Millions of individuals surviving a stroke have lifelong gait impairments that reduce their personal independence and quality of life. Reduced walking speed is one of the major problems limiting community mobility and reintegration. Previous studies have shown positive effect of robot-assisted gait training utilizing hip exoskeletons for individuals with gait impairments due to a stroke, leading to increased walking speed in post-treatment compared to pre-treatment assessments. However, no evidence emerged of a significant increasing in walking speed attributable to device usage compared to walking without the device. In this pilot investigation, we observed that hip flexion/extension assistance delivered by a portable bilateral powered hip exoskeleton increased overground self-selected walking speed by 20.2 ± 5.0% on average among six chronic post-stroke survivors. When comparing walking with and without the hip exoskeleton within the same experimental session, the observed speed increment resulted in statistically and clinically meaningful improvement (0.14 ± 0.03 m/s > minimal clinically important difference, p = 0.015). The increased walking speed was the result of a higher self-selected cadence and longer step length both on the paretic and nonparetic limbs. By facilitating gait, a bilateral hip exoskeleton could be a viable technology for extending locomotor mobility and facilitating gait training of individuals affected by post-stroke hemiparesis.

ABSTRACT Introduction In recent years, microprocessor-controlled knees have become available to people with lower-limb amputation. Although they may be associated with greater economic benefits and improved clinical outcomes when compared with non-microprocessor-controlled knees, some individuals discontinue use or do not utilize all the functions they provide. Better understanding of how the relationship between human factors and prosthetic function influences peoples' experience is needed to make microprocessor-controlled knees and their functions more accessible to users. Objectives The aims of this study were to explore the prosthetic history of highly active individuals with transfemoral amputation and identify the factors important for prosthetic satisfaction, use, and acceptance, as well as opportunities in advanced prosthetic development. Study Design A qualitative study design was used. Methods Semistructured interviews were conducted with five highly active people with transfemoral amputation using microprocessor-controlled knees. Results We identified several factors important for prosthetic satisfaction, use, and acceptance: 1) feeling in control of prosthesis, 2) consistency in functions of prosthesis, 3) intuitive prosthesis, 4) feeling unrestricted by prosthesis, 5) spontaneity, 6) easy to walk and change speed, 7) quiet function, 8) easy to trigger and transition between modes, 9) individually relevant modes, 10) harmonious function with ankle, 11) shock absorption, 12) waterproof, 13) appearance, and 14) weight. Conclusions Fostering trust through consistent and intuitive functions that can be used during various activities is perceived as highly important for satisfaction with prosthetic devices. Furthermore, expected long-term benefits associated with advanced devices are, alone, not sufficient motivation for their use. More intuitive triggering methods coupled with active assistance are necessary to make advanced solutions and their functions more accessible and beneficial. Finally, a multitude of individual characteristics and needs influence use and acceptance, highlighting the necessity of taking human factors into account in prosthetics. Clinical Relevance The results shed light on opportunities in future development of prosthetic knees and importance of human factors for powered prosthetic design. They further provide insight into aspects meaningful to highly active end users, affecting prosthetic use and satisfaction.

ABSTRACT Introduction Neuroprosthetic systems that can work with prosthetic legs are currently being developed to provide individuals with lower-limb amputation with intent control over their device and sensory feedback. No such system is commercially available, and the effects of providing functions that have previously not been available to lower-limb prosthetic users are unclear. Methods Here we present investigations of the perceptions of multiple stakeholders (prosthetic users, physician, psychologist, physiotherapist, prosthetist, and groups of prosthetic designers and engineers) on prosthetic user problems and the development of neuroprosthetics. The investigation entailed semistructured interviews, focus group discussions, and a contextual inquiry. Results Our findings indicate that prosthetic users may face several challenges that can potentially be addressed via neurological interfacing. We further identified criteria perceived as integral for the development of lower-limb neuroprostheses as well as considerations for the actualization of a usable system that reaches end users. Conclusions On the whole, the field of neuroprosthetics has great potential to increase the wellbeing, mobility, and quality of life of persons with lower-limb amputation.

