Literature Updates

Central Sleep Apnea in Children with Obstructive Sleep Apnea Syndrome and Improvement Following Adenotonsillectomy

Despite the belief that central sleep apneas (CSA’s) are solely related to central nervous system dysfunction, OSAS exerts some influence on the appearance of CSA in children. This retrospective chart review of polysomnography (PSG) data over a 10 year period aimed to demonstrate a positive association between CSA and OSAS in children 1 to 14 years of age without neurological conditions or craniofacial syndromes. A secondary aim was to demonstrate the impact of adenotonsillectomy on the severity of CSA in children with OSAS. There are conflicting mechanisms that try to explain the association between CSA and OSAS.

Altered Structural Brain Network Resulting from White Matter Injury in Obstructive Sleep Apnea

“For similar degrees of sleep apnea, the severity, diversity (mood, executive function, attention), and clustering of clinical symptoms remain largely unexplained. Using DTI to assess brain tissue integrity and brain network properties in OSA, we observed markers of WM injury and abnormalities in the structural brain network. Such changes provide a basis for altered functional connectivity and clinical symptom diversity. In addition, we found that the structural brain network was influenced by WM injury. Our findings provide new insights into the causes of functional deficits in sleep apnea syndromes.”

Predictors of Long-Term Adherence to Continuous Positive Airway Pressure in Patients with Obstructive Sleep Apnea and Cardiovascular Disease

“Poor adherence to CPAP commonly affects therapeutic response in those affected by obstructive sleep apnea (OSA). Among 1,121 participants in the SAVE study, aged 45–75 years with co-occurring moderate-to-severe OSA and cardiovascular disease, who were randomized to CPAP therapy, greater early adherence was most predictive of higher long-term adherence at 24 months. Other positive predictor variables were higher CPAP pressure, very loud snoring and country. While other variables were significant univariate predictors, they did not retain overall significance and explained only a small component of the variation in adherence. These data may be utilized to better target efforts to improve CPAP adherence.”

The Prospective Association of Objectively Measured Sleep and Cerebral White Matter Microstructure in Middle-Aged and Older Persons

“Middle-aged and older persons with more wake after sleep onset, lower sleep efficiency and corresponding shorter sleep duration have altered microstructure in the projection and association tracts, in the cingulum, and in the anterior forceps of corpus callosum. If future studies confirm our findings, poor sleep could be considered as a risk factor for microstructural alterations of white matter in the aging brain.”

A Global Comparison of Anatomic Risk Factors and Their Relationship to Obstructive Sleep Apnea Severity in Clinical Samples

Many preoperative OSA screening scores have been developed and validated (STOP-Bang, P-SAP, DES-OSA, …). To the best of our knowledge, none of them include ethnicity. In this very interesting study, the authors confirmed that gender has to be included in OSA preoperative screening, and very interestingly, they have demonstrated we must consider ethnicity in this preoperative screening. They compared the following ethnicities: Caucasians, African Americans, Asians, and South Americans. South American appears to have the highest risk of developing OSA. This information is important for the development or improvement of future preoperative OSA screening scores.

BOSTN Bundle Intervention for Perioperative Screening and Management of Patients With Suspected Obstructive Sleep Apnea: A Hospital Registry Study

OSA represents an important risk factor for postoperative complications.
In this very interesting study, the authors have highlighted that a preoperative screening followed by clinical management pathways could induce a reduction of the length of stay for OSA patients and that they required postoperative mechanical ventilation less frequently. This study highlights a new perspective for OSA management: adequate screening following by special clinical pathways could lead to reducing postoperative OSA complications.

Quality of Life of Obstructive Sleep Apnoea Patients Receiving Continuous Positive Airway Pressure Treatment: A Systematic Review and Meta-Analysis

Previous studies have shown conflicting results on the effect of continuous positive airway pressure (CPAP) on quality of life (QoL) in OSA patients. This systematic review investigated the effect of CPAP on QoL in OSA patients compared to sham CPAP, placebo pills, and conservative treatment. Studies were identified via Web of Knowledge, PubMed, PsychInfo, CINAHL, EMBASE, OpenGrey, and the Cochrane Library. Findings indicate that CPAP treatment may help to improve physical symptoms of OSA, whereas impaired psychological QoL still cannot be alleviated.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-Analysis

Perioperative diagnosis of OSA has important resource implications because screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. The objective of this systematic review was to evaluate the correlation of surface ultrasound images with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help improve perioperative screening. A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface ultrasound assessment. Of the initial 3865 screened articles, 21 studies (7 airway and 14 non-airway) evaluating 3339 patients were included. Airway US parameters with moderate to good correlation with OSA were distance between lingual arteries, resting tongue thickness, tongue base thickness during Muller maneuver (MM), and a combination of neck circumference and retropalatal (RP) diameter shortening during MM. Non-airway US parameters with low to moderate correlation with OSA were carotid intimal thickness and plaque presence. In conclusion, a number of airway and non-airway parameters were identified with moderate to good correlation with OSA. Future studies should elucidate the utility of PoCUS for perioperative OSA screening.

Electrocardiogram-Based Sleep Analysis for Sleep Apnea Screening and Diagnosis

This study aimed to first evaluate the reliability of cardiopulmonary coupling analysis for the detection of OSA by comparing with polysomnography (PSG) derived sleep outcomes. PSG data from 205 participants was obtained for the evaluation of cardiopulmonary coupling by ECG regarding the detection of OSA. Automated CPC analyses were based on ECG signals only. Respiratory event index (REI) derived from CPC and apnea-hypopnea index (AHI) derived from PSG were compared for agreement tests. Results showed that cardiopulmonary coupling -REI positively correlated with PSG-AHI (r = 0.851, p < 0.001). Findings indicate that in the future ECG signals may potentially serve as screening tools for OSA.

The Effect of Acute Exposure to Morphine on Breathing Variability and Cardiopulmonary Coupling in Men with Obstructive Sleep Apnea: A Randomized Controlled Trial

This study aimed to detect and quantify opioid-induced cardiorespiratory pattern changes during sleep in OSA patients using novel automated methods and to correlate these with conventional polysomnography (PSG) measures. Under a randomized double-blind placebo-controlled crossover design, 60 male OSA patients attended two one-night visits to the sleep laboratory, at least a week apart receiving either 40-mg controlled-release oral morphine dose or placebo. The authors analyzed the inter-breath interval (IBI) from the PSG flow channel to quantify breathing irregularity while cardiopulmonary coupling (CPC) was analyzed using the PSG electrocardiogram (ECG) channel. After morphine use, OSA patients had fewer breaths, a longer inter-breath interval and more irregular breathing compared to the placebo night. Consumption of 40 mg controlled-release morphine resulted in a longer breathing cycle and increased breathing irregularity but generally more stable sleep in OSA patients. The significant links between respiratory, cardiopulmonary and sleep-disordered breathing parameters may suggest a practical value in surrogate overnight cardiorespiratory measurements, because both respiratory flow and ECG can be detected by small portable devices.