Muerte encefálica: consideraciones clínicas y legales / Brain death: clinical and legal considerations

Temor y ambivalencia son aspectos centrales en la matriz sociocultural relacionada con la muerte encefálica. Para el médico que debe evaluar pacientes y certificar el diagnóstico de muerte encefálica es crucial contar con una sólida comprensión de la fisiopatología, los criterios diagnósticos y de los exámenes complementarios. La existencia de un marco legal coherente y completo para el diagnóstico de muerte encefálica, independiente de la potencial donación de órganos, es ciertamente crucial para el médico. La relevancia que tiene en este sentido el fallo del Tribunal Constitucional de Chile del 13 de agosto de 1995 se analiza en profundidad.

Fear and ambivalence are key aspects of the sociocultural frame related to brain death. For those physicians who have to evaluate patients and certify the diagnosis of brain death a sound comprehension of the physiopathology, the clinical features and the complementary diagnostic test is crucial. The existence of a comprehensive and coherent legal regulation for the diagnosis of brain death, clearly independent of the potential of organ donation is also crucial. The relevance of the judgment given in 1995 by the Chilean Constitutional Court to provide these consistency is pointed out.

Unidades de tratamiento del ataque cerebrovascular (UTAC) en Chile / Stroke units in Chile

Stroke is a major public health problem in Chile, with an incidence similar to that of many industrialized nations, it accounts for 10% of all deaths and ranks 5th in number of healthy years of life lost to a disease. Organized inpatient care for stroke patients has been shown in systematic reviews of randomized clinical trials to be effective in preventing death, disability and institutional care, without increasing length of stay compared to usual care. Organized stroke unit care is provided by multidisciplinary teams that exclusively manage stroke patients in a dedicated ward (stroke ward) of which there are various possible models; acute stroke units which accept patients acutely but discharge early (usually within 7 days). This could include an "intensive" model of care with continuous monitoring and high nurse staffing levels; comprehensive (i.e. combined acute and rehabilitation) stroke units which accept patients acutely but also provide rehabilitation for at least several weeks if necessary. The way in which stroke units affect outcome is through reduction of complications of immobility and probably non specific neuroprotection. Stroke units should deliver high quality evidence based interventions to all eligible patients and should maintain high standards of care through staff training, guidelines and protocols, audit and quality assurance. Given that stroke is one of the fifty six health priorities in the health reform, inpatient stroke care should be delivered through stroke units organized in hospitals throughout Chile.

Predicción clínica de aspiración en pacientes con patología neurológica aguda / Clinical prediction of aspiration in acute neurological patients

Glottic dysfunction is a frequent condition in patients with acute neurological diseases: the incidence in stroke patients is between 45 - 51 percent increasing mortality three times. The principal complication is aspiration, which demands the involvement of pulmonary physicians and neurologists. The purpose of this study is to evaluate wet voice, water swallow test and cervical auscultation as clinical predictors of aspiration using endoscopical observation as a gold standard. During a period of one year we have prospectively evaluated these tests in acute neurological patients hospitalized in an intensive care unit. Wet voice, 3 oz water swallow test and cervical auscultation demonstrated sensibilities of 66.7, 88.9 and 77.8 percent, with a respective specificity of 85.2, 59.3 and 77.8 percent. Positive predictive values were 60, 42.1 and 53.8 percent, with negative predictive values of 88.5, 94.1 and 91.3 percent respectively. These results support the utility of clinical aspiration screening as a simple and valuable technique that can be done at the bedside.

La disfunción glótica es una entidad prevalente en enfermos con patología neurológica aguda: compromete aproximadamente entre el 45 al 51 por ciento de los pacientes que padecen un ataque cerebrovascular, incrementando su mortalidad en una relación de 3/1. Su complicación principal es el síndrome aspirativo, que involucra diversas especialidades, entre ellas enfermedades respiratorias y neurología. El propósito de este estudio ha sido evaluar la fonación húmeda, el test del vaso de agua y la auscultación cervical como indicadores clínicos de aspiración frente a la certificación nasolaringoscópica, considerada patrón estándar de evaluación al lado de la cama del enfermo. Evaluamos prospectivamente durante un año a pacientes neurológicos agudos hospitalizados en una unidad de tratamiento intensivo. La fonación húmeda, el test del vaso de agua y la auscultación cervical demostraron sensibilidades de 66,7, 88,9 y 77,8 por ciento, con una especificidad respectiva de 85,2, 59,3 y 77,8 por ciento. Los valores predictivos positivo fueron de 60, 42,1 y 53,8 por ciento, con valores predictivos negativo de 88,5, 94,1 y 91,3 por ciento respectivamente. Nuestros resultados permiten afirmar que el monitoreo clínico de aspiración es un instrumento sencillo y valioso, que puede ser realizado al lado de la cama del enfermo.

