Adhesive Electrodes Research Articles

Abstract 11: Surface Electromyography-Based Gamification Therapy For Rehabilitation Of Upper Extremity Weakness: An Acceptability Study

Purpose: Upper extremity weakness may be debilitating and results from a variety of causes, including peripheral nerve and cervical spinal cord injury, stroke, and disuse atrophy. Therapy is critical for regaining function but patients are unable to engage with traditional methods of therapy until evidence of motor recovery is seen on clinical exam. In this study, we have developed an innovative system of gamified therapy that uses signals detected by surface electromyography (EMG), a well-established, noninvasive technique that measures electrical activity generated by muscle contractions from electrodes placed on the overlying skin. Methods: We constructed a highly sensitive custom surface EMG device and integrated it with multiple gaming platforms. In our system, adhesive electrodes are placed over a muscle of interest, and muscle activation greater than a set threshold triggers a single action in the virtual gaming environment. Patients with upper extremity weakness from any cause were recruited to use the surface EMG device to play games. Acceptability surveys were administered after each gaming session, and additional metrics to assess feasibility were examined, including task learning speed, length of gameplay session, high scores achieved, and technical problems encountered. Results: The sensitivity of our custom surface EMG device was assessed through simultaneous needle EMG recordings. Our device is capable of detecting muscle activation even during recruitment of a single motor unit, and signals recorded represent activity from the specific muscle of interest and not of opposing muscle groups nearby. Patients quickly learned how to activate their muscles to interact with the virtual gaming environment. Interestingly, patients lacking antigravity muscle strength, scoring as low as 2/5 on manual muscle testing, were still able to engage in reliable gameplay. Responses from acceptability surveys showed that the majority of patients found the surface EMG-based gaming platform to be motivating, enjoyable, easy to understand, and safe. Conclusion: Gamified therapy represents a novel approach to rehabilitation that promotes patient engagement, motivation, and compliance. The use of surface EMG signals as input for therapeutic gaming has tremendous potential for severe muscle weakness in the earliest stages of recovery, as nascent signals from underlying affected muscles are detectable on EMG before significant movement is observed on clinical exam. This creates the opportunity for earlier initiation of therapy in many patients with upper extremity weakness. In patients with brachial plexus injuries who have undergone nerve transfer surgeries, surface EMG-based therapy may have the added benefit of facilitating cortical retraining by helping patients learn the association between donor nerve activation and recipient muscle movement. Future studies are needed to assess the clinical efficacy of surface EMG-based gamification therapy in these distinct patient populations.

Effect of sternal electrode gap and belt rotation on the robustness of pulmonary electrical impedance tomography parameters

Objective:Non-adhesive textile electrode belts offer several advantages over adhesive electrodes and are increasingly used in neonatal patients during continuous electrical impedance tomography (EIT) lung monitoring. However, non-adhesive belts may rotate in unsedated patients and discrepancies between chest circumference and belt sizes may result in a gap between electrodes near the sternum. This project aimed to determine the effects of belt rotation and sternal electrode gap on commonly used lung EIT parameters.Approach:We developed a simulation framework based on a 3D finite-element model and introduced lung regions with little or no ventilation that could be changed according to a decremental positive end-expiratory pressure (PEEP) trial. Four degrees of sternal gap and belt rotation were simulated and their effect on the EIT parameters silent spaces, centre of ventilation, global inhomogeneity index and overdistension/collapsed lung (OD/CL) analysed. Additionally, seven premature infants were examined to assess the influence of leftward and rightward belt rotations in a clinical setting.Main results:Small violations of the electrode equidistance criterion and rotations of the belts less than one electrode space exert only minor effects on the EIT parameters and do not impede the interpretation. Rotations of two and three electrode spaces induce non-negligible effects that might lead to flawed interpretations. The ‘best PEEP’ determined with the OD/CL approach was robust and identifiable with all studied sternal gaps and belt rotations.Significance:We revealed an important challenge for neonatal EIT applications related to a wide electrode gap at the sternum and belt rotation, which should be avoided in clinical application.

Textile Electrocardiogram (ECG) Electrodes for Wearable Health Monitoring.