Introduction: Neuroprostheses that can relay signals to and from the nervous system and work with lower-limb prostheses are currently being developed to provide users with sensory feedback and/or intent control over their prostheses. Such systems incorporate functions not available to persons with lower-limb amputation before, and many of their potential benefits have not yet been addressed in performance-based outcome measures. As such, the evaluation of neuroprosthetic systems is considerably more difficult than that of current devices, which are already difficult due to limitations of testing strategies. This review includes an overview of performance-based measures for lower-limb prostheses as well as an appraisal of their utility for neuroprosthetic assessment. Methods: Electronic searches were conducted (2013-2019) in the PubMed (PM) database, the Web of Science (WOS), and Cochrane (CC), resulting in 72 included articles. Conclusions: There is an urgent need for further development of performance tests and metrics, as well as new strategies specifically intended for the evaluation of lower-limb neuroprosthetic systems.

This study was designed to investigate the feasibility and the potential effects on walking performance of a short gait training with a novel impairment-specific hip assistance (iHA) through a bilateral active pelvis orthosis (APO) in patients with acquired brain injury (ABI). Fourteen subjects capable of independent gait and exhibiting mild-to-moderate gait deficits, due to an ABI, were enrolled. Subjects presenting deficit in hip flexion and/or extension were included and divided into two groups based on the presence (group A, n = 6) or absence (group B, n = 8) of knee hyperextension during stance phase of walking. Two iHA-based profiles were developed for the groups. The protocol included two overground gait training sessions using APO, and two evaluation sessions, pre and post training. Primary outcomes were pre vs. post-training walking distance and steady-state speed in the 6-min walking test. Secondary outcomes were self-selected speed, joint kinematics and kinetics, gait symmetry and forward propulsion, assessed through 3D gait analysis. Following the training, study participants significantly increased the walked distance and average steady-state speed in the 6-min walking tests, both when walking with and without the APO. The increased walked distance surpassed the minimal clinically important difference for groups A and B, (respectively, 42 and 57 m > 34 m). In group A, five out of six subjects had decreased knee hyperextension at the post-training session (on average the peak of the knee extension angle was reduced by 36%). Knee flexion during swing phase increased, by 16% and 31%, for A and B groups respectively. Two-day gait training with APO providing iHA was effective and safe in improving walking performance and knee kinematics in ABI survivors. These preliminary findings suggest that this strategy may be viable for subject-specific post-ABI gait rehabilitation.

Lower limb amputation (LLA) destroys the sensory communication between the brain and the external world during standing and walking. Current prostheses do not restore sensory feedback to amputees, who, relying on very limited haptic information from the stump-socket interaction, are forced to deal with serious issues: the risk of falls, decreased mobility, prosthesis being perceived as an external object (low embodiment), and increased cognitive burden. Poor mobility is one of the causes of eventual device abandonment. Restoring sensory feedback from the missing leg of above-knee (transfemoral) amputees and integrating the sensory feedback into the sensorimotor loop would markedly improve the life of patients. In this study, we developed a leg neuroprosthesis, which provided real-time tactile and emulated proprioceptive feedback to three transfemoral amputees through nerve stimulation. The feedback was exploited in active tasks, which proved that our approach promoted improved mobility, fall prevention, and agility. We also showed increased embodiment of the lower limb prosthesis (LLP), through phantom leg displacement perception and questionnaires, and ease of the cognitive effort during a dual-task paradigm, through electroencephalographic recordings. Our results demonstrate that induced sensory feedback can be integrated at supraspinal levels to restore functional abilities of the missing leg. This work paves the way for further investigations about how the brain interprets different artificial feedback strategies and for the development of fully implantable sensory-enhanced leg neuroprostheses, which could drastically ameliorate life quality in people with disability.

