Vértigo con nistagmo vertical por administración de morfina intratecal y reversión con naloxona / Vertigo and vertical nystagmus associated with intrathecal morphine administration and resolution by naloxone

La anestesia regional combinada es utilizada frecuentemente como herramienta para el tratamiento del dolor postoperatorio. Los efectos secundarios de los opioides utilizados por esta vía son similares a los que se presentan luego de la administración sistémica. La aparición de vértigo con nistagmo vertical es un efecto adverso muy pocas veces descripto con el uso de morfina por vía intratecal, epidural o endovenosa. Comunicamos el caso de un paciente que presentó esta complicación en el postoperatorio de una nefrectomía parcial, luego de la administración de morfina intratecal, con resolución completa mediante el uso de naloxona endovenosa.

Combined regional anesthesia is frequently used as a tool for management of postoperative pain. The profile of side effects of the opioids used via this route is similar to those occurring after systemic administration. The onset of vertigo with vertical nystagmus is an adverse effect rarely described after the use of intrathecal, epidural or intravenous morphine. We report the case of a patient who presented this complication in the postoperative period of a partial nephrectomy, after the administration of intrathecal morphine, with complete resolution by intravenous naloxone.

Efeitos hemodinâmicos e metabólicos da terlipressina ou naloxona na ressuscitação cardiopulmonar: estudo experimental, randomizado e controlado / Hemodynamic and metabolic effects of terlipressin or naloxone in cardiopulmonary resuscitation: an experimental, randomized and controlled trial

Introdução: O prognóstico da parada cardiorrespiratória (PCR) em ritmo não chocável (assistolia/atividade elétrica sem pulso) é ruim e não melhorou significativamente nas últimas décadas. Embora a epinefrina seja o vasopressor recomendado, há evidências de que ela eleva o consumo de oxigênio, reduz a pressão de perfusão subendocárdica, causa grave disfunção miocárdica e piora a microcirculação cerebral durante a ressuscitação cardiopulmonar. Vasopressina foi muito estudada nos últimos anos e não se mostrou superior à epinefrina. Naloxona e terlipressina têm sido cogitadas como potenciais vasopressores no tratamento da PCR, entretanto há poucos estudos publicados e os resultados são controversos e inconclusivos. Objetivos: Avaliar os efeitos hemodinâmicos e metabólicos da terlipressina ou naloxona na PCR induzida por hipóxia e compará-las com o tratamento-padrão (epinefrina ou vasopressina). Métodos: Estudo experimental, randomizado, cego e controlado. Ratos Wistar adultos, machos, foram anestesiados, submetidos a traqueostomia e ventilados mecanicamente. A PCR foi induzida por obstrução da traqueia e mantida por 3,5 minutos. Em seguida, os animais foram ressuscitados de forma padronizada e randomizados em um dos grupos: placebo (n = 7), vasopressina (n = 7), epinefrina (n = 7), naloxona (n = 7) ou terlipressina (n = 21). Variáveis hemodinâmicas foram monitorizadas durante todo o experimento (via cateter intra-arterial e intraventricular) e mensuradas na base, no 10o (T10), 20o (T20), 30o (T30), 45o (T45) e 60o (T60) minutos pós-PCR. Amostras de sangue arterial foram coletadas para gasometria, hemoglobina, bioquímica e lactato em quatro momentos [base, 11o (T11), 31o (T31), e 59o (T59) minutos pós-PCR]. Resultados: Os grupos foram homogêneos e não houve diferença significativa entre eles nas variáveis de base...

Introduction: The prognosis of cardiac arrest (CA) with nonshockable rhythm (asystole/pulseless electrical activity) is poor and not improved significantly in recent decades. Epinephrine is the most commonly used vasopressor, although there is evidence that its use correlates with myocardial dysfunction and worsens the cerebral microcirculation. Vasopressin has been widely studied in recent years and was not superior to epinephrine. Naloxone and terlipressin have been considered as potential vasopressors in the treatment of CA, however, there are few published studies and the results are controversial and inconclusive. Objectives: To evaluate the hemodynamic and metabolic effects of terlipressin or naloxone in CA induced by hypoxia and compare with standard treatment with epinephrine or vasopressin. Methods: Experimental, randomized, blinded and controlled trial. Adult male Wistar rats were anesthetized, the proximal trachea was surgically exposed, and a 14-gauge cannula was inserted 10 mm into the trachea to the larynx. They were mechanically ventilated and monitored. The CA was induced by tracheal obstruction and maintained for 3.5 minutes. Subsequently, the animals were resuscitated using standard maneuvers and randomized to one of groups: placebo (n=7), vasopressin (n=7), epinephrine (n=7), naloxone (n=7) or terlipressin (n=21). Hemodynamic variables were monitored throughout the study (intra-arterial and intra-ventricular catheter) and measured at baseline, in the 10th (T10), 20th (T20), 30th (T30), 45th (T45) and 60th (T60) minute post-cardiac arrest. Arterial blood samples were collected for hemoglobin, biochemistry, blood gases and lactate at four moments: baseline, 11th (T11), 31st (T31) and 59th (T59) minute post-cardiac arrest. Results: The groups were homogenous and there were no significant differences among them regarding the baseline variables. The return of spontaneous circulation (ROSC) occurred in 57% of the animals (4 of 7) in the placebo...

