Table 3

 Mean (SE) daytime arterial blood gas tensions and spontaneous ventilation, hypercapnic responses, and polysomnography parameters after 4 weeks each of pressure and volume ventilation

OutcomePressureVolumeppC
*Unassisted ventilation.
p, raw probability; pC, Hochberg corrrection for multiple end points; Pi,max, maximal inspiratory mouth pressure; Pe,max, maximal expiratory mouth pressure; SNIP, sniff nasal inspiratory pressure; VTe, expired tidal volume; RRspon, spontaneous respiratory rate; MVe, expired minute ventilation; P0.1, pressure at mouth 100 ms after an occluded inspiratory effort; ΔVE/ΔPco2, slope of ventilatory response curve to inspired carbon dioxide; ΔP0.1/ΔPco2, slope of P0.1 against inspired carbon dioxide; RDI, respiratory disturbance index, number of apnoeas and hypopnoeas per hour of sleep; Tcco2, transcutaneous carbon dioxide; RRvent, respiratory rate during assisted ventilation; IPpeak, peak inspiratory pressure; IPmean, mean inspiratory pressure; Ti, measured inspiratory time; Te, measured expiratory time; TST, total sleep time; REM, rapid eye movement sleep; NREM, non-rapid eye movement sleep.
pH*7.38 (0.01)7.38 (0.01)0.560.56
HCO328.6 (0.68)29.5 (0.66)0.070.28
Pao2 (kPa)9.00 (0.23)8.68 (0.36)0.180.36
Paco2 (kPa)6.38 (0.12)6.61 (0.16)0.090.27
Sao292.3 (0.75)90.7 (1.17)0.040.20
Pi,max (cm H2O)−36.3 (5.1)−38.5 (4.9)0.471.00
Pe,max (cm H2O)66.2 (10.6)72.1 (10.7)0.311.00
SNIP (cm H2O)−36.0 (5.3)−37.7 (5.8)0.661.00
FEV1 (l)0.60 (0.04)0.61 (0.04)0.570.86
FVC (l)0.72 (0.06)0.76 (0.06)0.861.00
Spontaneous ventilation
VTe (ml)439 (26)396 (34)0.290.58
RRspon (bpm)25.4 (2.1)28.4 (2.2)0.090.36
MVe (l/min)10.8 (0.5)10.8 (0.6)0.800.80
P0.1 (cm H2O)−1.53 (0.17)−1.26 (0.11)0.180.54
Hypercapnic responses
ΔVE/ΔPco2 (l/min/kPa)2.87 (0.41)3.59 (0.63)0.150.31
MVe at 8 kPa (l/min)14.6 (1.2)13.7 (1.0)0.450.45
ΔP0.1/ΔPco2 (cm H2O/kPa)−0.91 (0.17)−0.72 (0.12)0.070.21
P0.1 at 8 kPa (cm H2O)−2.60 (0.44)−1.90 (0.35)0.0080.03
Polysomnography
Sao2 (%)92.8 (0.9)91.8 (1.1)0.201.00
Sao2 <90% (minutes)73 (32)107 (40)0.111.00
RDI (/hour)0.7 (0.7)0 (0)0.291.00
Tcco2 (kPa)4.3 (0.8)4.7 (0.6)0.761.00
VTe (ml)548 (75)546 (78)0.981.00
MVe (l/min)8.34 (0.91)8.38 (1.3)0.581.00
Minute leak (l/min)13.80 (1.93)5.87 (1.03)0.0010.01
Peak inspiratory flow (l/min)149 (21)152 (21)0.851.00
RRvent (bpm)15 (0.3)15.6 (0.3)0.191.00
IPpeak (cm H2O)24.2 (1.1)23.4 (1.1)0.851.00
IPmean (cm H2O)20.9 (1.1)14.8 (0.8)0.0010.008
Ti (s)1.53 (0.10)1.33 (0.05)0.070.56
Te (s)2.30 (0.13)2.38 (0.10)0.581.00
Ti/TiTOT0.40 (0.03)0.36 (0.02)0.110.75
Total sleep time (TST) (min)394 (16)416 (13)0.101.00
Latency (min)52 (10)41 (8)0.381.00
Efficiency (%)77 (8)85 (2)0.241.00
REM (% TST)12 (2)13 (2)0.521.00
NREM 1+2 (% TST)55 (6)54 (6)0.851.00
NREM 3+4 (% TST)26 (6)25 (5)0.681.00
Respiratory arousals (/hour)0.8 (0.4)0.0 (0.0)0.101.00
Non-respiratory arousals (/hour)16.0 (2.2)18.4 (4.6)0.441.00
Ventilator hours (/night at home)8.1 (0.7)8.4 (1.1)0.250.25