Franklin Sarmento da Silva Braga

Influência da lidocaína no bloqueio neuromuscular produzido pelo rocurônio: estudo em preparação nervo frênico-diafragma de rato

BACKGROUND AND OBJECTIVES: The action mechanism of local anesthetics (LA) on neuromuscular junction motivated several studies. When administered at low doses, they do not interfere on neuromuscular transmission. But high doses may compromise neuromuscular transmission and increase the effects of neuromuscular blockers. The objective of this study was to evaluate lidocaine interaction with rocuronium on rat diaphragm through its influence on neuromuscular block degree. METHODS: Rats, weighing between 250 and 300 g, were used. Preparation was set according to the technique described by Bulbring. Groups were formed (n = 5) according to the drug being studied: lidocaine - 20 µg.mL-1 (Group I); rocuronium - 4 µg.mL-1 (Group II), and rocuronium - 4 µg.mL-1 with lidocaine - 20 µg.mL-1 (Group III). The following items were assessed: 1) the extent of diaphragm muscle responses to indirect stimulation, both before and 60 minutes after adding lidocaine and a neuromuscular blocker; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP); 3) the effectiveness of neostigmine, and 4) aminopyridine on neuromuscular blockage reversal. RESULTS: When administered separately, lidocaine did not alter the extent of muscular responses. With the previous use of lidocaine, rocuronium neuromuscular blockage was 82.8% ± 1.91%, with a significant difference (p = 0.0079) when compared to the group with isolated rocuronium (57.8% ± 1.9%). Blockage was both partially and fully reverted by neostigmine and 4-aminopyridine, respectively. Lidocaine did not alter membrane potential and caused an initial increase on MEPP, followed by a blockage. CONCLUSIONS: Lidocaine increases the neuromuscular blocking produced by rocuronium. MEPP modifications identify a presynaptic action. The complete antagonism of 4-aminopyridine indicates a presynaptic component. This idea is supported by the partial antagonism through neostigmine.BACKGROUND AND OBJECTIVES The action mechanism of local anesthetics (LA) on neuromuscular junction motivated several studies. When administered at low doses, they do not interfere on neuromuscular transmission. But high doses may compromise neuromuscular transmission and increase the effects of neuromuscular blockers. The objective of this study was to evaluate lidocaine interaction with rocuronium on rat diaphragm through its influence on neuromuscular block degree. METHODS Rats, weighing between 250 and 300 g, were used. Preparation was set according to the technique described by Bulbring. Groups were formed (n = 5) according to the drug being studied: lidocaine - 20 microg.mL-1 (Group I); rocuronium - 4 microg.mL-1 (Group II), and rocuronium - 4 microg.mL-1 with lidocaine - 20 microg.mL-1 (Group III). The following items were assessed: 1) the extent of diaphragm muscle responses to indirect stimulation, both before and 60 minutes after adding lidocaine and a neuromuscular blocker; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP); 3) the effectiveness of neostigmine, and 4) aminopyridine on neuromuscular blockage reversal. RESULTS When administered separately, lidocaine did not alter the extent of muscular responses. With the previous use of lidocaine, rocuronium neuromuscular blockage was 82.8% +/- 1.91%, with a significant difference (p = 0.0079) when compared to the group with isolated rocuronium (57.8% +/- 1.9%). Blockage was both partially and fully reverted by neostigmine and 4-aminopyridine, respectively. Lidocaine did not alter membrane potential and caused an initial increase on MEPP, followed by a blockage. CONCLUSIONS Lidocaine increases the neuromuscular blocking produced by rocuronium. MEPP modifications identify a presynaptic action. The complete antagonism of 4-aminopyridine indicates a presynaptic component. This idea is supported by the partial antagonism through neostigmine.

Spinal anesthesia for cesarean section. Use of hyperbaric bupivacaine (10mg) combined with different adjuvants.

