Mechanical power in pediatric acute respiratory distress syndrome: a PARDIE study

BACKGROUND

Mechanical power is a composite variable for energy transmitted to the respiratory system over time that may better capture risk for ventilator-induced lung injury than individual ventilator management components. We sought to evaluate if mechanical ventilation management with a high mechanical power is associated with fewer ventilator-free days (VFD) in children with pediatric acute respiratory distress syndrome (PARDS).

METHODS

Retrospective analysis of a prospective observational international cohort study.

RESULTS

There were 306 children from 55 pediatric intensive care units included. High mechanical power was associated with younger age, higher oxygenation index, a comorbid condition of bronchopulmonary dysplasia, higher tidal volume, higher delta pressure (peak inspiratory pressure-positive end-expiratory pressure), and higher respiratory rate. Higher mechanical power was associated with fewer 28-day VFD after controlling for confounding variables (per 0.1 J·min-1·Kg-1 Subdistribution Hazard Ratio (SHR) 0.93 (0.87, 0.98), p = 0.013). Higher mechanical power was not associated with higher intensive care unit mortality in multivariable analysis in the entire cohort (per 0.1 J·min-1·Kg-1 OR 1.12 [0.94, 1.32], p = 0.20). But was associated with higher mortality when excluding children who died due to neurologic reasons (per 0.1 J·min-1·Kg-1 OR 1.22 [1.01, 1.46], p = 0.036). In subgroup analyses by age, the association between higher mechanical power and fewer 28-day VFD remained only in children < 2-years-old (per 0.1 J·min-1·Kg-1 SHR 0.89 (0.82, 0.96), p = 0.005). Younger children were managed with lower tidal volume, higher delta pressure, higher respiratory rate, lower positive end-expiratory pressure, and higher PCO2 than older children. No individual ventilator management component mediated the effect of mechanical power on 28-day VFD.

CONCLUSIONS

Higher mechanical power is associated with fewer 28-day VFDs in children with PARDS. This association is strongest in children < 2-years-old in whom there are notable differences in mechanical ventilation management. While further validation is needed, these data highlight that ventilator management is associated with outcome in children with PARDS, and there may be subgroups of children with higher potential benefit from strategies to improve lung-protective ventilation.

TAKE HOME MESSAGE

Higher mechanical power is associated with fewer 28-day ventilator-free days in children with pediatric acute respiratory distress syndrome. This association is strongest in children <2-years-old in whom there are notable differences in mechanical ventilation management.

Restricted kinematic alignment leads to uncompromised osseointegration of cementless total knee arthroplasty

PURPOSE

While kinematic alignment (KA) total knee arthroplasty (TKA) with cemented implants has been shown to provide equivalent or better results than mechanical alignment, its combination with cementless fixation has not yet been documented. The purpose of this study is to report (1) revision rate and causes, (2) clinical results based on patient report outcome measures (PROMs), and (3) radiological signs of implant dysfunction in patients with an uncemented TKA implanted with restricted KA (rKA), after a minimum follow-up of 2 years.

METHODS

This study included the first 100 consecutive uncemented cruciate retaining TKAs implanted between November 2015 and February 2018 by a single surgeon following rKA principles. At last follow-up, all adverse events and PROMs assessed by WOMAC, KOOS, and FJS scores were documented. Radiographic evaluation was performed to identify signs of implant loosening.

RESULTS

After a mean follow-up of 49 months (32, 60), no implant revision was performed for aseptic loosening. Three revisions were performed: one for malalignment, one for a deep infection, and one for instability. The mean WOMAC score was 20.1 (0-79, 21.3), the mean KOOS score was 71.5 (19.0-96.6, 19.8), and the mean FJS score was 65.9 (0-100, 29.6). No radiological evidence of implant aseptic loosening or osteolysis was identified.

CONCLUSION

This study shows that in 99% of our cases, rKA combined with the tested cementless TKA implant allowed for adequate secondary fixation and good functional outcomes in the short term. Favourable mid- to long-term implant survivorship is anticipated.

LEVEL OF EVIDENCE

III.

Prolonged mechanical ventilation after cardiac surgery: substudy of the Transfusion Requirements in Cardiac Surgery III trial

PURPOSE

Prolonged mechanical ventilation (MV) is a major complication following cardiac surgery. We conducted a secondary analysis of the Transfusion Requirements in Cardiac Surgery (TRICTS) III trial to describe MV duration, identify factors associated with prolonged MV, and examine associations of prolonged MV with mortality and complications.

METHODS

Four thousand, eight hundred and nine participants undergoing cardiac surgery at 71 hospitals worldwide were included. Prolonged MV was defined based on the Society of Thoracic Surgeons definition as MV lasting 24 hr or longer. Adjusted associations of patient and surgical factors with prolonged MV were examined using multivariable logistic regression. Associations of prolonged MV with complications were assessed using odds ratios, and adjusted associations between prolonged MV and mortality were evaluated using multinomial regression. Associations of shorter durations of MV with survival and complications were explored.

