Passive drowning: People who suddenly sink or have sunk due to a change in their circumstances. Examples include people who drown in an accident due to sudden loss of consciousness or sudden medical condition. Secondary drowning: Physiological response to foreign matter in the lungs due to drowning causing extrusion of liquid into the lungs (pulmonary edema) which adversely affects breathing. Silent drowning: Drowning without a noticeable external display of distress. Dry drowning
Dry drowning is a term that has never had an accepted medical definition, and that is currently medically discredited. Following the 2002 World Congress on Drowning in Amsterdam, a consensus definition of drowning was established: it is the "process of experiencing respiratory impairment from submersion/immersion in liquid." This definition resulted in only three legitimate drowning subsets: fatal drowning, non-fatal drowning with illness/injury, and non-fatal drowning without illness/injury. In response, major medical consensus organizations have adopted this definition worldwide and have officially discouraged any medical or publication use of the term "dry drowning". Such organizations include the International Liaison Committee on Resuscitation, the Wilderness Medical Society, the American Heart Association, the Utstein Style system, the International Lifesaving Federation, the International Conference on Drowning, Starfish Aquatics Institute, the American Red Cross, the Centers for Disease Control and Prevention (CDC), the World Health Organization and the American College of Emergency Physicians.Drowning experts have recognized that the resulting pathophysiology of hypoxemia, acidemia, and eventual death is the same whether water entered the lung or not.
CMS prevalence rates reported from the study are summarised below:

Ethiopia [3600–4100 m]: 0%
Tibetan Plateau (Tibetans): 0.91–1.2%
Indian Himalayas [3000–4200 m]: 4–7%
Kyrgyzstan [3000–4200 m]: 4.6%
Tibetan Plateau (Han Chinese): 5.6%
La Paz, Bolivia [3600 m]: 6% to 8%
Bolivia: 8–10%
Cerro de Pasco, Peru [4300 m]: 14.8–18.2%

References
External links

^  Online calculator illustrating blood oxygen carrying capacity at altitude