Table 3.
Comparison of the low O/R ratio group and the high O/R group
| Variables | Low O/R ratio group n = 14 |
High O/R ratio group n = 16 |
P value |
|---|---|---|---|
| Age (years) | 57 (45–75) | 66 (55–74) | 0.275 |
| APACHE II score | 16 (14–21) | 21 (15–26) | 0.166 |
| High-risk ARDS | 5/14 | 5/14 | 0.703 |
| Mild ARDS | 3/14 | 5/16 | 0.399 |
| Moderate ARDS | 4/14 | 5/16 | 1.000 |
| Severe ARDS | 2/14 | 1/16 | 1.000 |
| FiO2 (%) | 40 (30–60) | 40 (30–50) | 0.473 |
| PEEP at baseline (cmH2O) | 8 (5–10) | 6 (5–8) | 0.334 |
| PaO2/FiO2 at baseline | 208 (112–355) | 233 (187–331) | 0.759 |
| Vt at baseline (ml) | 410 (400–463) | 450 (380–503) | 0.759 |
| 28-day mortality | 3/14 | 4/16 | 0.811 |
| HR (bpm) | |||
| ZEEP | 91 (81–114) | 99 (82–105) | 0.951 |
| High PEEP | 91 (80–112) | 97 (83–105) | 0.918 |
| MAP (mmHg) | |||
| ZEEP | 86 (82–95) | 87 (79–89) | 0.886 |
| High PEEP | 86 (80–89) | 84 (76–97) | 0.984 |
| SpO2 (%) | |||
| ZEEP | 95 (90–99) | 97 (91–97) | 0.697 |
| High PEEP | 99 (96–99)¶ | 97 (94–99) | 0.131 |
| ΔSpO2 (%) | 3 (0–8) | 0 (− 1 to 5) | 0.093 |
| Shunt% | |||
| ZEEP | 26 (16–42) | 15 (9–24) | 0.013* |
| High PEEP | 11 (5–21)¶ | 16 (9–19) | 0.580 |
| ΔShunt% | − 12 (− 23 to − 5) | − 2 (− 7 to 6) | 0.002* |
| DeadSpace% | |||
| ZEEP | 20 (11–28) | 17 (8–25) | 0.448 |
| High PEEP | 13 (3–18)¶ | 13 (5–19) | 0.580 |
| ΔDeadSpace% | − 6 (− 16 to − 1) | − 4 (− 8 to 3) | 0.473 |
| VQMatch% | |||
| ZEEP | 47 (45–61) | 68 (59–75) | 0.001* |
| High PEEP | 74 (67–80)¶ | 73 (60–78) | 0.377 |
| ΔVQMatch% | 29.7 (22.5–34.4) | 3.6 (− 0.3 to 11) | < 0.0001* |
| GI | |||
| ZEEP | 0.427 (0.379–0.504) | 0.411 (0.365–0.505) | 0.355 |
| High PEEP | 0.360 (0.335–0.381)¶ | 0.425 (0.389–0.478) | 0.002* |
| ΔGI | − 0.071 (− 0.121 to − 0.028) | 0.015 (− 0.044 to 0.095) | 0.015* |
| EELI (AU) | |||
| ZEEP | 1500 (964–1850) | 1250 (1000–1775) | 0.918 |
| High PEEP | 6450 (4400–8325)¶ | 7850 (5450–13,000)¶ | 0.110 |
| ΔEELI (AU) | 5000 (3125–6850) | 6550 (3650–11,025) | 0.093 |
| R pixels | |||
| Total | 188 (107–260) | 94 (63–145) | 0.003* |
| Ventral | 99 (28–146) | 22 (4–43) | 0.355 |
| Dorsal | 102 (36–146) | 72 (58–105) | 0.001* |
| O pixels | |||
| Total | 0 (0–17) | 110 (93–149) | < 0.0001* |
| Ventral | 0 (0–17) | 107 (91–147) | < 0.0001* |
| Dorsal | 0 (0–0) | 0 (0–4) | 0.043* |
| O/R pixels ratio | 0 (0–0.12) | 1.0 (0.58–2.20) | < 0.0001* |
Δ = high PEEP − ZEEP
*Significantly different comparing the low O/R and high O/R groups
¶R < 0.05 compared to low PEEP