Continuous Compression Research Articles

In-depth analysis of the long-term processability of materials during continuous feeding

This study determined the feasibility of long-term continuous powder feeding and its effect on the overall process performance. Additionally, quantitative relationships were established between material properties, process settings and screw feeding responses during gravimetric feeding. Twelve divergent raw materials were processed over longer periods using a GEA Compact Feeder integrated in a continuous direct compression line (ConsiGma™ CDC-50). The resulting gravimetric feeding responses were combined with the material properties and process settings into an overall PLS model. The model elucidated the impact of the material descriptors for density; powder flow; particle size; compressibility; permeability and wall friction angle on the feeding process. Furthermore, long-term processing of the materials exhibited challenges related to the processability and refill consistency where a significant impact of the compressibility and cohesive/adhesive properties of the materials was observed. Overall, this approach provided insights into the feasibility of long-term continuous feeding which is not possible through ‘short-term’ feeding trials. Additionally, throughout this study, the need for material-specific adjustments of the feeding and refill equipment was highlighted.

100% visual inspection of tablets produced with continuous direct compression and coating

Visual appearance of tablets is an important property for patients. Since the visual appearance is most strongly influenced by the applied coating, this necessitates a high level of process control and homogeneity in the coating process. In recent years, a number of tablet coaters have been developed that can be used in combination with continuous tablet production lines. In this study, 180 kg of tablets were produced using a continuous direct compaction line with a throughput of 25 kg/h. Tablets were consequently subdivided into 12 lots and coated in a semi-batch drum coater directly after compression. For a detailed understanding of intra-lot and lot-to-lot variability, a 100% visual inspection of the tablets was performed using an automatic tablet inspection and sorting machine. All tablets were analyzed from all 6 sides and the unsuitable tablets were sorted out. In the worst lot, only 1 out of around 300 tablets was sorted out due to color mismatch. For some tablets, edge chipping was also observed, which would presumably not be detected during routine sampling. Root causes for the defects could be found in the intentionally chosen set of old punches and in the operation parameters of the coater. Nonetheless, the lot-to-lot variability according to all criteria was very low.

Radiographic Evaluation of Isolated Continuous Compression Staples for Midfoot and Chopart Arthrodesis

Category:Midfoot/Forefoot; HindfootIntroduction/Purpose:The use of continuous compression implants (nitinol staples) in orthopaedic surgery has increased secondary to advances in metal alloy engineering. Biomechanical studies provide useful data supporting the theoretical use of nitinol staples in the foot and ankle; however, clinical data is limited. There are several advantages of nitinol staples, including a lower profile when compared to traditional fixation methods. They are easy to apply and take up a smaller footprint than most plating techniques, thus decreasing surgical time and dissection. Additionally, continuous compression across the fusion site is maintained, as opposed to lag screw fixation. The purpose of this study was to determine the overall effectiveness, clinically and radiographically, of continuous compression implants (nitinol staples) to achieve stable arthrodesis in the midfoot and Chopart joints.Methods:A retrospective chart review was performed on 18 patients (37 joints) who underwent arthrodesis of the midfoot or Chopart joints utilizing isolated continuous compression implants between January 2017-December 2019. The primary outcome variable was radiographic evidence of arthrodesis on x-ray. X-rays were independently reviewed by three board-certified foot and ankle surgeons. All investigators were blinded towards the x-rays, and x-rays were randomized in terms of timing from surgery. Each investigator reviewed digital radiographs independently and recorded their radiographic finding responses. Joints were deemed fused if greater than 50% of the joint contained bridging bone radiographically. A partial fusion was defined as some bridging bone, but less than 50% of the joint involved, and nonunion was defined as no arthrodesis seen radiographically, broken hardware, or loss of reduction. Smokers and diabetics represented 22% and 11% of the patient population, respectively.Results:Radiographic union was seen in 88.8% of TMT joints (16/18) and 83.3% of midfoot joints overall (20/24). Nonunion rates were 11.2% (2/18) and 16.6% (4/24) respectively. Diabetes was associated for 50% (3/6) of nonunions. Mean time-to-fusion for TMT joints was 60 days. In Chopart joint fusions, nonunion rate was 46% (6/13), 2/6 (33%) were smokers. Overall, diabetes and smoking was associated with 40% (4/10) of all nonunion cases. TMT joint fusions had a significantly lower proportion of nonunion rates than hindfoot fusions (p=0.043). Radiographic Interobserver reliability was moderately strong between reviewers. Clinically, Chopart joint fusion patients had a significantly longer time course to weight bearing (p = 0.028). 8% (4/50) had broken hardware, all in nonunions, 75% (3/4) occurring in Chopart joints.Conclusion:Isolated nitinol staples are a viable option for midfoot arthrodesis, especially TMT joints, and offer multiple advantages when compared to traditional fixation methods. Staples are lower profile, eliminating hardware irritation and potential secondary surgeries, are technically less demanding, and time of application is decreased when compared to other methods. They offer the benefit of continuous compression of the fusion site, as well, and are rigid enough to maintain reduction. However, Chopart joints may require a more rigid fixation than CCI staples can provide, given the higher nonunion rate, and caution should be exercised in diabetics and smokers.

