Homogenized finite element analysis of distal tibia sections: Achievements and limitations.

High-resolution peripheral quantitative computed tomography (HR-pQCT) based micro-finite element (µFE) analysis allows accurate prediction of stiffness and ultimate load of standardised (∼1 cm) distal radius and tibia sections. An alternative homogenized finite element method (hFE) was recently validated to compute the ultimate load of larger (∼2 cm) distal radius sections that include Colles' fracture sites. Since the mechanical integrity of the weight-bearing distal tibia is gaining clinical interest, it has been shown that the same properties can be used to predict the strength of both distal segments of the radius and the tibia. Despite the capacity of hFE to predict structural properties of distal segments of the radius and the tibia, the limitations of such homogenization scheme remain unclear. Therefore, the objective of this study is to build a complete mechanical data set of the compressive behavior of distal segments of the tibia and to compare quantitatively the structural properties with the hFE predictions. As a further aim, it is intended to verify whether hFE is also able to capture the post-yield strain localisation or fracture zones in such a bone section, despite the absence of strain softening in the constitutive model. Twenty-five fresh-frozen distal parts of tibias of human donors were used in this study. Sections were cut corresponding to an in-house triple-stack protocol HR-pQCT scan, lapped, and scanned using micro computed tomography (µCT). The sections were tested in compression until failure, unloaded and scanned again in µCT. Volumetric bone mineral density (vBMD) and bone mineral content (BMC) were correlated to compression test results. hFE analysis was performed in order to compare computational predictions (stiffness, yield load and plastic deformation field pattern) with the compressive experiment. Namely, strain localization was assessed based on digital volume correlation (DVC) results and qualitatively compared to hFE predictions by comparing mid-slices patterns. Bone mineral content (BMC) showed a good correlation with stiffness (R2 = 0.92) and yield (R2 = 0.88). Structural parameters also showed good agreement between the experiment and hFE for both stiffness (R2 = 0.96, slope = 1.05 with 95 % CI [0.97, 1.14]) and yield (R2 = 0.95, slope = 1.04 [0.94, 1.13]). The qualitative comparison between hFE and DVC strain localization patterns allowed the classification of the samples into 3 categories: bad (15 sections), semi (8), and good agreement (2). The good correlations between BMC or hFE and experiment for structural parameters were similar to those obtained previously for the distal part of the radius. The failure zones determined by hFE corresponded to registration only in 8 % of the cases. We attribute these discrepancies to local elastic/plastic buckling effects that are not captured by the continuum-based FE approach exempt from strain softening. A way to improve strain localization hFE prediction would be to use longer distal segments with intact cortical shells, as done for the radius. To conclude, the used hFE scheme captures the elastic and yield response of the tibia sections reliably but not the subsequent failure process.

Clinical implementation of automated O2 titration in a tertiary care hospital.

Background: When treating acute respiratory failure, both hypoxemia and hyperoxemia should be avoided. SpO2 should be monitored closely and O2 flows adjusted accordingly. Achieving this goal might be easier with automated O2 titration compared to manual titration of fixed-flow O2 We evaluated the feasibility of using an automated O2 titration device in subjects treated for acute hypoxemic respiratory failure in a tertiary care hospital.Methods: Healthcare workers received education and training about oxygen therapy and were familiarized with an automated O2 titration device (FreeO2, Oxynov, Quebec City, Canada). A coordinator was available from 8 am to 5 pm during week days to provide technical assistance. The ability of the device to maintain SpO2 within the prescribed therapeutic window was recorded. Basic clinical information was recorded.Results: Subjects were enrolled from November 2020 to August 2022. We trained 508 healthcare workers on use of automated O2 titration which was finally used on 872 occasions in 763 subjects, distributed on the respiratory, COVID-19 and thoracic surgery wards and the emergency room. Clinical information could be retrieved for 609 (80%) subjects who were on the system for a median of 3 days (interquartile range: 2 to 6 days) representing 2567 subject-days of clinical experience with the device. In the 82 (14%) subjects for whom this information was available, the system maintained SpO2 within the prescribed targets 89% of the time. Ninety-six subjects experienced clinical deterioration as defined by the need to be transferred to the intensive care unit and/or requirement of high nasal flow oxygen but none of these events were judged to be related to the O2 device.Conclusions: Automated O2 titration could be successfully implemented in hospitalized subjects with hypoxemic respiratory failure from various causes. This experience should foster further improvement of the device and recommendations for an optimized utilization.

