Table 4.
Gas exchange.
| Variable | Group | BL | TLVsupine | OLVsupine | OLVsemilateral | OLVlateral | OLVprone | Sequence P = | Group P = | Position P = | ME P = | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| pHa | Normo | 7.38 ± 0.04 | 7.39 ± 0.03 | s, se, l, p | 7.29 ± 0.08 | l | 7.28 ± 0.1 | 7.31 ± 0.08 | 7.29 ± 0.08 | 0.481 | 0.304 | ≤ 0.001 | 0.629 | |||
| Hypo | 7.42 ± 0.07 | 7.39 ± 0.06 | 7.23 ± 0.13 | 7.25 ± 0.11 | 7.26 ± 0.12 | 7.25 ± 0.11 | ||||||||||
| PaCO2 [mmHg] | Normo | 54 ± 6 | 53 ± 5 | s, se, l, p | 65 ± 13 | 66 ± 12 | 63 ± 11 | 64 ± 13 | 0.464 | 0.425 | ≤ 0.001 | 0.273 | ||||
| Hypo | 50 ± 12 | 51 ± 7 | 72 ± 17 | 69 ± 13 | 69 ± 15 | 69 ± 15 | ||||||||||
| FIO2/PaO2 [mmHg] | Normo | 509 ± 50 | 562 ± 45 | s, se, l, p | 78 ± 18 | 89 ± 20 | 123 ± 45 | s, se, p | 78 ± 9 | 0.936 | 0.878 | ≤ 0.001 | 0.940 | |||
| Hypo | 504 ± 105 | 565 ± 64 | 85 ± 26 | 80 ± 24 | 101 ± 14 | 94 ± 24 | ||||||||||
| SaO2 [%] | Normo | 100 ± 1 | 99 ± 4 | s, se, l, p | 90 ± 7 | 91 ± 6 | 95 ± 5 | s | 91 ± 8 | 0.862 | 0.578 | ≤ 0.001 | 0.603 | |||
| Hypo | 100 ± 1 | 100 ± 0 | 85 ± 10 | 90 ± 9 | 94 ± 5 | 89 ± 8 | ||||||||||
| SvO2 [%] | Normo | 77 ± 7 | 78 ± 12 | s, se, p | 64 ± 9 | 64 ± 10 | 76 ± 9 | s, p | 65 ± 13 | 0.862 | 0.578 | ≤ 0.001 | 0.459 | |||
| Hypo | 78 ± 6 | 79 ± 6 | 62 ± 14 | 65 ± 12 | 67 ± 12 | 61 ± 16 |
Mean ± SD; Normo, normovolemia group; Hypo, hypovolemia group; BL, baseline; TLV, two-lung ventilation; OLV, one-lung ventilation; pHa, arterial pH, FIO2, fraction of inspired oxygen; PaO2, arterial partial pressure of oxygen; PaCO2, arterial partial pressure of carbon dioxide, SaO2, arterial oxygen saturation; SvO2, mixed venous oxygen saturation; ME, mixed effects position × group. Significance was accepted at P < 0.05. Differences between the two groups, respective body positions, and the sequences of interventions were compared using a linear mixed-effects model with repeated measures, with TLVsupine, OLVsupine, OLVsemilateral, OLVlateral, and OLVprone as within-subject factors and with group and sequence as fixed between subject-factors. The significance of the within-subject factors was corrected for sphericity according to Greenhouse–Geisser. Pairwise post-hoc multiple comparisons were performed according to LSD when appropriate. s P < 0.05 vs. OLVsupine, se P < 0.05 vs. OLVsemilateral, l P < 0.05 vs. OLVlateral, and p P < 0.05 vs. OLVprone.