[1] Univ Copenhagen, Rigshosp, DK-1168 Copenhagen, Denmark
[2] Bispebjerg Hosp, Copenhagen, Denmark
[3] Copenhagen Univ Hosp Gentofte, Dept Surg, Endoscop Unit, Gentofte, Denmark
[4] Heidelberg Univ, Thoraxklin, Dept Pneumol & Resp Crit Care Med, D-69115 Heidelberg, Germany