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1.
J Dent Educ ; 84(3): 367-376, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32176342

RESUMEN

The aim of this study was to evaluate the contribution of virtual reality to the conventional analogic training environment and show the complementarity of conventional techniques and virtual reality in the learning of dental students. All 88 first-year dental students at a dental school in France in early 2019 were randomly assigned to one of two groups: group 1 (n = 45) was assigned to cavity preparations on a haptic simulator (Virteasy) and group 2 (n = 43) was assigned to conventional practical work on plastic analogue teeth (Kavo). Following three training sessions, the students in group 1 took a final exam on the same plastic analogue teeth exercise. The results showed improvement in the drilling skill of both groups. The simulator-trained group (group 1) had similar results to the plastic analogue-trained group (group 2) in the final test on a plastic analogue tooth. In this study, virtual reality allowed an assessment based on objective criteria and reduced the subjectivity of evaluations conducted on plastic analogue teeth. Considering the saving of supervision and teaching time as well as the material gain offered by virtual reality, the learning methods of haptic simulators are educational options that should be considered by dental educators.


Asunto(s)
Preparación de la Cavidad Dental , Educación en Odontología , Entrenamiento Simulado , Competencia Clínica , Simulación por Computador , Francia , Humanos , Estudiantes de Odontología , Interfaz Usuario-Computador
2.
BMC Health Serv Res ; 20(1): 130, 2020 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-32085770

RESUMEN

BACKGROUND: In the organization of health care and health care systems, there is an increasing trend towards integrated care. Policy-makers from different countries are creating policies intended to promote cooperation and collaboration between health care providers, while facilitating the integration of different health care services. Hopes are high, as such collaboration and integration of care are believed to save resources and improve quality. However, policy-makers are likely to encounter various challenges and limitations when attempting to turn these great ideas into effective policies. In this paper, we look into these challenges. MAIN BODY: We argue that the organization of health care and integrated care is of public concern, and should thus be of crucial interest to policy-makers. We highlight three challenges or limitations likely to be encountered by policy-makers in integrated care. These are: (1) conceptual challenges; (2) empirical/methodological challenges; and (3) resource challenges. We will argue that it is still unclear what integrated care means and how we should measure it. 'Integrated care' is a single label that can refer to a great number of different processes. It can describe the integration of care for individual patients, the integration of services aimed at particular patient groups or particular conditions, or it can refer to institution-wide collaborations between different health care providers. We subsequently argue that health reform inevitably possesses a political context that should be taken into account. We also show how evidence supporting integrated care may not guarantee success in every context. Finally, we will discuss how promoting collaboration and integration might actually demand more resources. In the final section, we look at three different paradigmatic examples of integrated care policy: Norway, the UK's NHS, and Belgium. CONCLUSIONS: There seems widespread agreement that collaboration and integration are the way forward for health care and health care systems. Nevertheless, we argue that policy-makers should remain careful; they should carefully consider what they hope to achieve, the amount of resources they are willing to invest, and how they will evaluate the success of their policy.

3.
J Dent Educ ; 2019 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-31818988

RESUMEN

The aim of this study was to evaluate the contribution of virtual reality to the conventional analogic training environment and show the complementarity of conventional techniques and virtual reality in the learning of dental students. All 88 first-year dental students at a dental school in France in early 2019 were randomly assigned to one of two groups: group 1 (n=45) was assigned to cavity preparations on a haptic simulator (Virteasy) and group 2 (n=43) was assigned to conventional practical work on plastic analogue teeth (Kavo). Following three training sessions, the students in group 1 took a final exam on the same plastic analogue teeth exercise. The results showed improvement in the drilling skill of both groups. The simulator-trained group (group 1) had similar results to the plastic analogue-trained group (group 2) in the final test on a plastic analogue tooth. In this study, virtual reality allowed an assessment based on objective criteria and reduced the subjectivity of evaluations conducted on plastic analogue teeth. Considering the saving of supervision and teaching time as well as the material gain offered by virtual reality, the learning methods of haptic simulators are educational options that should be considered by dental educators.

