Table 3.
Oxygenation and primary outcome
| PEEP group (n = 31) | ZEEP group (n = 29) | Difference in means 95% CI | P value | |
| FIO2 | ||||
| Preoperative | 0.21 | 0.21 | ||
| After intubation | 0.31 ± 0.01 | 0.31 ± 0.01 | ||
| Before awakening | 0.31 ± 0.01 | 0.31 ± 0.02 | ||
| Postoperative | 0.21 | 0.21 | ||
| SpO2 (%) | ||||
| Preoperative | 98.1 ± 1.6 | 97.8 ± 1.5 | ||
| After intubation | 98.6 ± 1.7 | 98.6 ± 1.4 | ||
| Before awakening | 98.2 ± 1.4 | 98.8 ± 0.9 | −0.6 (−1.1 to 0.1) | 0.082 |
| Postoperative | 94.9 ± 2.3a | 95.4 ± 2.0b | −0.5 (−1.7 to 0.6) | 0.319 |
| PaO2 (kPa) | ||||
| Preoperative | 11.2 ± 1.0 | 11.4 ± 1.5 | ||
| After intubation | 17.6 ± 3.5 | 18.8 ± 2.8 | ||
| Before awakening | 18.3 ± 3.5 | 19.1 ± 3.2b | −0.8 (−2.6 to 0.9) | 0.336 |
| Postoperative | 10.2 ± 1.3 | 10.1 ± 1.3b | 0.1 (−0.6 to 0.8) | 0.797 |
| Estimated venous admixture (%) | ||||
| Preoperative | 9.9 ± 3.8 | 9.4 ± 5.2 | ||
| After intubation | 6.9 ± 5.1 | 5.3 ± 3.5 | ||
| Before awakening | 5.7 ± 5.2 | 4.4 ± 4.3b | 1.3 (−1.1 to 3.8) | 0.288 |
| Postoperative | 14.8 ± 7.3 | 14.9 ± 6.5b | −0.1 (−3.7 to 3.4) | 0.933 |
| PaO2/FIO2 ratio (kPa) | ||||
| Preoperative | 53.5 ± 4.9 | 54.3 ± 7.1 | ||
| After intubation | 57.0 ± 10.2 | 60.4 ± 9.2 | ||
| Before awakening | 58.5 ± 10.6 | 61.0 ± 9.5b | −2.5 (−7.7 to 2.7) | 0.346 |
| Postoperative | 48.4 ± 6.4 | 48.0 ± 6.0b | 0.4 (−2.8 to 3.7) | 0.797 |
| Change in estimated venous admixture | ||||
| Preoperative vs. before awakening | 4.2 ± 5.6 | 4.9 ± 6.7b | −0.7 (−2.6 to 3.9) | 0.687 |
| 45 min postoperatively vs. before awakeningc | 9.1 ± 6.1 | 10.6 ± 6.0b | −1.5 (−4.6 to 1.7) | 0.354 |
| Change in PaO2/FIO2 ratio | ||||
| Preoperative vs. before awakening | −5.0 ± 10.2 | −6.4 ± 10.3b | 1.4 (−6.8 to 3.9) | 0.598 |
| 45 min postoperatively vs. before awakening | −10.1 ± 9.0 | −13.0 ± 8.4b | 2.9 (−1.6 to 7.4) | 0.204 |
Data are presented as mean ± SD.
FIO2, inspired oxygen fraction; PaO2, arterial oxygen partial pressure; SpO2, peripheral oxygen saturation.
a
n = 29, two missing values in the PEEP group.
b
n = 28, one missing value in the ZEEP group.
c
Primary outcome. Before awakening is after the completion of surgery and after capnoperitoneum. The postoperative values were recorded at the time of sampling the postoperative blood gas (at room air), 45 min after extubation. Estimated venous admixture is expressed as a percentage of cardiac output. An increase represents more venous admixture and thus impaired oxygenation.