Table 1: Baseline patients’ characteristics. Data are expressed as mean ± SD, median (interquartile range), or number and percentage (%).

	HFO Group N = 111	Control Group N = 111	P
Age, years	62.9 ± 16.1	64.5 ± 13.7	0.4
Male sex	70 (63%)	73 (66%)	0.7
Comorbidities:
COPD	37 (33%)	34 (31%)	0.7
Heart disease	22 (20%)	23 (21%)	0.9
Diagnosis at admission:
Medical	66 (59%)	66 (59%)	1
Respiratory primary failure*	46 (41.4%)	41 (36.9%)
Cardiologic primary failure	2 (1.8%)	3 (2.7%)
Abdominal	6 (5.4%)	10 (9.1%)
Sepsis (other focus)	5 (4.5%)	8 (7.2%)
Other	7 (6.3%)	4 (3.6%)
Surgical	51 (45.9%)	47 (42.3%)	0.8
Scheduled surgery	31 (27.9%)	38 (34.2%)
Urgent surgery	20 (18.1%)	9 (8.1%)
Body mass index	27 ± 6.9	27 ± 7.1	0.8
APACHE II at ICU admission	15.1 ± 6.6	15.8 ± 7.5	0.6
APACHE II at extubation	9.6 ± 6.2	9.9 ± 7.1	0.8
PaO2/FiO2 at end of SBT	175 ± 21	180 ± 32	0.8
Length of mechanical ventilation before extubation, days	9.7 ± 4.8	10.1 ± 4.6	0.5
ICU-acquired paresis (MRC score < 48 points)	10 (9%)	7 (6%)	0.6
Corticosteroids (> 12 h before extubation)	16 (14%)	18 (16%)	0.8
High risk variables for reintubation:	66 (59%)	66 (59%)	1
Age > 65 years	54 (49%)	53 (48%)
Intubation due to heart failure	2 (2%)	1 (1%)
Moderate-to-severe COPD	29 (26%)	30 (27%)
APACHE II > 12 at extubation	52 (47%)	51 (46%)
Body mass index > 30	22 (20%)	24 (22%)
Inability to deal with respiratory secretions	1 (1%)	0 (0%)
Difficult or prolonged weaning	29 (26%)	27 (24%)
≥ 2 comorbidities	34 (31%)	33 (30%)
Mechanical ventilation > 7 days	56 (50%)	58 (52%)
Laryngeal edema after extubation	0 (0%)	4 (4%)	0.1

APACHE = acute physiology and chronic health evaluation; ARDS = acute respiratory distress syndrome; COPD = chronic obstructive pulmonary disease; MRC = Medical Research Council score; SBT = spontaneous breathing trial.

* Primary respiratory failure included severe pneumonia (23/21), aspiration (3/3), asthma exacerbation (2/1), pulmonary embolism (4/2), and COPD exacerbation (11/12), ARDS (3/2), respectively.