Wearable health-monitoring systems should be comfortable, non-stigmatizing, and able to achieve high data quality. Smart textiles with electronic elements integrated directly into fabrics offer a way to embed sensors into clothing seamlessly to serve these purposes. In this work, we demonstrate the feasibility of electrocardiogram (ECG) monitoring with sewn textile electrodes instead of traditional gel electrodes in a 3-lead, chest-mounted configuration. The textile electrodes are sewn with silver-coated thread in an overlapping zig zag pattern into an inextensible fabric. Sensor validation included ECG monitoring and comfort surveys with human subjects, stretch testing, and wash cycling. The electrodes were tested with the BIOPAC MP160 ECG data acquisition module. Sensors were placed on 8 subjects (5 males and 3 females) with double-sided tape. To detect differences in R peak detectability between traditional and sewn sensors, effect size was set at 10% of a sample mean for heart rate (HR) and R-R interval. Paired student’s t-tests were run between adhesive and sewn electrode data for R-R interval and average HR, and a Wilcoxon signed-rank test was run for comfort. No statistically significant difference was found between the traditional and textile electrodes (R-R interval: t = 1.43, p > 0.1; HR: t = −0.70, p > 0.5; comfort: V = 15, p > 0.5).

Non-contact sensing of neonatal pulse rate using camera-based imaging: a clinical feasibility study

Objective: Neonates and infants are patients who would benefit from less invasive vital sign sensing, especially from fewer cables and the avoidance of adhesive electrodes. Photoplethysmography imaging (PPGI) has been studied for medical applications in recent years: it is possible to assess various vital signs remotely, non-invasively, and without contact by using video cameras and light. However, studies on infants and especially on neonates in clinical settings are still rare. Hence, we conducted a single-center study to assess heart activity by estimating the pulse rate (PR) of 19 neonates. Approach: Time series were generated from tracked regions of interest (ROIs) and PR was estimated via a joint time-frequency analysis using a short-time Fourier transform. Artifacts, for example, induced by movement, were detected and flagged by applying a signal quality index in the frequency domain. Main results: The feasibility of PR estimation was demonstrated using visible light and near-infrared light at 850 nm and 940 nm, respectively: the estimated PR was as close as 3 heartbeats per minute in artifact-free time segments. Furthermore, an improvement could be shown when selecting the best performing ROI compared to the ROI containing the whole body. The main challenges are artifacts from motion, light sources, medical devices, and the detection and tracking of suitable regions for signal retrieval. Nonetheless, the PR extracted was found to be comparable to the contact-based photoplethysmography reference and is, therefore, a viable replacement if robust signal retrieval is ensured. Significance: Neonates are seldom measured by PPGI and studies reporting measurements on darker skin tones are rare. In this work, not only a single camera was used, but a synchronized camera setup using multiple wavelengths. Various ROIs were used for signal extraction to examine the capabilities of PPGI. In addition, qualitative observations regarding camera parameters and noise sources were reported and discussed.

A method to assess heart rate variability in neonate rats: validation in normotensive and hypertensive animals.

Several studies have focused on the heart rate variability (HRV) of murine species, while studies discussing HRV in murine neonates and infants remain scarce, since recording hemodynamic signals through invasive methods in small animals has been found to be quite challenging. Thus, this study aimed at describing and validating a novel method to assess HRV in newborn rats. An electrocardiogram (ECG) system was used to determine RR intervals in awake newborns and evaluate HRV in normotensive (Wistar) and hypertensive (SHR) neonate rats. After birth, ECG was recorded in the awake newborns, and they were allowed to rest on a heated surface, restricted only by the weight of the adhesive ECG electrodes. The electrodes were cut and adapted to provide more comfort to the animal, and gently placed on the newborn's skin. RR intervals were recorded over a 30-min period using an ECG system together with LabChart software (4 KHz). Three sequences of 5 min each from the ECG recording period were analyzed in time and frequency domains, using CardioSeries software. ECG data resulted in a clearly interpretable signal that was used to generate an RR interval sequence through time for the analysis of HRV. SHR neonates presented increased cardiac sympathovagal balance compared to Wistar neonates (low frequency/high frequency: 3.85±0.71 vs 0.90±0.09). In conclusion, the ECG setup here described may be used to record RR intervals to assess HRV in neonate rats, thus detecting early impairment of HRV in hypertensive newborns.

