Altitude;
Medical;
Research;
Institute,;
Xining;
810012,;
China;
Altitude;
Medical;
Research;
Center,;
Tibet;
University,;
Lhasa;
850002,;
China;
Care;
Unit;
of;
Qinghai;
Provincial;
People's;
Hospital,;
Xining;
810007,;
China;
of;
Inter.;
Med.,;
Qinghai;
Cardio-Cerebral-Vascular;
Hospital,;
Xining;
810012,;
China;
Division;
of;
Qinghai;
Provincial;
People's;
Hospital,;
Xining;
810000,;
China;