[1] Univ Amsterdam, Acad Med Ctr, Dept Intens Care Med, NL-1105 AZ Amsterdam, Netherlands
[2] Univ Amsterdam, Acad Med Ctr, Dept Internal Med, NL-1105 AZ Amsterdam, Netherlands
[3] Univ Amsterdam, Acad Med Ctr, Lab Expt Internal Med, NL-1105 AZ Amsterdam, Netherlands
[4] John Radcliffe Hosp, Intens Therapy Unit, Oxford OX3 9DU, England