Query: But more than 7% of deaths are related to cold—counting hypothermia, as well as increased blood pressure and risk of heart attack that results when the body restricts blood flow in response to frigid temperatures.”

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Drowning <=SEP=> Drowning is defined as respiratory impairment from being in or under a liquid . It is further classified by outcome into : death , ongoing health problems , and no ongoing health problems . Drowning itself is quick and silent , although it may be preceded by distress which is more visible .   Generally , in the early stages of drowning , very little water enters the lungs : a small amount of water entering the trachea causes a muscular spasm that seals the airway and prevents the passage of both air and water until unconsciousness occurs . This means a person drowning is unable to shout or call for help , or seek attention , as they can not obtain enough air . The instinctive drowning response is the final set of autonomic reactions in the 20 -- 60 seconds before sinking underwater , and to the untrained eye can look similar to calm safe behavior . Lifeguards and other persons trained in rescue learn to recognize drowning people by watching for these movements . If the process is not interrupted , loss of consciousness due to hypoxia is followed rapidly by cardiac arrest . At this stage , the process is still usually reversible by prompt and effective rescue and first aid . Survival rates depend strongly on the duration of immersion .   In 2013 , there were about 1.7 million cases of drowning . Unintentional drowning is the third leading cause of unintentional injury resulting in death worldwide . In 2013 , it was estimated to have resulted in 368,000 deaths , down from 545,000 deaths in 1990 . Of these deaths , 82,000 occurred in children less than five years old . It accounts for 7 % of all injury related deaths ( excluding those due to natural disasters ) , with 91 % of these deaths occurring in low-income and middle-income countries . Drowning occurs more frequently in males and the young . The rate of drowning in populations around the world varies widely according to their access to water , the climate and the national swimming culture .  Most drownings are preventable .

Hypothermia <=SEP=> 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. 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 his or her 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 , among others . Body temperature is usually maintained near a constant level of 36.5 -- 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 . 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 1500 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 in a near-drowning of a 7-year-old girl in Sweden . Survival after more than six hours of CPR has been described . In those in 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 , ypo , meaning `` under '' , and θερμία , thermía , meaning `` heat '' . The opposite of hypothermia is hyperthermia , an increased body temperature due to failed thermoregulation .

Underwater diving <=SEP=> Underwater diving is the practice of descending below the water 's surface to conduct underwater activities . In ambient pressure diving , the diver is exposed to the pressure of the surrounding water , and uses breathing apparatus for scuba diving or surface supplied diving , or when freediving , will breath-hold . The saturation diving technique reduces the risk of decompression sickness after long duration deep dives . Atmospheric diving suits may be used to isolate the diver from the effects of high ambient pressure . Although not usually considered to be diving , crewed submersibles can extend depth range , while remotely controlled or robotic diving machines can reduce the risk to human divers .   The diving environment exposes the diver to a wide range of hazards , and though the risks are largely controlled by appropriate diving skills , training , types of equipment and breathing gases used depending on the mode , depth and purpose of diving , it remains a relatively dangerous activity . Diving activities are restricted to relatively shallow depths ranging from around 40 m ( 130 ft. ) maximum for recreational Scuba diving to commercial saturation diving maximum around 534 metres ( 1,752 ft ) and 610 metres ( 2,000 ft ) wearing atmospheric diving suits . Diving is also restricted to conditions which are not excessively hazardous , though the level of risk acceptable to the diver can vary considerably . Occasionally diving may be done in liquids other than water .   Recreational diving , sometimes called sport diving or subaquatics , is a popular leisure activity . Technical diving is a form of recreational diving that achieves greater depths or endurance in more challenging conditions . Professional diving ( commercial diving , diving for scientific research purposes or diving for financial gain ) takes a range of diving activities to the underwater work site . Public safety diving is the underwater work done by law enforcement , fire rescue , and search & rescue/recovery dive teams , and may be done by professionals or volunteers . Military diving includes combat diving , clearance diving and ship 's husbandry diving . Underwater sports is a group of competitive sports using either free-diving , snorkeling or scuba technique , or a combination of these techniques . The term `` deep sea diving '' refers to underwater diving , usually with surface supplied equipment , and often refers specifically to the use of standard diving dress with the traditional copper helmet . `` Hard hat '' diving is any form of diving with a helmet , including the standard copper helmet , and other forms of free-flow and lightweight demand helmets .

