Anestesia espinal parte III. Mecanismos de acción / Spinal anesthesia part III. Mechanisms of action

Spinal anesthesia is a widely used technique in medical practice nowadays. Generally, nervous blockage is determined by three main factors. The first of them is the distribution of the local anesthetic in the cerebrospinal fluid (CSF), which can be affected by numerous factors, the most important of them being CSF volume. The second is absorption, which is greatest at the sites with higher drug concentration: this is the result of the accessibility, lipidic content and vascular irrigation of each area. The last of these factors is elimination, mediated mainly by the irrigation of the different compartments, and whose order differs from the mirror image of the onset's action order. The previously mentioned elements are the main sources of variation for the time needed to achieve desired effects, order in which fibers are affected and differential blockage. This text describes the principal mechanisms through which spinal anesthesia works, and the factors which can result in variations of its results.

La anestesia espinal es una técnica ampliamente utilizada en la práctica clínica. Por lo general, el bloqueo nervioso está determinado por tres factores principales. El primero es la distribución del anestésico local en el líquido cefalorraquídeo (LCR), que a su vez se ve afectado por una gran variedad de factores, destacando entre estos el volumen de LCR. El segundo es la absorción, la cual es mayor en los sitios en donde la concentración del fármaco también lo es: para esto afecta la accesibilidad, el contenido lipídico y la irrigación vascular de cada zona. El último factor es la eliminación, mediada principalmente por la irrigación de los distintos compartimentos, y cuyo orden es distinto a la imagen especular del inicio de acción. Los factores mencionados son los principales determinantes de los tiempos de demora de los bloqueos, el orden en el que se logra su acción en las distintas fibras y el bloqueo diferencial. Este texto pretende describir los principales mecanismos de acción mediante los cuales actúa la anestesia espinal y los factores que pueden determinar diferencias en los resultados de esta.

Safety and Efficacy of Prolonged Use of Dalbavancin in Bone and Joint Infections.

Dalbavancin is a lipoglycopeptide with potent activity against Gram-positive microorganisms, a long half-life, a favorable safety profile, and a high concentration in bone, which makes it an interesting alternative for treatment of osteoarticular infections. We performed a multicentric retrospective study of all patients with an osteoarticular infection (septic arthritis, spondylodiscitis, osteomyelitis, or orthopedic implant-related infection) treated with at least one dose of dalbavancin between 2016 and 2017 in 30 institutions in Spain. In order to evaluate the response, patients with or without an orthopedic implant were separated. A total of 64 patients were included. Staphylococcus epidermidis and Staphylococcus aureus were the most frequent microorganisms. The reasons for switching to dalbavancin were simplification (53.1%), adverse events (25%), or failure (21.9%). There were 7 adverse events, and no patient had to discontinue dalbavancin. In 45 cases, infection was related to an orthopedic implant. The implant material was retained in 23 cases, including that in 15 (65.2%) patients that were classified as cured and 8 (34.8%) that presented improvement. In 21 cases, the implants were removed, including those in 16 (76.2%) cases that were considered successes, 4 (19%) cases were considered improved, and 1 (4.8%) case that was considered a failure. Among the 19 cases without implants, 14 (73.7%) were considered cured, 3 (15.8%) were considered improved, and 2 (10.5%) were considered failures. The results show that dalbavancin is a well-tolerated antibiotic, even when >2 doses are administered, and is associated with a high cure rate. These are preliminary data with a short follow-up; therefore, it is necessary to gain more experience and, in the future, to establish the most appropriate dose and frequency.

Cirugía plástica y sus complicaciones: ¿en qué debemos fijarnos? / Plastic surgery and its complications: what we should look?

