Variability of blood eosinophils in patients in a clinic for severe asthma.

BACKGROUND: Blood eosinophils are used to determine eligibility for agents targeting IL-5 in patients with uncontrolled asthma. However, little is known about the variability of blood eosinophil measures in these patients before treatment initiation. OBJECTIVE: To characterize variability and patterns of variability of blood eosinophil levels in a real-world clinic for severe asthmatics. METHODS: Retrospective review of blood eosinophils measured over a 5-year period in patients enrolled in an urban clinic. Repeated measures of blood eosinophil levels in individuals were evaluated, and cluster analysis was performed to characterize patients by eosinophil patterns. Clinical characteristics associated with eosinophil levels and patterns of variability were analysed. RESULTS: Patients treated in the Bellevue Hospital Asthma Clinic within a 3-month period were identified (n = 219). Blood eosinophil measures were obtained over the previous 5 years. Only 6% (n = 13) of patients had levels that were consistently above 300 cells/µL. Nearly 50% (n = 104) had eosinophil levels that traversed the threshold of 300 cells/µL. In contrast, 102 (46%) had levels that never reached the threshold of 300 cells/µL. Cluster analyses revealed three clusters with differing patterns of levels and variability. There was a suggestion of decreased clinical control and increased atopy in the cluster with the greatest variability in blood eosinophil measures. CONCLUSION: In an urban clinic for patients referred for uncontrolled asthma, blood measures of eosinophils were variable and showed differing patterns of variability. These data reinforce the need to perform repeated eosinophil blood measures for appropriate designation for therapeutic intervention.

Role of normal sleep and sleep apnea in human memory processing.

A fundamental problem in the field of obstructive sleep apnea (OSA) and memory is that it has historically minimized the basic neurobiology of sleep's role in memory. Memory formation has been classically divided into phases of encoding, processing/consolidation, and retrieval. An abundance of evidence suggests that sleep plays a critical role specifically in the processing/consolidation phase, but may do so differentially for memories that were encoded using particular brain circuits. In this review, we discuss some of the more established evidence for sleep's function in the processing of declarative, spatial navigational, emotional, and motor/procedural memories and more emerging evidence highlighting sleep's importance in higher order functions such as probabilistic learning, transitive inference, and category/gist learning. Furthermore, we discuss sleep's capacity for memory augmentation through targeted/cued memory reactivation. OSA - by virtue of its associated sleep fragmentation, intermittent hypoxia, and potential brain structural effects - is well positioned to specifically impact the processing/consolidation phase, but testing this possibility requires experimental paradigms in which memory encoding and retrieval are separated by a period of sleep with and without the presence of OSA. We argue that such paradigms should focus on the specific types of memory tasks for which sleep has been shown to have a significant effect. We discuss the small number of studies in which this has been done, in which OSA nearly uniformly negatively impacts offline memory processing. When periods of offline processing are minimal or absent and do not contain sleep, as is the case in the broad literature on OSA and memory, the effects of OSA on memory are far less consistent.

Obstructive Sleep Apnea in Community Members Exposed to World Trade Center Dust and Fumes.

STUDY OBJECTIVES: A relationship between obstructive sleep apnea (OSA) and exposure to the World Trade Center (WTC) dust and fumes has been suggested in responders but little is known about a possible relationship in community members. We characterized sleep studies performed in community members with WTC dust exposure to improve our understanding of the relationship between the diagnosis and severity of OSA and WTC dust exposure in this population. METHODS: Single-center, retrospective study of patients enrolled in a clinical treatment program for community members with WTC dust exposure. Patients were included if they had undergone sleep studies for evaluation of possible OSA through September 2016 and provided written informed consent. RESULTS: The total number of patients included in the analysis was 143. Patients were predominantly male (61%), never smokers (59%) and had a median body mass index of 31 kg/m2. Most reported upper and lower respiratory symptoms. An apnea-hypopnea index (AHI) ≥ 5 events/h was measured in 66% of the patients, and respiratory disturbance index was ≥ 5 events/h in 97%. The proportion of patients with moderate-severe OSA (defined by the AHI 4% criteria) was 50%. Multivariate logistic regression revealed that acute WTC dust cloud exposure was associated with severity but not diagnosis of OSA. CONCLUSIONS: We identified a high rate of OSA in the WTC community cohort who were referred for sleep studies. Exposure to the massive WTC dust cloud caused by the WTC collapse was independently associated with the severity of OSA in this population. This finding highlights the role that environmental exposures may play in the development of OSA.