Unified validation of a refined second-generation HR-pQCT based homogenized finite element method to predict strength of the distal segments in radius and tibia.

INTRODUCTION: HR-pQCT based micro finite element (µFE) analyses are considered as "gold standard" for virtual biomechanical analyses of peripheral bone sites such as the distal segment of radius and tibia. An attractive alternative for clinical use is a homogenized finite element method (hFE) based on constitutive models, because of its much shorter evaluation times and modest computational resource requirements. Such hFE models have been experimentally validated for the distal segment of the radius, but neither for the distal segments of the tibia nor for both measurement sites together. Accordingly, the aim of the present study was to refine and experimentally validate an hFE processing pipeline for in vivo prediction of bone strength and stiffness at the distal segments of the radius and the tibia, using only one unified set of material properties. MATERIAL AND METHODS: An existing hFE analysis procedure was refined in several aspects: 1) to include a faster evaluation of material orientation based on the mean surface length (MSL) method, 2) to distinguish cortical and trabecular bone compartments with distinct material properties and 3) to directly superimpose material properties in mixed phase elements instead of densities. Based on an existing dataset of the distal segment of fresh-frozen radii (double sections 20.4 mm, n = 21) and a newly established dataset of the distal segment of fresh-frozen tibiae (triple sections, 30.6 mm, n = 25), a single set of material properties was calibrated on the radius dataset and validated on the tibia dataset by comparing hFE stiffness and ultimate load with respective experimental results, obtained by compressing the samples on a servo-hydraulic testing machine at a monotonic and quasi-static displacement rate up to failure. RESULTS: Using the identified set of material properties, the hFE-predicted stiffness and failure load were in excellent agreement with respective experimental results at both measurement sites (radius stiffness R2 = 0.93, slope = 1.00, intercept = 479 N/mm2/radius ultimate load: R2 = 0.97, slope = 1.00, intercept = 679 N; tibia stiffness R2 = 0.96, slope = 1.01, intercept = -1027 N/mm2/tibia ultimate load: R2 = 0.97, slope = 1.04, intercept = 394 N; combined dataset stiffness R2 = 0.95, slope = 1.01, intercept = -230 N/mm2/combined dataset ultimate load: R2 = 0.97, slope = 1.03, intercept = 495 N). DISCUSSION AND CONCLUSION: In conjunction with unified BV/TV calibration, the established hFE pipeline accurately predicts experimental stiffness and ultimate load of distal multi-sections at the radius and tibia. Processing time for non-linear analysis was substantially reduced compared to previous µFE and hFE methods but could be further minimized by estimating bone strength based on a fast and linear analysis like as is currently done with µ FE.

Impact of Airway Humidification Strategy in Mechanically Ventilated COVID-19 Patients.