Tratamiento del Síndrome de Retiro de Opiáceos: síndrome de retiro descrito como subjetivamente severo y objetivamente moderado / Drug therapy of opioid withdrawal

Si bien la dependencia a opiáceos es de baja frecuencia de aparición en nuestro medio, es importante conocer su manejo ya que requiere tratamiento farmacológico en la mayoría de los casos. En la actualidad, en nuestro país, se podría clasificar a las distintas poblaciones de pacientes capaces de presentar un síndrome de retiro a opiáceos en: pacientes sometidos a tratamiento crónico con opiáceos, pacientes internados en unidades de cuidados intensivos, neonato de madre adicta y pacientes adictos provenientes de la población en general o ligada al sistema de salud. Los programas de desintoxicación son caracterizados típicamente por un bajo índice de finalización del tratamiento y un alto índice de recaída. El síndrome de retiro a opiáceos es subjetivamente severo y objetivamente moderado y las metas de la terapia en el Síndrome de Retiro de Opiáceos son: evitar o reducir los síntomas objetivos y subjetivos de abstinencia; prevenir o tratar las complicaciones más serias; tratar las enfermedades psiquiátricas preexistentes o concurrentes; reducir la frecuencia o la severidad de las recaídas y rehabilitar a largo plazo.

Although the opiate dependence is of low frequency in our midst, it is important to know its management because it requires medical treatment in most cases. At present, in our country, we may classify the different patient populations able to submit an opioid withdrawal syndrome in patients undergoing chronic treatment with opioids, patients in intensive care units; neonatal mother addicted patients and addicts from the general population or linked to the health system. Detoxification programs are typically characterized by a low rate of completion of treatment and a high rate of relapse. The opioid withdrawal syndrome is objectively and subjectively severe and moderate and the goals of the therapy for the Opiates Withdrawal Syndrome are: to prevent or reduce the objective and subjective symptoms of abstinence; to prevent or treat its most serious complications; to treat preexisting or concurrent psychiatric disorders; to reduce the frequency or severity of relapses and to rehabilitate in the long term.

Analgesia in phasic and tonic pain tests in a pharmacological model of autotomy.

Self-mutilation or self-injurious behaviour is a well known behavioural disorder in humans. The proposition that this behaviour in animals is a response to chronic pain of peripheral nerve injury has been met with controversy. In the present study a pharmacological model, which produces no sensory or motor loss was used to study how autotomy is related to pain. In a group of rats autotomy was induced by amphetamine in phenoxybenzamine and reserpine treated animals. The pain tests, both phasic and tonic were then performed. The results of this study showed that a total analgesia was produced in both phasic and tonic pain tests, in animals that exhibited autotomy. Injection of naloxone in these animals prevented autotomy. A correlation between autotomy and no pain is suggested in this pharmacological model of autotomy.

Anti-hyperalgesic effect of electroacupuncture in a model of post-incisional pain in rats

Electroacupuncture has been proposed to be a low cost and practical method that allows effective pain management with minimal collateral effects. In this study we have examined the effect of electroacupuncture against the hyperalgesia developed in a model of post-incisional pain in rats. A 1-cm longitudinal incision was made through the skin and fascia of the plantar region of the animal hind paw. Mechanical hyperalgesia in the incision was evaluated 135 min after the surgery with von Frey filaments. The tension threshold was reduced from 75 g (upper limit of the test) to 1.36 + or - 0.36 g (mean + or - SEM) in control rats. It is shown that a 15-min period of electroacupuncture applied 120 min after surgery to the Zusanli (ST36) and Sanyinjiao (SP6) points, but not to non-acupoints, produces a significant and long-lasting reduction of the mechanical hyperalgesia induced by the surgical incision of the plantar surface of the ipsilateral hind paw. The tension threshold was reduced from 75 to 27.6 + or - 4.2 g in animals soon after the end of electroacupuncture. The mechanical threshold in this group was about 64 percent less than in control. Electroacupuncture was ineffective in rats treated 10 min earlier with naloxone (1 mg/kg, ip), thus confirming the involvement of opioid mechanisms in the antinociceptive effects of such procedure. The results indicate that post-incisional pain is a useful model for studying the anti-hyperalgesic properties of electroacupuncture in laboratory animals

Role of ketamine in convulsions.

