Anestesia regional intravenosa con anestésicos locales de larga duración. Actualización / Intravenous regional anesthesia with long-acting local anesthetics. An update

La anestesia regional intravenosa es una técnica ampliamente utilizada en intervenciones quirúrgicas de poca duración, especialmente en las extremidades superiores, y menos frecuentemente en las inferiores. Su primera aparición data de principios del siglo xx, cuando Bier inyectó procaína como anestésico local. La ejecución de esta técnica como anestesia quirúrgica no ha cambiado mucho desde entonces, si bien diversos fármacos, particularmente anestésicos locales de larga duración como ropivacaína y levobupivacaína en bajas concentraciones, han sido introducidos en la práctica clínica. Además, fármacos como opioides, bloqueantes neuromusculares, paracetamol, neostigmina, magnesio, ketamina, keterolaco y clonidina han sido investigados como complementarios a los anestésicos locales, y parecen aportar beneficios en cuanto al inicio de la anestesia y una más larga duración de la analgesia perioperatoria. Este artículo de revisión intenta dar una visión global de los conocimientos actuales en anestésicos locales de larga duración para anestesia regional intravenosa (AU)

Intravenous regional anesthesia is a widely used technique for brief surgical interventions, primarily on the upper limbs and less frequently, on the lower limbs. It began being used at the beginning of the 20th century, when Bier injected procaine as a local anesthetic. The technique to accomplish anesthesia has not changed much since then, although different drugs, particularly long-acting local anesthetics, such as ropivacaine and levobupivacaine in low concentrations, were introduced. Additionally, drugs like opioids, muscle relaxants, paracetamol, neostigmine, magnesium, ketamine, clonidine, and ketorolac, have all been investigated as adjuncts to intravenous regional anesthesia, and were found to be fairly useful in terms of an increased onset of operative anesthesia and longer lasting perioperative analgesia. The present article provides an overview of current knowledge with emphasis on long-acting local anesthetic drugs (AU)

Ziconotide, a new N-type calcium channel blocker, administered intrathecally for acute postoperative pain.

BACKGROUND AND OBJECTIVES: Voltage-sensitive calcium channel conductance is essential for the nervous system to signal a painful event. However, intrathecal administration of L-type calcium channel blockers does not provide analgesia. The present investigation was designed to assess the safety and analgesic efficacy of ziconotide, a new N-type calcium channel blocker, when administered intrathecally to patients with acute postoperative pain. METHODS: This randomized, double-blind, pilot study included patients undergoing elective total abdominal hysterectomy, radical prostatectomy, or total hip replacement. After intrathecal injection of local anesthetic and before surgical incision, a continuous intrathecal infusion of either placebo or 1 of 2 doses of ziconotide (0.7 microg/h or 7.0 microg/h) was started and continued for 48 to 72 hours postoperatively. Primary and secondary efficacy variables were the mean daily patient controlled analgesia (PCA) morphine equivalent consumption and visual analog pain intensity (VASPI) scores, respectively. RESULTS: Thirty patients received study drug; 26 were evaluable for efficacy. Mean daily PCA morphine equivalent consumption was less in patients receiving ziconotide than in placebo-treated patients, and the difference was statistically significant between 24 and 48 hours (P = .040). VASPI scores during the first 8 hours postoperatively were markedly lower in ziconotide-treated than in placebo-treated patients. In 4 of 6 patients receiving the high-dose of ziconotide (7 microg/h), adverse events, such as dizziness, blurred vision, nystagmus, and sedation contributed to study drug being discontinued after 24 hours. After ziconotide discontinuation, these symptoms resolved. CONCLUSIONS: Ziconotide showed analgesic activity, as shown by decreased PCA morphine equivalent consumption and lower VASPI scores. Because of a favorable trend of decreased morphine consumption with an acceptable side-effect profile in the low-dose ziconotide group, 0.7 microg/h may be closer to the ideal dose than 7 microg/h. Large-scale studies are required to clarify this issue.