Conventional leg prostheses do not convey sensory information about motion or interaction with the ground to above-knee amputees, thereby reducing confidence and walking speed in the users that is associated with high mental and physical fatigue1-4. The lack of physiological feedback from the remaining extremity to the brain also contributes to the generation of phantom limb pain from the missing leg5,6. To determine whether neural sensory feedback restoration addresses these issues, we conducted a study with two transfemoral amputees, implanted with four intraneural stimulation electrodes7 in the remaining tibial nerve (ClinicalTrials.gov identifier NCT03350061). Participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. These sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. We found that walking speed and self-reported confidence increased while mental and physical fatigue decreased for both participants during neural sensory feedback compared to the no stimulation trials. Furthermore, participants exhibited reduced phantom limb pain with neural sensory feedback. The results from these proof-of-concept cases provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.

Biomedical engineering is the application of engineering principles to biology and medicine, with the goal of improving the quality and effectiveness of patient care. Better understanding of the mechanisms underlying labor can contribute to preventing preterm birth, which is the main cause of mortality and morbidity in newborns. Studies on the electrohysterogram (EHG) have shown promising results regarding preterm labour prediction as well as other uses in obstetric care. A 16 electrode recording system in a 4-by-4 configuration on the abdomen can provide information on the propagation of uterine electrical activity. One of the main problems for researchers studying new technology is a shortage of data to enable analysis and hypothesis testing. In this respect, public access databanks are becoming increasingly important. A new category of scientific article, the Data Descriptor, has been designed to provide detailed descriptions of databases to maximize interpretation, search and reuse of the data. The main aim of this MSc project was to implement public access to 16-electrode EHG data recorded in Iceland. The second aim was to demonstrate the type of research that can be done using the database by studying the relationship between maternal clinical factors and the frequency components of contractions. The thesis describes the process of collecting, converting, annotating and de-identifying the 122 EHG recordings performed by the author between 2008 and 2010. The now publicly available Icelandic 16-electrode EHG database, found at PhysioNet, is then presented along with its Data Descriptor. The study on clinical factors and EHG data from the database suggests that a pregnant woman’s body mass index, age and obstetric history may influence frequency components of contractions. This could have implications for the development of a medical device for predicting preterm labour and at the same time demonstrates the use that can be made of the database. Biomedical engineering Electrohysterogram Preterm birth Database Public access Frequency analysis; I heilbrigðisverkfraeði er verkfraeðilegum aðferðum i laeknisfraeði beitt til að þroa ný taeki og aðferðir við greiningu og meðferð sjukdoma. Fyrirburafaeðingar eru aðal orsok dauða og veikinda nýbura en með þvi að auka skilninginn a mekaniskri virkni legsins myndast moguleikar a að spa fyrir um og koma i veg fyrir faeðingu fyrir timann. Rannsoknir a legrafritum benda til að þa taekni maetti nota við greiningu a fyrirburafaeðingum. Með þvi að nota 16 rafskaut i 4-sinnum-4 uppsetningu er haegt að greina utbreiðslu a rafvirkni legsins. Fyrir þa visindamenn sem eru að rannsaka nýja taekni er algengt vandamal að það vanti gogn til að vinna með. Vegna þessa hafa opnir gagnabankar orðið mikilvaegir i visindaþroun. Ný gerð visindagreina (e. Data Descriptor) hefur verið buin til sem lýsir gagnabonkum vel og eykur moguleika a tulkun, leit og nýtingu gagnanna. Megin tilgangur þessa meistaraverkefnis var að veita opinn aðgang að 16-rafskauta legrafritsmaelingum fra Islandi. Annað markmið var…

External recordings of the electrohysterogram (EHG) can provide new knowledge on uterine electrical activity associated with contractions. Better understanding of the mechanisms underlying labor can contribute to preventing preterm birth which is the main cause of mortality and morbidity in newborns. Promising results using the EHG for labor prediction and other uses in obstetric care are the drivers of this work. This paper presents a database of 122 4-by-4 electrode EHG recordings performed on 45 pregnant women using a standardized recording protocol and a placement guide system. The recordings were performed in Iceland between 2008 and 2010. Of the 45 participants, 32 were measured repeatedly during the same pregnancy and participated in two to seven recordings. Recordings were performed in the third trimester (112 recordings) and during labor (10 recordings). The database includes simultaneously recorded tocographs, annotations of events and obstetric information on participants. The publication of this database enables independent and novel analysis of multi-electrode EHG by the researchers in the field and hopefully development towards new life-saving technology.

