Anafilaxia en la evaluación preoperatoria / Anaphylaxis in the preanesthesia evaluation

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Electron microscopy of human peripheral nerves of clinical relevance to the practice of nerve blocks. A structural and ultrastructural review based on original experimental and laboratory data

ObjetivoEl principal objetivo fue describir la ultraestructura normal de los nervios periféricos y aportar todos aquellos aspectos relevantes para la práctica de los bloqueos anestésicos de los nervios periféricos.MétodoA partir de muestras de nervio ciático obtenidas de pacientes y muestras de saco dural, manguitos durales y nervios del plexo braquial disecados de cadáveres frescos se estudió la estructura del nervio periférico, incluyendo los fascículos y su composición topográfica, como así también la morfología de las cubiertas que revisten el nervio. Axones mielinizados, no mielinizados, fascículos, epineuro, perineuro y endoneuro fueron estudiados por microscopía óptica incluyendo métodos de inmunohistoquímica, y por microscopía electrónica de barrido y de transmisión. La estructura del perineuro, de los capilares intrafasciculares y su implicación en la barrera hematonerviosa fueron revisados.ResultadosCada uno de los elementos anatómicos fue analizado de forma individual, y los resultados fueron correlacionados con su impacto en la práctica clínica de la anestesia regional.ConclusionesLa práctica cotidiana de técnicas de anestesia regional y la visualización ecográfica de las estructuras nerviosas nos llevan a crear interpretaciones de la anatomía de los nervios cuyas repercusiones pueden ser importantes en la futura aplicación de la técnica. A este respecto, los resultados obtenidos en estudios ultraestructurales e histológicos están dirigidos a dar respuestas a esas dudas con origen en el entorno de las técnicas de la anestesia regional (AU)

AimThe goal is to describe the ultrastructure of normal human peripheral nerves, and to highlight key aspects that are relevant to the practice of peripheral nerve block anaesthesia.MethodUsing samples of sciatic nerve obtained from patients, and dural sac, nerve root cuff and brachial plexus dissected from fresh human cadavers, an analysis of the structure of peripheral nerve axons and distribution of fascicles and topographic composition of the layers that cover the nerve is presented. Myelinated and unmyelinated axons, fascicles, epineurium, perineurium and endoneurium obtained from patients and fresh cadavers were studied by light microscopy using immunohistochemical techniques, and transmission and scanning electron microscopy. Structure of perineurium and intrafascicular capillaries, and its implications in blood–nerve barrier were revised.ResultsEach of the anatomical elements is analyzed individually with regard to its relevance to clinical practice to regional anaesthesia.ConclusionsRoutine practice of regional anaesthetic techniques and ultrasound identification of nerve structures has led to conceptions, which repercussions may be relevant in future applications of these techniques. In this regard, the ultrastructural and histological perspective accomplished through findings of this study aims at enlightening arising questions within the field of regional anaesthesia (AU)

Utilización de fentanilo oral como premedicación en pacientes pediátricos / No disponible

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Preoxygenation by 8 deep breaths in 60 seconds using the Mapleson A (Magill), the circle system, or the Mapleson D system.

STUDY OBJECTIVE: To investigate the efficacy of preoxygenation by eight deep breaths in 60 seconds with the Mapleson A (Magill) system, the circle anesthesia system, or the Mapleson D system at an oxygen flow of 5 L/min or 10 L/min. DESIGN: Randomized, clinical study. SETTING: Operating room of a university hospital. SUBJECTS: 10 healthy volunteers. INTERVENTIONS: Volunteers underwent 6 preoxygenation trials consisting of 8 deep breaths in 60 seconds using the Mapleson A, Mapleson D, and the circle anesthesia systems at an oxygen flow of 5 L/min and 10 L/min. MEASUREMENTS: Fractional end-tidal oxygen concentration (F(ET)O(2)) was measured at 15-second intervals during preoxygenation. RESULTS: At an oxygen flow of 10 L/min, mean F(ET)O(2) values at 60 seconds of preoxygenation were comparable among the Mapleson A, Mapleson D, and the circle anesthesia systems (87 +/- 2.1%, 87 +/- 1.6%, 87 +/- 1.6%, respectively). Using an oxygen flow of 5 L/min, mean F(ET)O(2) values at 60 seconds were similar among the Mapleson A, Mapleson D, and circle anesthesia systems (74 +/- 4.1%, 75 +/- 2.6%, 74 +/- 4.4%, respectively); however, they were significantly lower than the corresponding values achieved at an oxygen flow of 10 L/min. CONCLUSIONS: The 8-deep-breaths in 60 seconds technique at an oxygen flow of 10 L/min can achieve adequate preoxygenation with the Mapleson A (Magill), Mapleson D, and circle anesthesia systems. Suboptimal preoxygenation is obtained with the three systems when the oxygen flow used is 5 L/min.