BACKGROUND: Humidification of inspiratory gases is mandatory in all mechanically ventilated patients in ICUs, either with heated humidifiers (HHs) or with heat and moisture exchangers (HMEs). In patients with COVID-19, the choice of the humidification device may have relevant impact on patients' management as demonstrated in recent studies. We reported data from 2 ICUs using either HME or HH. METHODS: Data from patients with COVID-19 requiring invasive mechanical ventilation during the first wave in 2 ICUs in Québec City were reviewed. In one ICU, HMEs were used, whereas heated-wire HHs were used in the other ICU. We compared ventilator settings and arterial blood gases at day one after adjustment of ventilator settings. Episodes of endotracheal tube occlusions (ETOs) or subocclusions and a strategy to limit the risk of under-humidification were reported. On a bench test, we measured humidity with psychrometry with HH at different ambient temperature and evaluated the relation with heater plate temperature. RESULTS: We reported data from 20 subjects positive for SARS-Cov-2, including 6 in the ICU using HME and 14 in the ICU using HH. In the HME group, PaCO2 was higher (48 vs 42 mm Hg) despite higher minute ventilation (171 vs 145 mL/kg/min predicted body weight [PBW]). We also reported 3 ETOs occurring in the ICU using HH. The hygrometric bench study reported a strong correlation between heater plate temperatures of the HH and humidity delivered. After implementation of measures to avoid under-humidification, including heater plate temperature monitoring, no more ETOs occurred. CONCLUSIONS: The choice of the humidification device used in subjects with COVID-19 had a relevant impact on ventilation efficiency (increased CO2 removal with lower dead space) and on complications related to low humidity, including ETOs that may be present with heated-wire HHs when used with high ambient temperatures.

Fabric-elasticity relationships of tibial trabecular bone are similar in osteogenesis imperfecta and healthy individuals.

Osteogenesis Imperfecta (OI) is an inherited form of bone fragility characterised by impaired synthesis of type I collagen, altered trabecular bone architecture and reduced bone mass. High resolution peripheral computed tomography (HR-pQCT) is a powerful method to investigate bone morphology at peripheral sites including the weight-bearing distal tibia. The resulting 3D reconstructions can be used as a basis of micro-finite element (FE) or homogenized finite element (hFE) models for bone strength estimation. The hFE scheme uses homogenized local bone volume fraction (BV/TV) and anisotropy information (fabric) to compute healthy bone strength within a reasonable computation time using fabric-elasticity relationships. However, it is unclear if these relationships quantified previously for healthy controls are valid for trabecular bone from OI patients. Thus, the aim of this study is to investigate fabric-elasticity relationships in OI trabecular bone compared to healthy controls. In the present study, the morphology of distal tibiae from 50 adults with OI were compared to 120 healthy controls using second generation HR-pQCT. Six cubic regions of interest (ROIs) were selected per individual in a common anatomical region. A first matching between OI and healthy control group was performed by selecting similar individuals to obtain identical mean and median age and sex distribution. It allowed us to perform a first morphometric analysis and compare the outcome with literature. Then, stiffness tensors of the ROIs were computed using µFE and multiple linear regressions were performed with the Zysset-Curnier orthotropic fabric-elasticity model. An initial fit was performed on both the OI group and the healthy control group using all extracted ROIs. Then, data was filtered according to a fixed threshold for a defined coefficient of variation (CV) assessing ROI heterogeneity and additional linear regressions were performed on these filtered data sets. These full and filtered data were in turn compared with previous results from µCT reconstructions obtained in other anatomical locations. Finally, the ROIs of both groups were matched according to their BV/TV and degree of anisotropy (DA). Linear regressions were performed using these matched data to detect statistical differences between the two groups. Compared to healthy controls, we found the OI samples to have significantly lower BV/TV and trabecular number (Tb.N.), significantly higher CV, trabecular separation (Tb.Sp.) and trabecular separation standard deviation (Tb.Sp.SD), but no differences in trabecular thickness (Tb.Th.). These results are in agreement with previous studies. The stiffnesses of highly heterogeneous ROIs were randomly lower with respect to the fabric-elasticity relationships, which reflects the limit of validity of the computational homogenisation methodology. This limitation does not challenge the fabric-elasticity relationship, which extrapolation to heterogeneous ROIs is probably reasonable but can simply not be evaluated with the employed homogenisation methodology. Moreover, due to their low BV/TV, the potential (unknown) errors on these heterogeneous ROIs would have negligible influence on whole bone stiffness in comparison to homogeneous ROIs which are orders of magnitude stiffer. The filtering of highly heterogeneous ROIs removed these low stiffness ROIs and led to similar correlation coefficients for both OI and healthy groups. Finally, the BV/TV and DA matched data revealed no significant differences in fabric-elasticity parameters between OI and healthy individuals. Moreover, the filtering step did not exclude a particular OI type. Compared to previous studies, the stiffness constants from the 61 µm resolution HR-pQCT ROIs were lower than for the 36 µm resolution µCT ROIs. In conclusion, OI trabecular bone of the distal tibia was shown to be significantly more heterogeneous and have a lower BV/TV than healthy controls. Despite the reduced linear regression parameters found for HR-pQCT images, the fabric-elasticity relationships between OI and healthy individuals are similar when the trabecular bone ROIs are sufficiently homogeneous to perform the computational stiffness analysis. Accordingly, the elastic properties used for FEA of healthy bones are also valid for OI bones.