Radiographic Evaluation of Isolated Continuous Compression Staples for Akin Osteotomy Fixation

Category:Bunion; OtherIntroduction/Purpose:The use of continuous compression implants (nitinol staples) in orthopaedic surgery has increased secondary to advances in metal alloy engineering. Biomechanical studies provide useful data supporting the theoretical use of nitinol staples in the foot and ankle. However, clinical data is limited. The purpose of this study was to determine the overall effectiveness, both clinically and radiographically, of continuous compression implants (nitinol staples) to achieve bony healing in the medially based, closing-wedge osteotomy of the proximal phalanx of the great toe (Akin osteotomy).Methods:A retrospective chart review was performed on 104 patients (107 feet) who underwent an Akin osteotomy using nitinol staples between January 1st, 2018 and February 20th, 2020. The primary outcome variable was radiographic evidence of healing on x-ray. X-rays were independently reviewed by three board-certified foot and ankle surgeons. All investigators were blinded towards the x-rays, and x-rays were randomized in terms of timing from surgery. Each investigator reviewed digital radiographs independently and recorded their radiographic finding responses. Osteotomies were deemed healed if greater than 50% of the osteotomy contained bridging bone. A partially healed osteotomy was defined as some bridging bone, but less than 50% of the overall osteotomy site, and a nonunion was defined as no healing seen radiographically, broken hardware, or loss of reduction.Results:Radiographic union (partial or full) was seen in 95% of Akin osteotomies (96/101) based on our parameters, with no loss of initial reduction. Only 2.8% (3/107) of the patient population had unplanned return to the operating room for reasons associated with the Akin osteotomy: one infection (0.9%), one irritable hardware removal (0.9%), and one traumatic disruption of fixation (0.9%). None of the eligible staples (0/106) were found to be fractured upon radiographic analysis. Smokers and diabetics represented 4.8 and 8.7 percent of the patient population, respectively.Conclusion:Since its inception in 1925, the Akin osteotomy has been described using several types of fixation methods. The results of this retrospective study show that continuous compression implants (nitinol staples) are a viable option for Akin osteotomy fixation, with low rates of complications (2.8%, 3/107) and high healing rates (95%, 96/101). Staples are lower profile, eliminating hardware irritation and potential secondary surgeries, are technically less demanding, and time of application is decreased when compared to other fixation methods. They offer the benefit of continuous compression of the fusion site, as well, and are rigid enough to maintain reduction.

