are impaired, the cold heart may be incapable of increasing cardiac output in response to a sudden drop in blood pressure. A victim’s vertical posture may also worsen low blood pressure. Low blood volume, secondary to combined cold- and immersion-induced urination, and increased blood viscosity only aggravate these effects. The net result of sudden removal of a hypothermic patient from the water is similar to the sudden deflation of antishock trousers on a patient in hypovolemic (low blood volume) shock: abrupt hypotension (low blood pressure). This has been demonstrated experimentally in mildly hypothermic human volunteers, and it has been suspected as a cause of post-rescue death in many immersion hypothermia victims. Accordingly, rescuers should attempt to maintain hypothermic patients in a horizontal position during retrieval from the water and aboard the rescue vehicle. If rescuers cannot recover the patient horizontally, they should place the victim in a supine posture as quickly as possible after removal from cold water.

The patient’s core temperature may continue to decline (depending on the quality of insulation provided, the patient’s own heat production, active or passive manipulation of extremities, and the site of core temperature measurement) even after he/she has been rescued. This phenomenon is called afterdrop. To diminish this effect, the patient’s physical activity must be minimized. Conscious patients should not be required to assist in their own rescue (for example, by climbing up a scramble net or ship’s ladder) or to ambulate once out of the water (as by walking to a waiting ambulance or helicopter). Physical activity increases afterdrop, presumably by increasing the blood flow to cold muscle tissue with relatively warm blood. As this blood is cooled, venous return contributes to a decline in heart temperature, increasing the risk of ventricular fibrillation. Experiments on moderately hypothermic volunteers (esophageal temperature 91° F) demonstrated a threefold greater afterdrop during treadmill walking than while lying still. Such an exercise-induced enhancement of afterdrop could precipitate post-rescue collapse and death. Throughout the rescue procedures and during subsequent management, hypothermic patients must be handled gently. Excessive mechanical stimulation of the cold heart is another suspected cause of deaths after rescue.

Once the patient has been brought aboard the recovery vessel, vital signs, including core body temperature (using the techniques previously mentioned), must be carefully measured. Measure pulse and respirations for a full minute to ensure accuracy. For mild hypothermia, (e.g., the patient is alert and vigorously shivering), remove the wet clothing, provide a barrier to evaporation, and insulate the patient from further heat loss (including the head and neck). For patients who are fully conscious and who can eat or drink, supplying sugar containing food or drinks is appropriate, in order to provide energy for the patient’s shivering. Warm fluids may also be provided. A hot shower or bath may be used for rewarming. Otherwise, insulate the patient in a sleeping bag so as to retain the heat of shivering. Heating pads or other warm objects may also be used, but their value is reduced because these external sources of heat usually decrease the patient’s shivering, which is a more efficient means of rewarming.

For moderate or severe hypothermia (e.g., the patient is not shivering, has a reduced level of consciousness or is unconscious), maintain the patient in a horizontal posture. Do not permit them to sit, stand or exercise, and do not put them in a hot shower or hot bath. If available, administer heated, humidified oxygen. Insulate them as above, but do not provide any food or fluids by mouth. Moderate or severely hypothermia victims have both a reduced gag reflex and a diminished cough reflex, thus increasing their risk for aspiration (inhaling) fluid or food particles. External sources of heat should be used to rewarm the patient (e.g., forced heated air, heating pads, hot water bottles, warmed blankets, radiant heat, body-to-body rewarming, etc.). However, be aware that cold skin is easily burned (severe burns have resulted from hot water bottles placed directly on hypothermic skin), so insulate the skin from direct contact to warm objects. If available, administer warm intravenous fluids (heated to 104-108° F). If the patient requires intubation, ventilate and pre-oxygenate for 3 minutes before intubating. Avoid hyperventilation. If the victim is in cardiopulmonary arrest (for severely hypothermic patients, check the pulse for 60 seconds before diagnosing pulselessness) CPR and modified techniques of Advance Cardiac Life Support (ACLS) must be instituted. Do NOT administer any of the
cardiac drugs used in the usual ACLS protocols, as the cold patient does not metabolize these drugs normally. If defibrillation is required, use only one shock if the core temperature is less than 86° F; further defibrillations are permitted at higher body temperatures, if necessary.

If you like graphics ... here's one to add to your collection, for hypothermia. Click on link to get the full graphic:

How to Survive Hypothermia
https://www.thereadystore.com/emergency-supplies/10121/how-to-survive-hypothermia/

 Hypothermia, in short, is when the bodies temperature dramatically drops to a dangerously low level. Usually, hypothermia occurs during the winter months where there is snow. However, if you're out hiking and get wet without changing into dry clothes before temperatures drop, you can still be at risk... ---CONTINUED ---

Hypothermia – A Cold Hearted Killer
http://asurvivalplan.com/2011/12/18/hypothermia-a-cold-hearted-killer/

Hypothermia is the lowering of the body’s “core” temperature to below 95 degrees. The human body has a nominal normal temperature of 98.6 degrees. It will try to maintain this temperature through warming in cold environments (shivering), and via cooling in warm (sweating). Blood flow is progressively reduced to the extremities – the hands and feet, then the arms and legs. The majority of the blood supply is restricted to circulating through the core to keep the blood warm, and the internal organs alive and functioning as close to normal as possible. It is a battle to prevent body heat from dissipating faster than it can be regenerated.   ---CONTINUED---

What Every Prepper Needs to Know About Hypothermia
https://www.backdoorsurvival.com/what-every-prepper-needs-to-know-about-hypothermia/

Hypothermia can be deadly so the more we know about it the better. Of course educating yourself regarding the effects of extremely cold weather on the human body is an important step to take before the icy cold weather sets in. That said, it is never too late to become informed, even if you are currently in the midst of a snow storm or a blizzard. ---CONTINUED---