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2.
Anaesth Crit Care Pain Med ; 42(4): 101262, 2023 08.
Article in English | MEDLINE | ID: mdl-37290697

ABSTRACT

OBJECTIVE: To provide guidelines to define the place of human factors in the management of critical situations in anaesthesia and critical care. DESIGN: A committee of nineteen experts from the SFAR and GFHS learned societies was set up. A policy of declaration of links of interest was applied and respected throughout the guideline-producing process. Likewise, the committee did not benefit from any funding from a company marketing a health product (drug or medical device). The committee followed the GRADE® method (Grading of Recommendations Assessment, Development and Evaluation) to assess the quality of the evidence on which the recommendations were based. METHODS: We aimed to formulate recommendations according to the GRADE® methodology for four different fields: 1/ communication, 2/ organisation, 3/ working environment and 4/ training. Each question was formulated according to the PICO format (Patients, Intervention, Comparison, Outcome). The literature review and recommendations were formulated according to the GRADE® methodology. RESULTS: The experts' synthesis work and application of the GRADE® method resulted in 21 recommendations. Since the GRADE® method could not be applied in its entirety to all the questions, the guidelines used the SFAR "Recommendations for Professional Practice" A means of secured communication (RPP) format and the recommendations were formulated as expert opinions. CONCLUSION: Based on strong agreement between experts, we were able to produce 21 recommendations to guide human factors in critical situations.


Subject(s)
Anesthesia , Anesthesiology , Humans , Critical Care
3.
Teach Learn Med ; 35(5): 537-549, 2023.
Article in English | MEDLINE | ID: mdl-36251797

ABSTRACT

Phenomenon: The urgency of having fair and trustworthy competency-based assessment in medical training is growing. Simulation is increasingly recognized as a potent method for building and assessing applied competencies. The growing use of simulation and its application in summative assessment calls for comprehensive and rigorously designed programs. Defining the current baseline of what is available and feasible is a crucial first step. This paper uses anesthesia and intensive care (AIC) in France as a case study in how to document this baseline. Approach: An IRB-approved, online anonymous closed survey was submitted to AIC residency program directors and AIC simulation program directors in France from January to February 2021. The researcher-developed survey consisted of 65 questions across five sections: centers' characteristics, curricular characteristics, courses' characteristics, instructors' characteristics, and simulation perceptions and perspectives. Findings: The participation rate was 31/31 (100%) with 29 centers affiliated with a university hospital. All centers had AIC simulation activities. Resident training was structured in 94% of centers. Simulation uses were training (100%), research and development (61%), procedural or organizational testing (42%), and summative assessment (13%). Interprofessional full-scale simulation training existed in 90% of centers. Procedural training on simulators prior to clinical patients' care was performed "always" in 16%, "most often" in 45%, "sometimes" in 29% and "rarely" or "not" in 10% of centers. Simulated patients were used in 61% of centers. Main themes were identified for procedural skills, full-scale and simulated patient simulation training. Simulation activity was perceived as increasing in 68% of centers. Centers expressed a desire to participate in developing and using a national common AIC simulation program. Insights: Based on our findings in AIC, we demonstrated a baseline description of nationwide simulation activities. We now have a clearer perspective on a decentralized approach in which individual institutions or regional consortia conduct simulation for a discipline in a relatively homogeneous way, suggesting the feasibility for national guidelines. This approach provides useful clues for AIC and other disciplines to develop a comprehensive and meaningful program matching existing expectations and closing the identified gaps.


Subject(s)
Anesthesia , Internship and Residency , Simulation Training , Humans , Curriculum , Surveys and Questionnaires , Clinical Competence , Critical Care
4.
Anaesth Crit Care Pain Med ; 41(1): 100991, 2022 02.
Article in English | MEDLINE | ID: mdl-34863967

