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Table 1 Baseline characteristics and perioperative data

From: Intraoperative mild hyperoxia may be associated with improved survival after off-pump coronary artery bypass grafting: a retrospective observational study

  Normoxia/near-normoxia (n = 229) Mild hyperoxia (n = 991) Severe hyperoxia (n = 173) P
Demographic data
 Age (y) 70 (63–75) 67 (60–73) 67 (58–73) 0.007
 Female 61 (26.6%) 227 (22.9%) 35 (20.2%) 0.298
 Body mass index (kg/m2) 25.4 (23.2–27.8) 24.0 (22.0–26.2) 23.1 (20.8–25.2) < 0.001
 Smoker 65 (28.4%) 311 (31.4%) 60 (34.7%) 0.401
Medical history
 Hypertension 164 (71.6%) 614 (62.0%) 91 (52.6%) <0.001
 Diabetes on insulin 33 (14.4%) 135 (13.6%) 21 (12.1%) 0.802
 Dyslipidaemia 72 (31.4%) 267 (26.9%) 39 (22.5%) 0.135
 Atrial fibrillation 16 (7.0%) 58 (5.9%) 10 (5.8%) 0.801
 Recent myocardial infarctiona 48 (21.0%) 148 (14.9%) 20 (11.6%) 0.023
 Congestive heart failure 17 (7.4%) 56 (5.7%) 16 (9.2%) 0.159
 Chronic lung disease 15 (6.6%) 38 (3.8%) 7 (4.0%) 0.186
 Extracardiac arteriopathy 46 (20.1%) 181 (18.3%) 33 (19.1%) 0.807
 Cerebrovascular disease 57 (24.9%) 225 (22.7%) 35 (20.2%) 0.543
 Previous cardiac surgery 3 (1.3%) 24 (2.4%) 2 (1.2%) 0.376
Preoperative clinical data
 Left ventricular systolic function     0.536
  Normal (EF > 50%) 155 (67.7%) 729 (73.6%) 122 (70.5%)  
  Moderate (EF 31–50%) 54 (23.6%) 198 (20.0%) 38 (22.0%)  
  Poor (EF 21–30%) 18 (7.9%) 52 (5.2%) 10 (5.8%)  
  Very poor (EF ≤ 20%) 2 (0.9%) 12 (1.2%) 3 (1.7%)  
 Pulmonary hypertensionb 41 (17.9%) 113 (11.4%) 15 (8.7%) 0.008
 Left main coronary artery disease 62 (27.1%) 254 (25.6%) 37 (21.4%) 0.399
 Renal impairmentc     0.444
  Normal (CC > 85 mL/min) 57 (24.9%) 245 (24.7%) 38 (22.0%)  
  Moderate (CC 50–85 mL/min) 108 (47.2%) 485 (48.9%) 82 (47.4%)  
  Severe (CC < 50 mL/min) 47 (20.5%) 191 (19.3%) 32 (18.5%)  
  On dialysis regardless of CC 17 (7.4%) 70 (7.1%) 21 (12.1%)  
  Haematocrit (%) 38 (5) 38 (4) 37 (4) 0.186
Surgery profile
 Emergency 18 (7.9%) 38 (3.8%) 4 (2.3%) 0.010
 No. of coronary artery anastomoses 3 (3–4) 4 (3–4) 3 (3–4) 0.368
 Duration of surgery (min) 365 (317–400) 360 (325–395) 325 (295–370) < 0.001
  1. Values are expressed as mean (standard deviation), median (interquartile range), or number (%)
  2. EF Ejection fraction, CC Creatinine clearance
  3. aMyocardial infarction within 90 days prior to surgery
  4. bDefined as the first intraoperative pulmonary artery systolic pressure measurement of > 30 mmHg
  5. cBased on creatinine clearance calculated using Cockcroft-Gault formula