Plastic surgeries are becoming more popular, being performed on a varied type of population and often as office-based procedures. Despite being highly elective procedures, they have risks and complications, which should be reported to patients by the health personnel. The most frequently performed procedures are breast augmentation and body liposuction. The most relevant complications associated with plastic surgery are pulmonary embolism and deep vein thrombosis, which is the leading cause of mortality in this type of surgery. Other complications are local anesthetics intoxication secondary to the use of tumescent solution in body liposuction, inadequate management of perioperative intravenous fluids, mild hypothermia and severe pain after surgery caused by poor postoperative analgesia. It is essential to prevent the described complications, which significantly increase morbidity, mortality and hospital stay. The perioperative measures that have demonstrated effectiveness in reducing perioperative risk are thromboprophylaxis, depending on the thrombotic risk categorization of each patient and the use of adequate concentrations of lidocaine and vasoconstrictor in the tumescent solution. Appropriate temperature monitorization and use of conservation measures in patients with exposure of large body surfaces is also an important issue, as is diligence in intraoperative fluid balance and administration of intravenous multimodal analgesia, adjusted to the magnitude of the surgery. In order to achieve this, proper communication between the surgical team, anesthesiologists and nurses is vital, as it permits implementation of specific measures that permit adequate monitorization, prevention of complications and analgesic management described above.

Las cirugías plásticas son cada vez más frecuentes, abarcando todo tipo de población y realizándose incluso en la consulta médica. Las cirugías estéticas más frecuentemente realizadas son aumento mamario y liposucción corporal. Son procedimientos quirúrgicos sumamente electivos, pero poseen riesgos y complicaciones asociados, los cuales deben ser debidamente informados a los pacientes. La complicación más relevante es el tromboembolismo pulmonar, generalmente asociado a trombosis venosa profunda, el cual es la primera causa de mortalidad en este tipo de cirugías. Otras complicaciones destacadas son intoxicación por anestésicos locales secundaria al uso de solución tumescente para liposucción corporal, inadecuado manejo de fluidos endovenosos perioperatorios, hipotermia inadvertida y dolor intenso por deficiente analgesia postoperatoria. Estas complicaciones aumentan significativamente la morbimortalidad y estadía hospitalaria, por lo que su prevención es fundamental. Las medidas que han demostrado disminución significativa de los riesgos y complicaciones perioperatorios en cirugía plástica son tromboprofilaxis según categorización del riesgo trombótico de cada paciente, revisar que la solución tumescente administrada para liposucciones tenga concentraciones adecuadas de lidocaína (idealmente utilizando vasoconstrictores coadyuvantes), utilizar medidas adecuadas de monitorización y conservación de temperatura en pacientes con gran superficie corporal expuesta, ser acuciosos en el balance intraoperatorio de fluidos endovenosos y administrar analgesia postoperatoria multimodal, balanceada y acorde a la magnitud del dolor. Es vital una adecuada comunicación entre el equipo de cirujanos, anestesiólogos, enfermeros e instrumentadores quirúrgicos con el objetivo de conocer las particularidades de las distintas cirugías plásticas e implementar las medidas de monitorización, prevención de complicaciones y manejo analgésico antes descritas.

Comunicación masiva del ramo superficial del nervio radial con el nervio cutáneo antebraquial lateral, implicancias anatomo-clínicas: reporte de un caso / Massive communication between the superficial branch of radial nerve and lateral cutaneous nerve of the forearm, anatomical and clinical implications: a case report

La distribución de los ramos nerviosos sensitivos en el borde lateral y en el dorso de la mano han sido descritos con mayor exactitud en las últimas décadas, debido al avance de las técnicas de electrodiagnóstico que ofrecen un alto rendimiento, las cuales han permitido detectar que alrededor del 40 por ciento de la población examinada presenta algún grado de variación anatómica en el territorio de distribución de los nervios involucrados. En este caso presentamos una variación anatómica bilateral extremadamente rara, que involucra al ramo superficial del nervio radial (NRS) y al nervio cutáneo antebraquial lateral (CABL); donde NRS se conecta de forma íntegra con el ramo medial de CABL, formándose así un tronco común (TC) que se distribuye por la región dorsal de la mano. Por su parte, el ramo lateral de CABL se distribuye por el borde lateral de la mano, ocupando el territorio cutáneo de NRS; situación que aparece descrita en la literatura especializada sólo una vez. El hallazgo de estas variaciones anatómicas en los cadáveres disecados con fines docentes en nuestro Departamento de Anatomía, tienen un valor formativo indiscutible para nuestros alumnos de pregrado y especialmente para los de postgrado, quienes pueden comprobar de primera mano la enorme variabilidad del ser humano, valorando las implicancias en la clínica diaria de este conocimiento anatómico.

