The Evaluation of Autonomic Arousals in Scoring Sleep Respiratory Disturbances with Polysomnography and Portable Monitor Devices: A Proof of Concept Study.

BACKGROUND: Autonomic arousals can be considered as surrogates of electroencephalography (EEG) arousals when calculating respiratory disturbance index (RDI). The main objective of this proof of concept study was to evaluate the use of heart rate acceleration (HRa) arousals associated with sleep respiratory events in a population undergoing full polysomnography (type 1) and in another undergoing portable monitor study (type 3). Our hypothesis is that when compared to other commonly used indexes, RDI based on HRa will capture more events in both types of recording. MATERIALS AND METHODS: A retrospective analysis was performed in two different populations of patients with suspected OSA: a) 72 patients undergoing one night of type 1 recording and b) 79 patients undergoing one night of type 3 recording. Variables for type 1 were 4% oxygen desaturation index (ODI), apnea/hypopnea index (AHI), RDI based on EEG arousals (RDIe), and RDI based on HRa with threshold of 5bpm (RDIa5). For type 3, variables were 4% ODI, AHI, and RDIa5 (it is not possible to calculate RDIe due to the absence of EEG). Calculated data were 1) Mean values for each sleep disturbance index in type 1 and 3 recordings; 2) Frequency of migration from lower to higher OSA severity categories using RDIa5 in comparison to AHI (thresholds: ≥5/h mild, ≥15/h moderate, ≥30/h severe); and 3) Bland-Altman plots to assess agreement between AHI vs RDIe and RDIa5 in type 1 population, and AHI vs RDIa5 in type 3 populations. RESULTS: More respiratory disturbance events were captured with RDIa5 index in both type 1 and type 3 recordings when compared to the other indexes. In type 1 recording, when using RDIa5 37% of patients classified as not having OSA with AHI were now identified as having OSA, and a total of 59% migrated to higher severity categories. In type 3 recording, similar results were obtained, as 37% of patients classified as not having OSA with AHI were now identified as having OSA using RDIa5, and a total of 55% patients migrated to higher severity categories. Mean differences for RDIa5 and AHI in type 1 and 3 populations were similar. CONCLUSION: The use of autonomic arousals such as HRa can help to detect more respiratory disturbance events when compared to other indexes, being a variable that may help to capture borderline mild cases. This becomes especially relevant in type 3 recordings. Future research is needed to determine its validity, optimization, and its clinical significance.

Autonomic Arousals as Surrogates for Cortical Arousals Caused by Respiratory Events: A Methodological Optimization Study in the Diagnosis of Sleep Breathing Disorders.

INTRODUCTION: Portable monitoring (PM) is an alternative to laboratory polysomnography (PSG) for diagnosing obstructive sleep apnea (OSA). However, PM tends to underestimate the apnea-hypopnea index (AHI), as it does not identify non-desaturating events associated with electroencephalographic (EEG) arousal. The objectives were to explore heart rate acceleration (HRa) and decrease in pulse transit time (PTT) as surrogates to EEG arousal for non-desaturating hypopnea and respiratory effort-related arousal (RERA), and to estimate cut-off values for their use with both total sleep time (TST), the standard method for PSG, and total recording time (TRT), the usual method for PM. METHODS: Twenty-four consecutive individuals with suspected OSA were studied with PSG. Calculated outcomes were: AHI, respiratory disturbance index with EEG arousal (RDIe) and autonomic arousal by HRa (RDI-HRa) and PTT decreases (RDI-PTT) at different time cut-offs. Using RDIe as reference, Bland Altman and intraclass coefficient of correlation (ICC) were used to calculate agreement between indexes, and receiver operating curves (ROC) for sensitivity/specificity of the different cut-offs. RESULTS: Autonomic arousals, limited to respiratory events, were present in 36% of non-desaturating hypopneas and 29% of RERAs. Using TST, RDI-HRa of 10 bpm (ICC= 0.89) and RDI-PTT with a decrease of -15 msec (ICC=0.90) agreed better with RDIe. With TRT, the RDI-HRa of 5 bpm agreed better with the RDIe (ICC=0.89). Bland-Altman plots showed mean differences of 1.53 between RDI-HRa10-TST and RDIe and 0.89 between RDI-HRa5-TRT and RDIe. CONCLUSION: Autonomic arousals (HRa and PTT) may be a suitable proxy of EEG arousals associated with respiratory events, using both TST and TRT. Therefore, they could potentially help to capture borderline symptomatic patients and to monitor treatment outcomes.

Sleep, chronic pain, and opioid risk for apnea.

Pain is an unwelcome sleep partner. Pain tends to erode sleep quality and alter the sleep restorative process in vulnerable patients. It can contribute to next-day sleepiness and fatigue, affecting cognitive function. Chronic pain and the use of opioid medications can also complicate the management of sleep disorders such as insomnia (difficulty falling and/or staying asleep) and sleep-disordered breathing (sleep apnea). Sleep problems can be related to various types of pain, including sleep headache (hypnic headache, cluster headache, migraine) and morning headache (transient tension type secondary to sleep apnea or to sleep bruxism or tooth grinding) as well as periodic limb movements (leg and arm dysesthesia with pain). Pain and sleep management strategies should be personalized to reflect the patient's history and ongoing complaints. Understanding the pain-sleep interaction requires assessments of: i) sleep quality, ii) potential contributions to fatigue, mood, and/or wake time functioning; iii) potential concomitant sleep-disordered breathing (SDB); and more importantly; iv) opioid use, as central apnea may occur in at-risk patients. Treatments include sleep hygiene advice, cognitive behavioral therapy, physical therapy, breathing devices (continuous positive airway pressure - CPAP, or oral appliance) and medications (sleep facilitators, e.g., zolpidem; or antidepressants, e.g., trazodone, duloxetine, or neuroleptics, e.g., pregabalin). In the presence of opioid-exacerbated SDB, if the dose cannot be reduced and normal breathing restored, servo-ventilation is a promising avenue that nevertheless requires close medical supervision.