An electrocardiogram-based analysis evaluating sleep quality in patients with obstructive sleep apnea.
OBJECTIVE
The study compares polysomnography (PSG) and cardiopulmonary coupling (CPC) sleep quality variables in patients with (1) obstructive sleep apnea (OSA) and (2) successful and unsuccessful continuous positive airway pressure (CPAP) response.


METHODS
PSGs from 50 subjects (32 F/18 M; mean age 48.4 ± 12.29 years; BMI 34.28 ± 9.33) were evaluated. OSA patients were grouped by no (n = 16), mild (n = 13), and moderate to severe (n = 20) OSA (apnea-hypopnea index (AHI) ≤ 5, >5-15, >15 events/h, respectively). Outcome sleep quality variables were sleep stages in non-rapid eye movement, rapid eye movement sleep, and high (HFC), low (LFC), very low-frequency coupling (VLFC), and elevated LFC broad band (e-LFCBB). An AHI ≤ 5 events/h and HFC ≥ 50 % indicated a successful CPAP response. CPC analysis extracts heart rate variability and QRS amplitude change that corresponds to respiration. CPC-generated spectrograms represent sleep dynamics from calculated coherence product and cross-power of both time series datasets.


RESULTS
T tests differentiated no and moderate to severe OSA groups by REM % (p = 0.003), HFC (p = 0.007), VLFC (p = 0.007), and LFC/HFC ratio (p = 0.038) variables. The successful CPAP therapy group (n = 16) had more HFC (p = 0.003), less LFC (p = 0.003), and e-LFCBB (p = 0.029) compared to the unsuccessful CPAP therapy group (n = 8). PSG sleep quality measures, except the higher arousal index (p = 0.038) in the unsuccessful CPAP group, did not differ between the successful and unsuccessful CPAP groups. HFC ≥ 50 % showed high sensitivity (77.8 %) and specificity (88.9 %) in identifying successful CPAP therapy.


CONCLUSIONS
PSG and CPC measures differentiated no from moderate to severe OSA groups and HFC ≥ 50 % discriminated successful from unsuccessful CPAP therapy. The HFC ≥ 50 % cutoff showed clinical value in identifying sleep quality disturbance among CPAP users.
Division of Sleep Medicine, National Jewish Health, 1400 Jackson St, Denver, CO 80206-2762, USA. HarringtonJ@NJHealth.org
John
J
Harrington
Preetam J
PJ
Schramm
Charles R
CR
Davies
Teofilo L
TL
Lee-Chiong
D000328:Adult; D000465:Algorithms; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017286:Polysomnography / Q000379:methods*; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*