4.
J Contemp Dent Pract ; 20(2): 263-269, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-31058645

RESUMEN

AIM: The aim of this article was to promote a methodology in the endodontic management of complex premolars with multiple root canals Background: The success of endodontic treatment depends on a meticulous clinical and radiographic analysis, the creation of a suitable access cavity and chemical and mechanical preparation, followed by three-dimensional filling of the entire root canal system. Consequently, it is essential to look for the presence of additional root canals to prevent endodontic treatment failure Case description: Two cases are presented. The first case concerned a 50-year-old male patient of North African origin who consulted in the context of a global prosthetic restoration including endodontic treatment of the maxillary left first premolar (tooth no. 24). The second case concerned a 29-year-old male patient of North African origin who was referred to us by his primary care practitioner in an urgent context of pain and infection present for two weeks (tooth no. 44). In both cases, it was the in-depth radiographic analysis, combined with manual exploration under the surgical micro- scope, that led to the relatively rare identification of a third root canal. Shaping, disinfection and three-dimensional filling of the entire root canal system were then performed in accordance with widely validated protocols. CONCLUSION: The maxillary and mandibular premolars, due to their highly variable root canal system configuration and a number of root canals and roots, appear to be teeth for which treatment is potentially complex. The acuteness of digital-tactile sense and the advent of 3D imaging and optical aids optimize the treatment of all the root canals of a tooth Clinical significance: These case reports demonstrate the importance of clinical and radiographic inspections to guide practitioners in the search for additional root canals in premolars and promote a methodological approach.


Asunto(s)
Cavidad Pulpar , Mandíbula , Adulto , Diente Premolar , Humanos , Masculino , Maxilar , Persona de Mediana Edad , Tratamiento del Conducto Radicular
5.
Acta Clin Belg ; : 1-8, 2019 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-30896377

RESUMEN

OBJECTIVES: Health care systems worldwide are changing and taking new forms. The old, more hierarchically oriented, model with individual institutional and bilateral interactions between primary, secondary, tertiary and quaternary care is being replaced by an integrated and dynamic network model. We aim to look at what role university hospitals will play in this future organization of health care. METHOD: In this paper, we look at the relevant literature on the history of academic medicine and university hospitals. Subsequently, we look at the challenges university hospitals are facing according to contemporary literature on the topic. RESULTS: Our current model of academic medicine with its university hospitals finds its origin in the institutionalization of the academic mission in the late 18th century. Currently, the sustainability of the model is under immense pressure. University hospitals are facing economic challenges, teaching challenges and research challenges. However, there is reason to believe that they can continue to play a role of importance in tomorrow's medicine. The organization of health care is undergoing two important changes. The first is the evolution towards a more dynamic and integrated network model. University hospitals can become an important hub within this network. The second change is an evolution towards evidence based medicine and translational research. CONCLUSION: Due to their unique tripartite mission, we argue that university hospitals can continue to play an important and critical role in promoting evidence-based medicine and speedy translation of new evidence.

6.
Int J Integr Care ; 18(3): 6, 2018 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-30093844

RESUMEN

Much is changing in health care organization today. A perspective or paradigm that is gaining ever increasing momentum is that of translational, extramural and integrated care. Current research suggests many potential benefits for integrated care and health care networks but the ethical issues are less frequently emphasized. Showing that integrated care can be beneficial, does not mean it is automatically ethically justified. We will argue for three ethical requirements such health care networks should meet. Subsequently we will look at the mechanisms driving the formation of networks and examine how these can cause networks to meet or fail to meet these ethical requirements or obligations. The three mechanisms we will examine are government, civil society and market mechanisms, which, we argue, should be balanced properly. Each mechanism is able to provide a relevant ethical perspective to health care networks. However, when the balance is skewed towards a single mechanism, health care networks might fail to promote one or more of the ethical requirements.

7.
BMC Med Ethics ; 19(1): 52, 2018 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-29866194

RESUMEN

BACKGROUND: Health care organization is entering a new age. Focus is increasingly shifting from individual health care institutions to interorganizational collaboration and health care networks. Much hope is set on such networks which have been argued to improve economic efficiency and quality of care. However, this does not automatically mean they are always ethically justified. A relevant question that remains is what ethical obligations or duties one can ascribe to these networks especially because networks involve many risks. Due to their often amorphous and complex structure, collective responsibility and accountability may increase while individual responsibility goes down. MAIN BODY: We argue that a business ethics approach to ethical obligations for health care networks, is problematic and we propose to opt for a patient perspective. Using the classic four principles of biomedical ethics (justice, nonmaleficence, beneficence and autonomy) it is possible to identify specific ethical duties. Based on the principle of justice, health care networks have an ethical duty to provide just and fair access for all patients and to be transparent to patients about how access is regulated. The principle of nonmaleficence implies an obligation to guarantee patient safety, whereas the principle of beneficence implies an obligation for health care networks to guarantee continuity of care in all its dimensions. Finally, the principle of autonomy is translated into a specific obligation to promote and respect patient choice. Networks that fail to meet any of these conditions are suspect and cannot be justified ethically. CONCLUSIONS: Faced with daunting challenges, the health care system is changing rapidly. Currently many hopes ride on integrated care and broad health care networks. Such networks are the topic of empirical debate, but more attention should be given to the ethical aspects. Health care networks raise new and pressing ethical issues and we are in need of a framework for assessing how and when such networks are justified.