The electrohysterogram (EHG) is a promising means of monitoring pregnancy and of detecting a risk of preterm labor. To improve our understanding of the EHG as well as its relationship with the physiologic phenomena involved in uterine contractility, we plan to model these phenomena in terms of generation and propagation of uterine electrical activity. This activity can be realistically modeled by representing the principal ionic dynamics at the cell level, the propagation of electrical activity at the tissue level and then the way it is reflected on the skin surface through the intervening tissue. We present in this paper the different steps leading to the development and validation of a biophysics based multiscale model of the EHG, going from the cell to the electrical signal measured on the abdomen.

The objective of this paper is to evaluate the novel method for analyzing the nonlinear correlation of the uterine electromyography (EMG). The application of this method may improve monitoring in pregnancy, labor detection, and preterm labor detection. Uterine EMG signals recorded from a 4 × 4 matrix of electrodes on the subjects' abdomen are used here. The propagation was analyzed using the nonlinear correlation coefficient h2. Signals from 49 women (36 during pregnancy and 13 in labor) at different gestational age were used. ROC curves were computed to evaluate the potential of three methods to differentiate between 174 contractions recorded during pregnancy and 115 contractions recorded during labor. The results indicate considerably better performance of the nonlinear correlation analysis (area under curve = 0.85) when compared to classical frequency parameters (area under curve = 0.76 and 0.66) in distinguishing labor contractions from normal pregnancy contractions. We conclude that the analysis of the propagation of the uterine electrical activity using the nonlinear correlation coefficient h2 is a promising way of improving the usefulness of uterine EMG signals for clinical purposes, such as monitoring in pregnancy, labor detection, and prediction of preterm labor.

Following resection for non-small cell lung cancer (NSCLC), patients are usually admitted to the post-anesthesia care unit (PACU)for a few hours before admission to a general ward (GW). However, some patients need ICU-admission, either immediately post-surgery or from the PACU or GW. The aim of this study was to investigate the indications and risk factors for ICU-admission.A retrospective study of 252 patients who underwent lobectomy, wedge resection or segmentectomy for NSCLC in Iceland during 2001-2010. Data was retrieved from medical records and patients admitted to the ICU compared to patients not admitted.Altogether 21 patients (8%) were admitted to the ICU, median length-of-stay being one day (range 1-68). In 11 cases (52%) the reasons for admission were intraoperative problems, usually hypotension or excessive bleeding. Ten patients were admitted from the GW (n=4) or PACU (n=6), due to hypotension (n=4), heart and/or respiratory failure (n=4) and reoperation for bleeding (n=2). There were three ICU-readmissions. Patients admitted to the ICU were six years older (p=0.004) and more often had chronic obstructive pulmonary disease and/or coronary artery disease. Tumor size, pTNM-stage, length of operation and the ratio of patients receiving TEA (thoracic epidural anaesthesia) were similar between groups. Over two-thirds of the ICU-patients had minor complications and around half had major complications, compared to 30% and 4%, respectively, for controls.ICU-admissions are infrequent following non-pneumonectomy lung resections for NSCLC, these patients being older with cardiopulmonary comorbidities. In half of the cases, admission to the ICU directly follows surgery and ICU-readmissions are few.