Oral PowderJect: a novel system for administering local anaesthetic to the oral mucosa.

OBJECTIVE: To assess the feasibility of using an Oral PowderJect (OPJ) to safely deliver a dose of dry powdered anaesthetic to the oral mucosa, producing an analgesic effect. DESIGN: Single centre: Part 1. An open, non-randomised safety study to check for mucosal damage; Part 2. A double blind sham controlled study to test the anaesthetic effect. SETTING: General practice. SUBJECTS: Adult, healthy volunteers (4 male, 10 female). MATERIALS AND METHODS: Part 1. An OPJ was used to deliver powdered lidocaine hydrochloride to the mucosal surface which was then checked visually for damage. Part 2. An OPJ containing lidocaine hydrochloride (active) or an empty OPJ (sham) was fired at the oral mucosa. The treated area and an untreated (control) site were probed with the back end of a dental needle. RESULTS: The OPJ delivery caused no visible mucosal damage. The median VAS score for pain on blunt probing was 10 for the OPJ active sites. This was significantly lower than the median VAS score for the sham sites at 30 (P = 0.0033) and the control sites at 58 (P < 0.0001). CONCLUSIONS: The OPJ can safely deliver powdered lidocaine hydrochloride to the oral mucosa without causing tissue damage. The OPJ delivery of powdered lidocaine hydrochloride can significantly reduce the pain from a blunt needle probe at 1 minute post delivery.

[Jet injection, a new method for the induction of anesthesia in children]. / Uj módszer az anaesthesia bevezetésére gyermekekben oltópisztollyal.

In order to shorten anaesthesia induction and to avoid pain of the intramuscular injection, we evaluated the efficacy and safety of midazolam given by a jet-injector, utilized solely for mass inoculations until now. Premedication with midazolam with the jet-injector, indeed, proved to be effective, rapid and safe in children. The best results were found in two groups receiving 150-200 microgram/kg midazolam. Within 5 minutes, it was easy to cannulate a vein in children injected by the jet-injector, whereas the effect of intramuscular injection developed slowly, within 7 minutes. In the latter group, cannulation of the vein was more difficult than in the other groups. The separation from the parents and anaesthetic induction were greatly facilitated by midazolam given by the jet-injector. Amnesia was present not only for anaesthetic induction but also for the injection. Recovery was not more prolonged in those premedicated with midazolam with the jet-injector than with midazolam administered by other routes: oral, rectal or nasal. The children induced with the aid of jet-injector had no unpleasant recall based on interviews with the patients and parents.

Routine pre-oxygenation using a Hudson mask. A comparison with a conventional pre-oxygenation technique.

Two techniques of pre-oxygenation were studied by continuous analysis of respired gases using a mass spectrometer in 10 healthy volunteers. The first was a conventional technique as commonly used in anaesthesia with a Bain system and tightly-fitting anaesthetic face-mask and an oxygen flow of 8 l.min-1. The second technique also used a Bain system with an oxygen flow of 8 l.min-1, but with a Hudson mask attached. The mean fractional end-tidal oxygen concentrations after 3 min were 0.812 and 0.46 respectively for each of the pre-oxygenation techniques against 0.16 for subjects breathing air. This represents a considerable increase in pulmonary oxygen reserve for both techniques. The second technique is not an alternative to conventional pre-oxygenation for emergency anaesthesia, but is a useful and simple method that is acceptable to both patient and anaesthetist in routine cases.