[Stroke units in Chile]. / Unidades de tratamiento del ataque cerebrovascular (UTAC) en Chile.

Stroke is a major public health problem in Chile, with an incidence similar to that of many industrialized nations, it accounts for 10% of all deaths and ranks 5th in number of healthy years of life lost to a disease. Organized inpatient care for stroke patients has been shown in systematic reviews of randomized clinical trials to be effective in preventing death, disability and institutional care, without increasing length of stay compared to usual care. Organized stroke unit care is provided by multidisciplinary teams that exclusively manage stroke patients in a dedicated ward (stroke ward) of which there are various possible models; acute stroke units which accept patients acutely but discharge early (usually within 7 days). This could include an "intensive" model of care with continuous monitoring and high nurse staffing levels; comprehensive (i.e. combined acute and rehabilitation) stroke units which accept patients acutely but also provide rehabilitation for at least several weeks if necessary. The way in which stroke units affect outcome is through reduction of complications of immobility and probably non specific neuroprotection. Stroke units should deliver high quality evidence based interventions to all eligible patients and should maintain high standards of care through staff training, guidelines and protocols, audit and quality assurance. Given that stroke is one of the fifty six health priorities in the health reform, inpatient stroke care should be delivered through stroke units organized in hospitals throughout Chile.

Does epinephrine improve the diagnostic accuracy of aspiration during labor epidural analgesia?

UNLABELLED: Aspiration reliably detects almost all IV multiorifice epidural catheters. Although a supplemental epinephrine 15-microg test dose may detect the rare IV catheter that does not yield blood on aspiration, false-positive epinephrine responses may cause some women to unnecessarily undergo repeat epidural catheter insertion. We evaluated 532 consecutive eligible patients requesting neuraxial labor analgesia. Patients were excluded if they had a contraindication to epinephrine or if they received intrathecal sufentanil/bupivacaine. Multiorifice catheters were inserted 4-6 cm into the epidural space as part of an epidural (n = 305) or combined spinal-epidural (n = 270) technique. We used aspiration, a lidocaine/epinephrine test dose, and bolus injection or infusion of dilute bupivacaine/sufentanil solutions to systematically determine IV, intrathecal, or epidural catheter location. Aspiration alone detected 47 of 48 intravascular catheters. There were 10 positive epinephrine responses: 2 were true positives, 7 were falsely positive (subsequent local anesthetic injection/infusion produced bilateral sensory change and analgesia), and 1 catheter was removed without further testing. Aspiration detected almost all intravascular catheters. Although the epinephrine test dose did detect one catheter that proved to be in a blood vessel, 87.5% of positive responses occurred in women without intravascular catheters. IMPLICATIONS: Epidural catheters may enter a blood vessel. Many clinicians use epinephrine to detect these catheters. Because aspiration alone detects almost all IV multiorifice catheters in laboring women, a subsequent epinephrine test dose may be unnecessary.

Labor epidural analgesia without an intravascular "test dose".

BACKGROUND: This study prospectively evaluated the ability of aspiration to detect intravascular placement of multiple-orifice epidural catheters. METHODS: Multiple-orifice, 20-gauge epidural catheters were inserted in 1,029 laboring women. Catheters were observed and aspirated for blood or cerebrospinal fluid before they were tested with 2 ml local anesthetic. If the results of this test were negative (no spinal anesthesia), the authors induced and maintained labor analgesia with a dilute local anesthetic and opioid solution. Patients with bilateral sensory change and effective labor analgesia had a "positive" epidural catheter. Women with unilateral block, inadequate analgesia despite some sensory change or those who delivered before being adequately assessed had "equivocal" catheters. Patients with neither analgesia nor sensory change had "negative" catheters. RESULTS: Aspiration and observation identified 60 intravenously placed catheters. Six catheters, which were placed initially in a blood vessel, were withdrawn until aspiration was negative, and then the anesthetic was infused. Four of these catheters were positive and two were still positioned intravascularly. Two other catheters may have been intravenously placed despite negative results of aspiration. The incidence of false-negative results of aspiration was 0 to 2 of 1,085 (upper limit of 95% CI, 0.2% to 0.4%). No patient showed any signs or symptoms of local anesthetic toxicity. CONCLUSIONS: Under the conditions of this study, which include using multiple-orifice catheters and dilute solutions of local anesthetic and opioid, aspiration and incremental drug injection alone safeguard against the risks of intravenously positioned local anesthetics. These results should not be extrapolated to other clinical settings without further study.

