The Nonsurgical Sleep Medicine Physician Role in the Development of an Upper Airway Stimulation Program.

BACKGROUND: Obstructive sleep apnea (OSA) is a common disorder in the US and other industrialized countries. Untreated OSA is associated with increased risk of coronary artery disease, cerebrovascular accidents, uncontrolled diabetes mellitus, poor workplace productivity, increased health care utilization, and higher risk of motor vehicle accidents. Continuous positive airway pressure (CPAP) is a commonly used treatment for OSA. CPAP nonadherence continues to be a major problem in clinical practice. METHODS: Upper airway stimulation (UAS) is an alternative option for management of OSA and has been shown to be safe and effective. This therapy involves electrical stimulation of the hypoglossal nerve to facilitate airway opening in the oropharynx. RESULTS: Although the UAS device is implanted by a surgeon in the operating room, the nonsurgical sleep medicine provider can play an important role in this type of therapy. CONCLUSIONS: This article outlines opportunities for a nonsurgical physician to become a leader in development of an institutional UAS program.

Respiratory Inductance Plethysmography Improved Diagnostic Sensitivity and Specificity of Obstructive Sleep Apnea.

BACKGROUND: Respiratory inductance plethysmography (RIP) is a tool used during a polysomnogram (PSG), which serves as a surrogate of respiratory effort and can help detect inspiratory air-flow limitation. We hypothesize that RIP can improve the sensitivity and specificity of scoring hypopneas when compared with both the recommended and acceptable criteria of the American Academy of Sleep Medicine. METHODS: We retrospectively analyzed a cohort of 12 subjects who had no obstructive sleep apnea (OSA) or mild OSA on PSG when scored by the American Academy of Sleep Medicine acceptable criteria for hypopneas but had high clinical suspicion for a diagnosis of OSA. These subjects were rescored using the American Academy of Sleep Medicine recommended criteria as well as RIP. Hypopnea was scored when there was a 50% decrease in the amplitude of the RIP sum channel (which combined input from chest and abdominal belts). OSA was diagnosed if the subjects had >5 respiratory events/h of sleep. The subject's response to CPAP was assessed by using a short questionnaire called the post-PSG sleep assessment. which evaluated subjective sleep quality. A positive response was considered an improvement in the post-PSG sleep assessment score after CPAP use. RESULTS: When scored using the American Academy of Sleep Medicine acceptable criteria, 10 subjects had a negative study, and 2 subjects had mild OSA for a sensitivity of 11% and specificity of 50%. When scored using the recommended criteria, 10 subjects had OSA, and 2 were negative, for a sensitivity of 78% and specificity of 70%. By RIP scoring, all 12 subjects had >5 respiratory events/h for a sensitivity of 100% and specificity of 75%. CONCLUSIONS: This small retrospective pilot study showed improved sensitivity and specificity when scoring hypopneas by RIP sum channel.

Biliary cast syndrome following liver transplantation: Predictive factors and clinical outcomes.

Biliary cast syndrome (BCS), the presence of biliary casts and debris causing biliary obstruction, occurs in 4%-18% of orthotopic liver transplant (OLT) recipients. Potential consequences include cholangitis and graft damage or loss. Limited data exist regarding the etiology and outcomes of BCS. The purpose of this study was to evaluate donor and recipient risk factors and determine the impact of BCS. A retrospective review of 355 OLT cases identified 9 BCS patients (2.5%) diagnosed by cholangiography. Twenty-six matched controls were also identified. The warm ischemic time was significantly longer in BCS patients. Other recipient and donor preoperative and intraoperative characteristics, including the donor risk index, revealed no significant differences. Overall patient survival showed a trend toward worse outcomes at 6, 12, and 18 months and end of follow-up in the BCS group. Overall graft survival was also worse in the BCS group at all time periods, with statistical significance demonstrated at 18 months and end of follow-up. The number of therapeutic biliary procedures and hospital readmissions was significantly higher in the BCS group. Twenty-two percent of the BCS patients required repeat OLT versus none of the control patients. In conclusion, BCS is an uncommon complication of OLT. Except for a longer warm ischemic time, recipient and donor factors did not predict the occurrence of BCS. BCS patients showed a significantly worse graft survival, as well as a trend toward worse patient survival. Given the negative impact of BCS on liver transplant outcomes, further studies appear justified.

Two-dimensional self-assembly in diblock copolymers.

Diblock copolymers confined to a two-dimensional surface may produce uniform features of macromolecular dimensions (approximately 10-100 nm). We present a mathematical model for nanoscale pattern formation in such polymers that captures the dynamic evolution of a solution of poly(styrene)-b-poly(ethylene oxide), PS-b-PEO, in solvent at an air-water interface. The model has no fitting parameters and incorporates the effects of surface tension gradients, entanglement or vitrification, and diffusion. The resultant morphologies are quantitatively compared with experimental data.