RESULTS

Prolonged MV occurred in 15% (725/4,809) of participants. Prolonged MV was associated with surgical factors indicative of complexity, such as previous cardiac surgery, cardiopulmonary bypass duration, and separation attempts; and patient factors such as critical preoperative state, left ventricular impairment, renal failure, and pulmonary hypertension. Prolonged MV was associated with perioperative but not long-term complications. After risk adjustment, prolonged MV was associated with perioperative mortality; its association with long-term mortality among survivors was weaker. Shorter durations of MV were not associated with increased risk of mortality or complications.

CONCLUSION

In this substudy of the TRICS III trial, prolonged MV was common after cardiac surgery and was associated with patient and surgical risk factors. Although prolonged MV showed strong associations with perioperative complications and mortality, it was not associated with long-term complications and had weaker association with long-term mortality among survivors.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT02042898); registered 23 January 2014. This is a substudy of the Transfusion Requirements in Cardiac Surgery (TRICS) III trial.

Preparation and physicochemical assessment of bioactive films based on chitosan and starchy powder of white turmeric rhizomes (Curcuma Zedoaria) for green packaging applications

In the current study, the bioactive films of chitosan/white turmeric (CH/WT) were prepared by employing solvent casting technique and analyzed their physicochemical and biological properties for active packaging applications. The successful inclusion of white turmeric into the chitosan matrix is confirmed by Fourier Transform Infrared Spectroscopy. Due to the presence of hydrogen bonding interaction, the active films exhibited good tensile properties, smooth surface morphology, miscibility, water resistance and UV barrier properties. The incorporation of white turmeric reduced the water vapour transmission rate and oxygen permeability (p < 0.05) in contrast with pristine film. The prepared blend films revealed soil degradation rate more than 60% within 15 days. Furthermore, the blend films exhibited lesser water solubility, moisture content and swelling index after addition of white turmeric to chitosan (p < 0.05). The prepared films revealed extensive antimicrobial activity against gram positive and gram negative bacteria. The antioxidant activity and total phenolic content were improved upon the incorporation of white turmeric. Moreover, the oil absorption rate of the blend films was decreased by 46% in comparison with pristine film. Overall, white turmeric incorporated chitosan films were employed as a green packaging material to extend the shelf life of the foodstuff.

The risk factors for mechanical complication in endoprosthetic reconstruction of knee osteosarcoma

BACKGROUND

The increased limb survival rates and higher functional demands have also increased the mechanical complication rates of megaprostheses. This study aimed to analyse possible risk factors which can predispose patients to mechanical complications.

METHODS

Patients with knee osteosarcoma referred to our clinic from 1992 to 2014 were investigated retrospectively. The patients who underwent surgical resection and endoprosthetic reconstruction with at least 5 years of follow up were analysed. The revision of the megaprosthesis due to a mechanical complication was accepted as an endpoint. The possible risk factors, including cement usage, implant material, joint mechanism, neoadjuvant radiotherapy, and anatomical localization of the lesion, were analysed for any association with mechanical complication rates.

RESULTS

A total of 118 patients were included for final analysis. The average age was 24.5 years (standard deviation ±10.1, range: 15-64). Mechanical complication rate was 22% which included 19 aseptic loosenings and seven implant failures. The average time to mechanical complication was 32.5 months. Overall, 5-year implant survival was 78%. Multiple regression analysis revealed that cement usage is an independent risk factor for mechanical complication (P = 0.007). Although the 5-year implant survival was higher in rotating hinge and titanium implants compared with fixed hinge and cobalt chrome, the multiple regression model did not yield a correlation with mechanical complication rates.

CONCLUSION

Cemented implants showed significantly higher mechanical complication rates compared with cementless ones in this series of knee osteosarcoma patients who underwent megaprosthetic reconstruction. Hinge mechanism and implant material did not have a significant effect on mechanical complication rates.

A randomized controlled trial comparing functional outcomes for navigated kinematically aligned total knee arthroplasty versus navigated mechanically aligned total knee arthroplasty : the MaKKRO trial

Aims

Nearly 99,000 total knee arthroplasties (TKAs) are performed in UK annually. Despite plenty of research, the satisfaction rate of this surgery is around 80%. One of the important intraoperative factors affecting the outcome is alignment. The relationship between joint obliquity and functional outcomes is not well understood. Therefore, a study is required to investigate and compare the effects of two types of alignment (mechanical and kinematic) on functional outcomes and range of motion.

