Impact of drone-specific dispatch instructions on the safety and efficacy of drone-delivered emergency medical treatments: A randomized simulation pilot study.

Introduction: Medical drones have potential for improving the response times to out-of-hospital emergencies. However, widespread adoption is hindered by unanswered questions surrounding medical dispatch and bystander safety. This study evaluated the impact of novel drone-specific dispatch instructions (DSDI) on bystanders' ability to interact effectively with a medical drone and provide prompt, safe, and high-quality treatment in a simulated emergency scenario. We hypothesized DSDI would improve bystanders' performance and facilitate safer bystander-drone interactions. Methods: Twenty-four volunteers were randomized to receive either DSDI and standard Medical Priority Dispatch (MPD) instructions or MPD alone in a simulated out-of-hospital cardiac arrest (OHCA) or pediatric anaphylaxis.,3 Participants in the DSDI group received detailed instructions on locating and interacting with the drone and its enclosed medical kit. The simulations were video recorded. Participants completed a semi-structured interview and survey. Results: The addition of DSDI did not lead to statistically significant changes to the overall time to provide care in either the anaphylaxis or OHCA simulations. However, DSDI did have an impact on bystander safety. In the MPD only group, 50% (6/12) of participants ignored the audio and visual safety cues from the drone instead of waiting for it to be declared safe compared to no DSDI participants ignoring these safety cues. Conclusions: All participants successfully provided patient care. However, this study indicates that DSDI may be useful to ensure bystander safety and should be incorporated in the continued development of emergency medical drones.

Bystander interaction with a novel multipurpose medical drone: A simulation trial.

Intro: Medical drones are an emerging technology which may facilitate rapid treatment in time-sensitive emergencies. However, drones rely on lay rescuers, whose interactions with multipurpose medical drones have not been studied, and the optimal drone design remains unclear. Methods: We conducted 24 simulations of adult out-of-hospital cardiac arrest (OHCA) and pediatric anaphylaxis with a prototype drone equipped with spoken and visual cues and a multipurpose medical kit. 24 layperson volunteers encountered one of the two scenarios and were supported through administering treatment by a simulated 911 dispatcher. Bystander-drone interactions were evaluated via a convergent parallel mixed methods approach using surveys, video event review, and semi-structured interviews. Results: 83% (20/24) of participants voiced comfort interacting with the drone. 96% (23/24) were interested in future interaction. Participants appreciated the drone's spoken instructions but found visual cues confusing. Participants retrieved the medical kit from the drone in a mean of 5 seconds (range 2-14) of drone contact; 79% (19/24) found this step easy or very easy. The medical kit's layered design caused difficulty in retrieving appropriate equipment. Participants expressed a wide range of reactions to the unique drone design. Conclusions: Laypeople can effectively and comfortably interact with a medical drone with a novel design. Feedback on design elements will result in further refinements and valuable insights for other drone designers. A multipurpose medical kit created more challenges and indicates the need for further refinement to facilitate use of the equipment.

Curvilinear walking elevates fall risk and modulates slip and compensatory step attributes after unconstrained human slips.

While much attention has been paid to understanding slip-related falls in humans, little has been focused on curvilinear paths despite their prevalence, distinct biomechanical demands and increased slipping threat. We determined the mechanics, compensatory stepping reactions and fall risk associated with slips during fixed-speed walking across ranges of path curvature, slipped foot and slip onset phase contexts possible in the community, which builds upon previous work by examining speed-independent effects of curvilinear walking. Twenty-one participants experienced 15 unconstrained slips induced by a wearable friction-reducing device as motion capture and harness load cell data were recorded. Falls were most likely after early stance slips to the inside foot and increased at tighter curvatures. Slip distance and peak velocity decreased as slips began later in stance phase, did not differ between feet, and accelerated on tighter paths. Slipping foot directions relative to heading transitioned from anterior (forward) to posterior (backward) as slips began later in stance, were ipsilateral (toward the slipping foot side) and contralateral (toward the opposite side) for the outside and inside foot, respectively, and became increasingly ipsilateral/contralateral on tighter curvatures. Compensatory steps were placed anteriorly and ipsilaterally after outside and inside foot slips, respectively, and lengthened at later onset phases for outside foot slips only. Our findings illustrate slip magnitude and fall risk relationships that suggest slip direction may influence the balance threat posed by a slip, imply that walking speed may modify slip likelihood, and indicate the most destabilizing curved walking contexts to target in future perturbation-based balance training approaches.