Effectiveness of a Superelastic Nitinol Device for Fixation of Syndesmosis in Ankle Fracture

Category:Ankle; TraumaIntroduction/Purpose:Syndesmosis injuries are increasingly common. Available fixation options are not yet optimal. The PUMA System (Panther Orthopedics, Sunnyvale, CA) is an FDA-cleared superelastic, nitinol-based fixation device for the ankle syndesmosis which provides stabilization without over-compression or loosening during cyclical loading. The spring-like design of the PUMA System allows physiological micro-motion while maintaining continuous compression and resisting syndesmosis widening, without material creep. The objective of this prospective study is to assess the effectiveness and complication rate of the PUMA device for treatment of fracture-associated syndesmosis injuries.Methods:We prospectively collected radiographic and clinical data on 32 consecutive patients treated for fracture-associated syndesmotic disruption with the PUMA SystemTM at 8 centers. Primary outcome measures included adverse event rates, radiographic evaluations for syndesmosis integrity and implant failure, and rates of revision surgery.Results:All 32 patients had successful repair of their ankle syndesmosis (Figure 1). The mean age of patients at time of operation was 42 years (range 16- 68). There were 13 females (13/32, 40.6%) and 19 (19/32, 59.4%) males. Postoperative radiographic evaluations confirmed satisfactory syndesmosis healing with maintained reduction in the ankle mortise in 33/33 (100%) ankles. There was no evidence of lysis, device migration or syndesmotic or medial clear space widening. There were no infections or soft tissue complications. All fractures healed. No devices required removal and there were no revision surgeries.Conclusion:The PUMA SystemTM provides physiologic stabilization of the syndesmosis due to the design features that allow for continuous compression without creep. We found no device-related complications nor construct failures in our series. The superelastic implant design allows physiologic motion at the syndesmosis but does not creep or stretch following displacement. This flexibility obviates the need for routine removal. The implant's low-profile buttons without suture and knot tying requirements eliminate the concern for subcutaneous knot irritation and slippage. Additional biomechanical and clinical outcomes study of this device may further optimize rehabilitation protocols for patients treated for syndesmotic injury.

Atomistic simulations to study shock and ultrashort pulse response of high entropy alloy

This article aimed to study the shock compression and ultrashort pulse shock compression behavior of multi-elemental alloy, high entropy alloy (HEA), and single-crystal Ni. Non-equilibrium molecular dynamics (NEMD) based simulations were utilized in this article with the help of EAM potential to capture the deformation under dynamic and complex loading scenarios in HEA (Co-Cr-Cu-Fe-Ni) and single-crystal Ni. Simulations were performed with continuous shock compression and ultra-short shock pulse traversing the atomic configuration at velocity 0.75 km/s. Simulation helps capture the distribution of pressure and velocities in the simulation box as a function of the time from the onset of the shock front. Simulation helps capture the distribution of pressure and velocities in the simulation box as a function of the time from the beginning of the shock front. It was concluded from the MD simulations that the insertion of nano-voids in the path of the shock front helps in dispersing the energy and reducing the speed of the shock front. Nano-voids significantly affect the shock deformation of crystals and help in inducing plastic deformation in the HEA and Ni, even at shock velocities below Hugoniot elastic limit (HEL). Nucleation of dislocation from the nano-voids is more significant in HEA crystal as compared to Ni. The onset of plastic deformation in HEA and higher dislocation densities helps in dispersing the energy of the shock front, and the performance of HEA improved at higher shock velocities. The results in this article will help develop high entropy alloys for applications containing complex loading scenarios such as high strain rate loading experienced in space structures and armor vehicles.

Lesser Tarsal Metatarsal Joint Fusion Using Nitinol Staples, Bone Marrow Aspirate Concentrate and a Calcaneal Bone Dowel: A Retrospective Comparative Analysis

