Table 1 Characteristics of the study population according to baseline ratio of veno-arterial carbon dioxide difference to arterio-venous oxygen difference (P_vaCO₂/C_avO₂): “low group” has P_vaCO₂/C_avO₂ < 1.4 mmHg/mL, and “high group” has P_vaCO₂/C_avO₂ ≥ 1.4 mmHg/mL. Data are expressed as the median (25–75% percentiles) or count (%)

No of patients

13

27

Demographic characteristics

 Age, years

66 (55 − 80)

71 (62 − 84)

0.29

 APACHE II Score

24 (23 − 27)

24 (17 − 32)

0.98

Comorbidities

 Diabetes, n (%)

7 (53)

4 (26)

0.02

 Cirrhosis, n (%)

2 (15)

5 (18)

0.99

Sepsis, n (%)

11 (84)

14 (51)

 Pulmonary infection

9 (81)

9 (33)

0.04

Shock, n (%)

3 (23)

10 (37)

0.48

 Septic

2 (15)

7 (26)

 Hypovolemic

0

2 (7)

 Cardiogenic

1 (7)

1 (4)

Invasive Ventilation, n (%)

7 (54)

14 (52)

0.98

PEEP, cm H₂O

8 (5 − 9)

6 (5 − 10)

0.92

Lactate, mmol/L

2.6 (2.1 − 3.2)

2.6 (1.8 − 4.5)

0.75

Hemoglobin (mg/dL)

12.1 (9.6 − 13.3)

11.3 (9.8 − 13.1)

0.58

Enhanced OER,n (%)

4 (30)

6 (22)

0.71

Crystalloids,n (%)

6 (46)

12 (44)

0.73

Fluid volume (ml/kg)

8.27 (6.2 − 12.5)

8.62 (6.3 − 15.8)

0.76

Fluid rate (ml/min)

21.3 (16.9 − 32.5)

19.2 (16.1 − 23.5)

0.35

Baseline metabolic variables

 S_cvO_2, %

63 (53 − 71)

70 (61 − 75)

0.18

 P_vaCO_2, mmHg

4.6 (3.2 − 6.6)

8.7 (7.3 − 11.5)

< 0.01

 P_vaCO₂/C_avO_2, mmHg/mL

1.0 (0.8 − 1.1)

2.1(1.7 − 2.4)

< 0.01

 Oxygen delivery, mL/min/m²

355 (251 − 390)

442 (305 − 511)

0.07

 Oxygen consumption, mL/min/m²

101 (89 − 119)

106 (92 − 160)

0.22

 Oxygen extraction, %

33 (25 − 42)

28 (25 − 36)

0.34

Baseline hemodynamic variables

 Cardiac Index, L/min/m²

2.1 (1.7 − 2.4)

3.1 (1.9 − 3.6)

0.16

 Stroke Volume, mL

44 (39 − 52)

56 (40 − 68)

0.22

 Heart rate, beats/min

93 (75 − 105)

95 (79 − 112)

0.81

 Pulse Pressure, mmHg

53 (39 − 68)

57 (45 − 65)

0.26

 Mean Arterial Pressure, mmHg

77 (69 − 85)

80 (69 − 87)

0.64

 Central Venous Pressure, mmHg

10 (3 − 11)

8 (4 − 11)

0.87