Eduardo Tsuyoshi Yamaguchi

Drogas de abuso e gravidez

CONTEXTO: Embora seja um problema crescente na populacao mundial, existem poucos trabalhos publicados sobre o uso de drogas durante a gravidez. OBJETIVOS: Abordar de maneira objetiva as drogas de abuso (alcool, cocaina, maconha e tabaco) mais comumente utilizadas pelas mulheres em idade reprodutiva. METODOS: Foi realizada revisao bibliografica (MEDLINE, LILACS) dos textos mais recentes abordando o uso de drogas de abuso em mulheres em idade reprodutiva. RESULTADOS: Foram descritas as principais consequencias da utilizacao de drogas de abuso, tanto para a mae quanto para o bebe. CONCLUSOES: Trata-se de um problema de saude publica pouco discutido, devendo envolver uma equipe multidisciplinar em sua abordagem. A publicacao de mais trabalhos se faz necessaria, a fim de se estabelecer a melhor estrategia de intervencao nesta populacao.BACKGROUND: Despite the fact that it has being a growing problem worldwide, very few works and papers have been published on drug use during pregnancy. OBJECTIVES: To objectively address the most commonly abused drugs (alcohol, cocaine, marijuana, and tobacco) by women of a reproductive age. METHODS: A literature review (MEDLINE, LILACS) of the most recent papers on drug abuse by women of reproductive age was carried out. RESULTS: The primary consequences of drug abuse both for the mother and the infant are described. CONCLUSIONS: This is a little discussed major public health issue which requires the involvement of a multidisciplinary team. The publication of a greater number of papers on the problem is necessary in order to establish the best strategy for addressing intervention in this population.

Expansão volêmica em raquianestesia para cesariana. Como realizá-la?

BACKGROUND AND OBJECTIVES In has been shown in non-obstetric patients, that a fast acute fluid preload immediately after spinal anesthesia was more effective than a slow preload before regional block to decrease the incidence and severity of arterial hypotension after spinal anesthesia. This study aimed at comparing the incidence of arterial hypotension and vasopressants consumption in parturients submitted to C-section under spinal anesthesia with different fluid preload regimens. METHODS Sixty term pregnant women submitted to C-section under spinal anesthesia. Patients were randomly distributed in three groups receiving acute preload (10 ml kg(-1) lactated Ringers) as follows: Group 1 (n = 20), before spinal anesthesia through 18G catheter; Group 2 (n = 20), after spinal anesthesia through 18G catheter and Group 3 (n = 20), after spinal anesthesia through 16G catheter with pressurizer. Blood pressure (BP) was monitored at 1-minute intervals until delivery and 0.2 mg bolus metaraminol was administered for any BP decrease from baseline values; 0.4 mg was administered for BP decrease >or= 20%. Control blood pressure was defined as the mean of three successive SBP values obtained before acute preload and spinal block. Variables studied were: preload rate, incidence of maternal arterial hypotension, nausea, vomiting, vasopressants consumption, Apgar scores and umbilical artery pH. RESULTS Acute preload was faster in Group 3 as compared to Groups 1 and 2 (201 +/- 61 vs 56 +/- 13 and 59 +/- 21 ml min(-1), p < 0.05). Groups were similar regarding the incidence of arterial hypotension, nausea and vomiting, metaraminol consumption, Apgar scores and umbilical artery pH. CONCLUSIONS Acute preload before or after spinal anesthesia performance, in a slow or fast rate, does not change vasopressants consumption, the incidence of maternal arterial hypotension, nausea and vomiting, as well as fetal wellbeing.JUSTIFICATIVA Y OBJETIVOS: En pacientes no obstetricas, se demostro que la expansion volemica rapida realizada inmediatamente despues de la inyeccion subaracnoidea del anestesico local era mas efectiva que la expansion volemica lenta, realizada previamente a la instalacion del bloqueo para reducir la incidencia y la gravedad de la hipotension arterial despues de raquianestesia. El objetivo del estudio fue comparar la incidencia de hipotension arterial y el consumo de vasopresores en embarazadas sometidas a cesarea bajo raquianestesia con diferentes regimenes de expansion volemica. METODO: Fueron evaluadas prospectivamente 60 embarazadas de termino sometidas a cesarea bajo raquianestesia. Las pacientes recibieron expansion volemica con 10 ml.kg-1 de solucion de Ringer con lactato como sigue: Grupo 1 (n = 20), antes de la raquianestesia a traves de cateter 18G; Grupo 2 (n = 20), despues de raquianestesia y con cateter 18G y Grupo 3 (n = 20) despues de raquianestesia con cateter 16G bajo accion de un presurizador. La presion arterial (PA) fue monitorizada a cada minuto y se administro 0,2 mg de metaraminol para cualquier diminucion de PA, a partir del valor de control y 0,4 mg para diminucion > 20%. La PA control fue definida como la media de tres valores sucesivos de PAS obtenidos antes de la expansion volemica y del bloqueo. Se estudio la velocidad de infusion de fluidos, incidencia de hipotension arterial materna, nausea y vomito, consumo de metaraminol, indice de Apgar y pH de la arteria umbilical. RESULTADOS: La velocidad de administracion de fluidos fue mayor en el Grupo 3 de que en los Grupos 1 y 2 (201 ± 61 vs 56 ± 13 y 59 ± 21 ml.min-1, p < 0,05). Los grupos fueron semejantes en relacion a la incidencia de hipotension arterial, nausea, vomito, consumo de metaraminol, indice de Apgar y pH de la arteria umbilical. CONCLUSIONES: La expansion volemica, realizada antes o despues de la instalacion de la raquianestesia, de manera rapida o lenta, no modifica el consumo de vasopresor, la ocurrencia de hipotension arterial materna, nausea o vomitos, y tampoco el bien estar fetal.