Asunto(s)
Bioética , Continuidad de la Atención al Paciente , Prestación de Atención de Salud/ética , Accesibilidad a los Servicios de Salud , Seguridad del Paciente , Autonomía Personal , Ética Basada en Principios , Discusiones Bioéticas , Prestación de Atención de Salud/organización & administración , Ética Médica , Humanos , Obligaciones Morales
8.
Health Care Anal ; 26(4): 362-379, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29594896

RESUMEN

The organisation of health care is rapidly changing. There is a trend to move away from individual health care institutions towards transmural integrated care and interorganizational collaboration in networks. However, within such collaboration and network there is often likely to be a pluralism of values as different health care institutions often have very different values. For this paper, we examine three different models of how we believe institutions can come to collaborate in networks, and thus reap the potential benefits of such collaboration, despite having different moral beliefs or values. A first way is the pragmatic way in which the different health care institutions avoid ethical reflection and focus on solutions. A second possible route is that of consensus where health care institutions base their collaboration on values that they all share. The third, and final, approach is that of compromise. Although moral compromise is often seen in a negative light, we argue that in many cases compromise might be necessary and ethically justified. In a final section, we will shift our focus from discussing various theoretical methods to allow collaboration to the potential content of consensus or compromise.


Asunto(s)
Diversidad Cultural , Prestación Integrada de Atención de Salud/ética , Prestación Integrada de Atención de Salud/organización & administración , Principios Morales , Integración de Sistemas , Comunicación , Consenso , Conducta Cooperativa , Humanos , Cultura Organizacional
9.
Am J Dent ; 30(3): 125-130, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29178756

RESUMEN

PURPOSE: To assess the influence of applicator tip diameter on the inclusion of porosities in three different flowable resin composites. METHODS: The initial porosity of three syringes [Filtek Supreme XTE Flowable (XTE), Grandio Flow (GRF), Gradia Direct Flo (GDF)] was determined by 3D tomography. 25 samples per syringe, i.e. 75 samples in total, were prepared using five applicator tips of different diameters (n= 5). The porosity of the 75 samples was assessed by 3D tomography. RESULTS: For each of the materials, the applicator tips, irrespective of type, all generated an increase in the average porosity percentage compared to the initial porosity of the syringes. For XTE and GRF, the applicator tips, irrespective of type, all generated a decrease in the average porosity volume compared to the initial average porosity volume in their respective syringes. Conversely, for GDF the average porosity volume of the samples was increased. Furthermore, for each of the materials, varying the diameter of the applicator tips had no significant influence on the porosity percentage and volume. Using the present study conditions, the applicator tip generated a variation in the initial porosity of the materials; however, the diameter of the tip had no influence on said variation. CLINICAL SIGNIFICANCE: It appears that practitioners can choose an applicator tip with a diameter that best suits the size and shape of the cavity to be filled using a syringe of flowable resin composite without this having any impact on the percentage and volume of porosities in the final filling of the cavity.


Asunto(s)
Resinas Compuestas/administración & dosificación , Resinas Compuestas/química , Instrumentos Dentales , Diseño de Equipo , Ensayo de Materiales , Porosidad , Microtomografía por Rayos X
10.
BMC Health Serv Res ; 17(1): 550, 2017 08 09.
Artículo en Inglés | MEDLINE | ID: mdl-28793893

RESUMEN

BACKGROUND: Multiple studies have investigated the outcome of integrated care programs for chronically ill patients. However, few studies have addressed the specific role hospitals can play in the downstream collaboration for chronic disease management. Our objective here is to provide a comprehensive overview of the role of the hospitals by synthesizing the advantages and disadvantages of hospital interference in the chronic discourse for chronically ill patients found in published empirical studies. METHOD: Systematic literature review. Two reviewers independently investigated relevant studies using a standardized search strategy. RESULTS: Thirty-two articles were included in the systematic review. Overall, the quality of the included studies is high. Four important themes were identified: the impact of transitional care interventions initiated from the hospital's side, the role of specialized care settings, the comparison of inpatient and outpatient care, and the effect of chronic care coordination on the experience of patients. CONCLUSION: Our results show that hospitals can play an important role in transitional care interventions and the coordination of chronic care with better outcomes for the patients by taking a leading role in integrated care programs. Above that, the patient experiences are positively influenced by the coordinating role of a specialist. Specialized care settings, as components of the hospital, facilitate the coordination of the care processes. In the future, specialized care centers and primary care could play a more extensive role in care for chronic patients by collaborating.