A Value-Based Comparison of the Management of Ambulatory Respiratory Diseases in Walk-in Clinics, Primary Care Practices, and Emergency Departments: Protocol for a Multicenter Prospective Cohort Study.

BACKGROUND: In Canada, 30%-60% of patients presenting to emergency departments are ambulatory. This category has been labeled as a source of emergency department overuse. Acting on the presumption that primary care practices and walk-in clinics offer equivalent care at a lower cost, governments have invested massively in improving access to these alternative settings in the hope that patients would present there instead when possible, thereby reducing the load on emergency departments. Data in support of this approach remain scarce and equivocal. OBJECTIVE: The aim of this study is to compare the value of care received in emergency departments, walk-in clinics, and primary care practices by ambulatory patients with upper respiratory tract infection, sinusitis, otitis media, tonsillitis, pharyngitis, bronchitis, influenza-like illness, pneumonia, acute asthma, or acute exacerbation of chronic obstructive pulmonary disease. METHODS: A multicenter prospective cohort study will be performed in Ontario and Québec. In phase 1, a time-driven activity-based costing method will be applied at each of the 15 study sites. This method uses time as a cost driver to allocate direct costs (eg, medication), consumable expenditures (eg, needles), overhead costs (eg, building maintenance), and physician charges to patient care. Thus, the cost of a care episode will be proportional to the time spent receiving the care. At the end of this phase, a list of care process costs will be generated and used to calculate the cost of each consultation during phase 2, in which a prospective cohort of patients will be monitored to compare the care received in each setting. Patients aged 18 years and older, ambulatory throughout the care episode, and discharged to home with one of the aforementioned targeted diagnoses will be considered. The estimated sample size is 1485 patients. The 3 types of care settings will be compared on the basis of primary outcomes in terms of the proportion of return visits to any site 3 and 7 days after the initial visit and the mean cost of care. The secondary outcomes measured will include scores on patient-reported outcome and experience measures and mean costs borne wholly by patients. We will use multilevel generalized linear models to compare the care settings and an overlap weights approach to adjust for confounding factors related to age, sex, gender, ethnicity, comorbidities, registration with a family physician, socioeconomic status, and severity of illness. RESULTS: Phase 1 will begin in 2021 and phase 2, in 2023. The results will be available in 2025. CONCLUSIONS: The end point of our program will be for deciders, patients, and care providers to be able to determine the most appropriate care setting for the management of ambulatory emergency respiratory conditions, based on the quality and cost of care associated with each alternative. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/25619.

Small Animal Shanoir (SAS) A Cloud-Based Solution for Managing Preclinical MR Brain Imaging Studies.

Clinical multicenter imaging studies are frequent and rely on a wide range of existing tools for sharing data and processing pipelines. This is not the case for preclinical (small animal) studies. Animal population imaging is still in infancy, especially because a complete standardization and control of initial conditions in animal models across labs is still difficult and few studies aim at standardization of acquisition and post-processing techniques. Clearly, there is a need of appropriate tools for the management and sharing of data, post-processing and analysis methods dedicated to small animal imaging. Solutions developed for Human imaging studies cannot be directly applied to this specific domain. In this paper, we present the Small Animal Shanoir (SAS) solution for supporting animal population imaging using tools compatible with open data. The integration of automated workflow tools ensures accessibility and reproducibility of research outputs. By sharing data and imaging processing tools, hosted by SAS, we promote data preparation and tools for reproducibility and reuse, and participation in multicenter or replication "open science" studies contributing to the improvement of quality science in preclinical domain. SAS is a first step for promoting open science for small animal imaging and a contribution to the valorization of data and pipelines of reference.

