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Table 1 Perioperative patient characteristics before and after matching

From: High-frequency oscillatory ventilation and short-term outcome in neonates and infants undergoing cardiac surgery: a propensity score analysis

  Before matching After matching
  HFOV group (n = 120) Overall controls (n = 3,422) P- valuea CMV group ( n = 120) P- valueb
Age (days) 27, 7.7 to 100.2 58, 10 to 149 0.001 33.0, 7.0 to 89.5 0.83
Weight (kg) 3.4, 2.9 to 4.3 3.9, 3.2 to 5.4 < 0.001 3.3, 2.8 to 4.2 0.93
Surgery with cardiopulmonary bypass, n (%) 109 (90.8) 2560 (74.8) < 0.001 110 (91.7) 0.80
Duration of cardiopulmonary bypass (min) 128.0, 99.5 to 177.0 109.0, 77.0 to 134.0 < 0.001 128.0, 90.0 to 165.0 0.64
Conventional ultrafiltration rate (mL kg-1 h-1) 93.3, 69.9 to 120.6 96.6, 66.9, 132.3 0.27 98.3, 87.2 to 127.3 0.40
Aristotle scorec 9.0, 7.5 to 10.8 8, 6 to 10 < 0.001 9.0, 7.3 to 10.8 0.99
Surgery with deep hypothermic circulatory arrest, n (%) 19 (15.8) 251 (7.3) < 001 21 (17.5) 0.72
Re-sternotomy, n (%) 19 (15.8) 406 (11.9) 0.19 16 (13.3) 0.59
Requiring re-operation, n (%) 13 (10.8) 177 (5.2) 0.007 16 (13.3) 0.56
Re-operated within 48 hours, n (%) 3 (2.5) 18 (0.5) 0.03 2 (1.7) 0.66
Extracorporeal membrane oxygenation, n (%) 0 23 (0.7)   0  
Requirement for delayed sternal closure, n (%) 56 (46.7) 331 (9.7) < 0.001 57 (47.5) 0.85
Delay to sternal closure (days) 3, 2 to 4.2 4, 2 to 6 0.21 4, 3 to 7 0.08
Acute kidney injury requiring renal replacement therapy, n (%) 42 (35.0) 127 (3.7) < 0.001 39 (32.5) 0.58
Requirement for renal replacement therapy on the day of surgery, n (%) 37 (30.8) 89 (2.6) < 0.001 32 (26.7) 0.36
Duration of renal replacement therapy (days) 2, 1 to 4 3, 2 to 6 0.02 3, 2 to 7 0.09
The propensity score 0.07, 0.02 to 0.31 0.02, 0.01 to 0.03   0.07, 0.02 to 031  
  1. The "HFOV group" included all patients switched to high frequency oscillation on the day of surgery, "Overall controls" included all patients ventilated exclusively conventionally during the study period, and the "CMV group" included the patients ventilated exclusively conventionally in the matched set.
  2. CMV, conventional mechanical ventilation; HFOV, high-frequency oscillatory ventilation.
  3. acalculated before matching, using unpaired tests which compared the HFOV group with overall controls
  4. bcalculated after matching, using paired tests which compared the HFOV group with the CMV group
  5. caccounting for the surgical complexity
  6. Data are shown as medians and inter-quartile ranges, or as numbers and percentages.