Properties of endodontic hand instruments used in rotary motion. Part 3. Resistance to bending and fracture.

Bending and torsional properties of 24 different types of nickel-titanium K-files, titanium-aluminium K-files and reamers, conventional stainless steel K-files and reamers, and flexible stainless steel instruments were investigated corresponding to ISO 3630-1 by determination of the bending moment on the one hand and the torque and angular deflection on the other. Numbers 15, 25, and 35 instruments were tested with a sample size of 10 instruments for each type and size. In ascending order of bending moment the instruments ranked: nickel-titanium K-files, titanium-aluminium K-files and reamers, flexible stainless steel instruments, conventional stainless steel K-files, and reamers. Nickel-titanium, titanium aluminium, and flexible stainless steel instruments displayed lower torque values than conventional stainless steel K-files and reamers. The average angular deflection ranged from 380 degrees (#15 reamer) to 2370 degrees (#35 K-file). Overall, the fracture risk of the instruments tested in this study was comparably low.

Properties of endodontic hand instruments used in rotary motion. Part 2. Instrumentation of curved canals.

The shaping abilities of nickel-titanium K-files, stainless steel reamers, K-files, and flexible stainless steel instruments with conventional cutting tips and with modified noncutting tips were investigated under standardized conditions using a computer-driven testing device simulating the clinical use of the instruments. Simulated root canals with a 42-degree curvature were sequentially enlarged from #15 to #35. Undesirable changes in the canal shape as a result of instrumentation occurred in all cases. None of the instruments were able to remove material on the whole length of the inner side of the curvature, whereas all instruments removed material on the whole length of the outer side of the curvature, resulting in slight to severe bulging. The extent of undesirable changes in the canal shape depended typically of the type of instrument used. Best instrumentation results were obtained with flexible instruments with noncutting tips.

Properties of endodontic hand instruments used in rotary motion. Part 1. Cutting efficiency.

Cutting efficiency of 24 different types of endodontic hand instruments, which are primarily designed for a rotary (reaming) working action, was investigated under standardized conditions. With a computer-driven testing device, resin specimens with simulated cylindrical canals were instrumented using a defined working motion simulating the clinical use of the instruments. Maximum penetration depth was the criterion for cutting efficiency. Sample size was 12 instruments for each type and size (#25 and #35). Nitinol K-files showed the least cutting efficiency. Stainless steel reamers and especially K-files showed better cutting efficiency than Nitinol K-files. Flexible stainless steel instruments displayed the best results. With regard to cutting efficiency, flexible stainless steel instruments were clearly superior to stainless steel reamers and K-files, and especially to Nitinol K-files.

Root canal instruments for manual use: cutting efficiency and instrumentation of curved canals.

The cutting efficiency of different endodontic hand instruments and the effects of instrumentation on curved canal shape were investigated under standardized experimental conditions using an automatic testing device. Cutting efficiency in rotary motion was assessed by determination of the maximum penetration depth of the instruments into a cylindrical canal in a special resin block (size 25 and size 35 instruments). Changes in canal shape were determined by instrumentation of standardized canals (42 degrees curvature) incrementally from size 15 to size 35. Except in the case of one instrument, size 35, in both sizes tested flexible instruments reached significantly (P < 0.05) greater maximum penetration depths than conventional reamers or K-files. Changes in the canal shape differed significantly between the different instruments in 13 of the 14 measuring points. Drastic undesirable changes in the canal shape (e.g. straightening or zip and elbow) occurred after instrumentation with reamers and K-files, but these changes were less noticeable after instrumentation with flexible instruments with conventional tips. After instrumentation with flexible instruments with modified tips there were few undesirable changes in shape. The conclusion could be drawn that flexible instruments, especially those with modified tips, were clearly superior to conventional reamers and K-files with regard to cutting efficiency and instrumentation of curved canals.

Reaction of inflamed periapical tissue to intracanal medicaments and root canal sealers.