BACKGROUND AND OBJECTIVES Combination of local anesthetics (LA) with adjuvants for spinal anesthesia improves block quality and prolongs the duration of analgesia. It was evaluated the maternal effects and neonatal repercussions of sufentanil, morphine, and clonidine combined with hyperbaric bupivacaine for elective cesarean section. METHOD Prospective, randomized, blinded study of 96 patients allocated into four groups: Group I (no adjuvant), Group II (sufentanil 5.0 μg), Group III (morphine 100 μg), and Group IV (clonidine 75 μg). It was evaluated the onset and level of sensory block, perioperative analgesia, degree and recovery time of motor block, duration of analgesia, sedation, and maternal-fetal repercussions. RESULTS The onset of blockade was significantly faster in groups with adjuvants compared with Group I. Patients in Groups I and III reported pain during the perioperative period. Duration of analgesia was significantly higher in Group II and time to motor block recovery was significantly higher in Group IV. Pruritus occurred in Groups II and III. Sedation was significant in Group IV and there was prolonged arterial hypotension in Group IV. CONCLUSION Addition of sufentanil and clonidine to hyperbaric bupivacaine provided adequate anesthesia for cesarean section and good postoperative analgesia. Clonidine caused more perioperative sedation and longer time to motor block recovery. Pruritus was evident when opioids were used.

Influence of Local Anesthetics on the Neuromuscular Blockade Produced by Rocuronium. Effects of Lidocaine and 50% Enantiomeric Excess Bupivacaine on the Neuromuscular Junction

BACKGROUND AND OBJECTIVES The effects of local anesthetics (LA) on neuromuscular transmission and their influence on the neuromuscular blockade produced by competitive neuromuscular blockers have not been fully investigated. The objective of this study was to evaluate, in vitro, the effects of lidocaine and 50% enantiomeric excess bupivacaine (S75-R25) on the neuromuscular blockade produced by rocuronium. METHODS The rats were divided in five groups (n = 5) according to the drug used: isolated lidocaine, bupivacaine (S75-R25), or rocuronium (groups I, II, and II); and rocuronium in preparations previously exposed to LAs (groups IV and V). The concentrations used were as follows: 20 microg x mL(-1), 5 microg x mL(-1), and 4 microg x mL(-1) of lidocaine, bupivacaine (S75-R25), and rocuronium, respectively. The following parameters were evaluated: 1) the strength of muscular contraction of the diaphragm to indirect electrical stimulations, before and 60 minutes after the isolated addition of the LAs and rocuronium, and the association AL-rocuronium; and 2) the effects of LAs on membrane potential (MP) and miniature end-plate potentials (MEPP). The effect of LAs on muscle contraction in response to acetylcholine was evaluated in chick biventer cervicis preparations. RESULTS Isolated lidocaine and bupivacaine (S75-R25) did not change the muscular response and the levels of MPs. In preparations exposed to LAs, rocuroniuminduced blockade was significantly greater than that produced by rocuronium alone. In chick biventer cervicis preparations, lidocaine and bupivacaine (S75R25) decreased contraction in response to acetylcholine. Lidocaine increased the frequency of MEPPs, which was followed by the blockade; bupivacaine (S75R25) caused a reduction in MEPPs followed by blockade. CONCLUSIONS Local anesthetics caused a potentiation of the neuromuscular blockade produced by rocuronium. The results showed pre- and post-synaptic effects.

Spinal anesthesia for elective ceasarean section: use of different doses of hyperbaric bupivacaine associated with morphine and clonidine

PURPOSE To comparatively study the efficacy and maternal and fetal side-effects of two doses of bupivacaine associated with morphine and clonidine, administered by the subarachnoid route for cesarean section. METHODS The study included 66 pregnant women at term, distributed into two groups. GI: bupivacaine 8.0 mg (1.6 mL) + clonidine 75 µg (0.5 mL) + morphine 100 µg (1.0 mL) and GII: bupivacaine 10 mg (2.0 mL) + clonidine 75 µg (0.5 mL) + morphine 100 µg (1.0 mL). The following parameters were assessed: onset and maximum level of sensory block; quality of intraoperative and postoperative analgesia; degree and duration of motor block; maternal repercussions and Apgar score. RESULTS The onset of sensory block, quality of intraoperative analgesia and total duration of analgesia were similar in both groups; maximum extent of sensory block predominated in T4; maximum degree of motor block (Bromage 3); time motor block regression was significantly longer in GII; Hemodynamic, respiratory repercussions, adverse maternal effects and Apgar scores were similar between groups. In both groups, there was a predominance of drowsy or sleeping patients. CONCLUSION The addition of morphine and clonidine to low doses of hyperbaric bupivacaine produced adequate anesthesia for cesarean section and good postoperative analgesia, without any maternal and fetal repercussions.

