[1] Harvard Univ, Sch Med, Massachusetts Gen Hosp, Dept Anesthesia Crit Care & Pain Med, 55 Fruit St,GRB 444, Boston, MA 02114 USA
[2] Cedars Sinai Med Ctr, Dept Anesthesiol, Los Angeles, CA 90048 USA
[3] Univ Bologna, Inst Ortoped Rizzoli, I-40126 Bologna, Italy
[4] White Mt Inst, The Sea Ranch, CA USA