Clinical polysomnographic methods for estimating pharyngeal collapsibility in obstructive sleep apnea.

STUDY OBJECTIVES: Obstructive sleep apnea has major health consequences but is challenging to treat. For many therapies, efficacy is determined by the severity of underlying pharyngeal collapsibility, yet there is no accepted clinical means to measure it. Here, we provide insight into which polysomnographic surrogate measures of collapsibility are valid, applicable across the population, and predictive of therapeutic outcomes. METHODS: Seven promising polysomnography-derived surrogate collapsibility candidates were evaluated: Vpassive (flow at eupneic ventilatory drive), Vmin (ventilation at nadir drive), event depth (depth of the average respiratory event), oxygen desaturation slope and mean oxygen desaturation (events-related averages), Fhypopneas (fraction of events scored as hypopneas), and apnea index. Evaluation included (1) validation by comparison to physiological gold-standard collapsibility values (critical closing pressure, Pcrit), (2) capacity to detect increased collapsibility with older age, male sex, and obesity in a large community-based cohort (Multi-Ethnic Study of Atherosclerosis, MESA), and (3) prediction of treatment efficacy (oral appliances and pharmacological pharyngeal muscle stimulation using atomoxetine-plus-oxybutynin). RESULTS: Pcrit was significantly correlated with Vmin (r = -0.54), event depth (r = 0.49), Vpassive (r = -0.38), Fhypopneas (r = -0.46), and apnea index (r = -0.46; all p < .01) but not others. All measures detected greater collapsibility with male sex, age, and obesity, except Fhypopneas and apnea index which were not associated with obesity. Fhypopneas and apnea index were associated with oral appliance and atomoxetine-plus-oxybutynin efficacy (both p < .05). CONCLUSIONS: Among several candidates, event depth, Fhypopneas, and apnea index were identified as preferred pharyngeal collapsibility surrogates for use in the clinical arena.

Predicting sleep apnea responses to oral appliance therapy using polysomnographic airflow.

STUDY OBJECTIVES: Oral appliance therapy is an increasingly common option for treating obstructive sleep apnea (OSA) in patients who are intolerant to continuous positive airway pressure (CPAP). Clinically applicable tools to identify patients who could respond to oral appliance therapy are limited. METHODS: Data from three studies (N = 81) were compiled, which included two sleep study nights, on and off oral appliance treatment. Along with clinical variables, airflow features were computed that included the average drop in airflow during respiratory events (event depth) and flow shape features, which, from previous work, indicates the mechanism of pharyngeal collapse. A model was developed to predict oral appliance treatment response (>50% reduction in apnea-hypopnea index [AHI] from baseline plus a treatment AHI <10 events/h). Model performance was quantified using (1) accuracy and (2) the difference in oral appliance treatment efficacy (percent reduction in AHI) and treatment AHI between predicted responders and nonresponders. RESULTS: In addition to age and body mass index (BMI), event depth and expiratory "pinching" (validated to reflect palatal prolapse) were the airflow features selected by the model. Nonresponders had deeper events, "pinched" expiratory flow shape (i.e. associated with palatal collapse), were older, and had a higher BMI. Prediction accuracy was 74% and treatment AHI was lower in predicted responders compared to nonresponders by a clinically meaningful margin (8.0 [5.1 to 11.6] vs. 20.0 [12.2 to 29.5] events/h, p < 0.001). CONCLUSIONS: A model developed with airflow features calculated from routine polysomnography, combined with age and BMI, identified oral appliance treatment responders from nonresponders. This research represents an important application of phenotyping to identify alternative treatments for personalized OSA management.

Incobotulinum Toxin-A Improves Post-Surgical and Post-Radiation Pain in Cancer Patients.

Cancer patients who undergo surgery or radiation can develop persistent focal pain at the site of radiation or surgery. Twelve patients who had surgery or radiation for local cancer and failed at least two analgesic medications for pain control were prospectively enrolled in a research protocol. Patients were injected up to 100 units of incobotulinum toxin A (IncoA) intramuscularly or subcutaneously depending on the type and location of pain (muscle cramp or neuropathic pain). Two patients passed away, one dropped out due to a skin reaction and another patient could not return for the follow up due to his poor general condition. All remaining 8 subjects (Age 31-70, 4 female) demonstrated significant improvement of Visual Analog Scale (VAS) (3 to 9 degrees, average 3.9 degrees) and reported significant satisfaction in Patients' Global Impression of Change scale (PGIC) (7 out of 8 reported the pain as much improved). Three of the 8 patients reported significant improvement of quality of life.

Pre-liver transplant protocols in dentistry.

The number of adults with end stage liver disease in the U.S., awaiting liver transplantation, has maintained a steady upward trend in recent years. Concurrently, the survival rate of liver transplant recipients has also been on the rise. To be able to safely treat this population, dentists should have familiarity with special management requirements of patients with end stage liver disease. This article reviews the historical background on liver transplantation and provides updated information on indications and evaluation protocols, treatment considerations in end stage liver disease, clinical dental management protocols prior to surgical procedures and dental considerations in the pre-liver transplant candidates.