The effects of arousal accompanying an apneic event on blood pressure and sympathetic nerve activity in severe obstructive sleep apnea

Clinical, polysomnographic, and heart rate variability in highland obstructive sleep apnea patients responding to one-night nocturnal oxygen supplementation: A post-hoc analysis from a randomized, crossover trial

OBJECTIVE

/Background: This study aimed to explore the clinical, polysomnographic, and heart rate variability (HRV) characteristics of highland obstructive sleep apnea (OSA) patients receiving one-night nocturnal oxygen supplementation (NOS) and to identify factors predicting response.

PATIENTS/METHODS

Thirty-four highland OSA patients living in Shangri-La were randomly assigned to receive NOS and sham oxygen in a randomized, placebo-controlled, crossover trial. Clinical assessments, polysomnography, and HRV were measured. A responder was defined as a ≥50% reduction in apnea-hypopnea index (AHI) with NOS compared with sham oxygen.

RESULTS

Eighteen participants responded and 16 did not respond, with a median (interquartile range [IQR]) age of 46.5 (36.5-53.0) and 48.0 (44.3-53.3) years, respectively. The median treatment effect (95% CI) on total AHI was -23.2/h (-30.0 to -17.5) and -12.0/h (-16.6 to -7.6) in responders and non-responders (p = 0.004), with similar effects on oxygen desaturation index. The mean OAH duration was prolonged by 7 s in responders together with improved sleep quality and daytime blood pressure. The mean OAH duration at baseline predicted responses to NOS with a sensitivity and specificity of 88.9% and 68.7% (AUC 0.809) at a cut-off point of 24.9 s. Changes in HRV parameters were negatively correlated with changes in mean oxygen saturation and daytime systolic blood pressure only in responders.

CONCLUSIONS

NOS significantly improved OSA severity and clinical outcomes in responders, which was related to improvements in parasympathetic activity. Highlanders with shorter mean OAH may be suitable candidates for NOS. These findings provide new information about tailored treatment strategies for highland OSA patients.

The influence of nocturnal use of complete dentures on cardiorespiratory parameters of patients with obstructive sleep apnea: a systematic review and meta-analysis

OBJECTIVE

To assess whether wearing complete dentures during sleep influences the cardiorespiratory parameters of patients with obstructive sleep apnea (OSA).

MATERIALS AND METHODS

A systematic review was performed based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to determine whether wearing complete dentures during sleep influences the cardiorespiratory parameters of patients with OSA. An electronic search was performed in four databases, PubMed/MEDLINE, Cochrane Library, Web of Science, and SCOPUS, and in the gray literature (TRIALS) until November 2021. This review included clinical trials, randomized clinical trials, and studies in which patients using conventional complete dentures were diagnosed with OSA using polysomnography and the cardiorespiratory parameters were measured using oximetry or polysomnography during sleep.

RESULTS

In total, 788 references were found in the database, and 12 articles were selected for full reading. Six articles were selected for qualitative and quantitative analyses after applying the inclusion and exclusion criteria and reading the full article. The meta-analysis showed that mean oxygen saturation (SpO₂) increased with the use of complete dentures (p = 0.001), but the other parameters showed no significant differences between those wearing and not wearing dentures during sleep.

CONCLUSIONS

The mean SpO₂ reduced in patients wearing complete dentures, but the other cardiorespiratory parameters evaluated were not affected.

CLINICAL RELEVANCE

This study indicates a possible influence of the use of complete dentures on the mean SpO₂ during sleep. The use of complete denture could aid other treatments in improving respiratory and sleep quality.

A novel parameter is better than the AHI to assess nocturnal hypoxaemia and excessive daytime sleepiness in obstructive sleep apnoea

To evaluate whether the percentage of total sleep time spent with apnoea and hypopnoea duration time (AHT%) is better than the apnoea-hypopnoea index (AHI) for the assessment of nocturnal hypoxaemia and excessive daytime sleepiness (EDS) in patients with obstructive sleep apnoea (OSA). Patients with suspected OSA were enrolled. Polysomnography, Epworth Sleepiness Scale, self-administered surveys and anthropometric measures were performed. The efficiency of AHT% and the AHI was evaluated for nocturnal hypoxaemia and EDS. A total of 160 eligible participants were analysed. The median AHT% in normal, mild, moderate and severe OSA patients was significantly different in the four-group patients with OSA. Spearman rank correlations analysis found that the associations were stronger between AHT% with percentage of total sleep time and O₂ saturation of < 90% and minimum nocturnal oxygen saturation than these parameters with the AHI. AHT% had a greater area under the curve than the AHI for predicting EDS in patients with OSA. AHT% was significantly higher in the EDS group. We present a novel parameter, AHT%, to evaluate nocturnal hypoxaemia and EDS in OSA patients. AHT% partially compensates for the shortcomings of the AHI. AHT% is better than the AHI for assessing nocturnal hypoxaemia and EDS. AHT% reflects different clinical characteristics associated with OSA from a new perspective.

Heart rate variability and obstructive sleep apnea: Current perspectives and novel technologies

Obstructive sleep apnea (OSA) is a highly prevalent condition, resulting in recurrent hypoxic events, sleep arousal, and daytime sleepiness. Patients with OSA are at an increased risk of cardiovascular morbidity and mortality. The mechanisms underlying the development of cardiovascular disease in OSA are multifactorial and cause a cascade of events. The primary contributing factor is sympathetic overactivity. Heart rate variability (HRV) can be used to evaluate shifts in the autonomic nervous system, during sleep and in response to treatment in patients with OSA. Newer technologies are aimed at improving HRV analysis to accelerate processing time, improve the diagnosis of OSA, and detection of cardiovascular risk. The present review will present contemporary understandings and uses for HRV, specifically in the realms of physiology, technology, and clinical management.