Highly adhesive, washable and stretchable on-skin electrodes based on polydopamine and silk fibroin for ambulatory electrocardiography sensing

Highly skin-adhesive, washable and stretchable electrodes were fabricated by combining polydopamine, silk fibroin, and SEBS/Au films for ambulatory electrocardiography sensing.

Determining the input impedance of ECG amplifiers using accurate electrode modelling

Objective: The influence of the skin-electrode-amplifier interface and the input impedance of ECG recording amplifiers on transient response performance is investigated using accurate modeling of surface contact electrodes. The paper aims to establish the input impedance requirements of ECG recording amplifiers based on the electrical properties of the electrodes. Approach: The IEC 60601 standard stipulates the performance requirements for electrocardiographs. Analyses and simulation of both dc and ac modes of coupling the electrodes to the input of the amplifier have been undertaken using an accurate double time-constant model of the electrodes in order to establish design constraints for amplifier input impedance to meet this performance specification. These have been backed up with bench tests. Main Results: Investigations carried out indicate that the minimum 10 MΩ resistance at the amplifier input recommended in the specification is insufficient when using some modern adhesive electrodes and increasingly popular un-gelled or dry electrodes. Design constraints are established based on the electrical properties of the electrodes. These constraints suggest that the input impedance of the amplifier should be as high as 10 GΩ and the amplifier ac coupled cut-off frequency should not to be higher than 0.05 Hz for all the electrode models considered. Significance: Signal distortions in the form of false S-wave creation and depression of the S-T segment have been observed when the previously recommended 10 MΩ input impedance is used in the amplifier. This distortion can lead to clinical misdiagnosis but can be avoided if the design constraints established in the paper are adopted.

Effects of percutaneous neuromodulation on the mechanical characteristics of the rectus femoris and the vastus lateralis in football players: a pilot study

Abstract Background and Aims Percutaneous neuromodulation is an ultrasound-guided technique aimed at the peripheral nerve, using an acupuncture needle as an electrode for a TENS type current which has demonstrated to have positive effects for pain but not for muscle activity. Tensiomyography (TMG) is a non-invasive assessment technique, which is reliable and provides instant information on the mechanical characteristics of superficial muscles. The aim of this study is to evaluate whether percutaneous neuromodulation produces effects on muscle contraction parameters. Material and Methods A longitudinal, analytic and experimental study with a control group, comprising a sample of 11 football players in the 3rd Division, randomly assigned to an intervention group (IG = 5) and a control group (CG = 6). Athletes were assessed using tensiomyography (TMG-S2, EMF-FURLAN & Co.) parameters: maximum deformation (Dm), response time (Td), contraction time (Tc), relaxation time (Tr) and time of contraction maintenance (Ts) of the rectus femoris (RF) and vastus lateralis (VL). Both legs were assessed immediately after the training session (Pre), after 10' rest period post intervention (Post1) and after 12 hours of rest on the following day (Post2). Both femoral nerves were intervened with a needle on the long axis and in a transverse section just below the same. An Electrostimulator (ITO, model ES- 160), was applied to the IG during 5' using a TENS current of 200µs, 1 Hz and with sufficient intensity to achieve a visible contraction of the quadriceps without discomfort. The channel was closed with adhesive electrodes placed medial to the ASIS. The CG received a placebo treatment with needles and electrodes placed on the same anatomical points and connected to an electrostimulator without current during 5' (Physio Invasiva device). Results On the right RF the Td decreased in the IG (pre/post2: P = 0.005) and between groups (post1: P = 0.017 and post2: P = 0.014). For Tc we found differences between the IG (pre/post2: P= 0.008) and the CG (post1/post2: P = 0.019). The left RF increased Tc in the CG (P = 0.036) and pre/post2 and Ts in the CG compared to the IG (post2: P = 0.0480.048). In the left VL Dm increased (pre/post2: P = 0.046 and post1/post2: P = 0.018), Td (pre/post2: P = 0.010) and Tc (pre/post2: P = 0.051 and post1/post2: P = 0.003) for the CG. In the IG, the right VL, both Td (P = 0.024) and Tc (P = 0.021) decreased between post1/post2. For the intragroup analysis (pre, post1 and post2) the Student's t-test was used, whereas for the intragroup analysis, the ANOVA was used (significance > P 0.05). Conclusions Considering the characteristics of the sample and understanding that the decrease of TMG parameters represents an improvement in the mechanical characteristics of the muscle, the findings of this pilot study suggest that the intervention with percutaneous neuromodulation in the IG produces greater recovery and improved activation after 12 hours on the RF and VL. However, the increase of these parameters in the CG results in greater fatigue.

