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Table 1 Patient demographics

From: Do heart and respiratory rate variability improve prediction of extubation outcomes in critically ill patients?

  Passed extubation Failed extubation P value*
  (N = 383)^ (N = 51)^  
Gender:    
  Males, n (%) 186 (48.6) 29 (56.7) 0.27
  Females, n (%) 191 (49.9) 21 (41.2) 0.24
Age (95% CI) 63 (61, 64) 65 (58, 69) 0.86
APACHE II score (95% CI) 19 (19, 20) 20 (18, 23) 0.21
Level of sedationx (95% CI) 0 (0, 0) 0 (−1, 0) 0.78
ICU admission diagnoses    
  Cardiovascular, n (%) 112 (25.4) 12 (20.0) 0.40
  Respiratory, n (%) 87 (19.7) 18 (30.0) 0.05
  Infections, n (%) 62 (14.1) 10 (16.7) 0.54
  Gastrointestinal, n (%) 34 (7.7) 3 (5.0) -
  Surgery, n (%) 33 (7.5) 3 (5.0) -
  Head, n (%) 36 (8.2) 1 (1.7) -
  Renal, n (%) 18 (4.1) 2 (3.3) -
  Trauma, n (%) 8 (1.8) 1 (1.7) -
  Overdose, n (%) 9 (2.0) 1 (1.7) -
  Pancreatitis, n (%) 3 (0.7) 1 (1.7) -
  Hepatobiliar, n (%) 5 (1.1) 0 (0.0) -
  Other, n (%) 34 (7.7) 8 (13.3) 0.12
Comorbidities+:    
  None, n (%) 237 (61.9) 28 (54.9) 0.34
  Lung, n (%) 90 (23.5) 15 (29.4) 0.35
  Heart, n (%) 81 (21.1) 13 (25.5) 0.48
  Both, n (%) 25 (6.5) 5 (9.8) 0.39
Ventilation settings pre-SBT:    
  PEEP (95% CI) (cm H2O) 10 (8 10) 8 (8 10) 0.90
  PS (95% CI) (cm H2O) 10 (10 10) 10 (10 10) 0.14
  FiO2, (95% CI) 30 (30 30) 30 (30 30) 0.04
Ventilation settings during SBT:    
  PEEP (95% CI) (cm H2O) 5 (5 5) 5 (5 5) 0.46
  PS (95% CI) (cm H2O) 5 (5 5) 5 (5 5) 0.01
  FiO2, (95% CI) 30 (30 30) 30 (30 30) 0.11
Perceived risk of failure:    
  N/A, n (%) 53 (13.8) 7 (13.7) 0.98
  Low, n (%) 117 (30.5) 6 (11.7) 0.005
  Average, n (%) 180 (47.0) 26 (51.1) 0.59
  High, n (%) 33 (8.7) 12 (23.5) 0.001
Respiratory rate: [breaths/min]    
  Pre-SBT (95% CI) 16.0 (16.0, 18.0) 18.0 (15.0, 22.0) 0.09
  During SBT (95% CI) 18.4 (17.9, 19.0) 21.7 (18.7, 25.0) 0.005
RSBI: [breaths/min/L]    
  Pre-SBT (95% CI) 34.1 (31.8, 36.4) 40.0 (32.5, 50.0) 0.16
  During SBT (95% CI) 42.7 (39.3, 45.6) 46.6 (40.0, 67.5) 0.005
  1. Low, average and high-risk categories were based on clinical impression. ^There is a maximum amount of 2% of missing values in each category, due to clinical data not recorded (for example males and females in the failed population add up to 50, instead of 51); *comparison between passed and failed using Wilcoxon rank-sum test to compare the medians, or chi-square test to compare the proportions (no P value was provided for those variables with less than five samples); xcomputed through Richmond agitation-sedation scale (RASS) score; +heart comorbidities are coronary artery bypass graft, dilated cardiomyopathy, congestive heart failure, and coronary artery disease; lung comorbidities are pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), asthma; ‘None’ corresponds to no lung or heart comorbidities. APACHE II, acute physiology and chronic health evaluation II; ICU, intensive care unit; SBT, spontaneous breathing trial; PEEP, positive end-expiratory pressure; PS, pressure support; FiO2, fraction of inspired oxygen.