ABSTRACT

BACKGROUND: Communication and teamwork are critical non-technical skills in the operating theatre. However, prevention of events associated with communication failures by large simulation-based programs remains to be evaluated. The objective was to assess the impact of an interprofessional simulation-based training course on communication, teamwork, checklist adherence, and safety culture. METHODS: We aimed to assess the impact of an interprofessional simulation-based training course on communication, teamwork, checklist adherence, and safety culture. We conducted a before-and-after interventional study based on a mixed-methods approach combining qualitative and quantitative evaluation criteria. The study was performed in a University Hospital with 39 operating theatres operated by 300 providers before (period 1) and after (period 2) an interprofessional simulation-based training course. Surgical procedures were observed, and the primary outcome measure was the rate of procedures with at least one communication failure associated with adverse event. Additional outcomes measured included the rate of other communication failures, checklist adherence, while teamwork and safety culture were assessed by questionnaires. RESULTS: In total, 46 970 communication episodes were analysed during 131 (period 1) and 122 (period 2) surgical procedures. One hundred sixty-four professionals attended 40 simulation-based sessions. The rate of procedures with at least one communication failure associated with adverse events was not significantly different between the 2 periods (38% in period 1 and 43% in period 2; P = 0.47). Nevertheless, the rate of communication failures reduced between period 1 and 2 (8117/28 303 (29%) vs. 3868/18 667 (21%), respectively; P < 0.01). Teamwork scores and checklist adherence increased significantly after the intervention (8.1 (7.2-8.7) in period 1 vs. 8.6 (8.0-9.2) in period 2; P < 0.01 and 17% (0-35 %) in period 1 vs. 44% (26-57 %) in period 2; P < 0.01). Safety culture ratings did not change significantly. CONCLUSION: This study shows that although the rate of procedures with at least one communication failure associated with adverse event (primary endpoint) was not significantly different, a large interprofessional simulation-based training course has a positive effect on communication failures, teamwork, and checklist adherence.


Subject(s)
Interprofessional Relations , Simulation Training , Communication , Humans , Patient Care Team , Safety Management
5.
Br J Anaesth ; 126(4): 854-861, 2021 04.
Article in English | MEDLINE | ID: mdl-33422288

ABSTRACT

BACKGROUND: Positive communication behaviour within anaesthesia teams may decrease stress response and improve clinical performance. We aimed to evaluate the effect of positive communication during medical handover on the subsequent team-based clinical performance in a simulated critical situation. We also assessed the effect of positive communication behaviour on stress response. METHODS: This single-centre RCT involved anaesthesia teams composed of a resident and a nurse in a high-fidelity scenario of anaesthesia-related paediatric laryngospasm after a standardised handover. During the handover, similar information was provided to all teams, but positive communication behaviour was adopted only for teams in the intervention group. Primary outcome was team-based clinical performance, assessed by an independent blinded observer, using video recordings and a 0-to 100-point scenario-specific scoring tool. Three categories of tasks were considered: safety checks before the incision, diagnosis/treatment of laryngospasm, and crisis resource management/non-technical skills. Individual stress response was monitored by perceived level of stress and HR variability. RESULTS: The clinical performance of 64 anaesthesia professionals (grouped into 32 teams) was analysed. The mean (standard deviation) team-based performance score in the intervention group was 44 (10) points vs 35 (12) in the control group (difference: +8.4; CI95% [0.4-16.4]; P=0.04). The effects were homogeneous over the three categories of tasks. Perceived level of stress and HR variability were not significantly different between groups. CONCLUSIONS: Positive communication behaviour between healthcare professionals during medical handover improved team-based performance in a simulation-based critical situation. CLINICAL TRIAL REGISTRATION: NCT03375073.


Subject(s)
Clinical Competence/standards , Communication , Critical Care/standards , Health Personnel/standards , Patient Care Team/standards , Patient Handoff/standards , Simulation Training/standards , Adult , Critical Care/methods , Female , Humans , Male , Prospective Studies , Simulation Training/methods
6.
Eur J Obstet Gynecol Reprod Biol ; 256: 6-16, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33161212