Barriers to the Initiation of Telecommunicator-CPR during 9-1-1 Out-of-Hospital Cardiac Arrest Calls: A Qualitative Study.

INTRODUCTION: Fewer than 10% of individuals who suffer out-of-hospital cardiac arrest (OHCA) survive with good neurologic function. Bystander CPR more than doubles the chance of survival, and telecommunicator-CPR (T-CPR) during a 9-1-1 call substantially improves the frequency of bystander CPR. OBJECTIVE: We examined the barriers to initiation of T-CPR. METHODS: We analyzed the 9-1-1 call audio from 65 EMS-treated OHCAs from a single US 9-1-1 dispatch center. We initially conducted a thematic analysis aimed at identifying barriers to the initiation of T-CPR. We then conducted a conversation analysis that examined the interactions between telecommunicators and bystanders during the recognition phase (i.e., consciousness and normal breathing). RESULTS: We identified six process themes related to barriers, including incomplete or delayed recognition assessment, delayed repositioning, communication gaps, caller emotional distress, nonessential questions and assessments, and caller refusal, hesitation, or inability to act. We identified three suboptimal outcomes related to arrest recognition and delivery of chest compressions, which are missed OHCA identification, delayed OHCA identification and treatment, and compression instructions not provided following OHCA identification. A primary theme observed during missed OHCA calls was incomplete or delayed recognition assessment and included failure to recognize descriptors indicative of agonal breathing (e.g., "snoring", "slow") or to confirm that breathing was effective in an unconscious victim. CONCLUSIONS: We observed that modifiable barriers identified during 9-1-1 calls where OHCA was missed, or treatment was delayed, were often related to incomplete or delayed recognition assessment. Repositioning delays were a common barrier to the initiation of chest compressions.

Factors Impacting Treatment of Out-of-Hospital Cardiac Arrest: A Qualitative Study of Emergency Responders.

Background Of the more than 250 000 emergency medical services-treated out-of-hospital cardiac arrests that occur each year in the United States, only about 8% survive to hospital discharge with good neurologic function. Treatment for out-of-hospital cardiac arrest involves a system of care that includes complex interactions among multiple stakeholders. Understanding the factors inhibiting optimal care is fundamental to improving outcomes. Methods and Results We conducted group interviews with emergency responders including 911 telecommunicators, law enforcement officers, firefighters, and transporting emergency medical services personnel (ie, emergency medical technicians and paramedics) who responded to the same out-of-hospital cardiac arrest incident. We used the American Heart Association System of Care as the framework for our analysis to identify themes and their contributory factors from these interviews. We identified 5 themes under the structure domain, which included workload, equipment, prehospital communication structure, education and competency, and patient attitudes. In the process domain, 5 themes were identified focusing on preparedness, field response and access to patient, on-scene logistics, background information acquisition, and clinical interventions. We identified 3 system themes including emergency responder culture; community support, education, and engagement; and stakeholder relationships. Three continuous quality improvement themes were identified, which included feedback provision, change management, and documentation. Conclusions We identified structure, process, system, and continuous quality improvement themes that may be leveraged to improve outcomes for out-of-hospital cardiac arrest. Interventions or programs amenable to rapid implementation include improving prearrival communication between agencies, appointing patient care and logistical leadership on-scene, interstakeholder team training, and providing more standardized feedback to all responder groups.

Current summary of the evidence in drone-based emergency medical services care.

Interventions for many medical emergencies including cardiac arrests, strokes, drug overdoses, seizures, and trauma, are critically time-dependent, with faster intervention leading to improved patient outcomes. Consequently, a major focus of emergency medical services (EMS) systems and prehospital medicine has been improving the time until medical intervention in these time-sensitive emergencies, often by reducing the time required to deliver critical medical supplies to the scene of the emergency. Medical indications for using unmanned aerial vehicles, or drones, are rapidly expanding, including the delivery of time-sensitive medical supplies. To date, the drone-based delivery of a variety of time-critical medical supplies has been evaluated, generating promising data suggesting that drones can improve the time interval to intervention through the rapid delivery of automatic external defibrillators (AEDs), naloxone, antiepileptics, and blood products. Furthermore, the improvement in the time until intervention offered by drones in out-of-hospital emergencies is likely to improve patient outcomes in time-dependent medical emergencies. However, barriers and knowledge gaps remain that must be addressed. Further research demonstrating functionality in real-world scenarios, as well as research that integrates drones into the existing EMS structure will be necessary before drones can reach their full potential. The primary aim of this review is to summarize the current evidence in drone-based Emergency Medical Services Care to help identify future research directions.