Impact of Catheter Ablation on Sleep Quality and Relationship Between Sleep Stability and Recurrence of Paroxysmal Atrial Fibrillation After Successful Ablation: 24-Hour Holter-Based Cardiopulmonary Coupling Analysis

Background

Sleep fragmentation and sleep apnea are common in patients with atrial fibrillation (AF). We investigated the impact of radio‐frequency catheter ablation (RFCA) on sleep quality in patients with paroxysmal AF and the effect of a change in sleep quality on recurrence of AF.

Methods and Results

Of 445 patients who underwent RFCA for paroxysmal AF between October 2007 and January 2017, we analyzed 225 patients who had a 24‐hour Holter test within 6 months before RFCA. Sleep quality was assessed by cardiopulmonary coupling analysis using 24‐hour Holter data. We compared cardiopulmonary coupling parameters (high‐frequency coupling, low‐frequency coupling, very‐low‐frequency coupling) before and after RFCA. Six months after RFCA, the high‐frequency coupling (marker of stable sleep) and very‐low‐frequency coupling (rapid eye movement/wake marker) was significantly increased (29.84%–36.15%; P<0.001; and 26.20%–28.76%; P=0.002, respectively) while low‐frequency coupling (unstable sleep marker) was decreased (41.25%–32.13%; P<0.001). We divided patients into 3 tertiles according to sleep quality before RFCA, and the risk of AF recurrence in each group was compared. The second tertile was used as a reference; patients with unstable sleep (Tertile 3) had a significantly lower risk of AF recurrence (hazard ratio [HR], 0.32; 95% CI, 0.12–0.83 for high‐frequency coupling; and HR, 0.22; 95% CI, 0.09–0.58 for low‐frequency coupling).

Conclusions

Sleep quality improved after RFCA in patients with paroxysmal AF. The recurrence rate was significantly lower in patients who had unstable sleep before RFCA. These results suggest that RFCA can influence sleep quality, and sleep quality assessment before RFCA may provide a risk marker for recurrence after RFCA in patients with paroxysmal AF.

Clinical characteristics of Asian patients with sleep apnea with low arousal threshold and sleep structure change with continuous positive airway pressure

PURPOSE

Low respiratory arousal threshold (ArTH) has been observed to be prevalent in patients with obstructive sleep apnea (OSA), and is associated with poor adherence to continuous positive airway pressure (CPAP) treatment. This study aimed to examine the associations between low ArTH and clinical characteristics. The second aim was to examine sleep structure changes between diagnostic polysomnography (PSG) and CPAP titration studies.

METHODS

PSG data for 3718 adults who had an apnea-hypopnea index (AHI) ≥ 5 were reviewed retrospectively, as well as 206 CPAP titration studies among these participants. Participants were dichotomized into low- and high-ArTH groups according to their PSG parameters. The associations between low ArTH and clinical characteristics were examined by multivariate logistic regressions. The sleep structure changes between PSG and CPAP titration studies were examined by repeated measures ANOVA.

RESULTS

Fifty percent of patients with OSA had low ArTH. Compared with high-ArTH patients, low-ArTH patients were less obese and composed of a higher percentage of women. In logistic regression models, low ArTH was associated with bruxism and nocturia, but not with illnesses after adjusting for AHI and body mass index. Compared with diagnostic PSG studies, low-ArTH patients had significantly decreased stage changes and increased percentage of rapid eye movement sleep during CPAP titration studies.

CONCLUSION

Low ArTH was prevalent in this large sample of patients with OSA. Arousal threshold was not associated with an increased risk of physical illnesses but was with certain clinical complaints. Low-ArTH patients benefited from CPAP titration study for improved sleep structure.

Different prognosis between severe and very severe obstructive sleep apnea patients; Five year outcomes

BACKGROUND

Obstructive sleep apnea (OSA) is characterized by augmented sympathetic nerve activity. In our previous study, patients with OSA and an apnea-hyperpnea index (AHI)>55events/h showed increased single-unit muscle sympathetic nerve activity compared to patients with OSA and AHI of 30-55events/h. However, the prognostic impact in these patients remains unclear.

METHODS

Ninety-one OSA patients were included. All patients who had indication for continuous positive airway pressure (CPAP) were treated with CPAP. Patients were divided into three groups: mild/moderate OSA (S), AHI<30events/h (n=44); severe OSA (SS), AHI 30-55events/h (n=29); and very severe OSA (VSS), AHI>55events/h (n=18). The primary endpoint was a composite outcome composed of death, cardiovascular events, stroke, and heart failure with hospitalization.

RESULTS

In the 5-year follow-up, the primary event rate in the SS group [3 events (7%)] was the same as that in the S group [3 events (10%)]. However, the VSS group showed a significantly higher primary event rate among the three groups [6 events (33%), p<0.05]. In Cox regression analysis, the VSS group had the highest hazard ratio compared to other risk factors.

CONCLUSIONS

CPAP was effective for preventing cardiovascular disease in patients with severe OSA, however patients with very severe OSA still had a high event rate, indicating that CPAP treatment might be insufficient to reduce the OSA-related risk burden in patients with very severe OSA. Additional systemic medical treatment for CPAP might be needed in patients with very severe OSA.