Table 2: Parameters which were evaluated in the two groups just before and at the end of SBT.

Variable Total population (N=77) SBT success
(N1=49)
SBT failure
(N2=29)
p
*Hb, g/dl 9.5 (2.4) 9.8 (2.2) 8.9 (1.9) 0.028
*FiO2 0.4 (0.1) 0.4 (0.1) 0.4 (0.1) 0.958
*PaO2/FiO2 273.3 (145.3) 280.1±95.7 292.4±90.1 0.601
*MIP, cm H20 40 (24) 40 (22) 40 (32) 0.395
SaO2 start, % 98 (1.5) 98 (1.4) 98 (1.7) 0.675
SaO2 end, % 97.7 (2) 97.8 (2) 97.5 (1) 0.014
ScvO2 start, % 75.6±8 76 ± 8.8 74.9 ± 6.6 0.573
ScvO2 end, % 75.3±8.4 77.2 ± 7.8 71.9 ± 8.4 0.007
PaO2 start, mm Hg 109.4±27.7 108.4±27.2 111.1±29 0.958
PaO2 end, mm Hg 98±31 104.9±32 91.3±27.7 0.063
pH start 7.43±0.04 7.42±0.05 7.43±0.04 0.680
pH end 7.42±0.04 7.42±0.04 7.42±0.04 0.840
HCO3 start 26.6±5.4 26.6±5.5 26.5±5.4 0.967
HCO3 end 27.1±5.9 26.8±6.1 27.5±5.6 0.592
PaCO2 start, mm Hg 40.9±9.5 41.2±10.2 40.5±8.5 0.744
PaCO2 end, mm Hg 42.3±11.2 41.9±11.9 43±10.1 0.690
O2ER start 22.7±8 22.3±8.8 23.3±6.6 0.611
O2ER end 22.5±8 20.9±7.7 25.4±7.9 0.020
HR start, beats/min 93.8±15.3 95.1±14.6 91.4±16.5 0.307
HR end, beats/min 99.4±16.1 99.4±15.2 99.5±17.8 0.968
MAP start, mm Hg 93.3±13.1 95.1±13.2 90.1±12.6 0.107
MAP end, mm Hg 95.1±14.7 96.9±14.9 91.8±13.9 0.136
#f/Vt 77.6±42.7 60±26.37 106.2±48.3 <0.001

SBT: Spontaneous breathing Trial; Hb: hemoglobin concentration; FiO2: Fraction of Inspired Oxygen; PaO2: arterial oxygen partial pressure; MIP: maximum inspiratory pressure; Start: measured just before the beginning of the SBT; End: measured at the end of SBT; SaO2: arterial oxygen saturation; ScvO2: central venous oxygen saturation; HCO3: bicarbonate anion; PaCO2: arterial carbon dioxide partial pressure; O2ER: Oxygen extraction ratio; HR: heart rate; MAP: mean systemic arterial blood pressure
* Measured only once, just before SBT initiation
# Measured only once, at the end of SBT