Physiologic Effects of High-Flow Nasal Cannula in Healthy Subjects.

BACKGROUND: High-flow nasal cannula (HFNC) is increasingly used in the management of acute and chronic respiratory failure. Little is known about the optimal settings for HFNC. This study was designed to assess the dose effect of HFNC on respiratory effort indexes and respiratory patterns in spontaneously breathing adults. METHODS: A randomized controlled crossover study was conducted in 10 healthy subjects. Five experimental conditions were evaluated: baseline with no therapy; 5 L/min with conventional nasal prongs; and HFNC at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (ie, esophageal pressure swing [ΔPes], esophageal pressure-time product, and work of breathing). Secondary outcomes included breathing pattern parameters and blood gases. Dead-space ventilation and washout were calculated based on minute ventilation, breathing frequency, and Radford equations. RESULTS: ΔPes increased from median (interquartile range [IQR] 3.2 (2.2-3.6) cm H2O at baseline to median (IQR) 5.7 (4.6-6.8) cm H2O at 60 L/min (P < .001). Neither esophageal pressure-time product nor work of breathing were modified during the tested conditions. The minute volume was significantly reduced at 40 and 60 L/min compared with baseline (P = .04), mostly driven by an important and dose-dependent reduction in breathing frequency, from median (IQR) 16 (15-18) breaths/min at baseline, to median (IQR) 8 (7-10) breaths/min at 60 L/min (P < .001). Capillary [Formula: see text] was stable in all the tested conditions. The calculated dead-space ventilation was reduced by half with HFNC. CONCLUSIONS: HFNC did not significantly modify work of breathing in healthy subjects. However, a significant reduction in the minute volume was achieved, capillary [Formula: see text] remaining constant, which suggests a reduction in dead-space ventilation with flows > 20 L/min. (ClinicalTrials.gov registration NCT02495675).

Family medicine physician teachers and residents' intentions to prescribe and interpret spirometry: a descriptive cross-sectional study.

Background: Spirometry is the best test to demonstrate airway obstruction, but remains underused in primary care. Objectives: We assessed, among family medicine physician teachers and residents, their intention to prescribe spirometry in patients suspected of chronic obstructive pulmonary disease and their intention to interpret the results. This evaluation is based on the theoretical framework proposed by Godin et al. for the study of factors influencing healthcare professionals' behavior. Methods: Participants of this descriptive cross-sectional study were recruited from eight Family medicine units (FMUs) of Laval University's network. They completed a 23-item self-administered questionnaire measuring their intention to prescribe and to interpret spirometry as well as some determinants of this intention (beliefs about capabilities, beliefs about consequences, social influence and moral norm). Answers to each of the items were scored on a Likert scale (score 1 to 7) where a higher score indicated a greater agreement with the statement. Results: Of the 284 eligible physicians, 104 were included. The mean score ± standard deviation of physicians' intention to prescribe spirometry (6.6 ± 0.7) was higher than to interpret the results (5.8 ± 1.5). Mean scores for all determinants of intention measured were also higher for prescription than for interpretation of spirometry. Conclusion: The results suggest that participants have a very strong intention to prescribe spirometry. Although the intention to interpret the results is positive, it is weaker than for the prescription of the test. Further studies will be needed to assess the barriers to spirometry interpretation.

Does the full-time presence of an intensivist lead to better outcomes in the cardiac surgical intensive care unit?

