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Table 1 Baseline characteristics

From: Prone positioning in severe ARDS requiring extracorporeal membrane oxygenation

  All (n = 158) Prone (n = 38) Supine (n = 120) p value
Demographics
 Age (years) 54.5 (41.8–64.0) 51.5 (38.5–64.0) 55.5 (44.0–64.0) 0.549
 Sex (male) 106 (67.1%) 28 (73.7%) 78 (65.0%) 0.321
 BMI (kg/m2) 24.7 (22.9–28.8) 24.8 (24.0–28.7) 24.4 (22.9–28.9) 0.566
 Underlying pulmonary disease 55 (34.8%) 12 (31.6%) 43 (35.8%) 0.631
  COPD 11 (7.0%) 1 (2.6%) 10 (8.3%) 0.229
  Asthma 10 (6.3%) 1 (2.6%) 9 (7.5%) 0.283
  Lung fibrosis 18 (11.4%) 5 (13.2%) 13 (10.8%) 0.694
  Cystic fibrosis 7 (4.4%) 2 (5.3%) 5 (4.2%) 0.775
  LTOT 11 (7.0%) 1 (2.6%) 10 (8.3%) 0.229
  Pulmonary hypertension 6 (3.8%) 0 (0.0%) 6 (5.0%) 0.160
 Comorbidities
  Nicotine abuse 47 (29.7%) 9 (23.7%) 38 (31.7%) 0.348
  Hypertension 49 (31.0%) 10 (26.3%) 39 (32.5%) 0.473
  Diabetes mellitus 24 (15.2%) 6 (15.8%) 18 (15.0%) 0.906
  CAD 20 (12.7%) 5 (13.2%) 15 (12.5%) 0.915
  Chronic renal failure 12 (7.6%) 6 (15.8%) 6 (5.0%) 0.029
  Chronic haemodialysis 2 (1.3%) 1 (2.6%) 1 (0.8%) 0.388
  Liver cirrhosis/hepatitis 17 (10.8%) 3 (7.9%) 14 (11.7%) 0.513
  Immunosuppression 57 (36.1%) 13 (34.2%) 44 (36.7%) 0.783
Procedural characteristics
 Oxygenation pre-ECMO
  FiO2 (%) 100 (80–100) 90 (80–100) 100 (80–100) 0.233
  Horowitz index (mmHg) 77.1 (63.1–107.1) 77.6 (60.1–105.2) 76.8 (63.2–109.0) 0.828
  D(A-a)O2 (mmHg) 531 (419–592) 492 (416–579) 542 (418–595) 0.369
 Duration of MV before ECMO (days) 1.3 (0.3–5.0) 2.2 (0.2–7.6) 1.1 (0.3–3.5) 0.133
 Prone positioning before ECMO 26 (16.5%) 7 (18.4%) 19 (15.8%) 0.708
 Acute renal failure 50 (31.6%) 13 (34.2%) 37 (30.8%) 0.696
 Scores
  SOFA score 14.0 (11.0–16.0) 13.0 (11.0–15.0) 14.0 (11.0–16.8) 0.146
  APACHE II score 26.0 (21.8–32.0) 24.0 (22.8–28.3) 27.0 (20.3–32.0) 0.364
  RESP score 1 (− 2.0–2.0) 0 (− 3.0–2.0) 1.0 (− 2.0–2.0) 0.702
 Causes of ARDS
  Pneumonia 116 (73.4%) 33 (86.8%) 83 (69.2%) 0.032
  Aspiration 15 (9.5%) 2 (5.3%) 13 (10.8%) 0.307
  Inhalation injury 1 (0.6%) 0 (0.0%) 1 (0.8%) 0.572
  Drowning 2 (1.3%) 0 (0.0%) 2 (1.7%) 0.423
  Autoimmune injury 10 (6.3%) 2 (5.3%) 8 (6.7%) 0.757
  Sepsis 10 (6.3%) 1 (2.6%) 9 (7.5%) 0.283
  Pancreatitis 1 (0.6%) 0 (0.0%) 1 (0.8%) 0.572
  Other injuries 3 (1.9%) 0 (0.0%) 3 (2.5%) 0.325
 Pulmonary pathogen spectrum
  Bacterial 62 (39.2%) 16 (42.1%) 46 (38.3%) 0.678
  Viral 30 (19.0%) 13 (34.2%) 17 (14.2%) 0.006
  Fungal 27 (17.1%) 14 (36.8%) 13 (10.8%) < 0.001
Pneumocystis jirovecii 11 (7.0%) 7 (18.4%) 4 (3.3%) 0.001
  1. APACHE II Acute Physiology and Chronic Health Evaluation, ARDS acute respiratory distress syndrome, BMI body mass index, COPD chronic obstructive pulmonary disease, CAD coronary artery disease, D(A-a)O2 alveolar-arterial gradient of oxygen concentration, ECMO extracorporeal membrane oxygenation, FiO2 fraction of inspired oxygen, LTOT long-term oxygen therapy, MV mechanical ventilation, RESP Respiratory Extracorporeal Membrane Oxygenation Survival Prediction, SOFA Sequential Organ Failure Assessment. Categorical variables are presented as frequency (percentages). Continuous variables are presented as median (IQR)