Background: The proportion of patients with non-small-cell lung cancer (NSCLC) who undergo surgery with curative intent is one measure of effectiveness in treating lung cancer. To the best of our knowledge, surgical resection rate (SRR) for a whole nation has never been reported before. We studied the SRR and surgical outcome of NSCLC patients in Iceland during a recent 15-year period.Methods: This was a retrospective study of all pulmonary resections performed with curative intent for NSCLC in Iceland from 1994 to 2008. Information was retrieved from medical records and from the Icelandic Cancer Registry. Patient demographics, postoperative tumor, node, metastasis stage, overall survival, and complication rates were compared over three 5-year periods.Results: Of 1530 confirmed cases of NSCLC, 404 were resected, giving an SRR of 26.4%, which did not change significantly during the study period. Minor and major complication rates were 37.4% and 8.7%, respectively. Operative mortality rates were 0.7% for lobectomy, 3.3% for pneumonectomy, and 0% for lesser resection. Five-year survival after all procedures was 40.7% and improved from the first to the last 5-year period (34.8% versus 43.8%, p = 0.04). Five-year survival for stages I and II together was 46.8%, with no significant change in stage distribution between periods. Five-year survival after pneumonectomy was 22.0%, which was significantly lower than for lobectomy (44.6%) and lesser resection (40.7%) (p < 0.005). Unoperated patients had a 5-year survival of 4.8%, as compared to 12.4% for all the NSCLC patients together.Conclusion: Compared with most other published studies, the SRR of NSCLC in Iceland is high. Short-term outcome is good, with a low rate of major complications and an operative mortality of only 1.0%. Five-year survival improved significantly over the study period.

Introduction: Following resection for non-small cell lung cancer (NSCLC), patients are usually admitted to the post-anesthesia care unit (PACU)for a few hours before admission to a general ward (GW). However, some patients need ICU-admission, either immediately post-surgery or from the PACU or GW. The aim of this study was to investigate the indications and risk factors for ICU-admission.Material and methods: A retrospective study of 252 patients who underwent lobectomy, wedge resection or segmentectomy for NSCLC in Iceland during 2001-2010. Data was retrieved from medical records and patients admitted to the ICU compared to patients not admitted.Results: Altogether 21 patients (8%) were admitted to the ICU, median length-of-stay being one day (range 1-68). In 11 cases (52%) the reasons for admission were intraoperative problems, usually hypotension or excessive bleeding. Ten patients were admitted from the GW (n=4) or PACU (n=6), due to hypotension (n=4), heart and/or respiratory failure (n=4) and reoperation for bleeding (n=2). There were three ICU-read-missions. Patients admitted to the ICU were six years older (p=0.004) and more often had chronic obstructive pulmonary disease and/or coronary artery disease. Tumor size, pTNM-stage, length of operation and the ratio of patients receiving TEA (thoracic epidural anaesthesia) were similar between groups. Over two-thirds of the ICU-patients had minor complications and around half had major complications, compared to 30% and 4%, respectively, for controls.Conclusion: ICU-admissions are infrequent following non-pneumonectomy lung resections for NSCLC, these patients being older with cardiopulmonary comorbidities. In half of the cases, admission to the ICU directly follows surgery and ICU-readmissions are few.

INTRODUCTION:A sublobar resection is performed on patients with non-small cell lung cancer (NSCLC) who are not candidates for a lobectomy due to reduced pulmonary function or comorbid disease. The aim of this study was to investigate the outcomes of these operations in Iceland.MATERIAL AND METHODS:A retrospective study of all patients with NSCLC who underwent wedge resection or segmentectomy with curative intent during 1994-2008. Data on indication, pathological TNM-stage, complications and overall survival was analyzed. All histological samples were re-evaluated.RESULTS:Forty four patients underwent 42 wedge and 5 segmental resections (age 69.1 yrs, 55.3% female), with 38.3% of cases detected incidentally. The majority of patients (55.3%) had a history of coronary artery disease and 40.4% had chronic obstructive pulmonary disease. Mean operative time was 83 minutes (range 30-131), mean intraoperative bleeding was 260 ml (range 100-650) and median hospital stay was 9 days (range 4-24). Pneumonia (14.9%) and prolonged air leakage (12.8%) were the most common complications. Two patients had major complications and 36.2% stayed in the intensive care unit overnight. No deaths occurred within 30 days of surgery. Adenocarcinoma was the most common histological type (66.7%). Most cases were stage IA/IB (78.7%), 17.0% were stage IIA/IIB and 4.3% were stage IIIA. One and 5 year survival was 85.1% and 40.9% respectively.CONCLUSION:In Iceland, both survival and complication rate after sublobar resection for NSCLC are comparable to results published for lobectomies, even though a higher percentage of patients have underlying cardiopulmonary disease.