OBJECTIVE: The study objective was to compare clinical outcomes in a dedicated adult cardiac surgery intensive care unit before and after the implementation of 24-hour intensivist coverage. METHODS: Between 2008 and 2016, 16,454 consecutive adult patients were admitted to the cardiac surgery intensive care unit after cardiac surgery. During this period, postoperative patients in the cardiac surgery intensive care unit were managed by intensivists during the day (group A); in July 2010, the nighttime coverage was transferred from the hands of residents and fellows to intensivists (group B). Postoperative outcomes before and after this change using 1-to-1 propensity score matching were examined. Patients were stratified a priori into low- and high-risk (<5% and ≥5% predicted mortality) based on the European System for Cardiac Operative Risk Evaluation II. RESULTS: Matched patients in group A had significantly higher cardiac surgery intensive care unit (2.1% vs 1.4%, P = .01) and in-hospital (2.7% vs 1.8%, P = .008) mortality. This higher mortality was only observed among high-risk group A patients who had significantly higher rates of cardiac surgery intensive care unit mortality (6.8% vs 4.1%, P = .01) and in-hospital mortality (8.5% vs 5.3%, P = .01) compared with the high-risk group B. The median duration of mechanical ventilation (5.8 vs 4.3 hours, P < .0001) and the risk of prolonged ventilation greater than 48 hours (5.3% vs 4%, P = .008) were significantly higher among group A patients; this higher rate of respiratory adverse events was observed in all strata of preoperative risk. CONCLUSIONS: In this large cohort of patients admitted to a dedicated adult cardiac surgery intensive care unit, 24-hour intensivist coverage was associated with reduced mortality among patients with an expected operative mortality 5% or greater. These data suggest that preoperative risk stratification and adaptive cardiac surgery intensive care unit physician staffing may result in improved clinical outcomes and optimized hospital resource use.

Evaluation of hyperoxia-induced hypercapnia in obese patients after cardiac surgery: a randomized crossover comparison of conservative and liberal oxygen administration.

PURPOSE: Recent studies on patients with stable obesity-hypoventilation syndrome have raised concerns about hyperoxia-induced hypercapnia in this population. This study aimed to evaluate whether a higher oxygen saturation target would increase arterial partial pressure of carbon dioxide (PaCO2) in obese patients after coronary artery bypass grafting surgery (CABG). METHODS: Obese patients having CABG were recruited. With a randomized crossover design, we compared two oxygenation strategies for 30 min each, immediately after extubation: a peripheral oxygen saturation (SpO2) target of ≥ 95% achieved with manual oxygen titration (liberal) and a SpO2 target of 90% achieved with FreeO2, an automated oxygen titration device (conservative). The main outcome was end-of-period arterial PaCO2. RESULTS: Thirty patients were included. Mean (standard deviation [SD]) body mass index (BMI) was 34 (3) kg·m-2 and mean (SD) baseline partial pressure of carbon dioxide (PCO2) was 40.7 (3.1) mmHg. Mean (SD) end-of-period PaCO2 was 42.0 (5.4) mmHg in the conservative period, compared with 42.6 (4.6) mmHg in the liberal period [mean difference - 0.6 (95% confidence interval - 2.2 to 0.9) mmHg; P = 0.4]. Adjusted analysis for age, BMI, narcotics, and preoperative PaCO2 did not substantively change the results. Fourteen patients were retainers, showing an elevation in mean (SD) PaCO2 in the liberal period of 3.3 (4.1) mmHg. Eleven patients had the opposite response, with a mean (SD) end-of-period PaCO2 decrease of 1.8 (2.2) mmHg in the liberal period. Five patients had a neutral response. CONCLUSION: This study did not show a clinically important increase in PaCO2 associated with higher SpO2 values in this specific population of obese patients after CABG. Partial pressure of carbon dioxide increased with liberal oxygen administration in almost half of the patients, but no predictive factor was identified. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02917668); registered 25 September, 2016.

Objective Evaluation of Multiple Sclerosis Lesion Segmentation using a Data Management and Processing Infrastructure.