ABSTRACT

INTRODUCTION: The objective of this study was to develop a new interdisciplinary teamwork scale, the Obstetric Team Performance Assessment (OTPA), for the management of the post-partum hemorrhage, through consensus agreement of obstetric caregivers. The goal is to provide a reliable tool for teaching and evaluating teams in high-fidelity simulation. METHODS: This prospective study is based on an expert consensus, using a Delphi method. The authors developed the "OTPA¼ specifically related to the management of post-partum hemorrhage, using existing recommendations. For the Delphi survey, the scale was distributed to a selected group of experts. After each round of Delphi, authors quantitatively analyzed each element of the scale, based on the percentages of agreement received, and reviewed each comment. This blind examination then led to the modification of the scale. The rounds were continued until 80-100 % agreement with a median overall response score equal to or greater than 8 was obtained for at least 60 % of items. Repeated 3 times, the process led to consensus and to a final version of the OTPA scale. RESULTS: From February to October 2018, 16 of the 33 invited experts participated in four Delphi cycles. Of the 37 items selected in the first round, only 19 (51.3 %) had an agreement of 80-100% with a median overall response score equal to or greater than 8 in the second round, and a third round was conducted. During this third round, 24 of the 37 items were validated (64.9 %) and 82 of the 88 sub-items obtained 80 %-100 % agreement (93.2 %). The fourth round consisted of proposing a weighting of the different items. CONCLUSION: Using a structured Delphi method, we provided a new interdisciplinary teamwork scale (OTPA), for the management of the post-partum hemorrhage. Thus, this scale will be able to be used during high-fidelity scenarii to assess performances of various teams facing a scenari of PPH. Moreover, this scale, focusing some crucial aspects of interdisciplinary teamwork will be useful for teaching purpose.


Subject(s)
Postpartum Hemorrhage , Consensus , Delphi Technique , Female , Humans , Postpartum Hemorrhage/diagnosis , Postpartum Hemorrhage/therapy , Pregnancy , Prospective Studies
7.
BMJ Open ; 10(6): e037299, 2020 06 21.
Article in English | MEDLINE | ID: mdl-32565477

ABSTRACT

INTRODUCTION: Some surgical site infections (SSI) could be prevented by following adequate infection prevention and control (IPC) measures. Poor compliance with IPC measures often occurs due to knowledge gaps and insufficient education of healthcare professionals. The education and training of SSI preventive measures does not usually take place in the operating room (OR), due to safety, and organisational and logistic issues. The proposed study aims to compare virtual reality (VR) as a tool for medical students to learn the SSI prevention measures and adequate behaviours (eg, limit movements…) in the OR, to conventional teaching. METHODS AND ANALYSIS: This protocol describes a randomised controlled multicentre trial comparing an educational intervention based on VR simulation to routine education. This multicentre study will be performed in three universities: Grenoble Alpes University (France), Imperial College London (UK) and University of Heidelberg (Germany). Third-year medical students of each university will be randomised in two groups. The students randomised in the intervention group will follow VR teaching. The students randomised in the control group will follow a conventional education programme. Primary outcome will be the difference between scores obtained at the IPC exam at the end of the year between the two groups. The written exam will be the same in the three countries. Secondary outcomes will be satisfaction and students' progression for the VR group. The data will be analysed with intention-to-treat and per protocol. ETHICS AND DISSEMINATION: This study has been approved by the Medical Education Ethics Committee of the London Imperial College (MEEC1920-172), by the Ethical Committee for the Research of Grenoble Alpes University (CER Grenoble Alpes-Avis-2019-099-24-2) and by the Ethics Committee of the Medical Faculty of Heidelberg University (S-765/2019). Results will be published in peer-reviewed medical journals, communicated to participants, general public and all relevant stakeholders.


Subject(s)
Education, Medical, Graduate , Operating Rooms , Randomized Controlled Trials as Topic , Surgical Wound Infection/prevention & control , Virtual Reality , Educational Measurement , Humans , Multicenter Studies as Topic , Students, Medical
8.
Anaesth Crit Care Pain Med ; 38(2): 121-130, 2019 04.
Article in English | MEDLINE | ID: mdl-29857186

ABSTRACT

In this road map for trauma in France, we focus on the main challenges for system implementation, surgical and radiology training and upon innovative training techniques. Regarding system organisation: procedures for triage, designation and certification of trauma centres are mandatory to implement trauma networks on a national scale. Data collection with registries must be created, with a core dataset defined and applied through all registries. Regarding surgical and radiology training, diagnostic-imaging processes should be standardised and the role of the interventional radiologist within the trauma team and the trauma network should be clearly defined. Education in surgery for trauma is crucial and recent changes in medical training in France will promote trauma surgery as a specific sub-specialty. Innovative training techniques should be implemented and be based on common objectives, scenarios and evaluation, so as to improve individual and team performances. The group formulated 14 proposals that should help to structure and improve major trauma management in France over the next 10 years.