Methods

The aim of the study is to compare navigated kinematically aligned TKAs (KA TKAs) with navigated mechanically aligned TKA (MA TKA) in terms of function and ROM. We aim to recruit a total of 96 patients in the trial. The patients will be recruited from clinics of various consultants working in the trust after screening them for eligibility criteria and obtaining their informed consent to participate in this study. Randomization will be done prior to surgery by a software. The primary outcome measure will be the Knee injury and Osteoarthritis Outcome Score The secondary outcome measures include Oxford Knee Score, ROM, EuroQol five-dimension questionnaire, EuroQol visual analogue scale, 12-Item Short-Form Health Survey (SF-12), and Forgotten Joint Score. The scores will be calculated preoperatively and then at six weeks, six months, and one year after surgery. The scores will undergo a statistical analysis.

Discussion

There is no clear evidence on the best alignment for a knee arthroplasty. This randomized controlled trial will test the null hypothesis that navigated KA TKAs do not perform better than navigated MA TKAs.

Cite this article: Bone Jt Open 2021;2(11):945–950.

Novel Fabrication and Biological Characterizations of AgNPs-decorated PEEK with gelatin functional nanocomposite to improve superior biomedical applications

There is an increasing interest in the use of polyether ether ketone (PEEK) for biomedical applications. Herein, we have developed silver nanoparticles (AgNPs) decorated PEEK with gelatin (GEL) nanocomposite hydrogel with enhanced antibacterial and biocompatibility through the blending method. The prepared highly porous PEEK/GEL/AgNPs nanocomposite hydrogel was characterized using SEM, TEM, FT-IR, and XRD analysis. The SEM image showed that AgNPs were encapsulated in the porous PEEK/GEL hydrogel; within this porous hydrogel, the AgNPs were homogeneously dispersed. Furthermore, the tensile strength, flexural strength, and Young's modulus were 99 ± 2.4 MPa, 154 ± 7.7 MPa, and 2.3 ± 0.1 GPa, respectively, when AgNPs were added to PEEK/GEL hydrogels exhibited the mechanical performances. The antibacterial assays demonstrate that the AgNPs-decorated PEEK/GEL nanocomposite hydrogel effectively inhibits the antibacterial effect against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, respectively. Then MC3T3-E1 cells were demonstrated the AgNPs-decorated PEEK/GEL nanocomposite hydrogel was significantly enhanced cell viability and superior alkaline phosphatase (ALP) activity compared with PEEK/GEL hydrogel. This work opens a new avenue of the facile and effective modification of PEEK/GEL/AgNPs nanocomposite hydrogel has increased in vitro antibacterial and biocompatibility properties has great potential to be used as biomedical applications.

Performance of three-dimensional printed nasopharyngeal swabs for COVID-19 testing

ABSTRACT

At the start of the COVID-19 pandemic, the US faced nationwide shortages of nasopharyngeal swabs due to both overwhelmed supply chains and an increase in demand. To address this shortfall, multiple 3D printed swabs were ultimately produced and sold for COVID-19 testing. In this work, we present a framework for mechanical and functional bench-testing of nasopharyngeal swabs using standard and widely available material testing equipment. Using this framework, we offer a comprehensive, quantitative comparison of the 3D printed swabs to benchmark their performance against traditional flocked swabs. The test protocols were designed to emulate the clinical use of the nasopharyngeal swabs and to evaluate potential failure modes. Overall, the 3D printed swabs performed comparably to, or outperformed, the traditional swabs in all mechanical tests. While traditional swabs outperformed some of the new 3D printed swabs in terms of sample uptake and retention, similar amounts of RNA were recovered from both 3D printed and traditional swabs.

The Effect of Sedation Protocol on Sedation Level and Pharmacological and Non-Pharmacological Interventions on Mechanically Ventilated Patients

Background:

The use of analgesics and sedatives to provide sedation for Patients in Intensive Care Unit (ICU) is inevitable. The present study aimed to determine the effect of sedation protocol using the Richmond Agitation- Sedation Scale on sedation level and amount of pharmacological and non-pharmacological interventions on patients under mechanical ventilation.

Materials and Methods:

This randomized clinical trial was conducted on 79 patients under mechanical ventilation in Zanjan. The patients were recruited using the blocking randomized sampling method. In the experiment group, the sedation was provided hourly, using the Richmond sedation Protocol, during the mechanical ventilation period. The level of sedation and pharmacological and nonpharmacological interventions were compared in the two groups using Fisher exact test.

Results:

Totally, 40 patients in the experiment and 39 patients in the control groups were evaluated. No significant difference was found between the two groups in terms of confounding variables (age, sex, level of consciousness, Acute Physiologic and Chronic Health Evaluation (APACHE) II criterion, underlying disease, and cause of hospitalization). The level of sedation in the experiment group was significantly closer to the ideal score of the Richmond Scale compared to the control group (p < 0.001). The experimental group received significantly more non-pharmacological interventions and fewer pharmacological interventions compared to the control group (P < 0.001).

Conclusions:

Using a sedation protocol could provide better sedation levels in patients under mechanical ventilation, and reduce the use of sedative medications, and consequently, the cost of hospitalization. Further research is suggested.