Influência de anestésicos locais sobre o bloqueio neuromuscular produzido pelo rocurônio: ação da lidocaína e da mistura enantiomérica em excesso de 50% de bupivacaína na junção neuromuscular

JUSTIFICATIVA Y OBJETIVOS: Los efectos de los anestesicos locales (AL), en la transmision neuromuscular y su influencia en el bloqueo neuromuscular producido por bloqueadores neuromusculares competitivos, todavia no se ha investigado lo suficiente. El objetivo del estudio, fue evaluar in vitro los efectos de la lidocaina y de la mezcla enantiomerica en exceso de 50% de bupivacaina (S75-R25) en el bloqueo neuromuscular producido por el rocuronio. METODOS: Algunos ratones se distribuyeron en cinco grupos (n = 5) de acuerdo con el farmaco estudiado: lidocaina, bupivacaina (S75-R25), rocuronio, aisladamente (Grupos I, II, III); rocuronio en preparaciones previamente expuestas a los AL (Grupos IV, V). Las concentraciones utilizadas fueron: 20 µg.mL-1, 5 µg.mL-1 y 4 µg.mL-1, para lidocaina, bupivacaina (S75-R25), y rocuronio, respectivamente. Se evaluo: 1) la fuerza de contraccion muscular del diafragma a la estimulacion electrica indirecta, antes y 60 minutos despues de la adicion de los AL y rocuronio aisladamente, y la asociacion AL - rocuronio; 2) efectos de los AL sobre el potencial de la membrana (PM) y potenciales de placa terminal en miniatura (PPTM). En una preparacion biventer cervicis de pollito, se evaluo el efecto de los AL en la respuesta de contraccion a la acetilcolina. RESULTADOS: La lidocaina y la bupivacaina (S75-R25) aisladamente, no alteraron las respuestas musculares y los valores del PM. En las preparaciones expuestas a los AL, el bloqueo por el rocuronio fue significativamente mayor con relacion al producido por el rocuronio aisladamente. En una preparacion biventer cervicis de pollito, la lidocaina y la bupivacaina (S75-R25), redujeron la respuesta de contraccion a la acetilcolina. La lidocaina aumento la frecuencia de los PPTM, seguido de bloqueo; la bupivacaina (S75-R25) genero una disminucion seguida de bloqueo. CONCLUSIONES: Los anestesicos locales potenciaron el bloqueo neuromuscular causado por el rocuronio. Los resultados mostraron una accion presinaptica y postsinaptica.

Phenobarbital influence on neuromuscular block produced by rocuronium in rats

PURPOSE To evaluate in vitro and in vivo neuromuscular blockade produced by rocuronium in rats treated with Phenobarbital and to determine cytochrome P450 and cytochrome b5 concentrations in hepatic microsomes. METHODS Thirty rats were included in the study and distributed into 6 groups of 5 animals each. Rats were treated for seven days with phenobarbital (20 mg/kg) and the following parameters were evaluated: 1) the amplitude of muscle response in the preparation of rats exposed to phenobarbital; 2) rocuronium effect on rat preparation exposed or not to phenobarbital; 3) concentrations of cytochrome P450 and cytochrome b5 in hepatic microsomes isolated from rats exposed or not to phenobarbital. The concentration and dose of rocuronium used in vitro and in vivo experiments were 4 microg/mL and 0,6 mg/kg, respectively. RESULTS Phenobarbital in vitro and in vivo did not alter the amplitude of muscle response. The neuromuscular blockade in vitro produced by rocuronium was significantly different (p=0.019) between exposed (20%) and not exposed (60%) rats; the blockade in vivo was significantly greater (p=0.0081) in treated rats (93.4%). The enzymatic concentrations were significantly greater in rats exposed to phenobarbital. CONCLUSIONS Phenobarbital alone did not compromise neuromuscular transmission. It produced enzymatic induction, and neuromuscular blockade in vivo produced by rocuronium was potentiated by phenobarbital.

