Comparative study of a single lead ECG in a wearable device.

BACKGROUND: Technological advances have led to electrocardiograph (ECG) functionality becoming increasingly accessible in wearable health devices, which has the potential to vastly expand the clinician's ability to monitor, diagnose, and manage cardiac health conditions. However, achieving the high signal quality necessary to make an accurate and confident diagnosis is inherently challenging on consumer device-acquired ECGs. Effective signal conditioning is crucial to make ECG data from wearable devices clinically actionable. OBJECTIVE: This study evaluates the heart rate (HR) performance of ECG data collected on the HeartKey® Test Watch, a single lead, dry electrode wrist wearable, against data acquired on two criterion devices: the Bittium® Faros 180, a gold standard wet electrode ambulatory monitoring device, and the HeartKey Chest Module. METHODS: ECG data was simultaneously acquired on three devices during a multi-stage protocol (sitting, walking, standing) designed to reflect the motion noise of real-life scenarios. Raw ECGs from the HeartKey Test Watch and HeartKey Chest Module were processed through HeartKey software, and the accuracy of the outputted heart rate data was compared to that of the criterion device at each stage of the protocol. A beat rejection analysis was performed to provide insight into the degree of high-frequency noise present in ECGs recorded on the HeartKey Test Watch. RESULTS: Data acquired on the HeartKey Test Watch and processed by HeartKey software generated HR metrics that closely matched that of the criterion devices throughout the protocol. Bland-Altman analysis showed a mean absolute HR difference of 0.74, 1.21, 0.80 bpm during the sitting, walking, and standing stages respectively, which is within the ± 10% or ±5 bpm range required by ANSI EC13. ECG data from the HeartKey Test Watch had a higher beat rejection rate relative to the HeartKey Chest Module (8.5% vs ∼0%) due to the excessive high-frequency noise generated during the motion-based protocol. CONCLUSION: HeartKey software demonstrated highly accurate HR performance, comparable to that of the criterion Faros device, when processing challenging ECG data acquired on a single lead, dry electrode wrist wearable during both non-motion and motion-based protocols.

A universal, high-performance ECG signal processing engine to reduce clinical burden.

BACKGROUND: Electrocardiogram (ECG) signal conditioning is a vital step in the ECG signal processing chain that ensures effective noise removal and accurate feature extraction. OBJECTIVE: This study evaluates the performance of the FDA 510 (k) cleared HeartKey Signal Conditioning and QRS peak detection algorithms on a range of annotated public and proprietary ECG databases (HeartKey is a UK Registered Trademark of B-Secur Ltd). METHODS: Seven hundred fifty-one raw ECG files from a broad range of use cases were individually passed through the HeartKey signal processing engine. The algorithms include several advanced filtering steps to enable significant noise removal and accurate identification of the QRS complex. QRS detection statistics were generated against the annotated ECG files. RESULTS: HeartKey displayed robust performance across 14 ECG databases (seven public, seven proprietary), covering a range of healthy and unhealthy patient data, wet and dry electrode types, various lead configurations, hardware sources, and stationary/ambulatory recordings from clinical and non-clinical settings. Over the NSR, MIT-BIH, AHA, and MIT-AF public databases, average QRS Se and PPV values of 98.90% and 99.08% were achieved. Adaptable performance (Se 93.26%, PPV 90.53%) was similarly observed on the challenging NST database. Crucially, HeartKey's performance effectively translated to the dry electrode space, with an average QRS Se of 99.22% and PPV of 99.00% observed over eight dry electrode databases representing various use cases, including two challenging motion-based collection protocols. CONCLUSION: HeartKey demonstrated robust signal conditioning and QRS detection performance across the broad range of tested ECG signals. It should be emphasized that in no way have the algorithms been altered or trained to optimize performance on a given database, meaning that HeartKey is potentially a universal solution capable of maintaining a high level of performance across a broad range of clinical and everyday use cases.

Clinical experience with repository corticotropin injection in patients with multiple sclerosis experiencing mood changes with intravenous methylprednisolone: a case series.

The elevated prevalence of neuropsychiatric symptoms and disorders among patients with multiple sclerosis (MS) is well recognized, as are potential neuropsychiatric side effects of treatment with corticosteroids. Both methylprednisolone (MP) and repository corticotropin injection (HP Acthar(®) gel) have demonstrated efficacy in reducing short-term disability after exacerbations of MS. Although historical data are limited, repository corticotropin injection has not generally been associated with detrimental neuropsychiatric effects. We describe six cases of patients with relapsing-remitting MS who had previously experienced detrimental mood changes with MP treatment. Some of these patients had previous histories of mood disorders or other neuropsychiatric symptoms prior to MS diagnosis. All six patients were subsequently treated with repository corticotropin injection for MS exacerbations and each demonstrated improvements in MS symptoms. This clinical experience suggests that repository corticotropin injection should be considered as an alternative for patients who do not tolerate corticosteroids or have difficulties associated with intravenous medication. Furthermore, the rate of neuropsychiatric side effects observed in these patients was low. These observations support repository corticotropin injection as a viable alternative for the treatment of acute exacerbations of MS, particularly in patients who have a history of neuropsychiatric disorders or symptoms either independently or in response to MP treatment. In reviewing both the published data and our own clinical experience regarding potential neuropsychiatric adverse events with treatment for MS exacerbations, we hope to stimulate further research into the potential efficacy and safety of repository corticotropin injection among patients with some form of neuropsychiatric complications that must be considered when establishing a treatment plan for MS.

Short women with severe sepsis-related acute lung injury receive lung protective ventilation less frequently: an observational cohort study.

INTRODUCTION: Lung protective ventilation (LPV) has been shown to improve survival and the duration of mechanical ventilation in acute lung injury (ALI) patients. Mortality of ALI may vary by gender, which could result from treatment variability. Whether gender is associated with the use of LPV is not known. METHODS: A total of 421 severe sepsis-related ALI subjects in the Consortium to Evaluate Lung Edema Genetics from seven teaching hospitals between 2002 and 2008 were included in our study. We evaluated patients' tidal volume, plateau pressure and arterial pH to determine whether patients received LPV during the first two days after developing ALI. The odds ratio of receiving LPV was estimated by a logistic regression model with robust and cluster options. RESULTS: Women had similar characteristics as men with the exception of lower height and higher illness severity, as measured by Acute Physiology and Chronic Health Evaluation (APACHE) II score. 225 (53%) of the subjects received LPV during the first two days after ALI onset; women received LPV less frequently than men (46% versus 59%, P < 0.001). However, after adjustment for height and severity of illness (APACHE II), there was no difference in exposure to LPV between men and women (P = 0.262). CONCLUSIONS: Short people are less likely to receive LPV, which seems to explain the tendency of clinicians to adhere to LPV less strictly in women. Strategies to standardize application of LPV, independent of differences in height and severity of illness, are necessary.