[1] Chiba Hokusoh Hosp, Nippon Med Sch, Hokusoh HEMS, Shock & Trauma Ctr, Inzai, Japan
[2] Kyorin Univ, Sch Med, Mitaka, Tokyo 181, Japan
[3] Keio Univ, Sch Med, Shinjyuku Ku, Tokyo 108, Japan
[4] Nippon Med Sch, Bunkyo Ku, 1-1-5 Sendagi, Tokyo 113, Japan
[5] Chiba Hokusoh Hosp, Nippon Med Sch, Inzai, Japan