Subject(s)
Delivery of Health Care/organization & administration , National Health Programs/organization & administration , Wounds and Injuries/therapy , Education, Medical/trends , France , Humans , Registries , Rehabilitation , Trauma Centers , Triage , Wounds and Injuries/diagnostic imaging , Wounds and Injuries/surgery
9.
Mater Sci Eng C Mater Biol Appl ; 82: 210-216, 2018 Jan 01.
Article in English | MEDLINE | ID: mdl-29025650

ABSTRACT

Chronic wound colonization by bacterial biofilms is common and can cause various complications. An anti-biofilm strategy was developed around the co-entrapment of a commercially available antiseptic, PHMB (polyhexamethylene biguanide 4mgmL-1), with EDTA (Ethylen diamine tetra acetic acid, 20mM) in a gelatin gel. The two active compounds act synergistically against bacterial biofilms, but their efficiency is strongly reduced (16-fold) when entrapped inside the 5% gelatin gel, and they weaken the mechanical properties (50-fold) of the gel. Increasing the gelatin concentration to 7% allows for good mechanical properties but large diffusional constraints. An active ephemeral gel, a chemical gel with controlled hydrolysis, was conceived and developed. When the ephemeral gel was solubilized after 48h, PHMB delivery increased, leading to good anti-biofilm activity. The various gels were examined over 24 and 48h of contact with P. aeruginosa and S. aureus biofilms, two types of bacterial biofilms frequently encountered in chronic wounds. The ephemeral gel eradicated the dense biofilms (>6.107CFU·cm-2) produced by either single or mixed strains; a similar efficiency was measured for biofilms from strains of both laboratory and clinical origin. The formulation was then adapted to develop a dressing prototype that is active against biofilms and fulfils the requirements of an efficient wound care system.


Subject(s)
Anti-Bacterial Agents/pharmacology , Biguanides/chemistry , Biofilms/drug effects , Edetic Acid/chemistry , Gels/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Bandages , Biguanides/pharmacology , Edetic Acid/pharmacology , Gelatin/chemistry , Pseudomonas aeruginosa/physiology , Rheology , Staphylococcus aureus/physiology
10.
Anaesth Crit Care Pain Med ; 37(1): 55-60, 2018 Feb.
Article in English | MEDLINE | ID: mdl-27659968

ABSTRACT

Ultrasound (US) guided needle positioning is safer than anatomical landmark techniques for central venous access. Hand-eye coordination and execution time depend on the professional's ability, previous training and personal skills. Needle guidance positioning systems (GPS) may theoretically reduce execution time and facilitate needle positioning in specific targets, thus improving patient comfort and safety. Three groups of healthcare professionals (41 anaesthesiologists and intensivists, 41 residents in anaesthesiology and intensive care, 39 nurse anaesthetists) were included and required to perform 3 tasks (positioning the tip of a needle in three different targets in a silicon phantom) by using successively a conventional US-guided needle positioning and a needle GPS. We measured execution times to perform the tasks, hand-eye coordination and the number of repositioning occurrences or errors in handling the needle or the probe. Without the GPS system, we observed a significant inter-individual difference for execution time (P<0.05), hand-eye coordination and the number of errors/needle repositioning between physicians, residents and nurse anaesthetists. US training and video gaming were found to be independent factors associated with a shorter execution time. Use of GPS attenuated the inter-individual and group variability. We observed a reduced execution time and improved hand-eye coordination in all groups as compared to US without GPS. Neither US training, video gaming nor demographic personal or professional factors were found to be significantly associated with reduced execution time when GPS was used. US associated with GPS systems may improve safety and decrease execution time by reducing inter-individual variability between professionals for needle-handling procedures.