Category:Midfoot/Forefoot; Lesser ToesIntroduction/Purpose:Estimates suggest nonunion rates following lesser tarsometatarsal (TMT) fusion are up to 11.4%. Various techniques have been employed to improve fusion rates; however, none have shown significant improvement compared to other techniques. Autologous bone dowels, bone marrow aspirate concentrate (BMAC) and continuous compression devices (CCDs), such as nitinol staples, have each shown promising fusion rates in orthopedic literature. There is limited data that suggests using these techniques in conjunction with one another has been successfully employed in the fusion of lesser TMT joints. The aim of this study was to describe our technique using autologous calcaneal bone graft, CCDs and BMAC for lesser TMT fusion and to investigate whether this method improves fusion rates and decreases time to fusion in comparison to traditional constructs.Methods:All patients undergoing arthrodesis of the lesser (2nd/3rd) TMT joints from January 2015 to January 2020 were identified. Exclusion criteria included inadequate clinical or radiographic follow-up, those with only 1st TMT joint arthrodesis, and those less than 18 years old. Chart review allowed patient demographics, risk factors and surgical approach to be identified.Twenty patients (28 lesser TMT joints) treated with arthrodesis by the senior surgeon met inclusion criteria. These patients were then divided into two groups: 1) novel treatment (Nitinol staple, BMAC and calcaneal dowel) and 2) traditional treatment (compression plate and screw construct). We then assessed for radiographic union, time to union and complications.Results:All lesser TMT joints in the novel treatment arm went on to successful clinical and radiographic fusion. The radiographic union rate of the traditional treatment arm was 92% (P=.08). Overall time to fusion was 56 and 82 days for the novel and traditional constructs respectively (P <.05). All patients, regardless of construct, had returned to full weight bearing and maintained hardware at most recent follow-up (minimum 6 months).Conclusion:Continuous compression devices such as the nitinol staple and use of biologic adjuvants appear to decrease nonunion rates and significantly shorten overall time to fusion in lesser TMT joints. Further investigation towards identifying patient specific factors for nonunion is warranted.

Effect of Early Supraglottic Airway Device Insertion on Chest Compression Fraction during Simulated Out-of-Hospital Cardiac Arrest: Randomised Controlled Trial.

Early insertion of a supraglottic airway (SGA) device could improve chest compression fraction by allowing providers to perform continuous chest compressions or by shortening the interruptions needed to deliver ventilations. SGA devices do not require the same expertise as endotracheal intubation. This study aimed to determine whether the immediate insertion of an i-gel® while providing continuous chest compressions with asynchronous ventilations could generate higher CCFs than the standard 30:2 approach using a face-mask in a simulation of out-of-hospital cardiac arrest. A multicentre, parallel, randomised, superiority, simulation study was carried out. The primary outcome was the difference in CCF during the first two minutes of resuscitation. Overall and per-cycle CCF quality of compressions and ventilations parameters were also compared. Among thirteen teams of two participants, the early insertion of an i-gel® resulted in higher CCFs during the first two minutes (89.0% vs. 83.6%, p = 0.001). Overall and per-cycle CCF were consistently higher in the i-gel® group, even after the 30:2 alternation had been resumed. In the i-gel® group, ventilation parameters were enhanced, but compressions were significantly shallower (4.6 cm vs. 5.2 cm, p = 0.007). This latter issue must be addressed before clinical trials can be considered.

Continuous direct compression: Development of an empirical predictive model and challenges regarding PAT implementation

In this study, an empirical predictive model was developed based on the quantitative relationships between blend properties, critical quality attributes (CQA) and critical process parameters (CPP) related to blending and tableting. The blend uniformity and API concentration in the tablets were used to elucidate challenges related to the processability as well as the implementation of PAT tools. Thirty divergent ternary blends were evaluated on a continuous direct compression line (ConsiGma™ CDC-50). The trials showed a significant impact of the impeller configuration and impeller speed on the blending performance, whereas a limited impact of blend properties was observed. In contrast, blend properties played a significant role during compression, where changes in blend composition significantly altered the tablet quality. The observed correlations allowed to develop an empirical predictive model for the selection of process configurations based on the blend properties, reducing the number of trial runs needed to optimize a process and thus reducing development time and costs of new drug products. Furthermore, the trials elucidated several challenges related to blend properties that had a significant impact on PAT implementation and performance of the CDC-platform, highlighting the importance of further process development and optimization in order to solve the remaining challenges.

Tracing electron density changes in langbeinite under pressure.