Asunto(s)
Enfermedad Crónica/terapia , Continuidad de la Atención al Paciente , Hospitales , Adulto , Cuidados Posteriores , Humanos , Cuidado de Transición
11.
J Clin Exp Dent ; 8(5): e534-e539, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27957266

RESUMEN

BACKGROUND: This study compared the storage modulus (E'), the loss modulus (E'') and the loss tangent (tan δ) of various flowable resin composites. MATERIAL AND METHODS: Grandio Flow (GRF), GrandioSo Heavy Flow (GHF), Filtek Supreme XTE (XTE) and Filtek Bulk Fill (BUL) flowable resins and Clinpro Sealant (CLI) ultra-flowable pit and fissure sealant resin were used. 25 samples were tested using a dynamical mechanical thermal analysis system in bending mode. Measurements were taken within a temperature range of 10 to 55°C. The results were statistically analyzed using mixed-effect and repeated-measure analysis of variance followed by paired multiple comparisons. RESULTS: For all the materials, the E' values decrease with temperature, whereas the tan δ values increase. Irrespective of the temperature, GHF and GRF present E' and E'' values significantly higher than all the other materials and CLI presents values significantly lower than all the other materials. Observation of the values for all the materials reveals a linear progression of the tan δ values with temperature. CONCLUSIONS: A variation in temperature within a physiological range generates modifications in mechanical properties without damaging the material, however. Filler content in volume terms appears to be the crucial parameter in the mechanical behavior of tested materials. Key words:Dynamic mechanical thermal analysis, elastic modulus, filler content, flowable resin composites, loss modulus, loss tangent.

12.
Int J Esthet Dent ; 10(1): 12-31, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25625125

RESUMEN

Amelogenesis imperfecta (AI) is a hereditary disorder caused by mutations of genes primarily involved in the enamel formation. Several different types of AI have been identified, based on the phenotype and on the mode of inheritance. Regardless of the type, the dental treatment tends to be the same, favoring the complete removal of the compromised enamel late in the patient's life. With the new dentistry guidelines that orient clinicians towards minimal invasiveness, it should be mandatory to intercept patients affected by AI earlier, not only to protect the dentition from further degradation but also to help patients improve their self-esteem. This article examines the restorative dentistry performed on a 24-year-old Caucasian female suffering from the hypoplastic type of AI, using only adhesive procedures. Due to the complex needs of the patient, an interdisciplinary approach was followed, involving orthodontics, periodontics, and restorative dentistry. A full-mouth adhesive rehabilitation was achieved by means of direct composite restorations, veneer/onlays and facial/palatal veneers. No elective endodontic therapy was necessary for restorative purposes. The esthetics, mechanics, and biological success were achieved and maintained. The bond to the enamel did not show signs of degradation (eg, discoloration or infiltration) even after 5 years of function. This is encouraging as it shows that adhesive techniques may be a reliable approach even in the presence of a compromised enamel layer.


Asunto(s)
Amelogénesis Imperfecta/rehabilitación , Cementos Dentales , Adulto , Femenino , Estudios de Seguimiento , Humanos , Resultado del Tratamiento , Adulto Joven
13.
J Clin Ethics ; 25(3): 207-18, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25192345