The effects of different intracanal medicaments and zinc oxide-eugenol based root canal sealers on an experimentally induced apical periodontitis were studied histologically in mesial roots of lower molars of Wistar rats. After root canal instrumentation each canal was filled either with an intracanal medicament twice for 3 days each time or with a sealer for 21 days. The intracanal medicament chlorophenol caused periapical tissue damage. P-chloroxylenol-camphor lead to periapical improvement as did 5% sodium-hypochlorite. 12% sodium-hypochlorite gave tissue damage. After intracanal medication with an aqueous suspension of calcium hydroxide periapical repair was clearly visible. A combination of a corticoid and an antibiotic appeared to induce damage of the periapical tissues. The root canal sealers Endomethasone and N2 essentially impaired periapical repair. The results were acceptable for Aptal-Zink-Harz root canal fillings after 21 days as well as after 56 days.

Organophosphate sensitive and insensitive carboxylesterases in human skin.

The influence of paraoxon and bis(4-nitrophenyl)phosphate (BNPP) on carboxylesterases of human skin is assayed. Both organophosphates have frequently been used as inhibitors of carboxylesterases of the B-esterase type. Homogenates from carefully washed skin have no paraoxon-cleaving activity and very little phosphodiesterase activity with BNPP. However, a number of skin enzymes are irreversibly inhibited by these compounds. Three zones of carboxylesterase bands can be detected in the soluble fraction of skin homogenate by isoelectric focusing. One zone containing 5 esterase bands in the pI-range of 6.7-7.0 and another zone at pI 4.9 are insensitive to organophosphate inhibition. The zone with the main esterase activities contains at least 6 bands in the range of pI 5.7-6.2. All of these are quickly and completely inhibited by paraoxon. The complex inhibition kinetics with BNPP and observations with differing substrates point to a functional heterogeneity. The esterases with pI-values in the range of 5.7 to 6.2 and the esterase with pI 4.9 can be enriched using anion exchange chromatography and FPLC. From the data presented here it is concluded that human skin contains at least four different carboxylesterases which act on simple aromatic esters.

[Solubility of enamel and synthetic hydroxylapatite on irradiation]. / Uber das Lösungsverhalten von Zahnschmlez und synthetischem Hydroxylapatit nach Bestrahlung.

The effect of Co 60-irradiation (70 Gy) on pulverized human enamel and synthetic hydroxyapatite was studied in vitro. Irradiated and non-irradiated samples were experimentally demineralized (pH 5.1) during a period of 28 days. In terms of solubility, defined as the equilibrium of saturation, there was no statistically significant difference between irradiated and non-irradiated enamel. However, in terms of solubility rates, defined as the amount of dissolved substance during the demineralization period, irradiated enamel showed a statistically significantly higher solubility rate than non-irradiated enamel. There was no effect of Co 60-irradiation on synthetic hydroxyapatite.

[Study of properties of electrical root canal length measuring instruments]. / Untersuchungen über Eigenschaften von elektrischen Wurzelkanal-Längenmessgeräten.

Six electrical instruments for locating the apex during endodontic treatment were tested in a laboratory investigation about currency, frequency and scale. Further we looked, whether all instruments show coincidence in the apex point. There are great differences in currency, frequency and scale (apex point). The reproducibility and the precision of an apex locator--at the time--depends an many factors and thus indication seems to be very limited.

[Ultrastructural findings of the muscles around lip clefts]. / Ultrastrukturelle Befunde der Muskulatur im Lippenspaltbereich.

Our electron microscopic observations show alterations of the muscles near the cleft margins confirming the theory resulting from light microscopic and immunohistochemical findings that the myogenic structures surrounding cleft margins are inferior tissue that is capable neither of regeneration nor of normal function. The clinical implication derived from these observations is that the tissue in the vicinity of the clefts should be generously excised when doing cheiloplasties.

[Auxiliary MR spectroscopy of blood plasma in the diagnosis of malignant head and neck tumors]. / NMR-Spektroskopie von Blutplasma als Hilfsmittel in der Diagnostik von malignen Tumoren im Kopf-Halsbereich.

Magnetic resonance (MR) spectroscopy of an EDTA or citrate plasma sample (also referred to as "Fossel test" after Fossel, who first described it) started out as a promising method for fast and simple diagnosis of malignancies. Although the results of our own studies of the head and neck area confirm this tendency, we believe--and so do meanwhile also other investigators--that the clinical use of this test in its present form is not feasible because of lacking specificity.