Pressure is well known to dramatically alter physical properties and chemical behaviour of materials, much of which is due to the changes in chemical bonding that accompany compression. Though it is relatively easy to comprehend this correlation in the discontinuous compression regime, where phase transformations take place, understanding of the more subtle continuous compression effects is a far greater challenge, requiring insight into the finest details of electron density redistribution. In this study, a detailed examination of quantitative electron density redistribution in the mineral langbeinite was conducted at high pressure. Langbeinite is a potassium magnesium sulfate mineral with the chemical formula [K2Mg2(SO4)3], and crystallizes in the isometric tetartoidal (cubic) system. The mineral is an ore of potassium, occurs in marine evaporite deposits in association with carnallite, halite and sylvite, and gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations. Single-crystal X-ray diffraction data for langbeinite have been collected at ambient pressure and at 1 GPa using a combination of in-house and synchrotron techniques. Experiments were complemented by theoretical calculations within the pressure range up to 40 GPa. On the basis of changes in structural and thermal parameters, all ions in the langbeinite structure can be grouped into 'soft' (potassium cations and oxygens) and 'hard' (sulfur and magnesium). This analysis emphasizes the importance of atomic basins as a convenient tool to analyse the redistribution of electron density under external stimuli such as pressure or temperature. Gradual reduction of completeness of experimental data accompanying compression did not significantly reduce the quality of structural, electronic and thermal parameters obtained in experimental quantitative charge density analysis.

Does the use of BariBoard™ improve adequacy of chest compressions in morbid obesity? A pilot study using a simulation model

BackgroundObesity is a growing health problem worldwide. Morbid obesity has been associated with significant barriers to effective thoracic cage compression during cardiopulmonary resuscitation. ObjectiveThe BariBoard™ purports to improve adequacy of chest compressions in morbidly obese patients. This study uses a simulation model to evaluate this. MethodsThis was a prospective blinded randomised-controlled crossover pilot trial using a simulation model of obesity. Participants, recruited from hospital departments and prehospital services, performed 2 minutes of continuous compressions on mannequins modified to emulate a morbidly obese patient. Participants were randomised by coin toss to a sequence of either control/intervention or intervention/control, with the BariBoard™ in the intervention arm. Accelerometers measured chest wall movement during compressions. The primary endpoint was a composite measure of compression adequacy (rate, depth, and recoil). Secondary endpoints comprised the individual components of the composite outcome, as both dichotomous outcomes (adequate vs. inadequate) and continuous variables. All endpoints were adjusted for potential confounders. ResultsOf 205 participants recruited, 201 were analysed. There was a significant difference in the primary outcome between the control and intervention arms (13.4% vs. 4.5%, respectively, p = 0.001) and between the control and intervention arms for the secondary endpoints of adequate compression depth (31.3% vs. 15.9%, p < 0.001) and recoil (63.7% vs. 41.3%, p < 0.001). After adjustment for confounders and interactions, there was no difference in overall efficacy (odds ratio: 0.62, 95% confidence interval: 0.20–1.90, p = 0.40). ConclusionThis pilot study describes the successful assessment of a device using a simulation model of obesity. Within these constraints and after adjustment for confounders, use of the BariBoard ™ did not improve efficacy of chest compressions.

A hybrid model for multipoint real time potency observation in continuous direct compression manufacturing operations

The ongoing transition from batch to continuous manufacturing offers both challenges and opportunities in the field of oral solid dosage form production. In turn, Process Analytical Technology (PAT) offers a path towards the successful deployment of continuous tablet manufacturing in rotary tablet presses. One promising PAT tool for this endeavour is the NIR-derived potency measurement. However, the high degree of noise in the data may hamper the extraction of useful information. For this reason, this work focused on the implementation of an adaptive Kalman filter algorithm that incorporates and reconciles the potency prediction given by one or more NIR probes with those of a semi-mechanistic compartmental model developed for the application at hand. This approach allowed for more robust concentration estimations. Furthermore, it was observed that potency levels in multiple locations in the studied tablet press (including those in the finished tablets) could be appropriately inferred using a single in-line measurement data stream. This methodology thus opens the door to advanced process control applications.