Mechanical or chemical and mechanical pleurodesis for spontaneous pneumothorax: what is the most effective approach in preventing recurrence? A systematic review and meta-analysis

OBJECTIVES

Surgical management of spontaneous pneumothorax typically involves wedge resection and mechanical pleurodesis. It is unclear whether combining mechanical and chemical pleurodesis can further reduce the recurrence rate. We have performed a meta-analysis of studies comparing the combined approach with mechanical pleurodesis alone.

METHODS

A comprehensive search of the existing literature was performed using PubMed, EMBASE and Web of Science for all types of studies that compared combined pleurodesis to a single approach. We used the Cochrane Risk of Bias Tool and Strengthening The Reporting of OBservational Studies in Epidemiology (STROBE) to assess the quality of the studies. Relative risk of pneumothorax recurrence was calculated, and the differences between the studies were examined. The primary outcome was the recurrence of pneumothorax.

RESULTS

Of 2301 eligible studies, 5 studies were included. Five hundred sixty-one patients who received combined pleurodesis were compared to 286 patients who received mechanical pleurodesis only. Patients treated with combined intervention had a 63% lower risk of developing a recurrent pneumothorax compared to single intervention [relative risk 0.37, 95% confidence interval (CI) 0.18-0.76; P = 0.006]. There were no statistically significant differences in the length of stay (standardized mean difference -0.17, 95% CI -0.39 to 0.05, P = 0.138), the duration of postoperative air leak (standardized mean difference 0.17, 95% CI -1.14 to 1.47, P = 0.804) or the duration of postoperative chest tube drainage (standardized mean difference -0.07, 95% CI -0.27 to 0.12, P = 0.471).

CONCLUSIONS

This meta-analysis demonstrated that combined intervention with mechanical and chemical pleurodesis for spontaneous pneumothorax may be more effective in preventing recurrence than mechanical pleurodesis alone. These findings will provide some guidance to surgeons in the decision-making process.

The incidence and characteristics of ventilator-associated pneumonia in a regional nontertiary Australian intensive care unit: A retrospective clinical audit study

BACKGROUND

Ventilator-associated pneumonia (VAP) is a common complication of mechanical ventilation in the intensive care unit. The incidence, patient characteristics, and outcomes have not been described in a regional Australian setting.

OBJECTIVES

Τhe primary objective was to establish the incidence of VAP in a regional intensive care unit using predetermined diagnostic criteria. The secondary objective was to compare the agreement between criteria-based and physician-based diagnostic processes. The tertiary objectives were to compare patient characteristics and clinical outcomes of cases with and without VAP.

METHODS

A retrospective clinical audit was performed of adult patients admitted to Rockhampton Intensive Care Unit, Australia, between 2013 and 2016. We included all patients ventilated for ≥72 h and not diagnosed with a pneumonia before or during the first 72 h of ventilation.

RESULTS

A total of 170 cases met the inclusion criteria. The incidence of VAP as per the criteria-based diagnosis was 27.3 cases per 1000 ventilator days (95% confidence interval [CI]: 18.4-36.2) and as per the physician-based diagnosis was 25.8 cases per 1000 ventilator days (95% CI: 17.1-34.4). There was a moderate chance-corrected agreement between the criteria- and physician-based diagnosis. Very obese cases (body mass index [BMI] ≥40) were nearly four times more likely to develop VAP than cases with normal BMI (BMI <30) (odds ratio: 3.664; 95% CI: 1.394-9.634; p = 0.008). After controlling for sex, BMI category, comorbidities, and Acute Physiology and Chronic Health Evaluation II scores, there was a trend (p = 0.283) for higher adjusted mortality rate for cases with VAP (10.1%, 95% CI: 4.8-21.5) than for those without VAP (6.1%, 95% CI: 3.0-12.4). Cases with VAP had a higher total hospital cost ($123,223 AUD vs $66,425 AUD, p < 0.001), than cases without VAP.

CONCLUSIONS

This is the first study reporting incidence of VAP in an Australian regional intensive care unit setting. An increased length of stay and significantly higher hospital costs warrant research investigating reliable and valid clinical prediction rules to forecast those at risk of VAP.

Robotic-assisted total knee arthroplasty improves accuracy and precision compared to conventional techniques

AIMS

Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA.

METHODS

A total of 220 consecutive primary TKAs between May 2016 and November 2018, performed by a single surgeon, were reviewed. Planned coronal plane component alignment and overall limb alignment were all 0° to the mechanical axis; tibial posterior slope was 2°; and polyethylene thickness was 9 mm. For RA-TKA, individual component position was adjusted to assist gap-balancing but planned coronal plane alignment for the femoral and tibial components and overall limb alignment remained 0 ± 3°; planned tibial posterior slope was 1.5°. Mean deviations from plan for each parameter were compared between groups for positioning and size and outliers were assessed.