Influence of stimulus frequency on blockade induced by pancuronium and rocuronium: study on rats phrenic nerve-diaphragm preparation

PURPOSE To evaluate the influence of two stimulation frequencies on the installation of neuromuscular blockade produced by pancuronium and rocuronium on the rat diaphragm. METHODS Diaphragms were submitted to an indirect frequency stimulation of 0.1 and 1 Hz (Groups I and II, respectively). Subgroups were formed (n=5) according to the neuromuscular blocker employed (pancuronium-2 microg/ml and rocuronium-4 microg/ml). The twitch height depression was evaluated at 5, 15 and 30 minutes after adding the neuromuscular blocker. RESULTS The decrease in twitch height was greater (p<0.01) with a frequency of 1 Hz at all time periods studied both in preparations that are blocked with pancuronium and in those that are blocked with rocuronium. CONCLUSION The frequency of stimulation interferes significantly with the installation of neuromuscular blockade produced by pancuronium and rocuronium, since the reduction in amplitude of the rat diaphragm response was greater for 1 Hz frequencies, at all periods studied.

Influence of lidocaine on the neuromuscular block produced by rocuronium: study in rat phrenic-diaphragmatic nerve preparation

BACKGROUND AND OBJECTIVES: The action mechanism of local anesthetics (LA) on neuromuscular junction motivated several studies. When administered at low doses, they do not interfere on neuromuscular transmission. But high doses may compromise neuromuscular transmission and increase the effects of neuromuscular blockers. The objective of this study was to evaluate lidocaine interaction with rocuronium on rat diaphragm through its influence on neuromuscular block degree. METHODS: Rats, weighing between 250 and 300 g, were used. Preparation was set according to the technique described by Bulbring. Groups were formed (n = 5) according to the drug being studied: lidocaine - 20 µg.mL-1 (Group I); rocuronium - 4 µg.mL-1 (Group II), and rocuronium - 4 µg.mL-1 with lidocaine - 20 µg.mL-1 (Group III). The following items were assessed: 1) the extent of diaphragm muscle responses to indirect stimulation, both before and 60 minutes after adding lidocaine and a neuromuscular blocker; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP); 3) the effectiveness of neostigmine, and 4) aminopyridine on neuromuscular blockage reversal. RESULTS: When administered separately, lidocaine did not alter the extent of muscular responses. With the previous use of lidocaine, rocuronium neuromuscular blockage was 82.8% ± 1.91%, with a significant difference (p = 0.0079) when compared to the group with isolated rocuronium (57.8% ± 1.9%). Blockage was both partially and fully reverted by neostigmine and 4-aminopyridine, respectively. Lidocaine did not alter membrane potential and caused an initial increase on MEPP, followed by a blockage. CONCLUSIONS: Lidocaine increases the neuromuscular blocking produced by rocuronium. MEPP modifications identify a presynaptic action. The complete antagonism of 4-aminopyridine indicates a presynaptic component. This idea is supported by the partial antagonism through neostigmine.BACKGROUND AND OBJECTIVES The action mechanism of local anesthetics (LA) on neuromuscular junction motivated several studies. When administered at low doses, they do not interfere on neuromuscular transmission. But high doses may compromise neuromuscular transmission and increase the effects of neuromuscular blockers. The objective of this study was to evaluate lidocaine interaction with rocuronium on rat diaphragm through its influence on neuromuscular block degree. METHODS Rats, weighing between 250 and 300 g, were used. Preparation was set according to the technique described by Bulbring. Groups were formed (n = 5) according to the drug being studied: lidocaine - 20 microg.mL-1 (Group I); rocuronium - 4 microg.mL-1 (Group II), and rocuronium - 4 microg.mL-1 with lidocaine - 20 microg.mL-1 (Group III). The following items were assessed: 1) the extent of diaphragm muscle responses to indirect stimulation, both before and 60 minutes after adding lidocaine and a neuromuscular blocker; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP); 3) the effectiveness of neostigmine, and 4) aminopyridine on neuromuscular blockage reversal. RESULTS When administered separately, lidocaine did not alter the extent of muscular responses. With the previous use of lidocaine, rocuronium neuromuscular blockage was 82.8% +/- 1.91%, with a significant difference (p = 0.0079) when compared to the group with isolated rocuronium (57.8% +/- 1.9%). Blockage was both partially and fully reverted by neostigmine and 4-aminopyridine, respectively. Lidocaine did not alter membrane potential and caused an initial increase on MEPP, followed by a blockage. CONCLUSIONS Lidocaine increases the neuromuscular blocking produced by rocuronium. MEPP modifications identify a presynaptic action. The complete antagonism of 4-aminopyridine indicates a presynaptic component. This idea is supported by the partial antagonism through neostigmine.