The association of race with CPR quality following out-of-hospital cardiac arrest

IntroductionPrevious studies have shown racial disparities in outcomes after out-of-hospital cardiac arrest. Although several treatment factors may account for these differences, there is limited information regarding differences in CPR quality and its effect on survival in underrepresented racial populations. MethodsWe conducted a secondary analysis of data from patients enrolled in the Pragmatic Airway Resuscitation Trial (PART). We calculated compliance rates with AHA 2015 high quality CPR metrics as well as compliance to intended CPR strategy (30:2 or continuous chest compression) based on the protocol in place for the first responding EMS agency. The primary analysis used general estimating equations logistic regression to examine differences between black and white patients based on EMS-assessed race after adjustment for potential confounders. Sensitivity analyses examined differences using alternate race definitions. ResultsThere were 3004 patients enrolled in PART of which 1734 had > 2 minutes of recorded CPR data and an EMS-assessed race (1003 white, 555 black, 176 other). Black patients had higher adjusted odds of compression rate compliance (OR: 1.36, 95% CI: 1.02–1.81) and lower adjusted odds of intended CPR strategy compliance (OR: 0.78, 95% CI: 0.63–0.98) compared to white patients. Of 974 transported to the hospital, there was no difference in compliance metric estimates based on ED-reported race. ConclusionCompression rate compliance was higher in black patients however compliance with intended strategy was lower based on EMS-assessed race. The remaining metrics showed no difference suggesting that CPR quality differences are not important contributors to the observed outcome disparities by race.

Effect of synchronous online vs. face-to-face cardiopulmonary resuscitation training on chest compression quality: A pilot randomized manikin study

The aim of the study was to compare the effect of synchronous online and face-to-face cardiopulmonary resuscitation (CPR) training on chest compressions quality in a manikin model. A total of 118 fourth-year medical students participated in this study. The participants were divided into two groups: the online synchronous teaching group and the face-to-face group. Then, the participants were further randomly distributed to 1 of 2 feedback groups: online synchronous teaching and training with feedback devices (TF, n = 30) or without feedback devices (TN, n = 29) and face-to-face teaching and training with feedback devices (FF, n = 30) or without feedback devices (FN, n = 29). In the FN group and FF group, instructors delivered a 45-min CPR training program and gave feedback and guidance during training on site. In the TN group and TF group, the participants were trained with an online lecture via Tencent Meeting live broadcasting. Finally, participants performed a 2-min continuous chest compression (CC) during a simulated cardiopulmonary arrest scene without the audiovisual feedback (AVF) device. The outcome measures included CC depth, CC rate, proportions of appropriate depth (50-60 mm) and CC rate (100-120/min), percentage of correct hand location position, and percentage of complete chest recoil. There was little difference in the CC quality between the synchronous online training groups and the face-to-face training groups. There was no statistically significant difference in CC quality between the TN group and FN group. There were also no statistically significant differences between the TF and FF groups in terms of correct hand position, CC depth, appropriate CC depth, complete chest recoil or CC rate. However, the FF group had a higher appropriate CC rate than the TF group (p = 0.045). In the face-to-face training groups, the AVF device group had a significantly greater CC depth, appropriate CC depth, CC rate, and appropriate CC rate. However, there was a lack of statistically significant differences in terms of correct hand position (p = 0.191) and appropriate CC depth (p = 0.123). In the synchronous online training groups, the AVF device had little effect on the CC rate (p = 0.851) and increased the appropriate CC rate, but the difference was not statistically significant (p = 0.178). Synchronous online training with an AVF device would be a potential alternative approach to face-to-face chest compression training. Synchronous online training with AVF devices seems to be a suitable replacement for face-to-face training to offer adequate bystander CPR chest compression training.

