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Table 2 Polysomnographic report: patients with and without CPAP treatment

From: Nocturnal CPAP improves walking capacity in COPD patients with obstructive sleep apnoea

  Overlap syndrome   COPD   
n = 22   n = 22
  Baseline With CPAP P Baseline With CPAP P P
Total sleep time (minutes) 294.3 ± 80.5 290.1 ± 94.9 0.758 287.8 ± 77.9 273.2 ± 71.7 0.408 0.760
Sleep efficiency (%) 67.2 ± 12.8 68.6 ± 14.3 0.833 66.3 ± 14.2 65.2 ± 12.9 0.650 0.699
AHI event. h-1 39.2 ± 16.5 4.6 ± 2.9 0.001 7.5 ± 4.1* 1.6 ± 1.4 0.001 0.001
ODI event. h-1 20.4 ± 16.2 3.1 ± 2.9 0.001 3.1 ± 2.2* 0.9 ± 1.1 0.001 0.001
Average SaO2% 93.3 ± 2.2 94.5 ± 1.7 0.011 93.8 ± 2.0 94.9 ± 2.1 0.001 0.866
Lowest SaO2% 80.3 ± 8.8 89.3 ± 3.9 0.001 87.0 ± 4.6* 90.2 ± 4.3 0.005 0.089
Wake% 26.6 ± 10.3 21.8 ± 13.7 0.211 25.5 ± 14.2 26.9 ± 12.7 0.578 0.124
N1% 23.0 ± 14.0 15.4 ± 8.9 0.010 20.3 ± 14.1 16.5 ± 8.7 0.079 0.296
N2% 39.5 ± 12.6 41.2 ± 14.9 0.700 34.0 ± 11.8 33.2 ± 11.6 0.941 0.751
N3% 2.3 ± 3.9 5.2 ± 6.1 0.001 7.5 ± 9.4 9.2 ± 11.4 0.235 0.191
REM% 8.5 ± 7.1 16.4 ± 10.3 0.004 12.2 ± 7.7 13.9 ± 7.5 0.144 0.026
CPAP pressure (cm H2O)   6.8 ± 1.8    4.9 ± 0.9*   
  1. *P < 0.05; when compared with baseline overlap syndrome group.
  2. P values represent comparisons between baseline and with CPAP in each corresponding group.
  3. P values represent comparisons with regards to the changes with CPAP treatment between overlap syndrome and COPD in each corresponding group.
  4. AHI apnoea/hypopnea index, ODI oxygen desaturation index, SWS slow wave sleep, REM rapid eye movement, CPAP continuous positive airway pressure.