RESUMEN

Continuous sedation at the end of life is a practice that has attracted a great deal of attention. An increasing number of guidelines on the proposed correct performance of the practice have been drafted. All of the guidelines stress the importance of using sedation in proportion to the severity of the patient's symptoms, thus to reduce the patient's consciousness no more than is absolutely necessary. As different patients can have different experiences of suffering, the amount of suffering should, ideally, be assessed subjectively; that is, via communication with the patient. Continuously sedated patients are often unable to communicate, however, making subjective methods of pain assessment unusable. For these patients, the degree of consciousness is the sole available measure. It therefore seems important to adequately measure how deeply the patient is sedated, thereby allowing sedation to be increased when it is too light and decreased when it is too heavy. This is in accordance with the idea that reducing consciousness is not an ethically neutral act. Although consciousness measuring techniques are a hot topic in anesthesiology, almost no research exists on the use of such techniques in the context of continuous sedation at the end of life. This article aims to review existing techniques to measure consciousness and to evaluate their applicability, efficiency, and invasiveness for patients who are continuously sedated until death. Techniques commonly used to assess the depth of sedation in continuously sedated patients are basic clinical assessment and sedation scales, as they are often considered reliable and non-invasive. These techniques might not be very reliable, however, since it is known that some patients are nonresponsive and yet aware. Moreover, sedation scales require stimulation of the patient (for example prodding, shaking, or providing painful stimuli), and can thus be considered invasive of one's bodily integrity or dignity. Other techniques, such as EEG (electroencephalography) derivatives, may score better on reliability and invasiveness. Yet these have so far never been compared to sedation scale scores for patients receiving continuous sedation at the end of life. Therefore, we conclude that, for both clinical and ethical reasons, research into the efficiency and applicability of other techniques, such as derivatives of EEG, are urgently needed.


Asunto(s)
Sedación Consciente , Estado de Conciencia , Sedación Profunda , Electroencefalografía , Manejo del Dolor , Estrés Psicológico/terapia , Ética Clínica , Ética Médica , Humanos , Personeidad , Reproducibilidad de los Resultados , Cuidado Terminal/ética , Cuidado Terminal/métodos , Cuidado Terminal/normas
14.
BMC Anesthesiol ; 11: 13, 2011 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-21702937

RESUMEN

BACKGROUND: The wide range of fresh gas flow - vaporizer setting (FGF - FD) combinations used by different anesthesiologists during the wash-in period of inhaled anesthetics indicates that the selection of FGF and FD is based on habit and personal experience. An empirical model could rationalize FGF - FD selection during wash-in. METHODS: During model derivation, 50 ASA PS I-II patients received desflurane in O2 with an ADU® anesthesia machine with a random combination of a fixed FGF - FD setting. The resulting course of the end-expired desflurane concentration (FA) was modeled with Excel Solver, with patient age, height, and weight as covariates; NONMEM was used to check for parsimony. The resulting equation was solved for FD, and prospectively tested by having the formula calculate FD to be used by the anesthesiologist after randomly selecting a FGF, a target FA (FAt), and a specified time interval (1 - 5 min) after turning on the vaporizer after which FAt had to be reached. The following targets were tested: desflurane FAt 3.5% after 3.5 min (n = 40), 5% after 5 min (n = 37), and 6% after 4.5 min (n = 37). RESULTS: Solving the equation derived during model development for FD yields FD=-(e(-FGF*-0.23+FGF*0.24)*(e(FGF*-0.23)*FAt*Ht*0.1-e(FGF*-0.23)*FGF*2.55+40.46-e(FGF*-0.23)*40.46+e(FGF*-0.23+Time/-4.08)*40.46-e(Time/-4.08)*40.46))/((-1+e(FGF*0.24))*(-1+e(Time/-4.08))*39.29). Only height (Ht) could be withheld as a significant covariate. Median performance error and median absolute performance error were -2.9 and 7.0% in the 3.5% after 3.5 min group, -3.4 and 11.4% in the 5% after 5 min group, and -16.2 and 16.2% in the 6% after 4.5 min groups, respectively. CONCLUSIONS: An empirical model can be used to predict the FGF - FD combinations that attain a target end-expired anesthetic agent concentration with clinically acceptable accuracy within the first 5 min of the start of administration. The sequences are easily calculated in an Excel file and simple to use (one fixed FGF - FD setting), and will minimize agent consumption and reduce pollution by allowing to determine the lowest possible FGF that can be used. Different anesthesia machines will likely have different equations for different agents.