A continuous spatial confining process towards high electrical conductivity of elastomer composites with a low percolation threshold

Electrically conducting elastomer composites are indispensable in the development of flexible, wearable and soft electronic products. The continuous fabrication of highly electrically conductive polymeric composites at large scale remains a technical challenge due to the lack of control of the dispersion and orientation of the conductive fillers, interfacial interaction and filler-filler network stability in the polymer matrices. Herein, an innovative design was investigated by combining continuous compression molding and curing through a flexible roller enabled continuous process. This approach forced the alignment of short carbon fibers (SCF) along the rolling direction in a polydimethylsiloxane (PDMS) matrix due to the deformation of the flexible roller and effectively condensed the conductive SCF network in PDMS. The distance between SCFs can be further reduced with the rolling cycles which is ascribed to a spatial confining-forced network assembly. With a rolling cycle of 20, dual electrical conducting percolation thresholds reached at 0.1 wt% and 0.5 wt% SCF, respectively. A maximum electrical conductivity of 49.69 S/m was achieved with a SCF loading of 4 wt%. A fiber contact model was proposed to predict the electrical conductivity of the composites. The PDMS/SCF composites were tested for conductive electrodes and flexible pressure sensors. The present work provides a facile method for continuous fabrication of conductive elastomeric composites, with potential for continuous fabrication of thermosetting composites.

Abstract 11532: Variation in Coronary Angiography Use in Out-of-Hospital Cardiac Arrest

Introduction: Current patterns of use of coronary angiography (CAG) among out-of-hospital cardiac arrest (OHCA) patients based on ST segment elevation (STE) on post-resuscitation ECG are not well described. Methods: Using data from the Continuous Chest Compressions trial between 2011 and 2016, we identified OHCA patients who survived to hospitalization. We examined rates of CAG across different trial clusters in the overall cohort and among pre-specified subgroups with presumed cardiac etiology of arrest e.g. initial shockable rhythm and STE on presenting ECG. Results: Of 26,148 OHCA patients across 49 trial clusters, 5608 survived to hospital admission. The mean age of patients was 64 years, with 65% men and 43% with initial shockable rhythm. Among patients with initial shockable rhythm 44% had STE on initial ECG compared with 18% of patients with initial non-shockable rhythm. Use of CAG was significantly higher in patients presenting with STE compared with no STE on initial ECG irrespective of initial rhythm: 70% vs. 31%, p&lt;0.001 for initial shockable rhythm and 28% vs. 5%, p&lt;0.001 for initial non-shockable rhythm. In the overall cohort, there was significant variation in CAG use across trial clusters ranging from 4% - 41% of patients within a trial cluster receiving CAG ( Figure ). This variation persisted among pre-specified subgroups with the proportion of patients within a trial cluster receiving CAG ranged from 11% - 75% for patients with initial shockable rhythm, 0% to 19% with initial non-shockable rhythm, 16% - 82% with STE, 2% - 28% without STE and 0% - 63% in patients with initial shockable rhythm and no STE on presenting ECG ( Figure ). Conclusion: There is a higher use of CAG in STE and shockable cardiac arrest, consistent with presumed cardiac etiology of arrest; however, there is large variation in the use of CAG across sites, even among patients with a presumed cardiac etiology of cardiac arrest suggesting challenges with interpretation of current guidelines.

Different Resting Methods in Improving Laypersons Hands-Only Cardiopulmonary Resuscitation Quality and Reducing Fatigue: A Randomized Crossover Study

ObjectiveTo determine the effects of different resting methods with various rest-start points or rest-compression ratios on improving cardiopulmonary resuscitation (CPR) quality and reducing fatigue during continuous chest compressions (CCC) in 10-min hands-only CPR scenario. MethodsThis prospective crossover study was conducted in 30 laypersons aged 18-65. Trained participants were randomized to follow different orders to perform following hands-only CPR methods: (1) CCC, 10-min CCC; (2) 4+6, 4-min CCC + 6-min of 10-s pause after 60-s compressions; (3) 2+8 (10/60), 2-min CCC + 8-min of 10-s pause after 60-s compressions; (4) 5/30, 2-min CCC + 8-min of 5-s pause after 30-s compressions; (5) 3/15, 2-min CCC + 8-min of 3-s pause after 15-s compressions. CPR quality (depth, rate, hands-off duration, chest compression fraction (CCF)) and participants’ fatigue indicators (heart rate, blood pressure, rating of perceived exertion (RPE)) were compared among methods of different rest-start points and different rest-compression ratios with CCC. ResultsTwenty-eight participants completed all methods. All resting methods reduced the trend of declining compression depth and the trend of increasing RPE while maintaining CCF of more than 86%. In methods with different rest-start points, the 2+8 method showed no difference in overall CPR quality or fatigue, but better CPR quality of every minute than 4+6 method. In methods with different rest-compression ratios, the 3/15 method showed the best CPR quality and the highest heart rate increment. ConclusionDuring prolonged hands-only CPR, appropriate transient rests were associated with higher CPR quality and lower subjectively perceived fatigue in laypersons.