Frequency and Intensity of Electrical Stimulation of Human Sympathetic Ganglia Affect Heart Rate Variability and Pain Threshold

The study relates to the selection of effective clinical treatments based on the changes associated with each electrical stimulation condition. The aim was to investigate the effects of electrical stimulation on the autonomic nervous system by evaluating the heart rate variability (HRV) and pain threshold in response to different interferential current conditions applied to the sympathetic ganglia. Forty five participants were randomly assigned to receive high frequency-low intensity (HF-LI), low frequency-high intensity (LF-HI), or high frequency-high intensity (HF-HI) electrical stimulation. We then used bipolar adhesive pad electrodes to stimulate the thoracic vertebrae T1–T4 for 20 min, and changes were evaluated before, immediately after and 30 min after electrical stimulation. Results revealed significant HRV immediately after HF-LI and LF-HI electrical stimulations. This present study finding of a reduction in HRV immediately after HF-HI electrical stimulation confirms HRV measurement reliability based on electrical stimulation parameters. Results revealed a significant increase in the pain threshold with HF-HI electrical stimulation than for the other conditions; there was also a shorter pain duration. The present study also showed a significant effect of the HF-LI and LF-HI conditions on the pain threshold immediately after electrical stimulation, but the results after 30 min only revealed significant changes in the LF-HI group, indicating a maintenance of the pain control period immediately and 30 min after electrical stimulation. Different conditions of electrical stimulation resulted in distinct changes in HRV and pain control duration.

Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve During Thyroidectomy with Adhesive Skin Electrodes

Alternative methods to overcome limitations of electromyogram (EMG) tube applied for intraoperative neuromonitoring (IONM) of recurrent laryngeal nerve (RLN) during thyroidectomy have been introduced. In this study, we evaluated the feasibility of adhesive skin electrodes for IONM of RLN in patients who underwent thyroidectomy. A total of 39 nerves at risk were prospectively enrolled in this study. Twenty-five patients with papillary thyroid carcinoma, 3 patients with follicular neoplasm, and 2 patients with Graves' disease underwent thyroidectomy. All patients were intubated with EMG tube, and two disposable pre-gelled surface electrodes were attached to skin at both upper margins of thyroid cartilage. We followed the standard procedure of IONM, and the latency (msec) and amplitude (μV) of each signal were recorded prospectively. Intraoperative neuromonitoring using skin adhesive electrodes was successful in all nerves at risk. Amplitudes of the signals in IONM were significantly lower compared to those from EMG tube at each step of IONM, while no significant difference was identified in latency between two methods. Four nerves at risk (10.3%) showed loss of signal (<100μV) during the steps of IONM from EMG tube, while all nerves at risk from adhesive skin electrodes showed acceptable biphasic EMG signal. We verified the usefulness of adhesive skin electrodes for IONM of RLN during thyroidectomy. Although lower amplitude remains the major limitation of this technique, adhesive skin electrodes may be considered an alternative method for IONM during thyroidectomy.

미주신경초종 수술 중 성대 근전도 감시의 유용성: 증례보고

Postoperative vagal dysfunction is a serious complication can lead to dysphonia, dysphagia, pharyngeal or airway obstruction. Therefore, intraoperative monitoring of vagus nerve during surgeries involving the lower brain stem is important to prevent such deficits. Monitoring of vagus nerve can be performed by monitoring free running and stimulated electromyography from the vocal cords. Recording using adhesive surface electrodes on the endotracheal tube approximating the vocal cords can be used to monitor vagus nerve. We report a case of vagal schwannoma with intraoperative vocal cord electromyographic monitoring during the craniotomy and tumor removal. Our case suggests that intraoperative vagus nerve monitoring using surface electrodes on the endotracheal tube could be aid in identifying neural structures and assessing the functional integrity.

Recurrent laryngeal nerve monitoring with surface electrodes in pediatric thyroid surgery.