Treating Prehospital Pain in Children: A Retrospective Chart Review Comparing the Safety and Efficacy of Prehospital Pediatric Ketamine and Opioid Analgesia.

Prior to 2020, pain management in the Washtenaw/Livingston County Medical Control Authority (W/L MCA) Emergency Medical Service (EMS) system in Southeast Michigan was limited to morphine, fentanyl, ketorolac, and acetaminophen. Based on the increasing evidence describing its safety and efficacy, ketamine was added to local protocols for pain management. This study aimed to evaluate differences in pain management and adverse effects of ketamine and opioid administration. Data from pediatric patients who received ketamine or an opioid in the W/L MCA EMS system from October 2019 to March 2021 were analyzed. The primary outcome was the difference in pain score, and the secondary outcome was adverse effects observed after analgesic administration. The decrease in pain scores was greater among ketamine patients (mean: 5.2) compared to opioid patients (mean: 2.9), p < 0.001. The prevalence of adverse effects was higher among patients in the ketamine group (28.6%) compared to patients in the opioid group (2.4%, p < 0.001). Of 14 patients who received ketamine, one 17-year-old male experienced mild anxiety (7.1%), two teenage females experienced mild dissociation (14.3%), and one 20-year-old female experienced mild nausea (7.1%). Overall, ketamine is a safe and effective option compared to opioids for pediatric patients experiencing moderate to severe prehospital pain.

Slipping mechanics during walking along curved paths depend on the biomechanical context at slip onset.

Curvilinear walking is common, causing limb- and radius-dependent asymmetries that distinguish it from straight walking and elevated friction demands that increase slip-and-fall risk. However, it is unclear how aspects of curvilinear walking influence the slip perturbations experienced. We cross-sectionally examined how three biomechanical slip contexts (slip onset phase, slipped foot relative to the path, path radius) influence slip direction, distance, and peak velocity. Eighteen young adults experienced unconstrained inside or outside foot slips during early, mid-, or late stance while following 1.0- or 2.0-m radius semicircular paths. We derived slip mechanics from motion-capture data and assessed their dependence on slip context using mixed-effects models. As slip onset phase progressed, slip directions exhibited an anterior-to-posterior transition, shortened mediolaterally, and accelerated anteroposteriorly. The slipped foot modified the direction transition, with inside and outside foot slips moving contralaterally and ipsilaterally, respectively. Inside foot slips were shorter and slower mediolaterally and longer anteroposteriorly than outside foot slips. Increasing path radius caused slips with greater mediolateral direction components. We show a range of context-dependent slips are possible, likely due to instantaneous magnitudes and orientations of shear ground reaction forces. Our results contribute to a comprehensive understanding of walking slips, which fall prevention methods can leverage.

Severity of Unconstrained Simultaneous Bilateral Slips: The Impact of Frontal Plane Feet Velocities Relative to the Center of Mass to Classify Slip-Related Falls and Recoveries.

Targeted interventions to prevent slip-related falls may be informed by specific kinematic factors measured during the reactive response that accurately discriminate recoveries from falls. But reactive responses to diverse slipping conditions during unconstrained simultaneous bilateral slips, which are closely related to real-world slips, are currently unknown. It is challenging to identify these critical kinematic factors due to the wide variety of upper and lower body postural deviations that occur following the slip, which affect stability in both the sagittal and frontal planes. To explore the utility of kinematic measurements from each vertical plane to discriminate slip-related falls from recoveries, we compared the accuracy of four Linear Discriminant Analysis models informed by predetermined sagittal or frontal plane measurements from the lower body (feet velocities relative to the center of mass) or upper body (angular momentum of trunk and arms) during reactive responses after slip initiation. Unconstrained bilateral slips during over-ground walking were repeatedly administered using a wearable device to 10 younger (24.7 ± 3.2 years) and 10 older (72.4 ± 3.9 years) adults while whole-body kinematics were measured using motion capture. Falls (n = 20) and recoveries (n = 40) were classified by thresholding the dynamic tension forces measured in an overhead harness support system and verified through video observation. Frontal plane measurements of the peak feet velocities relative to the center of mass provided the best classification (classification accuracy = 73.3%), followed by sagittal plane measurements (classification accuracy = 68.3%). Measurements from the lower body resulted in higher accuracy models than those from the upper body, but the accuracy of all models was generally low compared to the null accuracy of 66.7% (i.e., predicting all trials as recoveries). Future work should investigate novel models that include potential interactions between kinematic factors. The performance of lower limb kinematics in the frontal plane in classifying slip-related falls demonstrates the importance of administering unconstrained slips and measuring kinematics outside the sagittal plane.

