Article

Sleep and Breathing

, Volume 17, Issue 4, pp 1193-1200

Respiratory effort-related arousals contribute to sympathetic modulation of heart rate variability

  • Subani ChandraAffiliated withDivision of Pulmonary, Allergy and Critical Care, Columbia University College of Physicians and Surgeons
  • , Anthony L. SicaAffiliated withDivision of Pulmonary, Critical Care and Sleep Medicine, Hofstra North Shore-LIJ School of Medicine
  • , Janice WangAffiliated withDivision of Pulmonary, Critical Care and Sleep Medicine, Hofstra North Shore-LIJ School of Medicine
  • , Viera LakticovaAffiliated withDivision of Pulmonary, Critical Care and Sleep Medicine, Hofstra North Shore-LIJ School of Medicine
  • , Harly E. GreenbergAffiliated withDivision of Pulmonary, Critical Care and Sleep Medicine, Hofstra North Shore-LIJ School of Medicine Email author 

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Abstract

Purpose

Sympathetic activation induced by sleep-disordered breathing may contribute to cardiovascular morbidity. However, the apnea–hypopnea index (AHI) excludes respiratory effort-related arousals (RERAs) associated with inspiratory flow limitation without oxygen desaturation. We sought to determine whether RERAs are associated with sympathetic activation.

Methods

Twenty-five adults (12 males, 13 females) with AHI < 10/h and RERA index >5/h were included in this study. Power spectral density analysis was performed on two non-contiguous 10-min segments containing inspiratory flow limitation and arrhythmia-free electrocardiogram during N2 sleep. One segment contained RERA; the other did not, NO-RERA. Spectral power was described in a low-frequency domain (LF; 0.04–0.15 Hz), primarily sympathetic modulation, and a high frequency domain (HF; 0.15–0.4 Hz), parasympathetic modulation.

Results

Analyses of LF and HF powers were made using normalized and absolute values. LF power was greater during RERA compared to NO-RERA (50.3 vs. 30.1 %, p < 0.001) whereas HF power was greater during NO-RERA compared to RERA (69.9 vs. 49.7 %, p < 0.001). The LF/HF ratio was greater during RERA than NO-RERA (1.01 vs. 0.43, p < 0.001). Gender differences emerged using absolute values of power: The percentage increase in LF power during RERA relative to NO-RERA was significantly greater for females than males, 247.6 vs. 31.9 %, respectively (p < 0.02).

Conclusions

RERAs are associated with a marked increase in cardiac sympathetic modulation, especially in females. Patients with a high RERA index, even in the setting of a low or normal AHI, may be exposed to elevated sympathetic tone during sleep.

Keywords

Respiratory effort-related arousal Heart rate variability Sympathovagal balance Apnea–hypopnea index