Spinal Block with 10 mg of Hyperbaric Bupivacaine Associated with 5 μg of Sufentanil For Cesarean Section. Study of Different Volumes

BACKGROUND AND OBJECTIVES Several factors affect the cephalad dispersion of the anesthetic solution in the subarachnoid space; among them, physiological changes of pregnancy and the dose and volume of the local anesthetics should be mentioned. The objective of this study was to assess the effectivity and side effects of different volumes of the subarachnoid administration of the association of hyperbaric bupivacaine and sufentanil in cesarean sections. METHODS Forty patients, ASA I and II, undergoing elective cesarean section under spinal block were divided in two groups, according to the volume of the anesthetic solution: Group I (4 mL) and Group II (3 mL). The association of hyperbaric bupivacaine (10 mg(2) mL) and sufentanil (5 microg-1 mL) was used in both groups. In Group I, 1 mL of NS was added to the solution to achieve the volume of 4 mL. The following parameters were evaluated: latency of the blockade; upper limit of the sensorial blockade; degree of motor blockade; time for regression of the motor blockade; total duration of analgesia; maternal side effects; and neonatal repercussions. RESULTS Latency, the upper limit of the sensorial blockade, and the degree and time for regression of the motor blockade were similar in both groups; duration of analgesia was greater in Group I than in Group II, which was statistically significant. The incidence of side effects was similar in both groups. Maternal cardiocirculatory changes and neonatal repercussions were not observed. CONCLUSIONS Four milliliter of anesthetic solution composed of hyperbaric bupivacaine, 10 mg, associated with 5 microg of sufentanil was more effective than 3 ml of the same solution, providing better intra-and postoperative analgesia without maternal-fetal repercussions.

Anestesia espinhal com 10 mg de bupivacaína hiperbárica associada a 5 µg de sufentanil para cesariana: estudo de diferentes volumes

JUSTIFICATIVA Y OBJETIVOS: Diversos factores influyen en la dispersion cefalica de la solucion anestesica en el espacio subaracnoideo, entre los cuales se destacan las alteraciones fisiologicas inherentes al embarazo, baricidad, dosis y volumen del anestesico local. El objetivo de este estudio fue evaluar la efectividad y los efectos colaterales de diferentes volumenes de la asociacion de bupivacaina hiperbarica y sufentanil por via subaracnoidea en cesareas. METODO: Cuarenta pacientes, ASA I y II, sometidos a cesarea electiva bajo raquianestesia distribuidos en dos grupos, de acuerdo con el volumen de la solucion anestesica usada: Grupo I (4 mL) y Grupo II (3 mL). En los dos grupos, el anestesico local empleado fue la bupivacaina hiperbarica (10 mg-2 mL) asociada al sufentanil (5 µg-1 mL). En el Grupo I, para la obtencion del volumen de 4 mL, se anadio 1 mL de solucion fisiologica a 0,9%. Se evaluaron: latencia del bloqueo; nivel maximo del bloqueo sensitivo; grado del bloqueo motor; tiempo para regresion del bloqueo motor; duracion total de la analgesia; efectos adversos maternos y repercusiones neonatales. RESULTADOS: La latencia, el nivel maximo del bloqueo sensitivo, el grado y el tiempo para la regresion del bloqueo motor fueron similares en los dos grupos; la duracion de la analgesia fue mayor en el Grupo I, con una diferencia significativa con relacion al Grupo II. Los efectos adversos se dieron a menudo de forma similar en los dos grupos. Se registro la ausencia de las alteraciones cardiocirculatorias maternas y de las repercusiones neonatales. CONCLUSIONES: La bupivacaina hiperbarica en dosis de 10 mg asociada al sufentanil en dosis de 5 µg, con un volumen de 4 mL, fue mas eficaz que la misma asociacion en un menor volumen (3 mL), proporcionando una mejor analgesia intra y postoperatoria, sin repercusiones materno-fetales.