[1] UNIV CALIF, SAN DIAGO, SCH MED, DEPT MED, PULMA DIV, LA JOLLA, CA 92037 USA
[2] MASSACHUSETTS GEN HOSP, ANESTHESIA LABS, RESP UNIT, BOSTON, MA 02118 USA
[3] HARVARD UNIV, MED SCH, BOSTON, MA 02115 USA
[4] MASSACHUSETTS GEN HOSP, LAB COMP SCI, BOSTON, MA 02114 USA