RESULTS

In all, 103 M-TKAs and 96 RA-TKAs were included. In RA-TKA versus M-TKA, respectively: mean femoral positioning (0.9° (SD 1.2°) vs 1.7° (SD 1.1°)), mean tibial positioning (0.3° (SD 0.9°) vs 1.3° (SD 1.0°)), mean posterior tibial slope (-0.3° (SD 1.3°) vs 1.7° (SD 1.1°)), and mean mechanical axis limb alignment (1.0° (SD 1.7°) vs 2.7° (SD 1.9°)) all deviated significantly less from the plan (all p < 0.001); significantly fewer knees required a distal femoral recut (10 (10%) vs 22 (22%), p = 0.033); and deviation from planned polyethylene thickness was significantly less (1.4 mm (SD 1.6) vs 2.7 mm (SD 2.2), p < 0.001).

CONCLUSION

RA-TKA is significantly more accurate and precise in planning both component positioning and final polyethylene insert thickness. Future studies should investigate whether this increased accuracy and precision has an impact on clinical outcomes. The greater accuracy and reproducibility of RA-TKA may be important as precise new goals for component positioning are developed and can be further individualized to the patient. Cite this article: Bone Joint J 2021;103-B(6 Supple A):74-80.

2D transition metal carbides (MXenes) in metal and ceramic matrix composites

Two-dimensional transition metal carbides, nitrides, and carbonitrides (known as MXenes) have evolved as competitive materials and fillers for developing composites and hybrids for applications ranging from catalysis, energy storage, selective ion filtration, electromagnetic wave attenuation, and electronic/piezoelectric behavior. MXenes' incorporation into metal matrix and ceramic matrix composites is a growing field with significant potential due to their impressive mechanical, electrical, and chemical behavior. With about 50 synthesized MXene compositions, the degree of control over their composition and structure paired with their high-temperature stability is unique in the field of 2D materials. As a result, MXenes offer a new avenue for application driven design of functional and structural composites with tailorable mechanical, electrical, and thermochemical properties. In this article, we review recent developments for use of MXenes in metal and ceramic composites and provide an outlook for future research in this field.

Evaluating the impact of age and inflammatory duration on behavioral assessments of nociception

Pain is a prevalent issue for elderly individuals. Unfortunately, it remains unclear how acute and chronic pain differs as a function of age, and surprisingly, there is even disagreement on how the sensory and affective dimensions of pain change with age. Therefore, the current investigation evaluated such age differences with behavioral methodology using a preclinical model of arthritis. The primary factors of interest were age and chronicity of pain using behavioral assessments designed to measure sensory and affective dimensions of pain processing. Mechanical and thermal paw withdrawal thresholds demonstrated unique outcomes associated with sensory processing across age. The processing of pain affect measured by the Place Escape/Avoidance Paradigm (PEAP testing) also demonstrated age related effects. Overall, younger animals appeared more sensitive to nociceptive stimuli than older animals. However, the results from the current study suggest that chronicity of pain can be impactful for how older animals process pain related affect and avoidance. The finding of unique patterns of pain across age and duration of pain highlights the clinical literature. Future research should aim to elucidate mechanisms for affective processing of chronic pain in older subjects.

Literature Review to create Evidence Based Care Pathway for Isolated Adult Orbital Blowout Fractures

This review aims to develop an evidence-based pathway for isolated adult orbital blowout fractures. Evaluation of assessment methods, outcome measures, imaging modalities, and crucially, the optimal timing of surgical intervention was critically examined to develop a clinically applicable care pathway. A literature search was carried out using Scopus, PubMed and Web of Knowledge. The literature favors the use of HAR% ratio, Field of Binocular Single Vision (FOBSV) and Exophthalmometer as the core tests that should form part of the standardized assessment for blow-out fractures (BOFs). CT imaging remains gold standard, particularly to identify 'red-flags' warranting early intervention. There was some disagreement in relation to timing of intervention in adult fractures who continue to be symptomatic without initial extraocular muscle (EOM) entrapment and enophthalmos >3 mm, where early intervention within two weeks is not indicated. The limited literature available agreed that successful functional and radiological outcomes can be achieved with conservative or late surgical management following an extended observational period of four weeks, opposed to the conventional two weeks. An evidence-based care pathway has been created, confidently including the initial assessment methods, imaging modality, and the criteria for observation. A four-week observational period has been advocated due to evidence suggesting that there is no significant difference in outcomes from two-week observation, plus with careful functional evaluation, surgery may be avoided in some cases.

Noninvasive Home Mechanical Ventilation in Adult Myotonic Dystrophy Type 1: A Systematic Review

INTRODUCTION

Chronic hypercapnic respiratory failure induces considerable morbidity and mortality in patients with myotonic dystrophy type 1 (DM1). This study systematically reviews the effects of noninvasive home mechanical ventilation (HMV) on gas exchange, quality of life, survival, and compliance in DM1 patients.

METHODS

A systematic Medline and Embase search was performed (January 1995 to January 2020). Records were screened for eligibility criteria, data were extracted from included studies, and risk of bias was assessed. We present findings mainly using a narrative synthesis.

