Fig. 3.

Changes in arterial oxygen pressure (PaO₂, A), arterial carbon dioxide pressure (PaCO₂, B) and difference in the alveolar-arterial PO₂ difference (AaDO₂, C) from pre-insufflation in the supine position, during carbon dioxide insufflation (+ 30 min to + 4 h) in the head-down position, and after deflation in the supine position with increasing PEEP. PEEP: positive end-expiratory pressure, ZEEP: no PEEP, Data are expressed as mean ± SD. ^*P < 0.05 versus pre-insufflation. ^†P < 0.05 versus the ZEEP group.