Table 1

Participant characteristics

	Control-group	HI-NIV group
Subjects	13	13
Age, years	63±7	59±5
Female/male	6/7	9/4
BMI, kg/m²	23±5	25±4
Waist-hip ratio	0.96±0.1	0.93±0.1
Pulmonary function
FEV₁, L	0.6±0.2	0.6±0.2
FEV₁, % pred	22±8	22±6
FEV₁/FVC, %	46±13	45±9
TLC, L	9.3±1.6	8.7±1.3
TLC, % pred	159±31	157±26
RV, L	7.7±1.8	7.2±1.2
RV, % pred	352±79	351±66
RV/TLC, % pred	220±45	214±18
Raw, kPa s L⁻¹	1.1±0.3	1.3±0.4
Blood gas (rest)
ph	Room air	Room air
	n=10	n=12
	7.40±0.02	7.39±0.03
	With oxygen*	With oxygen*
	n=3	n=1
	7.36±0.05	7.32
PaCO₂, mm Hg	Room air	Room air
	n=10	n=12
	50.6±7.0	49.1±6.3
	With oxygen*	With oxygen*
	n=3	n=1
	53.5±7.1	68.9
PaO₂, mm Hg	Room air	Room air
	n=10	n=12
	52.8±7.9	52.3±7.7
	With oxygen*	With oxygen*
	n=3	n=1
	76.9±15.9	90.5
Oxygen therapy (flows)
Exercise, L min⁻¹	3.3±0.9	3.1±1.0
Night, L min⁻¹	1.9±0.7	1.7±0.8
Rest, L min⁻¹	1.7±1.1	1.6±0.8
Nocturnal non-invasive ventilation
Since months	21±29	37±24
Mean usage time, h	8.0±1.5	8.3±3.8
IPAP, cm H₂O	24.2±3.9	24.4±4.0
EPAP, cm H₂O	6.1±1.7	6.1±1.3
RR, breaths/min⁻¹	14.5±2.2	15.9±2.2
Exercise capacity
PWR-test, watt	44±17	44±17
CET, watt	32±13	32±13

Data presented as mean and SD or number. Baseline characteristics were comparable between groups (all p>0.05).
*Patient did not tolerate breathing without oxygen.
BMI, body mass index; CET, cycle endurance test; EPAP, expiratory positive airway pressure; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; IPAP, inspiratory positive airway pressure; PaCO₂, partial pressure of carbon dioxide; PaO₂, partial pressure of oxygen; pH, potential of hydrogen; PWR, peak work rate; Raw, airway resistance; RR, respiratory rate; RV, residual volume; TLC, total lung capacity.