Comparison of 3D printed anatomical model qualities in acetabular fracture representation.

Background: Acetabular fractures account for 10% of pelvis injuries, which are especially difficult to treat in developing countries with less access to resources. 3D printing has previously been shown to be a beneficial method of surgical planning, however the steep initial costs associated with purchasing a 3D printer may prevent some facilities form utilizing this technique. The purpose of this study was to develop 3D printed models for acetabular surgery using methodologies of varying cost to determine differences in model accuracy and overall quality. Methods: Five acetabular fracture models were developed from de-identified CT data using (I) proprietary and open-source segmentation software and (II) fused deposition modeling (FDM) and stereolithography (SLA) 3D printing methods. The distance between the posterior inferior iliac spine (PIIS) and the ischial spine as well as a unique fracture fragment for each model was compared between the different printing methodologies. The models were then given to 5 physicians and assessed on their overall accuracy compared to traditional 2D images. Results: Printing methodology did not affect the distance from PIIS to ischial spine (P=0.263). However, fracture fragment representation differed across 3D printed models, with the most accurate model produced by the high-end resin-based printer (P=0.007). The survey analysis showed that the low-cost printing methods produced models that were not as accurate in their representation of the fractured region (P=0.008). Conclusions: The differences between models developed using traditional methods and low-cost methods have slight differences but may still provide useful information when developing a surgical plan.

Novel Negative Pressure Procedural Tent Reduces Aerosolized Particles in a Simulated Prehospital Setting.

BACKGROUND/OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic has challenged the ability of Emergency Medical Services (EMS) providers to maintain personal safety during the treatment and transport of patients potentially infected. Increased rates of COVID-19 infection in EMS providers after patient care exposure, and notably after performing aerosol-generating procedures (AGPs), have been reported. With an already strained workforce seeing rising call volumes and increased risk for AGP-requiring patient presentations, development of novel devices for the protection of EMS providers is of great importance.Based on the concept of a negative pressure room, the AerosolVE BioDome is designed to encapsulate the patient and contain aerosolized infectious particles produced during AGPs, making the cabin of an EMS vehicle safer for providers. The objective of this study was to determine the efficacy and safety of the tent in mitigating simulated infectious particle spread in varied EMS transport platforms during AGP utilization. METHODS: Fifteen healthy volunteers were enrolled and distributed amongst three EMS vehicles: a ground ambulance, an aeromedical-configured helicopter, and an aeromedical-configured jet. Sodium chloride particles were used to simulate infectious particles and particle counts were obtained in numerous locations close to the tent and around the patient compartment. Counts near the tent were compared to ambient air with and without use of AGPs (non-rebreather mask, continuous positive airway pressure [CPAP] mask, and high-flow nasal cannula [HFNC]). RESULTS: For all transport platforms, with the tent fan off, the particle generator alone, and with all AGPs produced particle counts inside the tent significantly higher than ambient particle counts (P <.0001). With the tent fan powered on, particle counts near the tent, where EMS providers are expected to be located, showed no significant elevation compared to baseline ambient particle counts during the use of the particle generator alone or with use of any of the AGPs across all transport platforms. CONCLUSION: Development of devices to improve safety for EMS providers to allow for use of all available therapies to treat patients while reducing risk of communicable respiratory disease transmission is of paramount importance. The AerosolVE BioDome demonstrated efficacy in creating a negative pressure environment and workspace around the patient and provided significant filtration of simulated respiratory droplets, thus making the confined space of transport vehicles potentially safer for EMS personnel.

Assessment of telecommunicator cardiopulmonary resuscitation performance during out-of-hospital cardiac arrest using a standardized tool for audio review.