To prospectively evaluate 1) use of endotracheal tube (ETT) surface electrodes for recurrent laryngeal nerve (RLN) monitoring in thyroid surgery in children, and 2) effects of thyroid surgery on the RLN in children. Patients <18 years old undergoing thyroidectomy were included. Vocal cord mobility was assessed pre- and postoperatively. RLNs were monitored using adhesive or integrated electrodes. Recordings were made before and after dissection, and area under the curve and latency were compared using mixed models. Twenty-five children (44 nerves at risk), mean (standard deviation) age 13.1 (3.4) years (range 4.5-17.4 years), underwent thyroidectomy. Twelve (46%) monitors were adhesive. One nerve had unobtainable responses. Nerveäna Power Index (NPI) (Neurovision Medical Products, Ventura, CA) decreased, and latency increased pre- versus postdissection at all amplitudes (P < 0.0001), with change in slope of NPI affected by tumor size (P < 0.05). Postdissection, the NPI was lower, and the latency was longer when stimulating low in the neck versus near the cricothyroid joint at all stimulating amplitudes (P < 0.0001), with change in NPI related to tumor size (P < 0.0001). Changes were not associated with decreased vocal cord mobility, aspiration, or voice change. One patient had a temporary unilateral paresis that resolved by 7 weeks, and another had normal movement 3 weeks postoperatively and developed a paresis 2 months postoperatively. ETT surface electrodes are reliable for RLN monitoring in thyroid surgery in children. Thyroid surgery is associated with a decrease in RLN stimulability that is related to tumor size. The site of RLN stimulation matters when evaluating the nerve. 4 Laryngoscope, 130:1583-1589, 2020.

Sensor Fusion for Unobtrusive Respiratory Rate Estimation in Dogs

Respiration is vital to land-dwelling mammals; besides, salient information is encoded in the respiratory rate. Objective assessment of the respiratory rate is difficult in dogs; in particular, if the unobtrusive measurement is desired. The goal of this work was to develop and evaluate a method for unobtrusive sensing of respiratory rate in dogs. For this, the “FlexPock” multisensor system, originally developed for unobtrusive estimation of heart rate and respiratory rate in humans via magnetic impedance; accelerometry; and optical measurements, was used to assess canine respiratory rate. In a proof-of-concept study with 10 healthy dogs of different breeds and sizes, a total of 240 minutes of data was recorded in the phases standing, sitting, lying down, and walking. An algorithm was developed that estimates the respiratory rate by fusing the information from multiple sensors for increased accuracy and robustness. To discard unusable data, a simple yet effective signal quality metric was introduced. Impedance pneumography recorded using adhesive electrodes was used as a reference. Analysis of the raw FlexPock data revealed that the magnetic impedance and accelerometry were the best individual sensing modalities and fusion of these data further increased the accuracy. Using leave-one-dog-out cross-validation, the average estimation error was 9.5% at a coverage of 50.1%. However, strong variation between dogs and phases was observed. During the walking phase, neither reference nor unobtrusive sensor reported usable results, while the sitting phase exhibited the best performance. In conclusion, the fusion of magnetic impedance and accelerometry can be used for unobtrusive respiratory rate estimation in stationary dogs.

A bionic tactile plastic hydrogel-based electronic skin constructed by a nerve-like nanonetwork combining stretchable, compliant, and self-healing properties

To completely mimic the tactile sensing of natural skin, flexible conductive hydrogels (CHs) have been assembled into bionic skin. However, most CHs cannot perfectly rebuild the feeling of human skin due to their highly linear structure. In addition, CHs are difficult to meet the super-stretchable, rapid self-healing properties at the same time. Here, we innovatively incorporated a proanthocyanins/reduced graphene oxide (PC/rGO) composite with a nerve-like nanonetwork into a glycerol-plasticized polyvinyl alcohol-borax (PVA-borax) hydrogel system to obtain a bionic tactile PC/rGO/PVA hydrogel-based electronic skin, which perfectly simulates the tactual sensation of human skin and integrates excellent stretchability (>5000%), compliance (1 mm), self-healing (3 s, 95.73%) ability for the first time. Due to its unique structure and mechanical properties, this electronic skin has remarkable wearable and strain-sensitive (GF = 14.14) properties, which can mimic and detect some real skin epidermis movements such as finger bending, facial expression changes, and throat vocalization. Interestingly, the hydrogel can also be used as an adhesive electrode for the accurate detection of electrocardiograph (ECG) and electromyography (EMG) signals. More importantly, this work provides a new route in mimicking the natural skin’s tactile ability through a hierarchical design of hydrogel networks.