The distribution of the sensory nerve branches in the lateral and the back of the hand have been described more accurately in the past decades due to advancement of high performance electro-diagnostic variation techniques, which indicate that approximately 40 percent of the population examined have some degree of anatomical variation in the distribution area of the nerves involved. In this case we present an extremely rare, bilaterally detected variation, involving the superficial branch of the radial nerve (SBRN) and lateral antebrachial cutaneous nerve of the forearm (LABCN), where the SBRN is connected integrally with the medial branch of LABCN, forming a common trunk (CT) distributed by the dorsal region of the hand. Furthermore, the lateral branch of the LABCN is distributed in the lateral border of the hand, occupying the area of the skin of the SBRN, an event that is described only once in the literature. The discovery of these anatomical variations in dissected cadavers for teaching purposes, in the Department of Anatomy, have an undeniable educational value for our undergraduate students and especially for the graduate who can observe the enormous variability of human beings first hand, and value implications of this anatomical knowledge in daily clinic.

[Evaluation of 2 tuberculosis chemoprophylaxis regimens in patients infected with human immunodeficiency virus. The GECMEI Group]. / Evaluación de dos pautas de quimioprofilaxis tuberculosa en pacientes infectados por el virus de la inmunodeficiencia humana. Grupo GECMEI.

OBJECTIVE: To assess the compliance, tolerance and efficacy of a short chemoprophylaxis regimen (IR) for tuberculosis using isoniazid (INH) plus rifampin (RIF) during 3 months versus a standard regimen (I) of isoniazid during 12 months in HIV positive patients. MATERIAL AND METHODS: Prospective, comparative, randomized and open clinical trial in four general hospitals and one prison hospital of Castilla-La Mancha. Prophylaxis was administered to PPD-positive patients and to anergic patients according to the CDC recommendations (1991). Patients were randomized in two treatment groups: regimen IR, isoniazid 300 mg daily and rifampin 600 mg daily; regimen I, isoniazid 300 mg during 12 months. RESULTS: 133 patients were included, 64 to regimen I and 69 to regimen IR. Regimen IR had a better tolerance with a 28% of adverse effects versus 55% in regimen I. Hepatotoxicity was more frequent in regimen I with a RR = 2.2 (CI 95% 1.23-4.01). Severe hepatotoxicity leading to treatment withdrawal was related to drug administration time and was more frequent in the 12 months regimen group. Short regimen showed a better compliance, without significant differences. Tuberculosis incidence rate was a 4.23 cases/100 persons--year for regimen I and 2.08 in regimen IR, with a relative risk for developing tuberculosis with regimen IR group of 0.51 (CI 95% 0.09-2.8) versus regimen I group, without statistical significance. Prison stay was associated to a significant risk for tuberculosis, regardless of both regimens (RR = 9.2 CI 95%, 1.06-80.2). CONCLUSIONS: In HIV-infected patients with PPD(+) or anergic, regimen with IR is at least as effective as regimen I for preventing the development of tuberculous disease, and has less adverse effects.

Hipoxemia nocturna después de cirugía abdominal: factores asociados y rol de la oxigenoterapia / Nocturnal hypoxemia after abdominal surgery: associated factors and usefulness of oxygen therapy

Fifteen elective patients (6 M, 9 F, 51+-8 years old) scheduled for laparotomy (n=8) or laparoscopy (n=7) were studied. Ventilatory parameters and pulse oximetry were measured pre and postoperatively. Patients were randomly assigned to receive oxygen by nasal cannula either during the first or the second postoperative night. PONH (Sat2 85) developed in seven patients (47 per cent)of which four had undergone laparoscopic surgery. PONH was more frequent in mildly obese patients and those presenting preoperative hypoxemia (p=0.03). Peak flow was lower in patients presenting PONH (p=0.04). In five patients, PONH was associated with significant tachycardia. Oxygen administration was associated with a higher SatO2 and prevented PONH in 6/7 patients. PONH is a common event in patients older than 40 years scheduled for open or laparascopic abdominal surgery, and develops more frequently in those with preoperative nocturnal hypoxemia and greater ventilatory impairment. PONH can be prevented, most of the time, with oxygen administration