Heart Rate Responses to Autonomic Challenges in Obstructive Sleep Apnea

Abstract

Obstructive sleep apnea (OSA) is accompanied by structural alterations and dysfunction in central autonomic regulatory regions, which may impair dynamic and static cardiovascular regulation, and contribute to other syndrome pathologies. Characterizing cardiovascular responses to autonomic challenges may provide insights into central nervous system impairments, including contributions by sex, since structural alterations are enhanced in OSA females over males. The objective was to assess heart rate responses in OSA versus healthy control subjects to autonomic challenges, and, separately, characterize female and male patterns. We studied 94 subjects, including 37 newly-diagnosed, untreated OSA patients (6 female, age mean±std: 52.1±8.1 years; 31 male aged 54.3±8.4 years), and 57 healthy control subjects (20 female, 50.5±8.1 years; 37 male, 45.6±9.2 years). We measured instantaneous heart rate with pulse oximetry during cold pressor, hand grip, and Valsalva maneuver challenges. All challenges elicited significant heart rate differences between OSA and control groups during and after challenges (repeated measures ANOVA, p<0.05). In post-hoc analyses, OSA females showed greater impairments than OSA males, which included: for cold pressor, lower initial increase (OSA vs. control: 9.5 vs. 7.3 bpm in females, 7.6 vs. 3.7 bpm in males), OSA delay to initial peak (2.5 s females/0.9 s males), slower mid-challenge rate-of-increase (OSA vs. control: −0.11 vs. 0.09 bpm/s in females, 0.03 vs. 0.06 bpm/s in males); for hand grip, lower initial peak (OSA vs. control: 2.6 vs. 4.6 bpm in females, 5.3 vs. 6.0 bpm in males); for Valsalva maneuver, lower Valsalva ratio (OSA vs. control: 1.14 vs. 1.30 in females, 1.29 vs. 1.34 in males), and OSA delay during phase II (0.68 s females/1.31 s males). Heart rate responses showed lower amplitude, delayed onset, and slower rate changes in OSA patients over healthy controls, and impairments may be more pronounced in females. The dysfunctions may reflect central injury in the syndrome, and suggest autonomic deficiencies that may contribute to further tissue and functional pathologies.

Global Brain Blood-Oxygen Level Responses to Autonomic Challenges in Obstructive Sleep Apnea

“…The most notable difference in the global BOLD signal between sexes appeared in the cold pressor challenge, which was also reflected in very different heart rate responses in female vs. male OSA patients [20]. The cold pressor involves a combination of temperature and pain stimulation, and since females and males respond differently to objectively similar painful stimuli [53], [54], it is conceivable that the pain component contributes to those vascular differences.…”

Prelimbic prefrontal cortex mediates respiratory responses to mild and potent prolonged, but not brief, stressors

“…Patients with this condition experience intermittent episodes of hypoxia and hypercapnia as well as sleep disturbance, which lead to a dysfunction of the prefrontal cortex (Beebe and Gozal, 2002). Interestingly, these patients exhibit increased cardiac responses to physical stressors (Macey et al, 2013). Furthermore, children with obstructive sleep apnoea exhibit a decreased basal respiratory rate and an elevated respiratory response to arousal (Baumert et al, 2011).…”

Cardiovascular impact of obstructive sleep apnea: does gender matter?

“…OSA patients presented impaired heart rate response compared KEYWORDS: cardiovascular disease • female • gender • obstructive sleep apnea • treatment with healthy controls: lower amplitude, delayed onset and slower rate changes. However, females with OSA had had worse pattern of heart rate response when compared with men counterparts [9].…”

“…However, it is not entirely clear whether markers of sympathetic activation are increased in both males and females with OSA. Macey and colleagues studied heart rate responses to autonomic challenges (cold pressor, handgrip and Valsalva maneuver) in both genders with and without OSA patients [9]. OSA patients presented impaired heart rate response compared KEYWORDS: cardiovascular disease • female • gender • obstructive sleep apnea • treatment with healthy controls: lower amplitude, delayed onset and slower rate changes.…”