OBJECTIVE: Telecommunicator cardiopulmonary resuscitation (T-CPR) is a critical component of optimized out-of-hospital cardiac arrest (OHCA) care. We assessed a pilot tool to capture American Heart Association (AHA) T-CPR measures and T-CPR coaching by telecommunicators using audio review. METHODS: Using a pilot tool, we conducted a retrospective review of 911 call audio from 65 emergency medical services-treated out-of-hospital cardiac arrest (OHCA) patients. Data collection included events (e.g., OHCA recognition), time intervals, and coaching quality measures. We calculated summary statistics for all performance and quality measures. RESULTS: Among 65 cases, the patients' mean age was 64.7 years (SD: 14.6) and 17 (26.2%) were women. Telecommunicator recognition occurred in 72% of cases (47/65). Among 18 non-recognized cases, reviewers determined 12 (66%) were not recognizable based on characteristics of the call. Median time-to-recognition was 76 seconds (n = 40; IQR:39-138), while median time-to-first-instructed-compression was 198 seconds (n = 26; IQR:149-233). In 36 cases where coaching was needed, coaching on compression-depth occurred in 27 (75%); -rate in 28 (78%); and chest recoil in 10 (28%) instances. In 30 cases where repositioning was needed, instruction to position the patient's body flat occurred in 18 (60%) instances, on-back in 22 (73%) instances, and on-ground in 22 (73%) instances. CONCLUSIONS: Successful collection of data to calculate AHA T-CPR measures using a pilot tool for audio review revealed performance near AHA benchmarks, although coaching instructions did not occur in many instances. Application of this standardized tool may aid in T-CPR quality review.

Novel Negative Pressure Helmet Reduces Aerosolized Particles in a Simulated Prehospital Setting.

BACKGROUND/OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic has created challenges in maintaining the safety of prehospital providers caring for patients. Reports have shown increased rates of Emergency Medical Services (EMS) provider infection with COVID-19 after patient care exposure, especially while utilizing aerosol-generating procedures (AGPs). Given the increased risk and rising call volumes for AGP-necessitating complaints, development of novel devices for the protection of EMS clinicians is of great importance.Drawn from the concept of the powered air purifying respirator (PAPR), the AerosolVE helmet creates a personal negative pressure space to contain aerosolized infectious particles produced by patients, making the cabin of an EMS vehicle safer for providers. The helmet was developed initially for use in hospitals and could be of significant use in the prehospital setting. The objective of this study was to determine the efficacy and safety of the helmet in mitigating simulated infectious particle spread in varied EMS transport platforms during AGP utilization. METHODS: Fifteen healthy volunteers were enrolled and distributed amongst three EMS vehicles: a ground ambulance, a medical helicopter, and a medical jet. Sodium chloride particles were used to simulate infectious particles, and particle counts were obtained in numerous locations close to the helmet and around the patient compartment. Counts near the helmet were compared to ambient air with and without use of AGPs (non-rebreather mask [NRB], continuous positive airway pressure mask [CPAP], and high-flow nasal cannula [HFNC]). RESULTS: Without the helmet fan on, the particle generator alone and with all AGPs produced particle counts inside the helmet significantly higher than ambient particle counts. With the fan on, there was no significant difference in particle counts around the helmet compared to baseline ambient particle counts. Particle counts at the filter exit averaged less than one despite markedly higher particle counts inside the helmet. CONCLUSION: Given the risk to EMS providers by communicable respiratory diseases, development of devices to improve safety while still enabling use of respiratory therapies is of paramount importance. The AerosolVE helmet demonstrated efficacy in creating a negative pressure environment and provided significant filtration of simulated respiratory droplets, thus making the confined space of transport vehicles potentially safer for EMS personnel.

Outdoor walking exhibits peak ankle and knee flexion differences compared to fixed and adaptive-speed treadmills in older adults.

