Table 4.

Independent outcome predictors identified by logistic regression.

	P	Cut-off	AUC	Youden’s Index	Se	Sp	PPV	NPV
Extubation after SBT
Weight Balance (kg)	0.01	0.5	0.64	0.28	0.79	0.49	0.61	0.70
SD1 before SBT (ms)	0.03	25.8	0.57	0.18	0.49	0.69	0.62	0.56
SpO2 during SBT (%)	0.04	91.5	0.76	0.41	0.56	0.85	0.78	0.67
EWSO2 before SBT	0.001	12.8	0.67	0.28	0.47	0.81	0.71	0.60
EWSO2 during SBT	0.006	11.1	0.80	0.50	0.75	0.76	0.75	0.76
Extubation Success 72-h
BMI	< 0.0001	23.6	0.67	0.33	0.61	0.73	0.44	0.84
P0.1 before SBT (cmH2O)	0.02	3.3	0.53	0.28	0.30	0.98	0.88	0.73
SpO2 during SBT (%)	0.007	95.5	0.61	0.24	0.87	0.24	0.31	0.89
MAP during SBT (mmHg)	0.02	104.5	0.72	0.35	0.52	0.83	0.50	0.84
SAP during SBT (mmHg)	0.02	145.5	0.68	0.33	0.69	0.64	0.38	0.86
EWSO2 during SBT	0.03	11.9	0.61	0.23	0.74	0.49	0.33	0.85
SD2 prior SBT (ms)	0.01	19.9	0.58	0.22	0.82	0.41	0.33	0.86
Estimated FiO2 after extubation (%)	0.03	29.0	0.60	0.27	0.54	0.74	0.33	0.87
EWSO2 after extubation	< 0.0001	16.2	0.72	0.43	0.91	0.52	0.29	0.96
Extubation Success Day-7
BMI (kg/m2)	< 0.0001	23.6	0.67	0.36	0.63	0.73	0.44	0.85
MAP before SBT (mmHg)	< 0.0001	93.5	0.68	0.29	0.56	0.73	0.42	0.83
SAP before SBT (mmHg)	< 0.0001	142.5	0.63	0.33	0.59	0.74	0.44	0.84
EWSO2 before SBT	< 0.0001	22.3	0.54	0.17	0.94	0.23	0.29	0.92
EWSO2 during SBT	< 0.0001	12.4	0.61	0.22	0.77	0.45	0.31	0.86
EWSO2 after extubation	< 0.0001	16.2	0.72	0.43	0.91	0.52	0.29	0.96
LF before SBT (Hz)	0.03	120.0	0.57	0.18	0.78	0.40	0.31	0.84

A p value equal or below 0.05 was considered statistically significant. Parameters with an AUC higher than 0.70 are depicted in black tone.

Cut-off: best value for the parameter, determined by ROC Curve analysis; ROC: Receiver Operating Characteristic; AUC: Area Under the Curve; Se: Sensibility; Sp: Specificity; PPV: Positive Predictive Value; NPV: Negative Predictive Value; SBT: Spontaneous Breathing Test; SD1: Poincaré plot standard deviation perpendicular the line of identity; SD2: Poincaré plot standard deviation along the line of identity; LF: peak frequency of the low-frequency band of the plethysmography signal (0.04–015 Hz); SpO2: pulse oximetry; EWSO2: early-warning score oxygen; BMI: body-mass index; P0.1: negative pressure measured 100 ms after the initiation of an inspiratory effort performed against a closed respiratory circuit; SAP: systolic arterial pressure; MAP: mean arterial pressure; estimated FiO₂: estimated oxygen inspiratory fraction, derived from the mean oxygen flow rate.

Significant values are in bold.