The effect of continuous positive airway pressure (CPAP) treatment on reducing cardiovascular disease risk in sleep apnea subjects remains inconclusive. It is plausible that pathological respiratory chemoreflex activation (high loop gain) is a predictive signal biomarker. To determine whether narrow band (e-LFCNB%) metric derived from cardiopulmonary coupling analysis is related with blood pressure reduction after CPAP. A secondary analysis of the Apnea Positive Pressure Long-term Efficacy Study (APPLES). The elevated low frequency coupling - narrow band (e-LFCNB %) metric derived from cardiopulmonary coupling analysis detects periodic breathing (as a surrogate for high loop gain), and was estimated in baseline polysomnogram. Linear regression analysis was performed to identify the potential association between e-LFCNB% of total sleep time and the observed reduction in blood pressure following the specified treatment. A total of 388 subjects received CPAP and had e-LFCNB % measurements. At 2 months, 90/322 subjects had e-LFCNB ≥ 4% at baseline. At 6 months 137/313 subjects had e-LFCNB higher than 2% at baseline. For morning systolic blood pressure, e-LFCNB ≥ 4% [β: 2.534, standard error (SE): 1.198, p: 0.035] was positively related with the extent of systolic blood pressure reductions after 2 months CPAP treatment and e-LFCNB ≥ 2% was marginally related with systolic blood pressure decrement after 6 months (β: 2.162, SE: 1.173, p: 0.066). For the morning diastolic blood pressure, e-LFCNB ≥ 2% predicted reductions at 6 months of treatment (β: 1.883, SE: 0.888, p: 0.035). e-LFCNB % (probable high loop gain) was positively related to systolic blood pressure reduction (short-term) and diastolic blood pressure reduction (longer-term), following CPAP.
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