We present a study of multiple sclerosis segmentation algorithms conducted at the international MICCAI 2016 challenge. This challenge was operated using a new open-science computing infrastructure. This allowed for the automatic and independent evaluation of a large range of algorithms in a fair and completely automatic manner. This computing infrastructure was used to evaluate thirteen methods of MS lesions segmentation, exploring a broad range of state-of-theart algorithms, against a high-quality database of 53 MS cases coming from four centers following a common definition of the acquisition protocol. Each case was annotated manually by an unprecedented number of seven different experts. Results of the challenge highlighted that automatic algorithms, including the recent machine learning methods (random forests, deep learning, …), are still trailing human expertise on both detection and delineation criteria. In addition, we demonstrate that computing a statistically robust consensus of the algorithms performs closer to human expertise on one score (segmentation) although still trailing on detection scores.

Indirect somatic embryogenesis of Theobroma cacao L. in liquid medium and improvement of embryo-to-plantlet conversion rate.

The establishment of cocoa embryogenic cell lines in liquid medium starting from high frequency somatic embryogenesis (HFSE) callus is described. The growth kinetics of the cultures during the multiplication and the expression steps conducted in 250 mL Erlenmeyer flasks were described for three genotypes selected for their agronomical traits (EET95, EET96, and EET103). The glucose and dissolved oxygen concentrations and the absorption of Murashige and Skoog medium macronutrients (nitrate, ammonium, potassium, sulfate, calcium, phosphorus, and magnesium) were monitored. The multiplication of the embryogenic calluses in a medium containing 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) at 1 mg L-1, initiated with an inoculation density of 20 g L-1 of callus, was achieved. The growth rate was characterized by two phases, with the second being concomitant with a depletion of phosphorus and magnesium, and a decrease in the embryogenic potential of the callus. The expression of the callus embryogenic capacity was conducted in an auxin-free medium. The embryo production starting from 1 and 5 g L-1 inoculation densities was compared. When placed in the optimal expression conditions in flasks, 1 g of callus produced 1000 to 1500 embryos within 5 to 7 wk. Finally, two paths for improving the plantlet regenerative capacities of cocoa SE produced in liquid medium were identified. Supplementing the expression medium with myo-inositol used as an osmotic agent at a concentration of 50 g L-1 increased the embryo-to-plantlet conversion rate from 13-16% to 40-48%. A 6-wk culture of the embryos on a maturation medium in Petri dishes optimized their subsequent development into plantlets.

Effects of High-Flow Nasal Cannula on the Work of Breathing in Patients Recovering From Acute Respiratory Failure.

OBJECTIVES: High-flow nasal cannula is increasingly used in the management of respiratory failure. However, little is known about its impact on respiratory effort, which could explain part of the benefits in terms of comfort and efficiency. This study was designed to assess the effects of high-flow nasal cannula on indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min) in adults. DESIGN: A randomized controlled crossover study was conducted in 12 patients with moderate respiratory distress (i.e., after partial recovery from an acute episode, allowing physiologic measurements). SETTING: Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada. SUBJECTS: Twelve adult patients with respiratory distress symptoms were enrolled in this study. INTERVENTIONS: Four experimental conditions were evaluated: baseline with conventional oxygen therapy and high-flow nasal cannula at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min). Secondary outcomes included tidal volume, respiratory rate, minute volume, dynamic lung compliance, inspiratory resistance, and blood gases. MEASUREMENTS AND MAIN RESULTS: Esophageal pressure variations decreased from 9.8 (5.8-14.6) cm H2O at baseline to 4.9 (2.1-9.1) cm H2O at 60 L/min (p = 0.035). Esophageal pressure-time product/min decreased from 165 (126-179) to 72 (54-137) cm H2O • s/min, respectively (p = 0.033). Work of breathing/min decreased from 4.3 (3.5-6.3) to 2.1 (1.5-5.0) J/min, respectively (p = 0.031). Respiratory pattern variables and capillary blood gases were not significantly modified between experimental conditions. Dynamic lung compliance increased from 38 (24-64) mL/cm H2O at baseline to 59 (43-175) mL/cm H2O at 60 L/min (p = 0.007), and inspiratory resistance decreased from 9.6 (5.5-13.4) to 5.0 (1.0-9.1) cm H2O/L/s, respectively (p = 0.07). CONCLUSIONS: High-flow nasal cannula, when set at 60 L/min, significantly reduces the indexes of respiratory effort in adult patients recovering from acute respiratory failure. This effect is associated with an improvement in respiratory mechanics.

