Transkingdom Control of Microbiota Diurnal Oscillations Promotes Metabolic Homeostasis

The authors of this study demonstrate that there are significant bacterial species that contribute to the microbiota of the mammalian gut which are regulated by circadian principles.  By altering the timing of feeding, introducing circadian distortion by simulating jet lag in mice, or by using genetic mutants animals that lack critical components of the cellular circadian clock (PER1/2 knockout), the normal cyclical presence and activity of various microbes in the gut is altered.  The consequence of this disruption as studied in this work includes significant weight gain and glucose intolerance in test mice, a finding which is interestingly ablated by the administration of oral antibiotics.   As further evidence, the authors show replication of metabolic dysfunction when microbiota from human jet lagged subjects is transplanted into the gut of germ free mice under normal conditions indicating that this dysbiosis is not only persistent after jet lag but may be regulated by intrinsic principles in the microbial pool that are unaffected by an otherwise normally functioning host environment. In summary, this article demonstrates that circadian disruption causes dysbiosis of mammalian gut microbiota causing persistent deleterious metabolic changes and may be amenable to simple therapeutic interventions.

A Matched Cohort Study of Postoperative Outcomes in Obstructive Sleep Apnea

In this matched cohort study, the authors analyzed whether patients with obstructive sleep apnea (OSA) diagnosed from polysomnography data obtained before or after surgery from a health administrative database from Manitoba, Canada, between 1987-2008, were at increased risk for postoperative complications compared with controls. Patients with a preoperative diagnosis of obstructive sleep apnea (OSA) and prescription of continuous positive airway pressure therapy were less than half as likely to experience postoperative cardiovascular complications – specifically cardiac arrest and shock. Respiratory complications were twice as likely in OSA patients, regardless of whether the OSA diagnosis was known at the time of surgery or after surgery. The OSA severity, type of surgery, age and other comorbidities were also important risk modifiers. Although this study has the limitations inherent to using health administrative data, it is the largest study that has used polysomnography to compare perioperative outcomes between undiagnosed and diagnosed OSA.

Effect of Sedative-Hypnotics, Anesthetics and Analgesics on Sleep Architecture in Obstructive Sleep Apnea

This article critically reviewed the literature relevant to preoperative screening for OSA, prevalence of OSA in surgical populations and changes in postoperative sleep architecture relevant to OSA patients … in regard to the effects of sedative-hypnotics, anesthetics and analgesics on sleep architecture, the underlying mechanisms and the relevance to OSA.

Chronic Sleep Fragmentation Induces Endothelial Dysfunction and Structural Vascular Changes in Mice

Long-term sleep fragmentation induces vascular endothelial dysfunction and mild blood pressure increases. Sleep fragmentation also leads to morphologic vessel changes characterized by elastic fiber disruption and disorganization, increased recruitment of inflammatory cells, and altered expression of senescence markers, thereby supporting a role for sleep fragmentation in the cardiovascular morbidity of OSA.

Delirium Transitions in the Medical ICU: Exploring the Role of Sleep Quality and Other Factors

Written by one of the more productive groups in the field, the authors evaluated the link of perceived sleep quality ratings along with other patient and ICU risk factors with the development of delirium on a daily basis in 223 medical ICU patients over a 201 day period. Interestingly, the author’s found no association between daily perceived sleep quality ratings and transition to delirium. As reported in other publications, the authors found infusion of benzodiazepines and opioids in mechanically ventilated patients as risk factors for the development of delirium.

Sleep in the Intensive Care Unit: A Review

In this article, the authors review and update the reader on what is currently known with regards to staging and measuring sleep. It offers a nice review on the characteristics of sleep in the ICU. There is a very nice section of sleep deprivation and immune function. Most of the article focuses on causes of abnormal sleep in the ICU and reviews much of what is already known. It concludes with a nice review of how to promote sleep in the ICU.

Sleep Disturbance in Older ICU Patients

In this study, the authors note aging is associated with specific changes to both the quantity and quality of sleep and that these changes make it hard to adjust sleep and wake rhythms to changing environmental conditions. In the context of the ICU, an environment already known to alter sleep, the authors evaluated sleep in patients admitted to the ICU who were older than age 80. The authors reviewed four studies on sleep in the elderly. This study was helpful in bring much of the resaerch of sleep in elderly ICU patients into one location. However, much is still needed in the study of sleep in this frail and vulnerable population.