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Table 1 Baseline characteristics of the patients

From: Lower versus higher hemoglobin threshold for transfusion in ARDS patients with and without ECMO

Characteristic Higher-threshold group
(N = 96)
Lower-threshold group
(N = 96)
P value SMD
Age (years) 52.0 (37.8–61.0) 51.0 (38.0–61.0) 0.85 0.040
Male sex, n (%) 59 (61.5) 68 (70.8) 0.22 0.199
Body mass index (kg/cm) 27.3 (24.1–31.2) 26.3 (23.4–29.7) 0.27 0.152
Charlson comorbidity index 2.0 (1.0–4.0) 2.0 (0.0–5.0) 0.99 0.076
Immunocompromised, n (%) 22 (22.9) 22 (22.9) 0.99 < 0.001
Year of admission, n (%)    < 0.001 1.830
 2007–2010 41 (42.7) 9 (9.4)   
 2011–2014 46 (47.9) 14 (14.6)   
 2015–2018 9 (9.4) 73 (76.0)   
SOFA at ARDS onset 12.0 (9.0–15.0) 12.0 (9.0–16.0) 0.80 0.022
SAPS II at ARDS onset 57.5 (38.0–69.2) 57.0 (41.8–68.0) 0.74 0.030
RASS at ARDS onset − 5.0 (− 5.0 to − 4.0) − 5.0 (− 5.0 to − 4.4) 0.49 < 0.001
Chronic lung disease, n (%) 25 (26.0) 26 (27.1) 0.99 0.024
Pulmonary origin, n (%) 78 (81.2) 77 (80.2) 0.99 0.026
Mechanical ventilation before admission (days) 1.0 (0.5–6.5) 1.5 (1.0–5.8) 0.59 0.004
ARDS severity, n (%)    0.99 < 0.001
 Mild 0 (0) 0 (0)   
 Moderate 10 (10.4) 10 (10.4)   
 Severe 86 (89.6) 86 (89.6)   
ARDS etiology, n (%)    0.67 0.228
 Pneumonia 64 (66.7) 57 (59.4)   
 Aspiration 10 (10.4) 14 (14.6)   
 Sepsis 7 (7.3) 6 (6.2)   
 Pancreatitis 2 (2.1) 5 (5.2)   
 Other 13 (13.5) 14 (14.6)   
Rescue therapy
 Inhaled nitric oxide, n (%) 80 (83.3) 62 (64.6) 0.005 0.437
 Prone positioning, n (%) 72 (75.0) 67 (69.8) 0.52 0.117
Extracorporeal life support, n (%)    0.85 0.132
  No ECLS 33 (34.4) 37 (38.5)   
  ECLA 9 (9.4) 6 (6.2)   
  ECMO 50 (52.1) 49 (51.0)   
  Combined 4 (4.2) 4 (4.2)   
Ventilation parameters after initial optimization
 PaO2:FiO2 (mmHg) 129 (93–174) 130 (100–182) 0.65 0.050
 Oxygenation index 17.5 (12.5–26.3) 17.9 (11.6–26.2) 0.70 0.082
 PEEP (cm H2O) 16.0 (14.3–18.3) 18.0 (14.1–19.8) 0.23 0.035
 Driving pressure (cm H2O) 16.0 (12.9–19.2) 16.0 (13.2–18.1) 0.87 0.009
 Tidal volume (ml/kg PBW) 5.5 (3.8–7.1) 5.8 (4.1–6.9) 0.83 0.096
 Compliance (ml/cm H2O) 27 (19.0–36.4) 30 (20.7–38.2) 0.41 0.028
ECMO initiation (ICU day) 0 (0–0) 0 (0–0) 0.55 0.050
ECMO pump flow (l/min) 3.8 (3.0–4.3) 3.8 (3.2–4.2) 0.88 0.090
ECMO sweep gas flow (l/min) 4.0 (3.0–6.8) 4.0 (3.0–6.0) 0.44 0.156
Septic shock, n (%) 53 (55.2) 47 (50.5) 0.56 0.094
Lactate (mg/dl) 19.0 (13.0–43.5) 19.0 (11.8–56.8) 0.95 0.007
pH 7.3 (7.2–7.4) 7.3 (7.2–7.3) 0.98 0.019
RRT, n (%) 60 (62.5) 63 (65.6) 0.76 0.065
  1. Data are expressed as median [25%, 75% quartiles] or frequencies [%], as appropriate. P values were calculated using the exact Wilcoxon–Mann–Whitney test and the Fisher’s exact test, as appropriate. Standardized mean differences (SMD) are provided
  2. SOFA Sequential Organ Failure Assessment, SAPS Simplified Acute Physiology Score, RASS Richmond Agitation-Sedation Scale, ECLS extracorporeal life support, ECLA pumpless extracorporeal lung assist, ECMO extracorporeal membrane oxygenation, PEEP positive end-expiratory pressure, PBW predicted body weight, ICU intensive care unit, RRT renal replacement therapy