Clinical Adult Literature Updates from May 2016

The Association Between Obstructive Sleep Apnea and Alzheimer’s Disease: A Meta-Analysis Perspective

Alzheimer’s disease (AD) and obstructive sleep apnea (OSA) are highly prevalent, and the prevalence of OSA syndrome in patients with AD remains unknown. The auhtors collected all available published clinical data and analyzed them through a quantitative meta-analytical approach by calculating the aggregate odds ratio for OSA in AD vs. healthy control was 5.05 and homogeneous. This reflects that patients with AD have a five times higher chance of presenting with OSA than cognitively non-impaired individuals of similar age. Moreover, they also found that around half of patients with AD have experienced OSA at some point after their initial diagnosis. Future research should focus on the pathophysiological intercations betwneen the two syndromes, and establish causality. This evidence also promotes intensive screening for OSA amongst patients with AD.

Effects of Exercise Training on Sleep Apnoea in Patients with Coronary Artery Disease: a Randomised Trial

Overnight rostral fluid shift to the neck and lungs may contribute to the pathogenesis of obstructive sleep apnea (OSA) and central sleep apnea (CSA). The authors hypothesized that exercise training will decrease daytime leg fluid accumulation and overnight rostral fluid shift thereby decreasing the severity of OSA and CSA in patients with coronary artery disease (CAD). Patients with CAD and OSA or CSA (apnea-hypopnea index >15 events per h) were randomized to 4 weeks of aerobic exercise training or to a control group. The Apnea-hypopnea index decreased significantly more in the exercise group than in the control group (p=0.047), in association with a greater reduction in the overnight change in leg fluid volume (p=0.04) and by a significantly greater increase in the overnight change in UA-XSA in the exercise group (p=0.04). This study adds to the expanding literature and the beneficial effects of aerobic exercise in this vulnerable patient population.

Updated Adaptive Servo-Ventilation Recommendations for the 2012 AASM Guideline: “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses”

In light of recent results of a multicenter RCT (the SERVE-HF trail), and use of adaptive servo-ventilation (ASV) for the treatment of central sleep apnea syndrome (CSAS) related to congestive heart failure (CHF) has been controversial. An update of the 2012 systematic review and meta-analyses were performed that demonstrated an improvement in LVEF and a normalization of AHI in all patients. However, they also found that an increased risk of cardiac mortality in patients with an LVEF of ≤45% and moderate or severe CSA predominant sleep-disordered breathing. These data supported a Standard level recommendation against the use of ASV to treat CHF-associated CSAS in patients with an LVEF of ≤45% and moderate or severe CSAS, and an Option level recommendation for the use of ASV in the treatment CHF-associated CSAS in patients with an LVEF >45% and mild CSAS. The ultimate judgment regarding propriety of any specific care must be made by the clinician as per the AASM.

Is Perioperative Fluid and Salt Balance a Contributing Factor in Postoperative Worsening of Obstructive Sleep Apnea?

This article summarizes the evidence on the impact of fluid and salt balance on obstructive sleep apnea severity and reviews the potential anesthetic implications of excessive fluid and salt volume on worsening sleep apnea in the perioperative period.

Does Obstructive Sleep Apnea Influence Perioperative Outcome? A Qualitative Systematic Review for the Society of Anesthesia and Sleep Medicine Task Force on Preoperative Preparation of Patients with Sleep-Disordered Breathing

This systematic review found that patients with OSA had worse outcomes for pulmonary and combined complications versus control patients. The association between OSA and in-hospital mortality varied among studies with 9 studies showing no impact of OSA on mortality, 3 studies suggesting a decrease in mortality and 1 study reporting increased mortality.

Sleep Apnea and Circadian Extracellular Fluid Change as an Independent Factor for Nocturnal Polyuria

In this study 104 patients who underwent PSG for suspected sleep apnea syndrome completed questionnaires to evaluate sleep disordered breathing and lower urinary tract symptoms and had voiding frequency and voided volumes recorded over 24 hrs. Body composition was estimated in the morning and night using bioelectric impedance analysis. Patients with nocturnal polyuria had higher AHI and a larger circadian change in extracellular fluid adjusted to lean body mass than those without nocturnal polyuria. The relation was more evident in patients who were 65 or older. CPAP improved nocturnal polyuria.