Subject(s)
Anesthesiologists , Needles , Nurse Anesthetists , Adult , Clinical Competence , Critical Care , Female , Humans , Internship and Residency , Male , Middle Aged , Patient Comfort , Patient Safety , Phantoms, Imaging , Physicians , Prospective Studies , Psychomotor Performance , Video Games
11.
Anaesth Crit Care Pain Med ; 35(4): 255-60, 2016 Aug.
Article in English | MEDLINE | ID: mdl-27085221

ABSTRACT

BACKGROUND: Intraoperative use of oesophageal Doppler (OD) was associated with improved postoperative outcomes through the optimization of perioperative fluid management. We studied the effect on haemodynamics of a goal-directed fluid management approach, guided by OD, during elective spine surgery in the prone position. METHODS: Intraoperative fluid and vasopressor administration were directed according to one of two randomly chosen decision-making algorithms driven by either OD (OD group; n=33 patients) or standard parameters (standard group; n=34 patients). Both groups were monitored by OD, however haemodynamics management in the standard group was blinded to OD information. OD algorithm used corrected flow time as the primary variable to guide haemodynamics management. Mean arterial blood pressure (MAP) was maintained within 75% of the preoperative value for both groups. The primary outcome was the duration of intraoperative hypotensive episodes during prone position. RESULTS: The proportion of procedure duration with MAP below the predefined threshold was greater in the Standard group than in the OD group: 34% (15-62) (median, interquartile range) versus 17% (5-35) of the observation period, respectively (P=0.01). They were also more frequent in the Standard group: 7 (3-11) per patient versus 3 (1-7) per patient (P<0.001). The requirement and dosing of ephedrine and infused colloids over the observation period did not significantly differ between the two groups. The OD parameters were comparable between the two groups during prone position. CONCLUSION: OD monitoring during spine surgery in prone position is feasible and may help physicians to reduce the duration of hypotensive episodes during this surgical procedure.


Subject(s)
Echocardiography, Doppler/methods , Echocardiography, Transesophageal/methods , Hemodynamics , Intraoperative Care/standards , Prone Position , Aged , Algorithms , Arterial Pressure , Blood Pressure , Female , Fluid Therapy , Humans , Hypotension/epidemiology , Hypotension/physiopathology , Intraoperative Complications/epidemiology , Intraoperative Complications/physiopathology , Male , Middle Aged , Prospective Studies , Spine/surgery
12.
Anaesth Crit Care Pain Med ; 34(6): 339-44, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26545576

ABSTRACT

BACKGROUND: Medical competence requires the acquisition of theoretical knowledge and technical skills. Severe trauma management teaching is poorly developed during internship. Nevertheless, the basics of major trauma management should be acquired by every future physician. For this reason, the major trauma course (MTC), an educational course in major traumatology, has been developed for medical students. Our objective was to evaluate, via a high fidelity medical simulator, the impact of the MTC on medical student skills concerning major trauma management. METHODS: The MTC contains 3 teaching modalities: posters with associated audio-guides, a procedural workshop on airway management and a teaching session using a medical simulator. Skills evaluation was performed 1 month before (step 1) and 1 month after (step 3) the MTC (step 2). Nineteen students were individually evaluated on 2 different major trauma scenarios. The primary endpoint was the difference between steps 1 and 3, in a combined score evaluating: admission, equipment, monitoring and safety (skill set 1) and systematic clinical examinations (skill set 2). RESULTS: After the course, the combined primary outcome score improved by 47% (P<0.01). Scenario choice or the order of use had no significant influence on the skill set evaluations. CONCLUSION: This study shows improvement in student skills for major trauma management, which we attribute mainly to the major trauma course developed in our institution.