BACKGROUND: Walking mechanics recorded with a traditional treadmill may not be the same as the mechanics exhibited during activities of daily living due to constrained walking speeds. Adaptive-speed treadmills allow for unconstrained walking speeds similar to outdoor walking. The aim of this study was to determine differences in kinematic walking parameters of older adults between adaptive-speed treadmill (AST), fixed-speed treadmill (FST) and outdoor walking. We hypothesized that self-selected walking speed (SSWS) during AST walking and outdoor walking would increase compared to FST walking. Furthermore, we hypothesized that AST walking and outdoor walking would increase peak knee flexion, hip flexion, and ankle plantarflexion angles compared to FST walking independent of walking speed changes. METHODS: Fourteen older adult participants were asked to complete 3 min of FST and AST walking on a split-belt treadmill. Participants were also asked to complete 6 min of outdoor walking following a circular route in a neighboring park. A wireless inertial measurement unit-based motion capture system was used to record lower extremity kinematics during all walking conditions. RESULTS: The outdoor walking condition produces significantly higher SSWS compared to FST (p < 0.001) and AST (p = 0.02) conditions. A significantly faster SSWS was exhibited during the AST condition compared to the FST condition (p = 0.026). Significantly higher peak ankle plantarflexion angles are exhibited during the outdoor walking condition compared to the AST (p < 0.001, g = 1.14) and FST (p < 0.001, g = 1.13) conditions after accounting for walking speed. There was a significantly lowered difference between the outdoor walking condition and both AST (p = 0.029, g = 0.49) and FST (p = 0.013, g = 0.63) conditions in peak knee flexion angles after accounting for SSWS. There are no significant differences between outdoor, AST, and FST conditions on peak hip flexion angles. Older adults exhibit changes in peak ankle plantarflexion and peak knee flexion angles during outdoor walking compared to treadmill walking but not between treadmill controller types. We found no differences in the kinematics exhibited by older adults between both AST and FST walking. CONCLUSIONS: Incorporating unconstrained walking speed with the AST while maintaining similar FST sagittal plane kinematics may allow for more translatable conditional balance and walking rehabilitation.

Acrobatic squirrels learn to leap and land on tree branches without falling.

Arboreal animals often leap through complex canopies to travel and avoid predators. Their success at making split-second, potentially life-threatening decisions of biomechanical capability depends on their skillful use of acrobatic maneuvers and learning from past efforts. Here, we found that free-ranging fox squirrels (Sciurus niger) leaping across unfamiliar, simulated branches decided where to launch by balancing a trade-off between gap distance and branch-bending compliance. Squirrels quickly learned to modify impulse generation upon repeated leaps from unfamiliar, compliant beams. A repertoire of agile landing maneuvers enabled targeted leaping without falling. Unanticipated adaptive landing and leaping "parkour" behavior revealed an innovative solution for particularly challenging leaps. Squirrels deciding and learning how to launch and land demonstrates the synergistic roles of biomechanics and cognition in robust gap-crossing strategies.

Unconstrained slip mechanics and stepping reactions depend on slip onset timing.

Slips can occur at any time during stance. Accordingly, time-dependent tangential ground reaction forces likely produce a diverse range of slipping foot mechanics when traction is lost, thus requiring flexible recovery strategies to prevent falls. However, previous research has focused on slip onset in early stance, often with experimental anteroposterior constraints on the slipping foot, despite the diversity of environmental slips and falls. This study aimed to determine the effects of slip onset time on slip direction, severity (distance and velocity), and compensatory stepping responses. Ten young adults received slipping perturbations at different times during the stance phase of walking via a wearable device that reduces available friction while allowing the slipping foot to slide freely within the horizontal plane. Slip direction, distance, and peak velocity, compensatory step direction and distance, and upper body angular momentum magnitude and plane of rotation were derived from kinematic data. All outcome measurements significantly correlated with the time of slip onset. Slip direction and the plane of rotation of angular momentum deviated widely from the sagittal plane, exhibiting laterally-directed components exceeding those in the anteroposterior direction. As slip onset occurred later in stance, slip severity decreased while compensatory steps became longer and progressed from a posterior to anterior placement. These results provide insight into critical times within stance when slips are most severe, and into the diversity of slipping mechanics caused by changes in slip onset time.

A novel wearable device to deliver unconstrained, unpredictable slip perturbations during gait.