It can be concluded from the present study that ketamine showed dose-dependent anticonvulsant effect on MES in mice. It is presumed that this anticonvulsant effect of ketamine could be due to blockade of excitatory amino acid NMDA receptors. It was potentiated by anticonvulsants like diazepam and DPH but was found to be insensitive to naloxone. These findings suggest the involvement of NMDA receptors and their antagonists in epilepsy. Ketamine thus can be given as add-on therapy in refractory cases, and may prove to be useful as an anticonvulsant in future.

Efectos respiratorios y usos del remifentanilo: farmacología comparada / Respiratory effects and uses of remifentanil

En la última década, los anestesiólogos incrementaron el uso de opioides sintéticos en el intraoperatorio. Sus principales ventajas son: producir analgesia profunda, mínima depresión cardiovascular, disminuir la respuesta endocrina al estrés, poder ser revertidos por antagonistas competitivos, poseer escasa toxicidad orgánica y no desencadenar hipertermia maligna. Los opioides tienen, como contrapartida, la capacidad de provocar depresión respiratoria postoperatoria importante, dosis-dependiente. Algunas características farmacocinéticas de los opioides utilizados no satisfacen integramente algunos requerimientos de los anestesiólogos. Es por ello que la investigación prosigue, básicamente, en dos direcciones: terminación previsible de su efecto farmacológico y menor depresión respiratoria postoperatoria. El remifentanilo es un agonista de los receptores mu, con una relativa unión a los receptores kappa y delta. Su perfil farmacodinámico es similar a los del fentanilo y el alfentanilo. Su farmacocinética le permite comportarse como una droga de acción corta. Es metabolizado por esterasas sanguíneas y de otros tejidos, permitiendo un extenso y rápido metabolismo, sin participación hepática. Sus características cinéticas permiten pensar que su uso será adecuado en aquellas situaciones en las que se requiere una relación dosis-efecto previsible, rápidos cambios en la profundidad, una rápida desaparición de la depresión respiratoria, un plano anestésico profundo con rápida recuperación y un bloqueo autonómico profundo.

Opioid receptor mediated anticonvulsant effect of pentazocine.

Intraperitoneal (i.p.) administration of (+/-) pentazocine (10, 30 & 50 mg/kg), a Sigma opioid agonist, resulted in a dose dependent anticonvulsant action against maximal electroshock seizures in mice. This anticonvulsant effect of pentazocine was not antagonized by both the doses of naloxone (1 and 10 mg/kg) suggesting thereby that its anticonvulsant action is probably mediated by Sigma opiate binding sites. Its anticonvulsant effect was potentiated by both the anticonvulsant drugs viz. diazepam and diphenylhydantoin. Morphine, mu opioid agonist, on the other hand, failed to protect the animals against maximal electroshock seizures when it was given in doses of 10-40 mg/kg body wt.

Simposio: cirugía experimental en México (parte I). Utilidad de la naloxona en la sepsis peritoneal: modelo experimental en rata / Symposium: Experimental surgery in Mexico (part l). Usefulnes of naloxone in peritoneal sepsis: experimental model in rats

Evaluar la utilidad de diferentes secuestradores de radicales libres de oxígeno en el manejo de la sepsis peritoneal, en asociación con la administración de antibióticos. Diseño: Estudio en animales, prospectivo, con análisis estadístico. Material y método: Se emplearon ratas Wistar a las que se les produjo sepsis peritoneal por ligadura y punción del ciego. Doce horas posterior a la lesión se les administró intraperitonealmente alguno de los fármacos en estudio, que fueron; naloxona, piroxicam, clonixinato de lisina, naproxeno y Ketorolaco, Se registró sobrevida acumulada y el desarrollo de sepsis peritoneal generalizada. Resultados: En los animales tratados con naloxona se observó una sobrevida mayor, así como frecuencia de sepsis peritoneal generalizada, con diferencia estadísticamente significativa. Conclusiones: La naloxona en combinación con antibióticos mejoró la sobrevida y favoreció el desarrollo de sepsis peritoneal localizada

Antídotos de uso reciente

Los antídotos son sustancias cuya función es contrarrestar el efecto farmacológico y tóxico de otras sustancias, teniendo en cuenta la importancia de las medidas generales en el manejo del intoxicado (baño general, emesis, lavado gástrico, carbón activado, catárticos). Cada día aparecen sustancias nuevas con dichas características. En el presente artículo se pretende dar información breve y detallada sobre las propiedades farmacológicas, indicaciones, dosificación, efectos secundarios y contraindicaciones de algunos de uso general (carbón activado, soluciones electrolíticas con polietilenglycol) y principalmente de algunos específicos de uso reciente: flumazenil, fragmentos Fab-antidigoxina, glucagón, naloxona, clonidina, N-acetil-cisteína, azul de metileno, nitrito y tiosulfato de sodio, ácido-2-3-dimercaptosuccínico, penicilina benzatínica, glicopirrolato y S-adenosil-metionina.