Subject(s)
Audiovisual Aids , Clinical Competence , Patient Simulation , Students, Medical , Traumatology/education , Wounds and Injuries/therapy , Curriculum , Education, Medical, Undergraduate , Educational Measurement , Endpoint Determination , Humans , Monitoring, Physiologic , Patient Safety , Prospective Studies
13.
Intensive Care Med ; 40(12): 1832-42, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25348858

ABSTRACT

PURPOSE: Mild therapeutic hypothermia (TH) is recommended as soon as possible after the return of spontaneous circulation to improve outcomes after out-of-hospital cardiac arrest (OHCA). Preclinical data suggest that the benefit of TH could be increased if treatment is started during cardiac arrest. We aimed to study the impact of intra-arrest therapeutic hypothermia (IATH) on neurological injury and inflammation following OHCA. METHODS: We conducted a 1:1 randomized, multicenter study in three prehospital emergency medical services and four critical care units in France. OHCA patients, irrespective of the initial rhythm, received either an infusion of cold saline and external cooling during cardiac arrest (IATH group) or TH started after hospital admission (hospital-cooling group). The primary endpoint was neuron-specific enolase (NSE) serum concentrations at 24 h. Secondary endpoints included IL-6, IL-8, and IL-10 concentrations, and clinical outcome. RESULTS: Of the 245 patients included, 123 were analyzed in the IATH group and 122 in the hospital-cooling group. IATH decreased time to reach temperature ≤ 34 °C by 75 min (95% CI: 4; 269). The rate of patients admitted alive to hospital was not different between groups [IATH n = 41 (33%) vs. hospital cooling n = 36 (30%); p = 0.51]. Levels of NSE and inflammatory biomarkers were not different between groups [median NSE at 24 h: IATH 96.7 µg/l (IQR: 49.9-142.8) vs. hospital cooling 97.6 µg/l (IQR: 74.3-142.4), p = 0.64]. No difference in survival and cerebral performance were found at 1 month. CONCLUSIONS: IATH did not affect biological markers of inflammation or brain damage or clinical outcome.


Subject(s)
Brain Ischemia/etiology , Brain Ischemia/prevention & control , Hypothermia, Induced , Inflammation/etiology , Inflammation/prevention & control , Out-of-Hospital Cardiac Arrest/complications , Out-of-Hospital Cardiac Arrest/therapy , Adult , Aged , Aged, 80 and over , Cold Temperature , Female , France , Humans , Male , Middle Aged , Sodium Chloride/administration & dosage , Survival Analysis , Treatment Outcome
14.
Macromol Biosci ; 13(6): 687-95, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23420679

ABSTRACT

The release of molecules entrapped within biogels is dictated by diffusion laws. Innovative biogel architectures are conceived and tested to control small molecule delivery from gelatin gels. The ionic interactions modulate the release of small molecules. Alginate is then added to gelatin gels and further hydrolyzed; the influence of viscosity is discussed. Next, various mixed gels are compared, such as a gelatin-alginate IPN and the original architecture of an alginate gel entrapped in a gelatin gel with or without a polysaccharidase. The relative influence of ionic interactions and diffusional constraints on the delivery of small charged molecules is explored, and a solution for controlling diffusion is proposed for any situation.


Subject(s)
Alginates/metabolism , Coloring Agents/metabolism , Drug Delivery Systems , Gelatin/metabolism , Gels/metabolism , Polysaccharide-Lyases/metabolism , Animals , Bromthymol Blue/metabolism , Diffusion , Elastic Modulus , Eosine Yellowish-(YS)/metabolism , Glucuronic Acid/metabolism , Hexuronic Acids/metabolism , Ions , Methylene Blue/metabolism , Microspheres , Polysaccharides/chemistry , Sus scrofa , Time Factors
15.
Intensive Care Med ; 36(9): 1514-20, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20490780