15.
Anesth Analg ; 111(2): 368-79, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19861357

RESUMEN

BACKGROUND: With the growing use of pharmacokinetic (PK)-driven drug delivery and/or drug advisory displays, identifying the PK model that best characterizes propofol plasma concentration (Cp) across a variety of dosing conditions would be useful. We tested the accuracy of 3 compartmental models and 1 physiologically based recirculatory PK model for propofol to predict the time course of propofol Cp using concentration-time data originated from studies that used different infusion schemes. METHODS: Three compartmental PK models for propofol, called the "Marsh," the "Schnider," and the "Schüttler" models, and 1 physiologically based recirculatory model called the "Upton" model, were used to simulate the time course of propofol Cp. To test the accuracy of the models, we used published measured plasma concentration data that originated from studies of manual (bolus and short infusion) and computer-controlled (target-controlled infusion [TCI] and long infusion) propofol dosing schemes. Measured/predicted (M/P) propofol Cp plots were constructed for each dataset. Bias and inaccuracy of each model were assessed by median prediction error (MDPE) and median absolute prediction error (MDAPE), respectively. RESULTS: The M/P propofol Cp in the 4 PK models revealed bias in all 3 compartmental models during the bolus and short infusion regimens. In the long infusion, a worse M/P propofol Cp at higher concentration was seen for the Marsh and the Schüttler models than for the 2 other models. Less biased M/P propofol Cp was found for all models during TCI. In the bolus group, after 1 min, a clear overprediction was seen for all 3 compartmental models for the entire 5 min; however, this initial error resolved after 4 min in the Schnider model. The Upton model did not predict propofol Cp accurately (major overprediction) during the first minute. During the bolus and short infusion, the Marsh model demonstrated worse MDPE and MDAPE compared with the 3 other models. During short infusion, MDAPE for the Schnider and Schüttler models was better than the Upton and the Marsh models. All models showed similar MDPE and MDAPE during TCI simulations. During long infusion, the Marsh and the Schüttler models underestimated the higher plasma concentrations. CONCLUSION: When combining the performance during various infusion regimens, it seems that the Schnider model, although still not perfect, is the recommended model to be used for TCI and advisory displays.


Asunto(s)
Anestésicos Intravenosos/administración & dosificación , Anestésicos Intravenosos/farmacocinética , Modelos Biológicos , Modelos Estadísticos , Propofol/administración & dosificación , Propofol/farmacocinética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anestésicos Intravenosos/sangre , Niño , Preescolar , Simulación por Computador , Diseño de Equipo , Humanos , Infusiones Intravenosas , Inyecciones Intravenosas , Persona de Mediana Edad , Monitoreo Intraoperatorio/instrumentación , Propofol/sangre , Reproducibilidad de los Resultados , Distribución Tisular , Adulto Joven
16.
Anesthesiology ; 111(4): 790-804, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19741484

RESUMEN

BACKGROUND: Propofol and sevoflurane display additivity for gamma-aminobutyric acid receptor activation, loss of consciousness, and tolerance of skin incision. Information about their interaction regarding electroencephalographic suppression is unavailable. This study examined this interaction as well as the interaction on the probability of tolerance of shake and shout and three noxious stimulations by using a response surface methodology. METHODS: Sixty patients preoperatively received different combined concentrations of propofol (0-12 microg/ml) and sevoflurane (0-3.5 vol.%) according to a crisscross design (274 concentration pairs, 3 to 6 per patient). After having reached pseudo-steady state, the authors recorded bispectral index, state and response entropy and the response to shake and shout, tetanic stimulation, laryngeal mask airway insertion, and laryngoscopy. For the analysis of the probability of tolerance by logistic regression, a Greco interaction model was used. For the separate analysis of bispectral index, state and response entropy suppression, a fractional Emax Greco model was used. All calculations were performed with NONMEM V (GloboMax LLC, Hanover, MD). RESULTS: Additivity was found for all endpoints, the Ce(50, PROP)/Ce(50, SEVO) for bispectral index suppression was 3.68 microg. ml(-1)/ 1.53 vol.%, for tolerance of shake and shout 2.34 microg . ml(-1)/ 1.03 vol.%, tetanic stimulation 5.34 microg . ml(-1)/ 2.11 vol.%, laryngeal mask airway insertion 5.92 microg. ml(-1) / 2.55 vol.%, and laryngoscopy 6.55 microg. ml(-1)/2.83 vol.%. CONCLUSION: For both electroencephalographic suppression and tolerance to stimulation, the interaction of propofol and sevoflurane was identified as additive. The response surface data can be used for more rational dose finding in case of sequential and coadministration of propofol and sevoflurane.


