Blood shift, the shifting of blood to the thoracic cavity, the region of the chest between the diaphragm and the neck, to avoid the collapse of the lungs under higher pressure during deeper dives.The reflex action is automatic and allows both a conscious and an unconscious person to survive longer without oxygen underwater than in a comparable situation on dry land. The exact mechanism for this effect has been debated and may be a result of brain cooling similar to the protective effects seen in people who are treated with deep hypothermia.The actual cause of death in cold or very cold water is usually lethal bodily reactions to increased heat loss and to freezing water, rather than any loss of core body temperature. Of those who die after plunging into freezing seas, around 20% die within 2 minutes from cold shock (uncontrolled rapid breathing and gasping causing water inhalation, a massive increase in blood pressure and cardiac strain leading to cardiac arrest, and panic), another 50% die within 15 – 30 minutes from cold incapacitation (loss of use and control of limbs and hands for swimming or gripping, as the body protectively shuts down the peripheral muscles of the limbs to protect its core), and exhaustion and unconsciousness cause drowning, claiming the rest within a similar time. A notable example of this occurred during the sinking of the Titanic, in which most people who entered the −2 °C (28 °F) water died within 15–30 minutes. [S]omething that almost no one in the maritime industry understands.
Epidemiology
In 2019 alone, roughly 236,000 people died from drowning, thereby causing it to be the third leading cause of unintentional death globally trailing only traffic injuries and falls.In many countries, drowning is one of the main causes of preventable death for children under 12 years old. In the United States in 2006, 1100 people under 20 years of age died from drowning. The United Kingdom has 450 drownings per year, or 1 per 150,000, whereas in the United States, there are about 6,500 drownings yearly, around 1 per 50,000. In Asia suffocation and drowning were the leading causes of preventable death for children under five years of age; a 2008 report by UNICEF found that in Bangladesh, for instance, 46 children drown each day.Due to a generally increased likelihood for risk-taking, males are four times more likely to have submersion injuries.In the fishing industry, the largest group of drownings is associated with vessel disasters in bad weather, followed by man-overboard incidents and boarding accidents at night, either in foreign ports or under the influence of alcohol. Scuba diving deaths are estimated at 700 to 800 per year, associated with inadequate training and experience, exhaustion, panic, carelessness and barotrauma. South Asia
Deaths due to drowning is high in the South Asian region with India, China, Pakistan and Bangladesh accounting for up to 52% of the global deaths.