ABSTRACT

PURPOSE: The early diagnosis of traumatic internal carotid artery dissection (TICAD) is essential for initiating appropriate treatment and improving outcome. We searched for criteria from transcranial Doppler (TCD) measurements on admission that could be associated with subsequent TICAD diagnosis in patients with traumatic brain injury (TBI). METHODS: We conducted a retrospective 1:4 matched (age, mean arterial blood pressure) cohort study of 11 TBI patients with TICAD and absent or mild brain lesions on initial CT scan, 22 TBI controls with comparable brain CT scan lesions (controls 1), and 22 TBI controls with more severe brain CT scan lesions (controls 2) on admission. TCD measurements were obtained on admission from both middle cerebral arteries (MCA). All patients had subsequent CT angiography to diagnose TICAD. RESULTS: A >25% asymmetry in the systolic blood flow velocity between the two MCA was found in 9/11 patients with TICAD versus 0/22 in controls 1 and 5/22 in controls 2 (p < 0.01). The combination of this asymmetry with an ipsilateral pulsatility index < or =0.80 was found in 9/11 patients with TICAD versus none in the two groups of controls (p < 0.01). CONCLUSIONS: Our results suggest that significant asymmetry in the systolic blood flow velocity between the MCAs and a reduced ipsilateral pulsatility index could be criteria from TCD measurements associated with the occurrence of TICAD in head-injured patients. If prospectively validated, these findings could be incorporated in screening protocols for TICAD in patients with TBI.


Subject(s)
Brain Injuries/diagnostic imaging , Carotid Artery, Internal, Dissection/diagnostic imaging , Middle Cerebral Artery/diagnostic imaging , Ultrasonography, Doppler, Transcranial/methods , Adolescent , Adult , Aged , Brain Injuries/complications , Carotid Artery Diseases/diagnostic imaging , Carotid Artery, Internal, Dissection/etiology , Case-Control Studies , Cohort Studies , Female , Humans , Male , Middle Aged , Middle Cerebral Artery/pathology , Pulsatile Flow , Retrospective Studies , Risk Factors , Trauma Severity Indices , Ultrasonography, Interventional , Young Adult
16.
Biomacromolecules ; 9(1): 13-20, 2008 Jan.
Article in English | MEDLINE | ID: mdl-18047290

ABSTRACT

Ephemeral gels, called Enzgels, successively undergo sol-gel and then gel-sol transition under the action of two antagonistic enzymes, transglutaminase and protease. Molecular and macroscopic properties of Enzgels are directly dependent on the enzymatic activities and their ratios. This work studies the characteristics of Enzgels according to the specificity of three different proteases: thermolysin, trypsin, and collagenase. The experiments are conducted using three types of gelatin networks, one created only by triple helices, one only by covalent bonds, and the last network by both triple helices and covalent bonds. Rheology and polarimetry measurements show that the evolution of Enzgels is directly dependent on the specificity of the protease used. Moreover, gelatin network conformation has different influences according to this proteolytic specificity. Collagenase is not very sensitive to gelatin conformation, whereas trypsin is very limited by the presence of covalent bonds. This study considerably expands the knowledge of Enzgel properties.


Subject(s)
Gels , Peptide Hydrolases/metabolism , Transglutaminases/metabolism , Hydrogen Bonding , Rheology , Substrate Specificity
17.
Biomacromolecules ; 8(11): 3613-8, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17949036

ABSTRACT

The enzyme-catalyzed gel-sol transition of calcium-alginate obtained by internal gelling strategy with the help of an entrapped alginate lyase is described. We show that alginate molecules and enzyme-produced oligoalginates shorten the gel time of physical gelatin gels (5% and 1.5%), probably due to local protein concentration increase. Interpenetrated networks composed of calcium-alginate and of gelatin were obtained only if elongation of gelatin helices inside a pre-existing calcium-alginate network could occur and only for low gelatin concentration (1.5%). The physical gelatin network is almost reversible inside the alginate one. Both networks can be obtained in the presence of alginate lyase, but gel-sol transition of calcium-alginate cannot be obtained in the presence of gelatin.


Subject(s)
Alginates/chemistry , Gelatin/chemistry , Gelatin/metabolism , Phase Transition , Alginates/metabolism , Calcium/chemistry , Catalysis , Elasticity , Flavobacterium/enzymology , Gels/chemistry , Gels/metabolism , Glucuronic Acid/chemistry , Glucuronic Acid/metabolism , Hexuronic Acids/chemistry , Hexuronic Acids/metabolism , Macrocystis/metabolism , Molecular Structure , Polysaccharide-Lyases/metabolism , Rheology , Viscosity
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