RESULTS

Twenty-eight relevant full-text articles were screened for eligibility criteria. Nine studies were included. Randomized controlled trials were not found. Studies had either an observational (n = 8) or interventional (n = 1) design. In the pooled data analysis, HMV showed to improve mean oxygen saturation with 4.8% and decreased mean carbon dioxide values with 3 mm Hg. Compliance varied widely between studies, from no use to more than 12 h per day. Quality of life was not studied extensively, but some studies reported positive effects of HMV on symptoms of chronic respiratory failure. HMV may improve survival in DM1 patients with chronic hypercapnic respiratory failure.

CONCLUSION

This review shows that HMV can improve gas exchange and relieve symptoms with a possible survival benefit in DM1 patients with chronic hypercapnic respiratory failure. Future studies should focus on developing strategies to optimize the timing of HMV initiation and to promote compliance.

Melatonin-doped polymeric nanoparticles reinforce and remineralize radicular dentin: Morpho-histological, chemical and biomechanical studies

OBJECTIVES

To investigate the effectiveness of novel polymeric nanoparticles (NPs) doped with melatonin (ML) in reducing dentin permeability and facilitating dentin remineralization after endodontic treatment.

METHODS

The effect of undoped NPs and ML-doped NPs (ML-NPs) was tested in radicular dentin, at 24 h and 6 m. A control group without NPs was included. ML liberation was measured. Radicular dentin was assessed for fluid filtration. Dentin remineralization was analyzed by scanning electron microscopy, AFM, Young's modulus (Ei), Nano DMA-tan delta, and Raman analysis.

RESULTS

ML release ranged from 1.85 mg/mL at 24 h to 0.033 mg/mL at 28 d. Both undoped NPs and ML-NPs treated dentin exhibited the lowest microleakage, but samples treated with ML-NPs exhibited hermetically sealed dentinal tubules and extended mineral deposits onto dentin. ML-NPs promoted higher and durable Ei, and functional remineralization at root dentin, generating differences between the values of tan delta among groups and creating zones of stress concentration. Undoped-NPs produced closure of some tubules and porosities at the expense of a relative mineral amorphization. Chemical remineralization based on mineral and organic assessments was higher in samples treated with ML-NPs. When using undoped NPs, precipitation of minerals occurred; however, radicular dentin was not mechanically reinforced but weakened over time.

SIGNIFICANCE

Application of ML-NPs in endodontically treated teeth, previous to the canal filling step, is encouraged due to occlusion of dentinal tubules and the reinforcement of the radicular dentin structure.

Systematic review of cognitive impairment and brain insult after mechanical ventilation

We conducted a systematic review following the PRISMA protocol primarily to identify publications that assessed any links between mechanical ventilation (MV) and either cognitive impairment or brain insult, independent of underlying medical conditions. Secondary objectives were to identify possible gaps in the literature that can be used to inform future studies and move toward a better understanding of this complex problem. The preclinical literature suggests that MV is associated with neuroinflammation, cognitive impairment, and brain insult, reporting higher neuroinflammatory markers, greater evidence of brain injury markers, and lower cognitive scores in subjects that were ventilated longer, compared to those ventilated less, and to never-ventilated subjects. The clinical literature suggests an association between MV and delirium, and that delirium in mechanically ventilated patients may be associated with greater likelihood of long-term cognitive impairment; our systematic review found no clinical study that demonstrated a causal link between MV, cognitive dysfunction, and brain insult. More studies should be designed to investigate ventilation-induced brain injury pathways as well as any causative linkage between MV, cognitive impairment, and brain insult.

Effect of the compaction parameters on the final structure and properties of a press-coated tablet (Tab-in-Tab): Experimental and numerical study of the influence of core and shell dimensions

With increasing interest in chronopharmaceutics, press-coated tablets have become a key technology in the field of modified release drug delivery systems. Although their benefits in terms of drug release have been largely studied, the comprehension of the compaction process of press-coated tablets is yet to complete. Particularly, the effects of geometrical parameters like the ratios between the thickness/diameter of the core and the thickness/diameter of the whole tablet were so far not much considered. Moreover, there is only few studies in the literature about the effect of the press-coating compression on the final structure and properties of the core. The present work consists in a joint experimental and numerical study that aims to assess these points. The study revealed high stress concentrations on the core during compression, causing high permanent deformations of the core, especially when the ratio between the core thickness and the total tablet thickness was high. The mechanical properties of the core tablet were also shown to be impacted: its density and strength were found to decrease before increasing again along the coating-compression. This effect was highlighted to be dependent on the triaxiality of the stress state (i.e. the ratio between the stresses in the different directions), itself depending on the two studied geometrical parameters. As the properties of the core affect the release attributes, ratios between the dimensions of the core and the dimensions of the whole tablet (thickness, diameter) should be taken into account as critical parameters for the manufacture of press-coated tablets.