Asunto(s)
Anestesia , Anestésicos por Inhalación/efectos adversos , Anestésicos Intravenosos/efectos adversos , Éteres Metílicos/efectos adversos , Propofol/efectos adversos , Adolescente , Adulto , Algoritmos , Interpretación Estadística de Datos , Interacciones Farmacológicas , Electroencefalografía/efectos de los fármacos , Entropía , Femenino , Humanos , Máscaras Laríngeas , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Estudios Prospectivos , Sevoflurano , Adulto Joven
17.
Anesthesiology ; 111(4): 805-17, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19741485

RESUMEN

BACKGROUND: Conventional compartmental pharmacokinetic models wrongly assume instantaneous drug mixing in the central compartment, resulting in a flawed prediction of drug disposition for the first minutes, and the flaw affects pharmacodynamic modeling. This study examined the influence of the administration rate and other covariates on early phase kinetics and dynamics of propofol by using the enlarged structural pharmacokinetic model. METHODS: Fifty patients were randomly assigned to one of five groups to receive 1.2 mg/kg propofol given with the rate of 10 to 160 mg . kg(-1). h(-1). Arterial blood samples were taken frequently, especially during the first minute. The authors compared four basic pharmacokinetic models by using presystemic compartments and the time shift of dosing, LAG time. They also examined a sigmoidal maximum possible drug effect pharmacodynamic model. Patient characteristics and dose rate were obtained to test the model structure. RESULTS: Our final pharmacokinetic model includes two conventional compartments enlarged with a LAG time and six presystemic compartments and includes following covariates: dose rate for transit rate constant, age for LAG time, and weight for central distribution volume. However, the equilibration rate constant between central and effect compartments was not influenced by infusion rate. CONCLUSIONS: This study found that a combined pharmacokinetic-dynamic model consisting of a two-compartmental model with a LAG time and presystemic compartments and a sigmoidal maximum possible drug effect model accurately described the early phase pharmacology of propofol during infusion rate between 10 and 160 mg . kg(-1). h(-1). The infusion rate has an influence on kinetics, but not dynamics. Age was a covariate for LAG time.


Asunto(s)
Anestésicos Intravenosos/administración & dosificación , Anestésicos Intravenosos/farmacocinética , Hipnóticos y Sedantes/administración & dosificación , Hipnóticos y Sedantes/farmacocinética , Propofol/administración & dosificación , Propofol/farmacocinética , Adulto , Anciano , Algoritmos , Anestésicos Intravenosos/farmacología , Teorema de Bayes , Relación Dosis-Respuesta a Droga , Electroencefalografía/efectos de los fármacos , Femenino , Humanos , Hipnóticos y Sedantes/farmacología , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Monitoreo Intraoperatorio , Propofol/farmacología
18.
J Dent Child (Chic) ; 76(2): 149-55, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19619429

RESUMEN

PURPOSE: The purpose of this study was to evaluate the influence of photopolymerization mode with a light emitting diode (LED) lamp on the curing contraction kinetics and degree of conversion of 3 resin-based restorative materials. METHODS: The curing contraction kinetics of Admira (ADM), Filtek P60 (P60), and Filtek Flow (FLO) were measured by the glass slide method. The materials were exposed to light from a 1,000 mW/cm-(2) power LED lamp (Elipar Freelight 2) in 3 modes: 2 continuous modes of 20 and 40 seconds (C20 and C40), and 1 exponential mode (E20; 5 seconds of exponential power increase followed by 15 seconds of maximum intensity). The degree of conversion (DC) was measured for each of the materials, and each of the modes by Fourier transformed infra-red spectrometry. RESULTS: P60 had the significantly lowest final contraction and FLO the highest among all light exposure modes. The C20 and C40 modes did not produce any difference in contraction or degree of conversion. The E20 mode led to a significant slowing of contraction speed combined with greater final contraction. CONCLUSIONS: Use of a LED lamp (1,000 mW/cm2) in continuous mode reduces the exposure time by half for identical curing shrinkage and degree of conversion.


Asunto(s)
Resinas Compuestas/química , Luces de Curación Dental , Materiales Dentales/química , Metacrilatos/química , Siloxanos/química , Cinética , Ensayo de Materiales , Espectroscopía Infrarroja por Transformada de Fourier
19.
Anesth Analg ; 108(3): 828-34, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19224790