BACKGROUND: Task-specific perturbation training is a widely studied means of fall prevention, utilizing techniques that induce slips or slip-like perturbations during gait. Though effective, these methods only simulate narrow ranges within the larger space of possible slipping conditions encountered in daily life. Here we describe and test a novel, wearable apparatus designed to address these limitations and simulate a diverse range of slipping disturbances. METHODS: The device consists of wireless triggering and detachable outsole components that provide adequate friction with the floor when secured to the wearer's foot, but suddenly create a low-friction surface underfoot upon release. "Benchtop" tests were carried out to quantify device triggering characteristics (i.e. cutting temperature, release delay) and the resulting friction reduction. The device was also tested on six healthy young adults (3 female, age 23 ± 2.4 years), who walked with and without the device to observe how gait kinematics and spatiotemporal parameters were influenced, then performed 12 walking trials ending with a slip delivered by the device. Each participant also completed a survey to obtain opinions on device safety, device comfort, slip realism, and slip difficulty. A linear mixed effects analysis was employed to compare subject spatiotemporal parameters with and without the apparatus, as well as correlation coefficients and root mean square errors (RMSE) to assess the impact of the device on lower limb gait kinematics. Slip onset phases, distances, directions, velocities, and recovery step locations were also calculated. RESULTS: This device rapidly diminishes available friction from static coefficients of 0.48 to 0.07, albeit after a substantial delay (0.482 ± 0.181 s) between signal reception and outsole release. Strong correlations (R > 0.93) and small RMSE between gait kinematics with and without the device indicate minimal effects on natural gait patterns, however some spatiotemporal parameters were significantly impacted. A diverse range of slip perturbations and recovery steps were successfully elicited by the device. CONCLUSIONS: Our results highlight the efficacy and utility of a wearable slipping device to deliver diverse slip conditions. Such an apparatus enables the study of unconstrained slips administered across the gait cycle, as well as during different locomotor behaviors like turning, negotiating slopes, and level changes.

Comparing single and multi-joint methods to detect knee joint proprioception deficits post primary unilateral total knee arthroplasty.

BACKGROUND: The use of various single-joint proprioception measurements has resulted in contradictory findings after knee arthroplasty. The use of balance as a surrogate measure to assess knee proprioception post-operation has resulted in further confusion. The aim of this study was to measure single joint knee proprioception in participants after unilateral knee arthroplasty, and compares it to multi-joint balance. METHODS: Eleven participants at 1 year after unilateral total knee arthroplasty and twelve age-matched controls were enrolled. The threshold to detect passive motion and the sensory organization test were used to measure single joint knee proprioception and multi-joint balance respectively. Two-way ANOVA and independent t-tests were used to measure differences between and within groups. Regression analysis was used to measure the association between proprioception and balance measurements. FINDINGS: Surgical knees demonstrated significantly more deficient proprioception compared to the non-surgical knees and both knees of the control groups during flexion (P < 0.01) and extension (P < 0.05). Non-surgical knees showed similar proprioception to both knees of the control group during flexion and extension. Within the knee arthroplasty group, only deficiencies during flexion showed significant correlation with Sensory Organization Test visual ratio. No additional differences between both groups during balance measurements, nor any correlations between local joint proprioception and balance were seen. INTERPRETATION: These findings indicate deficient surgical knee proprioception in participants one year after unilateral total knee arthroplasty. Limited associations between measurements indicate that balance may be a poor measure of single-joint proprioception.

Effects of aging on the relationship between cognitive demand and step variability during dual-task walking.

A U-shaped relationship between cognitive demand and gait control may exist in dual-task situations, reflecting opposing effects of external focus of attention and attentional resource competition. The purpose of the study was twofold: to examine whether gait control, as evaluated from step-to-step variability, is related to cognitive task difficulty in a U-shaped manner and to determine whether age modifies this relationship. Young and older adults walked on a treadmill without attentional requirement and while performing a dichotic listening task under three attention conditions: non-forced (NF), forced-right (FR), and forced-left (FL). The conditions increased in their attentional demand and requirement for inhibitory control. Gait control was evaluated by the variability of step parameters related to balance control (step width) and rhythmic stepping pattern (step length and step time). A U-shaped relationship was found for step width variability in both young and older adults and for step time variability in older adults only. Cognitive performance during dual tasking was maintained in both young and older adults. The U-shaped relationship, which presumably results from a trade-off between an external focus of attention and competition for attentional resources, implies that higher-level cognitive processes are involved in walking in young and older adults. Specifically, while these processes are initially involved only in the control of (lateral) balance during gait, they become necessary for the control of (fore-aft) rhythmic stepping pattern in older adults, suggesting that attentional resources turn out to be needed in all facets of walking with aging. Finally, despite the cognitive resources required by walking, both young and older adults spontaneously adopted a "posture second" strategy, prioritizing the cognitive task over the gait task.