Table 2.
Main outcomes derived from sleep studies during the first night and the following morning at each location.
| Variables | 490 m | 2,048 m placebo | 2,048 m NOT | P, ANOVA |
|---|---|---|---|---|
| ECG analysis | ||||
| Heart rate, bpm | 73 (66; 82) | 82 (71; 85)*¶ | 78 (67; 84) | <0.001 |
| QT duration, ms | 380 (365; 410) | 375 (355; 390)*¶ | 390 (370; 400) | <0.001 |
| QTc duration, ms | 417 (404; 439) | 426 (405; 440)* | 420 (405; 440) | 0.028 |
| 90th percentile QTc, ms | 422 (410; 436) | 430 (406; 445)* | 427 (405; 446) | 0.016 |
| 95th percentile QTc, ms | 424 (412; 438) | 432 (408; 447)* | 430 (408; 447) | 0.024 |
| QTc max, ms | 439 (425; 455) | 444 (418; 457) | 442 (420; 452) | 0.397 |
| TpTe, ms | 60 (55; 70) | 60 (55; 75) | 65 (60; 70) | 0.581 |
| TpTe c, ms | 65 (62; 73) | 68 (60; 79) | 71 (61; 80) | 0.836 |
| VES, 1/h | 0.3 (0.0; 2.4) | 1.6 (0.1; 14.5) | 0.3 (0.1; 2.9) | 0.341 |
| SVES, 1/h | 1.8 (0.4; 10.0) | 2.4 (0.4; 7.8) | 2.2 (0.5; 7.5) | 0.362 |
| Complex arrhythmia, 1/h | 0 (0; 0) | 0 (0; 0) | 0 (0; 0) | 0.249 |
| Pulse wave analysis | ||||
| Peak-to-peak time, ms | 160 (150; 180) | 160 (153; 178) | 170 (160; 190) | 0.559 |
| Stiffness index, m/s | 10.2 (9.2; 11.1) | 10.5 (9.2; 11.1) | 10.1 (8.9; 10.5) | 0.388 |
| Pulse transit time, ms | 345 (337; 364) | 332 (325; 351)*¶ | 352 (338; 365) | <0.001 |
| Reflection index | 0.74 (0.68; 0.79) | 0.75 (0.62; 0.76)* | 0.75 (0.65; 0.78) | 0.034 |
| Nocturnal oxygenation and capnography | ||||
| Mean nocturnal SpO2, % | 92 (90; 94) | 86 (83; 89)*¶ | 97 (95; 98)* | <0.001 |
| ODI, 1/h | 3.6 (1.3; 13.7) | 37.8 (16.7; 59.5)*¶ | 0.6 (0.1; 2.6)* | <0.001 |
| PtcCO2, mmHg | 41 (37; 46) | 44 (42; 48)*¶ | 48 (42; 52)* | <0.001 |
| Morning evaluation | ||||
| BP systolic, mmHg | 122 (111; 135) | 125 (112; 137) | 125 (116; 134) | 0.679 |
| BP diastolic, mmHg | 70 (65; 77) | 69 (62; 82) | 69 (65; 80) | 0.762 |
| BP mean, mmHg | 85 (80; 94) | 86 (78; 98) | 86 (82; 98) | 0.695 |
| Arterial blood gases | ||||
| pH | 7.44 (7.43; 7.46) | 7.47 (7.45; 7.49)* | 7.47 (7.45; 7.48)* | <0.001 |
| PaCO2, kPa | 5.1 (4.7; 5.2) | 4.7 (4.2; 7.9)* | 4.5 (4.0; 5.0)* | <0.001 |
| PaO2, kPa | 9.0 (8.3; 9.8) | 8.1 (7.3; 8.6)* | 8.0 (7.2; 8.4)* | <0.001 |
| SaO2, % | 94.4 (92.5; 95.3) | 90.1 (87.7; 92.1)* | 90.6 (87.6; 91.8)* | <0.001 |
Median (quartiles). Arterial blood gases were performed in the morning, 10 min after awakening and while breathing ambient air. 90th and 95th percentiles of QTc were calculated from the average 1-min QTc values over the complete night.
NOT, nocturnal oxygen therapy; QTc, corrected QT time using the Bazett formula; QTc max, the 1-min interval with the longest QT interval during the night; TpTe, time between Tpeak and Tend; TpTe c, TpTe corrected for heart rate using the Bazett formula; VES and SVES, ventricular and supraventricular arrhythmia; Complex arrhythmias, including bigeminy, trigeminy, couplets, and triplets; Peak-to-peak time, the time difference between the pulse wave contour-derived systolic and diastolic maximum; Stiffness index, calculated from the height of a participant divided by the Peak-to-peak time; Pulse transit time, the time between the ECG R-peak to the time at 50% pulse wave amplitude; Reflection index, calculated by dividing the diastolic amplitude by the systolic amplitude of the systolic and diastolic maximum derived from the pulse wave contour; SpO2, arterial oxygenation measured by finger oximetry; ODI, oxygen desaturation index defined as number of >3% dips in SpO2; PtcCO2, transcutaneous carbon dioxide; BP, blood pressure.
P <0.05 vs. 490 m;
P <0.05 vs. NOT.