A review on native well-preserved chitin nanofibrils for materials of high mechanical performance

Novel chitin nanofibrils (ChNF) demonstrate excellent mechanical properties due to a long and extended polymer conformation. The current study highlights the importance of preserving ChNFs for stronger nanomaterials. Various chitin sources - crab, lobster, shrimp, squid pen, mushrooms, and insects have been reviewed. We have discussed preparation protocols and the physical properties of ChNF and presented the mechanical performance of nanomaterials. ChNF close to the native state uses fewer chemicals for treatment and shows a higher molar mass, degree of acetylation, crystallinity index, micrometer length, and a smaller diameter (3 nm), making them cheap, eco-friendly, and competitive to cellulose or synthetic fibrils. A highly acetylated or partially deacetylated ChNF forms a stable colloidal suspension, and it is possible to prepare from it strong films, hydrogels, aerogels, foams, polymer matrix nanocomposites, and microfibers. Moreover, it is possible to regenerate, functionalize, or cross-link the ChNFs to improve nanomaterials' mechanical performance. The preparation protocols remain the key to these achievements. However, the chemical techniques are not friendly ecologically and may hydrolytically degrade the chitin. The biological processes using enzymes or microorganisms are much better but still inefficient. Besides, the processing time limits the rapid preparation of the fibrils in the long-term perspective.

Ionic liquid-loaded microcapsules doped into dental resin infiltrants

Resin infiltrants have been effectively applied in dentistry to manage non-cavitated carious lesions in proximal dental surfaces. However, the common formulations are composed of inert methacrylate monomers. In this study, we developed a novel resin infiltrant with microcapsules loaded with an ionic liquid (MC-IL), and analyzed the physical properties and cytotoxicity of the dental resin. First, the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf₂) was synthesized. BMI.NTf₂ has previously shown antibacterial activity in a dental resin. Then, MC-IL were synthesized by the deposition of a preformed polymer. The MC-IL were analyzed for particle size and de-agglomeration effect via laser diffraction analysis and shape via scanning electron microscopy (SEM). The infiltrants were formulated, and the MC-IL were incorporated at 2.5%, 5%, and 10 wt%. A group without MC-IL was used as a control. The infiltrants were evaluated for ultimate tensile strength (UTS), contact angle, surface free energy (SFE), and cytotoxicity. The MC-IL showed a mean particle size of 1.64 (±0.08) μm, shriveled aspect, and a de-agglomeration profile suggestive of nanoparticles' presence in the synthesized powder. There were no differences in UTS among groups (p > 0.05). The incorporation of 10 wt% of MC-IL increased the contact angle (p < 0.05), while the addition from 5 wt% reduced the SFE in comparison to the control group (p < 0.05). The human cell viability was above 90% for all groups (p > 0.05). The incorporation of microcapsules as a drug-delivery system for ionic liquids may be a promising strategy to improve dental restorative materials.

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Ionic liquid was used as core of synthesized polymeric-based microcapsules.

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Microcapsules doped with ionic liquid were incorporated into a dental resin.

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The dental resins presented proper mechanical and biocompatibility properties.

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The particles incorporation reduced the surface free energy of dental resins.

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Biointeractivity may be obtained through MC-IL addition into dental resins.

Mussel-inspired double cross-linked hydrogels with desirable mechanical properties, strong tissue-adhesiveness, self-healing properties and antibacterial properties

Developing multifunctional hydrogels with good mechanical properties, tissue-adhesiveness, self-healing properties and antioxidant, blood clotting and antibacterial properties is highly desirable for biomedical applications. In this study, a series of multifunctional chitosan-based double cross-linked hydrogels were prepared using a facile method based on quaternized chitosan (QCS) and polyacrylamide (PAM) using polydopamine (PDA) as a novel connecting bridge. Investigation on the content of dopamine (DA) and QCS revealed that the catechol-mediated interactions played an important role in the hydrogel properties. Results showed that the hydrogel exhibited the best mechanical properties when QCS = 12 wt% and DA = 0.4 wt%. Tensile and compressive strength was 13.3 kPa and 67.8 kPa, respectively, and the hydrogel presented strong and repeatable tissue-adhesiveness (27.2 kPa) to porcine skin, as well as good stretchability (1154%). At room temperature, the hydrogel exhibited high self-healing efficiency (90% after 2 h of healing). Antibacterial test results showed that the hydrogel killed 99.99% S. aureus and E. coli. Moreover, the vaccarin-loaded hydrogel exhibited a pH-responsive drug release profile with superior cytocompatibility compared to the pure hydrogel. In summary, this strategy combined double cross-linking and catechol-mediated chemistry to shed new light on the fabrication of novel multifunctional hydrogels with desirable mechanical properties, strong tissue adhesiveness and self-healing abilities.