Cardiovascular disease <=SEP=> Cardiovascular disease ( CVD ) is a class of diseases that involve the heart or blood vessels . Cardiovascular disease includes coronary artery diseases ( CAD ) such as angina and myocardial infarction ( commonly known as a heart attack ) . Other CVDs include stroke , heart failure , hypertensive heart disease , rheumatic heart disease , cardiomyopathy , heart arrhythmia , congenital heart disease , valvular heart disease , carditis , aortic aneurysms , peripheral artery disease , thromboembolic disease , and venous thrombosis .   The underlying mechanisms vary depending on the disease in question . Coronary artery disease , stroke , and peripheral artery disease involve atherosclerosis . This may be caused by high blood pressure , smoking , diabetes , lack of exercise , obesity , high blood cholesterol , poor diet , and excessive alcohol consumption , among others . High blood pressure results in 13 % of CVD deaths , while tobacco results in 9 % , diabetes 6 % , lack of exercise 6 % and obesity 5 % . Rheumatic heart disease may follow untreated strep throat .   It is estimated that 90 % of CVD is preventable . Prevention of atherosclerosis involves improving risk factors through : healthy eating , exercise , avoidance of tobacco smoke and limiting alcohol intake . Treating risk factors , such as high blood pressure , blood lipids and diabetes is also beneficial . Treating people who have strep throat with antibiotics can decrease the risk of rheumatic heart disease . The effect of the use of aspirin in people who are otherwise healthy is of unclear benefit .   Cardiovascular diseases are the leading cause of death globally . This is true in all areas of the world except Africa . Together they resulted in 17.9 million deaths ( 32.1 % ) in 2015 up from 12.3 million ( 25.8 % ) in 1990 . Deaths , at a given age , from CVD are more common and have been increasing in much of the developing world , while rates have declined in most of the developed world since the 1970s . Coronary artery disease and stroke account for 80 % of CVD deaths in males and 75 % of CVD deaths in females . Most cardiovascular disease affects older adults . In the United States 11 % of people between 20 and 40 have CVD , while 37 % between 40 and 60 , 71 % of people between 60 and 80 , and 85 % of people over 80 have CVD . The average age of death from coronary artery disease in the developed world is around 80 while it is around 68 in the developing world . Disease onset is typically seven to ten years earlier in men as compared to women .

Shock (circulatory) <=SEP=> Circulatory shock , commonly known as shock , is a life-threatening medical condition of low blood perfusion to tissues resulting in cellular injury and inadequate tissue function . The typical signs of shock are low blood pressure , rapid heart rate , signs of poor end-organ perfusion ( i.e. : low urine output , confusion , or loss of consciousness ) , and weak pulses .   The shock index ( SI ) , defined as heart rate divided by systolic blood pressure , is an accurate diagnostic measure that is more useful than hypotension and tachycardia in isolation . Under normal conditions , a number between 0.5 and 0.8 is typically seen . Should that number increase , so does suspicion of an underlying state of shock . Blood pressure alone may not be a reliable sign for shock , as there are times when a person is in circulatory shock but has a stable blood pressure .   Circulatory shock is not related to the emotional state of shock . Circulatory shock is a life-threatening medical emergency and one of the most common causes of death for critically ill people . Shock can have a variety of effects , all with similar outcomes , but all relate to a problem with the body 's circulatory system . For example , shock may lead to hypoxemia ( a lack of oxygen in arterial blood ) or cardiac and/or respiratory arrest .   One of the key dangers of shock is that it progresses by a positive feedback mechanism . Poor blood supply leads to cellular damage , which results in an inflammatory response to increase blood flow to the affected area . This is normally very useful to match up supply with tissue demand for nutrients . However , if enough tissue causes this , it will deprive vital nutrients from other parts of the body . Additionally , the ability of the circulatory system to meet this increase in demand causes saturation , a major result of which is that other parts of the body begin to respond in a similar way , thus exacerbating the problem . Due to this chain of events , immediate treatment of shock is critical to survival .