Unusual Cause of Life-Threatening Hemoptysis During Cardiac Operation: Surgical Management Revisited.

The surgical management of life-threatening perioperative hemoptysis has been vastly replaced by radiologic embolization. In some situations, surgical therapy can prove useful. This case report describes life-threatening hemoptysis of an unusual cause during coronary artery bypass grafting, managed through an original technique of temporary pulmonary vascular exclusion by thoracotomy.

Influence of trainee involvement on procedural characteristics for linear endobronchial ultrasound.

BACKGROUND: Linear endobronchial ultrasound (EBUS) is a safe and effective method for the diagnostic sampling of mediastinal lymph nodes. However, there is a learning curve associated with the procedure and operator experience influences diagnostic yield. We sought to determine if trainee involvement during EBUS influences procedural characteristics, complication rate, and diagnostic yield. METHODS: We performed a retrospective analysis of 220 subjects who underwent an EBUS procedure at our center from December 2012 to June 2013. Procedures were performed by six different interventional pulmonologists with substantial experience with EBUS or by a trainee under their direct supervision. Procedural characteristics and complications were recorded. Diagnostic yield and specimen adequacy were compared between groups. RESULTS: EBUS was performed in 220 patients with a trainee involved (n = 116) or by staff physician alone (n = 104). Patient characteristics, and the number and size of lymph node stations sampled were similar. EBUS duration was longer (16.0 vs. 13.7 minutes; P = 0.002) and the total dose of lidocaine used was higher (322.3 vs. 304.2 mg; P = 0.045) when a trainee was involved. The rate of adequate specimens sampled was comparable between the groups (92.0 vs. 92.0%; P = 0.60). Diagnostic yield was lower when a trainee was involved in the EBUS procedure (52.6 vs. 68.3%; P = 0.02). CONCLUSION: Trainee involvement significantly increased EBUS duration and the dose of local anesthesia used for the procedure. Diagnostic yield was lower when a trainee was involved. Factors accounting for this difference in yield, despite adequate samples being obtained, warrant further investigation.

Evaluation of Pulmonary Nodules Using the Spyglass Direct Visualization System Combined With Radial Endobronchial Ultrasound: A Clinical Feasibility Study.

BACKGROUND: Sampling of peripheral pulmonary nodules with radial endobronchial ultrasound (p-EBUS) increases diagnostic yield of bronchoscopy. However, diagnostic yield is influenced by numerous factors. OBJECTIVE: We evaluated the use of SpyGlass, a one millimeter diameter optic fiber, to obtain images of the distal mucosa and of pulmonary lesions detected with p-EBUS to determine if visual aspect of the distal mucosa was predictive of diagnosis. METHODS: We prospectively recruited subjects investigated for peripheral nodules. Bronchoscopy was performed and p-EBUS was used to locate the lesion through a guide sheath. The Spyglass fiber was introduced in the sheath to obtain images of the distal bronchial mucosa. Tissue sampling was subsequently done. RESULTS: Fifteen patients were enrolled in the study. A final diagnosis of malignancy was confirmed in 80%. All lesions could be located using p-EBUS (100%). Diagnostic sensitivity for p-EBUS was 58.3%. Distal mucosa could be imaged with SpyGlass in 14/15 patients (93.3%). Mucosal appearance was described as abnormal in 7 out of the 15 subjects. Mean SpyGlass procedure time was 6.5 minutes. No direct complication was reported. CONCLUSION: Spyglass can be used in combination with p-EBUS to obtain images of the distal bronchial mucosa and peripheral pulmonary nodules. More patients will be needed to confirm whether mucosal appearance can be predictive of malignancy.