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.

Long-term azithromycin therapy to reduce acute exacerbations in patients with severe chronic obstructive pulmonary disease.

RATIONALE: According to clinical trials, azithromycin taken daily for 1 year, decreased exacerbations of chronic obstructive pulmonary disease (COPD). OBJECTIVES: Effectiveness evaluation of long-term azithromycin to reduce exacerbations in severe COPD patient on optimal therapy in real-life practice. METHODS: We conducted a retrospective observational study of severe COPD patients who were prescribed azithromycin (PA)(250 mg, at least 3 times weekly for at least 6 months). Comparison group included severe COPD patients not prescribed azithromycin (NPA). Data were extracted from clinical chart review. MAIN RESULTS: Study included 126 PA and 69 NPA patients. They had severe airflow obstruction, mostly emphysema and one-third bronchiectasis. A predominant feature in the PA group was respiratory tract colonization with Pseudomonas aeruginosa. The mean number of exacerbations per patient per year in the PA group was 3.2 ±â€¯2.1 before initiating azithromycin, and 2.3 ±â€¯1.6 during following year on therapy (p < 0.001). Patients in the NPA group had 1.7 ±â€¯1.3 and 2.5 ±â€¯1.7 exacerbations during first and second follow-up year respectively (p < 0.001). Exacerbation changes from pre to post differed between groups (p < 0.001). Decrease in emergency visits and hospital admissions was significant in PA group. Exacerbation reductions and patient proportions having ≥2 exacerbations extended to the second year of treatment. CONCLUSION: These data showed that long-term azithromycin reduces exacerbation numbers in severe COPD patients, and benefits persist beyond one year. Desirable effects are more likely to outweigh the risks and adverse events in patients colonized with Pseudomonas aeruginosa.