Cómo realizar la reanimación cardiopulmonar neonatal / How to carry out neonatal cardiopulmonary resuscitation

Para realizar la reanimación cardiopulmonar neonatal se comunica un "esquema de toma de decisiones" que clasifica a los neonatos en cuatro categorías: en la primera están los neonatos sanos que sólo requieren rutinarias de reanimación. La calificación Apgar no es útil para determinar cuándo iniciar la reanimación ni para tomar decisiones en el curso de la misma; tampoco es un criterio de valor para determinar una posible lesión neurológica a largo plazo, ésta sólo podrá inferirse cuando se reúnen los siguientes requisitos: Apgar de 0 a 3 a los 10 minutos de vida, hipotonía de varias horas de duración y crisis convulsivas.

Evaluation of drug effects on spinal cord injury--an experimental study in monkeys.

Contusion injury is produced experimentally in anaesthetised monkeys by weight drop method. A group of animals having laminectomy alone served as sham controls. Drugs were administered 30 min after injury initially. Naloxone and nifedipine were administered as single dose administration immediately after injury. Dipyridamole and DMSO were administered daily for a period of 1 week. Acetylcholinesterase (AchE) was estimated in 2 spinal tissue segments, S1-at the site of injury and S2-the segment above the site of injury, at the end of 1 week after sacrificing the animals. Contusion injury produced significant decrease in specific activity of AchE in the traumatised segment of the experimental animals. The non-traumatised adjacent segment did not show any significant change. Nifedipine, naloxone and DMSO produced a decrease in AchE activity in S1 and S2 segments. Monkeys developed paraplegia after contusion injury. A score 2+ was observed after 1 week as compared to the score of 4+ of sham controls. Single dose administration of naloxone seemed to reverse the motor deficit by getting a score of 3+; other drugs did not produce any beneficial effect on motor deficit.

Participation of opioid receptors in the modulation of the analgesic response by adrenal and gonadal glands

The invovlement of opiodi receptors in the analgesic response was evaluated by the tail-immersion test in simultaneously adrenalectomized and ovariectomized female Wistar rats (210-250g). The reaction time (mean ñ SEM) for tail withdrawal from hot water decreased significantly 2 weeks after surgery (3.52 ñ 0.20 s) when compared to intact animals (6.09 ñ 0.23 s). Hormonal replacement with dexamethasone (50*/day) did not affect reaction time (3.38 ñ 0.19 s). However, this response was restored by combined adrenal and gonadal steroid substitution (estradiol 5*g/day and progesterone 1.5*g 6h before the test) therapy (5.11 ñ 0.45 s) in animal treated with dexamethasone plus estradiol and 5.04 ñ 0.43 s in animals treated with dexamethasone plus estradiol plus progesterone). Naloxone (2mg/Kg decreased the reaction time of animals treated with adrenal and gonadal steroids (5.11 ñ 0.45 vs 4.15 ñ 0.44 and 5.04 ñ 0.43 vs 3.87 ñ 0.28 s, respectively, before and after naloxone) but failed to decrease it in rats treated with dexamethasone only (3.88 ñ 0.18 vs 4.34 ñ 0.25 s, before and after naloxone). These observations indicate that gonadal steroids are the most important steroid factors involved in the reaction time to tail immersion in hot water and confirm other reports that the opioid pathways modulating the neuronal circuitry require the presence of these hormones

Medical management of acute cerebral ischemia

El ACV isquémico es una de las causas más frecuentes de muerte e invalidez. A pesar de su alta incidencia, el manejo del ACV agudo sigue siendo controvertido. La mayoría de las formas corrientes de terapéutica están diseñadas para reducir las complicaciones de un ACV reciente o prevenir recidivas.Los datos experimentales sugieren que el tiempo óptimo para la intervención terapéutica debería situarse en las horas inmediatas posteriores a la isquemia cerebral

Tratamiento del dolor postoperatorio en cirugía torácica / Pain treatment postoperative in thoracic surgery

Con el objeto de abolir o disminuir el dolor durante el postoperatorio inmediato, 58 pacientes con diferentes tipos de toracotomías amplias fueron tratados con inyección de morfina en el espacio peridural. Fue administrada a través de un catéter introducido a nivel lumbar. La disminución del dolor fue significativa en todos los casos. No se observó contaminación del espacio peridural ni de los catéteres. La morfina administrada en el espacio epidural es un método efectivo y seguro para el control del dolor durante el postoperatorio inmediato de la cirugía del tórax.