Porous structure design and mechanical behavior analysis based on TPMS for customized root analogue implant

Compared with the traditional dental implant with screw structure, the root analogue implant (RAI) is customized to fit with the wall of the alveolar bone, which helps to accelerate the clinical implantation process. However, a solid RAI made of Ti6Al4V material has a much higher Young's modulus than the surrounding bone tissue, which can cause a stress shielding effect and thereby lead to implant failure. Also, a solid RAI is not conducive to the growth of osteoblasts. To overcome these problems, a porous structure design and optimization method for customized RAIs is proposed. A triply periodic minimal surface (TPMS) offers a smooth surface with pore interconnectivity, which can satisfy the biological/mechanical implantation requirements and efficiently construct many complex bone scaffolds. P and G structures with four degrees of porosity (30%, 40%, 50%, and 60%) were designed and prepared as cubic samples. The Young's modulus, Poisson's ratio, and yield strength of each sample were measured through compression experiments. Additionally, the stress distribution at the interface between the customized RAI and surrounding bone tissue under different pore structures and porosities was evaluated by finite element analysis (FEA). It was found that the quantitative relationships between the Young's modulus/Poisson's ratio and porosity of the P and G structures were consistent with the rules of the percolation model. The yield strengths of the P and G structures with four different porosities were all greater than the yield strength of cortical bone, which satisfies the implantation conditions. Furthermore, the P and G structures with 30% and 40% porosity were proved by FEA to have no stress shielding effect, promote the growth of surrounding bone tissue, and form long-term and stable osseointegration. It can be concluded that the porous RAI constructed with a TPMS can reduce the stress shielding effect, which is beneficial for accelerating the clinical implantation process.

Response profile of fibular repositioning tape on ankle osteokinematics, arthrokinematics, perceived stability and confidence in chronic ankle instability

BACKGROUND

Preliminary evidence suggests that fibular repositioning tape reduces risk of recurrent ankle injuries, but the underlying mechanism has not been investigated.

OBJECTIVE

To investigate the effects of fibular repositioning tape on ankle osteokinematics, arthrokinematics and perceived stability and confidence in individuals with chronic ankle instability immediately post-tape and following exercise.

DESIGN

Cross-sectional repeated measures study.

METHOD

Passive ankle plantarflexion-inversion range of motion, weight-bearing dorsiflexion range of motion, anteroposterior translation, inversion-eversion tilt, and perceived ankle stability and confidence during hopping were assessed before and immediately after the application of fibular repositioning tape and after 15 min of exercise in 14 individuals with chronic ankle instability.

RESULTS

Ankle plantarflexion-inversion range of motion, inversion-eversion tilt and anteroposterior translation were reduced immediately after the application of tape compared to pre-tape (p < 0.01). After exercise, total inversion-eversion tilt was significantly lower than pre-tape (p = 0.01), but there were no differences for any of the other mechanical outcomes. Dorsiflexion range of motion did not differ between conditions (p > 0.11). Perceived ankle stability, ankle and task confidence were greater immediately post-tape and post-exercise compared to pre-tape (p < 0.01).

CONCLUSIONS

Fibular repositioning tape was associated with a restriction of ankle total inversion-eversion tilt and improved perceived ankle stability and confidence both immediately after application of tape and after participating in exercise. This data provides grounds for exploring mechanical and psychological mechanisms underpinning any clinical efficacy of fibular repositioning tape.

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty: a prospective randomized controlled trial

AIMS

The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery.

METHODS

An analysis of 38 patients who underwent TKA and 32 who underwent bi-UKA was performed as a secondary study from a prospective, single-centre, randomized controlled trial. CT imaging was used to measure coronal, sagittal, and axial alignment of the knee preoperatively and at three months postoperatively to determine changes in anatomy that had occurred as a result of the surgery. The hip-knee-ankle angle (HKAA) was also measured to identify any differences between the two groups.

RESULTS

The pre- to postoperative changes in joint anatomy were significantly less in patients undergoing bi-UKA in all three planes in both the femur and tibia, except for femoral sagittal component orientation in which there was no difference. Overall, for the six parameters of alignment (three femoral and three tibial), 47% of bi-UKAs and 24% TKAs had a change of < 2° (p = 0.045). The change in HKAA towards neutral in varus and valgus knees was significantly less in patients undergoing bi-UKA compared with those undergoing TKA (p < 0.001). Alignment was neutral in those undergoing TKA (mean 179.5° (SD 3.2°)) while those undergoing bi-UKA had mild residual varus or valgus alignment (mean 177.8° (SD 3.4°)) (p < 0.001).

CONCLUSION

Robotic-assisted, cruciate-sparing bi-UKA maintains the natural anatomy of the knee in the coronal, sagittal, and axial planes better, and may therefore preserve normal joint kinematics, compared with a mechanically aligned TKA. This includes preservation of coronal joint line obliquity. HKAA alignment was corrected towards neutral significantly less in patients undergoing bi-UKA, which may represent restoration of the pre-disease constitutional alignment (p < 0.001). Cite this article: Bone Joint J 2020;102-B(11):1511-1518.