Table 1.

Physiological data of the healthy volunteers during sham ventilation (SV) and Bilevel ventilation (BV)

	SV N= 20	BV of 8–15 cmH2O N= 20	BV of 13–20 cmH2O N= 20
HR (bpm)	66.4 ± 7.2	70.6 ± 7.8 *	73.9 ± 8.3 †‡
BF (bpm)	13 ± 2.3	15 ± 2.9 *	15 ± 3.6 †
ETCO2(mmHg)	40.2 ± 5.2	30.5 ± 6.1 *	25.2 ± 5.3 †‡
SBP (mmHg)	104.7 ± 10.4	102.5 ± 10.8	103.5 ± 12.6
DBP (mmHg)	67.7 ± 7.5	70.5 ± 9.2	71 ± 8.7
SpO2(%)	96.5 ± 1.1	97.2 ± 0.7 *	97.4 ± 0.9 †

HR= heart rate, presented in beats per minute (bpm); BF= breathing frequency, in breathes per minute (bpm); ETCO₂= end-tidal of carbon dioxide, in millimeters of mercury (mmHg); SBP= systolic blood pressure, in mmHg; DBP= diastolic blood pressure, in mmHg; SpO_2:= peripheral oxygen saturation, Bilevel of 8–15 presented as a percentage;

^*Bilevel of 8–15 cmH₂O versus SV;

^†Bilevel of 13–20 cmH₂O versus SV;

^‡Bilevel of 13–20 cmH₂O versus cmH₂O. Repeated-measures analysis of variance (ANOVA) with the Tukey post-test. Data expressed in mean and standard deviation.