Literature Updates from November 2013

Measuring Sleep: Accuracy, Sensitivity, and Specificity of Wrist Actigraphy Compared to Polysomnography

Actigraphy is overall a useful and valid means for estimating total sleep time and wakefulness after sleep onset in field and workplace studies, with some limitations in specificity.

The Interplay of Stress and Sleep Impacts BDNF Level

The authors suggest that sleep acts “… as a key mediator at the connection between stress and BDNF. Whether sleep is maintained or disturbed might explain why some individuals are able to handle a certain stress load while others develop a mental disorder.”

Hippocampal Sleep Spindles Preceding Neocortical Sleep Onset in Humans

“…we observed that sleep spindles consistently occurred in the hippocampus several minutes before sleep onset…. wakefulness and sleep are not mutually exclusive states, but rather part of a continuum resulting from the complex interaction between diffuse neuromodulatory systems and intrinsic properties of the different thalamocortical modules.”

Sleep Drives Metabolite Clearance From the Adult Brain

The authors present a study that features an interesting and innovative approach of looking at the restorative properties of sleep. The restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system.

Improvement of Intensive Care Unit Sound Environment and Analyses of Consequences on Sleep: An Experimental Study

In this study, the authors evaluated if modification of the ICU sound environment in a way feasible could improve sleep. Study participants were healthy male volunteers who were exposed to originally recorded ICU noise and peak reduced ICU noise. These different noise exposures where evaluated for their impact on sleep. Using polysomnography over four nights, subjects were evaluated after exposure to two nights of different maximum sound levels. The authors discovered that during ICU exposure nights, sleep was more fragmented with less slow wave sleep, more arousals and more time awake. Unfortunately, the reduction of maximal A-weighted levels from 64 to 56 dB was not enough to have a clear improved effect on sleep quality in this study.

Sleep, Anxiety and Fatigue in Family Members of Patients Admitted to the Intensive Care Unit: A Questionnaire Study

In the hustle and bustle on the intensive care unit, family members can often be stressed. Despite intensivist best efforts, family members can experience health problems related to a family member’s ICU experience. In this timely and important study, the authors remind us not to only be mindful of our patient’s sleep deprivation, but also their loved one’s (our other patients) sleep experience. In this study, the author’s state that one of the first ways families suffer is loss of sleep. Using the General Sleep Disturbance Scale (GSDS), Beck Anxiety Index (BAI) and Lee Fatigue Scale (NRS-F), the authors created a questionnaire to evaluate sleep fatigue and anxiety during the intensive care unit admission. 94 people responded to the survey, 43.6% of whom were children. 43.5% of the respondents stated sleep quality was poor to very poor. Only 15.2% stated sleep was good/very good. Anxiety, tension and fear were the biggest contributors to poor sleep. The most common suggestion to improve sleep was more information regarding the patient’s health and relaxation techniques. Hence, when thinking of sleep in the ICU, do not forget the patient’s family and their ICU related sleep disturbances.

Non-Pharmacologic Interventions to Improve the Sleep of Hospitalized Patients: A Systematic Review

While not looking at the ICU directly, evaluating non-pharmacologic interventions to improve the sleep of hospitalized patients is a discussion that could be of great benefit to the intensivist. In this review, the authors evaluated 13 studies, including four randomized controlled trials with over 1150 patients. As with many reviews of the literature, the authors found great heterogeneity in the trials with regards to interventions, patient populations, outcome measures and length of follow up. The authors found that daytime light exposure improved sleep quality 7–18%, improved sleep hygiene improved sleep 5% and relaxation techniques improved sleep 0–38%. These finding are interesting and may help the hospital physician determine where initial interventions to improve sleep can be made. However, the authors comment that there is insufficient evidence that any non-pharmacologic intervention improves sleep in general inpatients and further studies are needed.

Continuous Positive Airway Pressure and Noninvasive Ventilation Adherence in Children

In this prospective cohort study, continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) treatment data was analyzed in 62 consecutive patients (age>2 years), where the majority had OSA (80%). Treatment was initiated in a specialized pediatric NIV unit followed up at home. Long-term CPAP/NIV adherence at home was extremely high (up to 9 hours), and no correlation was found between type of interface, age, type or duration of ventilation, or efficacy of nocturnal gas exchange. Thus highlighting the importance of close collaboration of the health care team, patient, family and trained pediatric homecare providers to increase adherence to therapy.


Does Treatment of SDB in Children Improve Cardiovascular Outcome?

The aim of this review is to summarise the findings of studies to date which have investigated the cardiovascular outcomes in children treated for SDB and to make recommendations for future management of this very common disease.

Novel Pharmacological Approaches for Treatment of Obstructive Sleep Apnea in Children

Surgical approaches for pediatric OSA may not be as effective as previously anticipated. Accordingly, expanded use of existing systemic or topical anti-inflammatory agents or development of novel compounds targeting selected immune cell populations underlying pathophysiological determinants of OSA is needed.