RESUMEN

BACKGROUND: The combination of propofol-remifentanil for procedural deep sedation in spontaneously breathing patients is characterized by the frequent incidence of side effects, especially respiratory depression. These side effects may be due to either the drug combination or the drug delivery technique. Target-controlled infusion (TCI) might optimize drug delivery. In this prospective, randomized, double-blind study in patients undergoing elective colonoscopy, we thus tried to answer two questions: first, if adding remifentanil to propofol surpasses the disadvantages of the combination of these two products, and second, if administration of remifentanil via TCI decreases the incidence of side effects, compared to manually controlled administration. METHODS: Patients undergoing elective colonoscopy were randomly assigned to receive remifentanil via manually controlled continuous infusion (MCI) (0.125 microg x kg(-1) x min(-1) for 2 min followed by a continuous infusion of 0.05 microg x kg(-1) x min(-1)), TCI remifentanil (1 ng/mL), or placebo (normal saline either as TCI or manual infusion of equivalent rate). All patients received TCI propofol, adjusted to a target concentration level that provided deep sedation in which patients were not responsive to verbal commands, but maintained spontaneous ventilation without assistance. RESULTS: Significantly more patients in the placebo group showed movement, cough and hiccup, which transiently interfered with the examination. There were no clinically significant differences in hemodynamic or recovery variables among all groups. Remifentanil administered via TCI resulted in a decrease in propofol requirements. The incidence of hypopnea and apnea was less frequent when remifentanil was administered via TCI compared to MCI (TCI n = 7, MCI n = 16, P < 0.05). CONCLUSION: The combination of remifentanil and propofol for deep sedation in spontaneously breathing patients, offered better conditions for colonoscopy than propofol used as a single drug. Remifentanil administered via TCI resulted in a decrease in propofol dosing and in a lower incidence in apnea and respiratory depression (TCI n = 7, MCI n = 16, P < 0.05), compared to manually controlled administration of remifentanil.


Asunto(s)
Sedación Profunda , Hipnóticos y Sedantes/administración & dosificación , Piperidinas/administración & dosificación , Adolescente , Adulto , Anciano , Colonoscopía , Electroencefalografía/efectos de los fármacos , Femenino , Hemodinámica/fisiología , Humanos , Hipnóticos y Sedantes/efectos adversos , Hipnóticos y Sedantes/farmacocinética , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Piperidinas/efectos adversos , Piperidinas/farmacocinética , Medicación Preanestésica , Propofol , Remifentanilo , Mecánica Respiratoria , Inconsciencia , Adulto Joven
20.
Anesth Analg ; 107(4): 1200-10, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18806028

RESUMEN

BACKGROUND: Closed-loop control of the hypnotic component of anesthesia has been proposed in an attempt to optimize drug delivery. Here, we introduce a newly developed Bayesian-based, patient-individualized, model-based, adaptive control method for bispectral index (BIS) guided propofol infusion into clinical practice and compare its accuracy and clinical feasibility under direct observation of an anesthesiologist versus BIS guided, effect compartment controlled propofol administration titrated by the anesthesiologist during ambulatory gynecological procedures. METHODS: Forty ASA patients were randomly allocated to the closed-loop or manual control group. All patients received midazolam 1 mg IV and alfentanil 0.5 mg IV before induction. In the closed-loop control group, propofol was administered using the previously described closed-loop control system to reach and maintain a target BIS of 50. In the manual control group, the propofol effect-site concentration was adapted at the discretion of the anesthesiologist to reach and maintain a BIS as close as possible to 50. Induction characteristics, performance, and robustness during maintenance and recovery times were compared. Hemodynamic and respiratory stability were calculated as clinical feasibility parameters. RESULTS: The closed-loop control system titrated propofol administration accurately resulting in BIS values close to the set point. The closed-loop control system was able to induce the patients within clinically accepted time limits and with less overshoot than the manual control group. Automated control resulted in beneficial recovery times. Our closed-loop control group showed similar acceptable clinical performance specified by similar hemodynamic, respiratory stability, comparable movement rates, and quality scores than the manual control group. CONCLUSIONS: The Bayesian-based closed-loop control system for propofol administration using the BIS as a controlled variable performed accurate during anesthesia for ambulatory gynecological procedures. This control system is clinical feasibility and can be further validated in clinical practice.


Asunto(s)
Anestesia por Circuito Cerrado , Anestesia Intravenosa , Anestésicos Intravenosos/administración & dosificación , Electroencefalografía , Propofol/administración & dosificación , Adolescente , Adulto , Procedimientos Quirúrgicos Ambulatorios , Teorema de Bayes , Femenino , Procedimientos Quirúrgicos Ginecológicos , Humanos , Infusiones Intravenosas , Persona de Mediana Edad , Modelos Estadísticos , Recuperación del Oocito
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