A sublobar resection is performed on patients with non-small cell lung cancer (NSCLC) who are not candidates for a lobectomy due to reduced pulmonary function or comorbid disease. The aim of this study was to investigate the outcomes of these operations in Iceland.A retrospective study of all patients with NSCLC who underwent wedge resection or segmentectomy with curative intent during 1994-2008. Data on indication, pathological TNM-stage, complications and overall survival was analyzed. All histological samples were re-evaluated.Forty four patients underwent 42 wedge and 5 segmental resections (age 69.1 yrs, 55.3% female), with 38.3% of cases detected incidentally. The majority of patients (55.3%) had a history of coronary artery disease and 40.4% had chronic obstructive pulmonary disease. Mean operative time was 83 minutes (range 30-131), mean intraoperative bleeding was 260 ml (range 100-650) and median hospital stay was 9 days (range 4-24). Pneumonia (14.9%) and prolonged air leakage (12.8%) were the most common complications. Two patients had major complications and 36.2% stayed in the intensive care unit overnight. No deaths occurred within 30 days of surgery. Adenocarcinoma was the most common histological type (66.7%). Most cases were stage IA/IB (78.7%), 17.0% were stage IIA/IIB and 4.3% were stage IIIA. One and 5 year survival was 85.1% and 40.9% respectively.In Iceland, both survival and complication rate after sublobar resection for NSCLC are comparable to results published for lobectomies, even though a higher percentage of patients have underlying cardiopulmonary disease.

Most of the studies on the synchronization between EHG signals, recorded during the same contractions at different locations, are limited to the use of only two channels. Multichannel techniques have however been widely applied to EEG signals but rarely to EHG. In this paper, we investigate the use of multichannel uterine EMG signals for classifying contractions. We compare the performance of phase synchronization in distinguishing between labor and normal pregnancy contractions by using either only two channels or a 4x4 matrix positioned on the woman's abdomen. We used two indexes to measure the phase synchronization: mean phase coherence and phase entropy. ROC curves indicate that the use of multichannel signals can significantly improve the classification rate of pregnancy and labor contractions.

The analysis of the electrical activity of the uterus recorded externally, the electrohysterogram (EHG), may find an application in the prediction of labor. In the literature parameters that are supposed to be related to the excitability of the uterine cells have almost exclusively been used for this purpose. In the present paper we evaluate the possible use of synchronization parameters for EHG measured in several places on the uterus for this prediction. The EHG is mainly composed of two frequency components called FWL and FWH. These components may be related to the synchronization and the excitability phenomenon respectively. In order to study independently these frequency components, we extracted the corresponding ridges of the wavelet transform of the EHG using the GVF-snake method. For each frequency component we computed parameters that are related to the frequency content of the signals and parameters that consider the synchronization relationship between signals. The synchronization parameters used were the mean phase coherence and the phase entropy. The values of the different parameters were compared during pregnancy and labor by statistical analysis. The detection quality of each parameter was evaluated using ROC curves. Our results suggest that synchronization parameters could be used for the detection of labor in addition to the classical previously published parameters. Another important result of our study is that both FWH and FWL seem related to excitability but only FWL seems to be related to the synchronization of the uterus at term.

Labor prediction using the electrohysterogram has immediate clinical applications and has been the aim of several studies in recent years. Studies using various linear methods such as classic spectral analysis do not give clinically useful results. In this paper we present the use of two methods that investigate nonlinearity to predict normal labor. We show the comparison between a linear method that is known from the literature (mean power frequency) and two nonlinear methods (approximate entropy and time reversibility) using ROC analysis. The comparison indicates that the best method for pretreatment to classify pregnancy and labor signals is time reversibility. The results indicate that time reversibility is a very promising tool for distinguishing between labor and physiological contractions during pregnancy. This could be the first step in developing a clinical application method to predict preterm labor.