3D Printed MXene Aerogels with Truly 3D Macrostructure and Highly Engineered Microstructure for Enhanced Electrical and Electrochemical Performance.

Assembling 2D materials such as MXenes into functional 3D aerogels using 3D printing technologies gains attention due to simplicity of fabrication, customized geometry and physical properties, and improved performance. Also, the establishment of straightforward electrode fabrication methods with the aim to hinder the restack and/or aggregation of electrode materials, which limits the performance of the electrode, is of great significant. In this study, unidirectional freeze casting and inkjet-based 3D printing are combined to fabricate macroscopic porous aerogels with vertically aligned Ti3 C2 Tx sheets. The fabrication method is developed to easily control the aerogel microstructure and alignment of the MXene sheets. The aerogels show excellent electromechanical performance so that they can withstand almost 50% compression before recovering to the original shape and maintain their electrical conductivities during continuous compression cycles. To enhance the electrochemical performance, an inkjet-printed MXene current collector layer is added with horizontally aligned MXene sheets. This combines the superior electrical conductivity of the current collector layer with the improved ionic diffusion provided by the porous electrode. The cells fabricated with horizontal MXene sheets alignment as current collector with subsequent vertical MXene sheets alignment layers show the best electrochemical performance with thickness-independent capacitive behavior.

Design and application of rescue stretcher dedicated for cardiopulmonary resuscitation mechanical compression device

Continuous chest compressions during the transportation of patients with cardiac arrest have always been a difficult part in the field of pre-hospital emergency cardiopulmonary resuscitation (CPR). How to ensure continuous high-quality chest compressions is an important part of the patient's entire rescue process. At present, mechanical compression devices are commonly used to provide continuous high-quality chest compressions during the transportation. However, the installation process of the mechanical compression device involves posture changes of the patient, the placement of the device base, etc., and it is very likely to affect the continuous high-quality CPR treatment in the pre-hospital emergency process with limited human resources. Therefore, the First Affiliated Hospital of Huzhou University and Huzhou University jointly designed a rescue stretcher dedicated for CPR mechanical compression device, and has obtained the national utility model patent (ZL 2019 2 1005444.9). The main design feature of this stretcher is that the base of the compression device is combined with the stretcher, which eliminates the installation and fixation process of the base during the installation of the mechanical compression device, shortens the installation time. It has certain clinical applications value.

The protective effect of tight-fitting powered air-purifying respirators during chest compressions.

Airborne personal protective equipment is required for healthcare workers when performing aerosol-generating procedures on patients with infectious diseases. Chest compressions, one of the main components of cardiopulmonary resuscitation, require intense and dynamic movements of the upper body. We aimed to investigate the protective effect of tight-fitting powered air-purifying respirators (PAPRs) during chest compressions. This single-center simulation study was performed from February 2021 to March 2021. The simulated workplace protection factor (SWPF) is the concentration ratio of ambient particles and particles inside the PAPR mask; this value indicates the level of protection provided by a respirator when subjected to a simulated work environment. Participants performed continuous chest compressions three times for 2 min each time, with a 4-min break between each session. We measured the SWPF of the tight-fitting PAPR during chest compression in real-time mode. The primary outcome was the ratio of any failure of protection (SWPF <500) during the chest compression sessions. Fifty-four participants completed the simulation. Overall, 78% (n = 42) of the participants failed (the measured SWPF value was less than 500) at least one of the three sessions of chest compressions. The median value and interquartile range of the SWPF was 4304 (685-16,191). There were no reports of slipping down of the respirator or mechanical failure during chest compressions. Although the median SWPF value was high during chest compressions, the tight-fitting PAPR did not provide adequate protection.