Study Objectives: To evaluate the ability of chest wall EMG (CW-EMG) using surface electrodes to classify apneas as obstructive, mixed, or central compared to classification using dual channel uncalibrated respiratory inductance plethysmography (RIP). Methods: CW-EMG was recorded from electrodes in the eighth intercostal space at the right mid-axillary line. Consecutive adult clinical sleep studies were retrospectively reviewed, and the first 60 studies with at least 10 obstructive and 10 mixed or central apneas and technically adequate tracings were selected. Four obstructive and six central or mixed apneas (as classified by previous clinical scoring) were randomly selected. A blinded experienced scorer classified the apneas on the basis of tracings showing either RIP channels or the CW-EMG channel. The agreement using the two classification methods was determined by kappa analysis and intraclass correlation. Results: The percentage agreement was 89.5%, the kappa statistic was 0.83 (95% confidence interval 0.79 to 0.87), and the intraclass correlation was 0.83, showing good agreement. Of the 249 apneas classified as central by RIP, 26 were classified as obstructive (10.4%) and 7 as mixed (2.8%) by CW-EMG. Of the 229 events classified as central by CW-EMG, 7 (3.1%) were classified as obstructive and 6 (2.6%) as mixed by RIP. Conclusions: Monitoring CW-EMG may provide a clinically useful method of detection of respiratory effort when used with RIP and can prevent false classification of apneas as central. RIP can rarely detect respiratory effort not easily discernible by CW-EMG and the combination of the two methods is more likely to avoid apnea misclassification. Keywords: apnea, diaphragmatic EMG, polysomnography, respiratory effort Citation: Berry RB, Ryals S, Girdhar A, Wagner MH. Use of chest wall electromyography to detect respiratory effort during polysomnography.

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Study Objectives: To evaluate the ability of a transformed electrocardiography (ECG) signal recorded using standard electrode placement to detect inspiratory bursts from underlying surface chest wall electromyography (EMG) activity and the utility of the transformed signal for apnea classification compared to uncalibrated respiratory inductance plethysmography (RIP). Methods: Part 1: 250 consecutive adult studies without regard to respiratory events were retrospectively reviewed. The ECG signal was transformed with high pass filtering and viewed with increased sensitivity and channel clipping to determine the fraction of studies with inspiratory burst visualization as compared to chest wall EMG (right thorax). Part 2: 445 consecutive studies were reviewed to select 40 with ≥ 10 obstructive and ≥ 10 mixed or central apneas (clinical scoring). Five obstructive and 5 central or mixed apneas were randomly selected from each study. A blinded scorer classified the apneas using either RIP or a transformed ECG signal using high pass filtering and QRS blanking. The agreement between the two classifications was determined by kappa analysis. Results: Part 1: Inspiratory burst visualization was noted in the transformed ECG signals and chest wall EMG signals in 83% and 71% of the studies (P < .001). Part 2: The percentage agreement between RIP and transformed ECG signal classification was 88.5%, the kappa statistic was 0.81 (95% CI 0.76 to 0.86) and interclass correlation was 0.84, showing good agreement. Conclusions: A transformed ECG signal can exhibit inspiratory bursts in a high proportion of patients and is potentially useful for detecting respiratory effort and apnea classification.

2016-10-17T18:53:41

Inappropriate PET-MPI was rarely abnormal, associated with low catheterization rates, and failed to detect occult ischemia for any subjects. The clinical utility of inappropriate PET-MPI is negligible.

apparent on the original visit. She came with a family member who reported sudden onset and rapid worsening of the patient's cognition with new issues of confusion and disorientation. Short-term memory was poor, but long-term memory remained intact. Mini-Mental Status Examination yielded 2 out of 3 correct for recall. Hyperhidrosis was more prominent occurring during wakefulness hours as well as during sleep.The patient's sleep-wake schedule was erratic with intermittent brief dozing day and night. Her sleep behaviors, such as dressing herself, combing her hair, and tying her shoes, were more complex. Initially dream enactment behaviors were simpler with calling out and sitting up in bed. She was unresponsive during these periods, amnestic for her actions in sleep, but awoke oriented. Despite efforts to use PAP, the patient would disassemble her interface while asleep. She reported horizontal diplopia, new-action tremor, and a 12-lb weight loss. Her pertinent vital signs were blood pressure 164/108 and heart rate 110 bpm. Comprehensive metabolic panel, thyroid function tests, urinalysis, and head computed tomography were unrevealing. Repeat PSG was attempted on continuous positive airway pressure with the patient demonstrating little sleep ( Table 1).A 51-year-old woman presented with insomnia for 2 months and daytime sleepiness for 6 months. The patient attributed the insomnia to stress from recent life events. Her Epworth Sleepiness Scale score was 18 of 24. Observers of the patient reported loud snoring, apneas, kicking, and dream enactment. The patient had hyperhidrosis during sleep.Family history was positive for hypertension and dementia. Social history excluded tobacco, alcohol, or illicit drug usage. Review of symptoms was significant for heart palpitations, headaches, and depression. The patient's medical history was negative with no medications.Physical examination revealed a blood pressure of 140/90 and body mass index of 30.3 kg/m 2 . The patient's Mallampati score was class IV. Physical examination was otherwise unremarkable. Neurological examination showed normal reflexes, gait, and intellect with good recent and remote memory recall.Diagnostic polysomnography (PSG) showed apnea-hypopnea index, 84.4 events/h; periodic limb movement index, 10.7 events/h; reduced total sleep time (140 minutes); increased stage N1 sleep; and no stage N3 or R sleep. Minimum oxygen saturation was 80%. Sleep spindles were absent.The patient refused an in-laboratory positive airway pressure (PAP) titration, and was placed on auto-adjusting PAP therapy for her severe obstructive sleep apnea.At follow-up, 8 weeks after starting auto-adjusting PAP therapy, the patient demonstrated cognitive impairment not

in Canada. Direct-to-consumer advertising may have helped escalate niacin use, specifically Niaspan in the United States, with its prominent "intervention-style" ads. 11 Our study is limited in that we did not have access to patient-level data to determine whether niacin prescribing was clinically appropriate. Our study only evaluated the prescription niacin market; niacin use likely exceeds our estimates since some niacin products can be purchased over the counter. In conclusion, our study shows that prescription niacin sales are substantial and growing, even in the absence of contemporary supportive trial evidence. The discordance between sales and evidence should be a focus of professional dialogue about the role of this medication in the medical armamentarium.

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