Non-contact respiration monitoring using impulse radio ultrawideband radar in neonates.

Vital sign monitoring in neonates requires adhesive electrodes, which often damage fragile newborn skin. Because impulse radio ultrawideband (IR-UWB) radar has been reported to recognize chest movement without contact in adult humans, IR-UWB may be used to measure respiratory rates (RRs) in a non-contact fashion. We investigated the feasibility of radar sensors for respiration monitoring in neonates without any respiratory support to compare the accuracy and reliability of radar measurements with those of conventional impedance pneumography measurements. In the neonatal intensive care unit, RRs were measured using radar (RRRd) and impedance pneumography (RRIP) simultaneously. The neonatal voluntary movements were measured using the radar sensor and categorized into three levels (low [M0], intermediate [M1] and high [M2]). RRRd highly agreed with RRIP (r = 0.90; intraclass correlation coefficient [ICC] = 0.846 [0.835–0.856]). For the M0 movement, there was good agreement between RRRd and RRIP (ICC = 0.893; mean bias −0.15 [limits of agreement (LOA) −9.6 to 10.0]). However, the agreement was slightly lower for the M1 (ICC = 0.833; mean bias = 0.95 [LOA −11.4 to 13.3]) and M2 (ICC = 0.749; mean bias = 3.04 [LOA –9.30 to 15.4]) movements than for the M0 movement. In conclusion, IR-UWB radar can provide accurate and reliable estimates of RR in neonates in a non-contact fashion. The performance of radar measurements could be affected by neonate movement.

A novel disposable self-adhesive inked paper device for electrochemical sensing of dopamine and serotonin neurotransmitters and biosensing of glucose

In this work, we detail the progress of a novel electrochemical disposable device, which has a relatively low cost and easy production, with a novel conductive ink, that consists of graphite and automotive varnish mixture, deposited over a self-adhesive paper, granting an easy production with relatively low cost. The electrode surface was characterized by scanning electron microscopy, X-ray powder diffraction and Fourier transforms infrared and Raman, cyclic voltammetry and electrochemical impedance spectroscopies. In addition, the proposed electrode was applied for individual electrochemical determination of dopamine and serotonin. The device achieved a linear response between 30 and 800 μmol L−1 and a limit of detection (LOD) of 0.13 μmol L−1, by square wave voltammetry for dopamine and a linear range from 6.0 to 100 μmol L−1, with a LOD of 0.39 μmol L−1, by differential pulse voltammetry for serotonin. Later, the working electrode was modified with glucose oxidase and dihexadecyl phosphate film in order to obtain a biosensor. At this stage, CV was applied to detect glucose in the range of 1.0–10 μmol L−1 and LOD of 0.21 μmol L−1. By three different techniques and analytes, the sensoring and biosensoring processes presented high reproducibility. The proposed adhesive electrode is easy to prepare, disposable, within non-restrictive nature, which allows an approach of a new device for electrochemical sensing and biosensing.

Continuous 4-week ECG monitoring with adhesive electrodes reveals AF in patients with recent embolic stroke of undetermined source.

BackgroundAtrial fibrillation (AF) frequently escapes routine stroke workup due to its unpredictable and often asymptomatic nature, leaving a significant portion of patients at high risk of recurrent stroke. Recent trials emphasized continuous electrocardiogram (ECG) monitoring in the detection of occult AF. We screened AF in patients meeting the embolic stroke of unknown source (ESUS) criteria using an external miniaturized recorder with an adhesive electrode.MethodsPatients aged ≥50 with recent ESUS were prospectively screened and assigned to wear a 1‐lead ECG device capable to record continuous ECG for up to 4 weeks. Electrodes were replaced every 3–4 days. Primary outcome was proportion of patients completing at least 80% of monitoring. Secondary outcome measures included incidence of AF and initiation of oral anticoagulation therapy after AF detection.ResultsFifty‐seven patients were monitored (mean age 64.5 ± 8.2 years, median delay from stroke to the start of monitoring 8 days, IQR 4–44). Of these, 51 patients (89.5%) completed at least 80% of the desired monitoring period. We detected AF ≥30 s in seven patients (12.3%), all of whom initiated anticoagulation therapy. Atrial fibrillation was revealed in six patients (85.7%) within the first week of monitoring. Compared to patients without AF, patients with AF were older (70.6 ± 5.1 vs. 63.6 ± 8.3 years, p < 0.011) and more obese (body mass index 30.0 ± 3.4 vs. 26.6 ± 4.6, p < 0.039).ConclusionsProlonged ECG monitoring with an external device using adhesive electrodes is feasible in ESUS patients, since nine out of ten patients used the device appropriately and AF was detected in one out of eight patients.

Automated preterm infant sleep staging using capacitive electrocardiography

Objective: To date, mainly obtrusive methods (e.g. adhesive electrodes in electroencephalography or electrocardiography) have been necessary to determine the preterm infant sleep states. As any obtrusive measure should be avoided in preterm infants because of their immature skin development, we investigated the possibility of automated sleep staging using electrocardiograph signals from non-adhesive capacitive electrocardiography. Approach: Capacitive electrocardiography data from eight different patients with a mean gestational age of 30 ± 2.5 weeks are compared to manually annotated reference signals from classic adhesive electrodes. The sleep annotations were performed by two trained observers based on behavioral observations. Main results: Based on these annotations, classification performance of the preterm infant active and quiet sleep states, based on capacitive electrocardiography signals, showed a kappa value of 0.56 ± 0.20. Adding wake and caretaking into the classification, a performance of kappa 0.44 ± 0.21 was achieved. In-between sleep state performance showed a classification performance of kappa 0.36 ± 0.12. Lastly, a performance for all sleep states of kappa 0.35 ± 0.17 was attained. Significance: Capacitive electrocardiography signals can be utilized to classify the central preterm infant sleep states, active and quiet sleep. With further research based on our results, automated classification of sleep states can become an essential instrument in future intensive neonatal care for continuous brain maturation monitoring. In particular, being able to use capacitive electrocardiography for continuous monitoring is a significant contributor to reducing disruption and harm for this extremely fragile patient group.

Hydrophone based on 3D printed polypropylene (PP) piezoelectret

Every year, different areas of knowledge are becoming more interested in 3D-printing technology. Recently, this technology was also proved to be feasible for creating sensitive materials such as piezoelectrets. This Letter extends the concept of a 3D printed piezoelectret to produce a pressure sensitive film that can be employed as an ultrasonic transducer for underwater applications, such as hydrophones. In order to achieve this, a two-layer polypropylene film was printed using a filament-based 3D printer. Afterwards, adhesive electrodes were attached on both sides of the film and electrical charging was applied. Later, the 3D printed film was mounted in a metal housing specially designed to keep the film in direct contact with the water and to isolate the electronic amplification. The validation was performed using a piezoelectric ceramic made of lead zirconate titanate (PZT), immersed in a water tank, to produce ultrasonic sweeps to be sensed by the 3D printed transducer. These tests revealed sensor sensitivities up to 600 mV and promote a precise detection of the acoustic resonance frequency of the PZT at 43.7 kHz.

Intraoperative neurophysiological monitoring during thoracoscopic removal of the paravertebral spinal tumor (from practice)

Bol’shaya Sukharevskaya Sq., Moscow 129090, RussiaThe study objective is to describe the clinical case of intraoperative neurophysiologic monitoring (IONM) using the electromyography-triggered stimulation during the thoracoscopic removal of an extradural Th2–Th3level tumor.Materials and methods. The case describes the removal of the right Th2–Th3pleural cavity paravertebral tumor that has compressed the phrenic nerve. The patient underwent thoracoscopic surgery supported by IONM. An electromyography-triggered stimulation with a monopolar stimulator that was inserted through the thoracoscopic access into the thoracic cavity under video control identified the phrenic nerve. Results. The thoracoscopy in combination with electromyography-triggered stimulation allowed to avoid open surgery. The use of traditional IONM for spinal surgery would not identify the diaphragmatic nerve and prevent its unintentional damage.Conclusion. IONM scenarios can be successfully enhanced with a electromyography-triggered stimulation of the phrenic nerve. Adhesive disposable electrodes for muscle response recording and stimulus return are useful without any deterioration of informativity.