Sufentanil subaracnóideo associado à bupivacaína hiperbárica para analgesia de parto: É possível reduzir a dose do opióide?

BACKGROUND AND OBJECTIVES The association of isobaric bupivacaine to lower spinal sufentanil dose provides satisfactory analgesia and lower incidence of side effects. This study aimed at evaluating quality of analgesia and incidence of side effects of decreased spinal sufentanil doses associated to hyperbaric bupivacaine for labor analgesia. METHODS Participated in this study 69 healthy term pregnant patients in active labor. Patients were randomly allocated in three groups receiving spinal combination of 2.5 mg hyperbaric bupivacaine and 1 mL saline solution (Control Group); 2.5 mg hyperbaric bupivacaine and 2.5 microg sufentanil (S2.5 Group) or 2.5 mg hyperbaric bupivacaine and 5 microg sufentanil (S5 Group). Pain, using a visual analogue scale (VAS), and side effects were evaluated at 5-minute intervals for the first 15 minutes and then at 15-minute interval until delivery. Study would end with delivery or when patient requested rescue analgesia (VAS > 3 cm). RESULTS Groups S2.5 and S5 presented longer analgesia duration (67.2 +/- 38.6 and 78.9 +/- 38.7 minutes, respectively) and a larger number of patients with effective analgesia (100% and 95.6%, respectively) as compared to Control group where mean analgesia duration was 35.9 +/- 21.6 minutes (p < 0.05) with 69.6% of patients with effective analgesia (p < 0.05). CONCLUSIONS The association of sufentanil to hyperbaric bupivacaine improves quality and prolongs analgesia duration. When associated to 2.5 mg hyperbaric bupivacaine, there is no benefit in administering more than 2.5 microg of sufentanil for labor pain relief.JUSTIFICATIVA Y OBJETIVOS: La adicion de bupivacaina isobarica a dosis menores de sufentanil por via subaracnoidea promueve analgesia de cualidad satisfactoria, con menor incidencia de efectos colaterales. El objetivo del estudio fue evaluar la calidad de la analgesia y la incidencia de efectos colaterales de dosis reducidas de sufentanil subaracnoideo asociados a bupivacaina hiperbarica en analgesia de parto. METODO: Fueron estudiadas prospectivamente 69 embarazadas de termino en trabajo de parto. Las embarazadas fueron aleatoriamente divididas en tres grupos que recibieron, en el espacio subaracnoideo, la combinacion de 2,5 mg de bupivacaina hiperbarica y 1 mL de solucion fisiologica (Grupo Control); 2,5 mg de bupivacaina hiperbarica y 2,5 µg de sufentanil (Grupo S2,5) o 2,5 mg de bupivacaina hiperbarica y 5 µg de sufentanil (Grupo S5). El dolor, de acuerdo con la escala analogico visual (EAV) de dolor y la incidencia de efectos colaterales fueron evaluadas a cada 5 minutos en los primeros quince minutos y a seguir a cada 15 minutos hasta el nacimiento. El estudio terminaba con el nacimiento, o cuando la paciente solicitaba medicacion analgesica de rescate (EAV > 3 cm). RESULTADOS: Los grupos S2,5 y S5 presentaron mayor duracion de analgesia (67,2 ± 38,6 y 78,9 ± 38,7 minutos, respectivamente) y mayor porcentaje de pacientes con analgesia efectiva (100% y 95,6%, respectivamente) que el grupo Control, en el cual la duracion media de analgesia fue de 35,9 ± 21,6 minutos (p < 0,05) y el porcentaje de pacientes con analgesia efectiva fue de 69,6% (p < 0,05). CONCLUSIONES: La adicion de sufentanil a la bupivacaina hiperbarica mejora la calidad y prolonga la duracion de la analgesia. Cuando asociado a 2,5 mg de bupivacaina hiperbarica, no hay ventaja de administrar dosis superior a 2,5 µg de sufentanil para alivio del dolor del trabajo de parto.

Ocitocina em cesarianas: qual a Melhor Maneira de Utilizá-la?

BACKGROUND AND OBJECTIVES Oxytocin is the uterotonic used in obstetric anesthesia, and its prophylactic and therapeutic administration is justified because it reduces the incidence of post-partum hemorrhage. However, the ideal infusion regimen in elective cesarean sections has not been determined yet. The objective of this study was to review the main physiological and pharmacological characteristics of oxytocin and to discuss its rational use by anesthesiologists in view of its side effects. CONTENTS Oxytocin is produced by the hypothalamus and stored in the posterior lobe of the pituitary gland. In the uterus, is causes contraction of the smooth muscle, which is very important to control hemorrhage after uterine emptying. It also affects other systems, and the reduction in peripheral vascular resistance with consequent hypotension is very important. The extra-uterine actions of oxytocin are important when administered in high doses or in bolus, especially in parturients under anesthesia (spinal block or general anesthesia) with hypovolemia or preexistent alterations in the cardiovascular system. Several infusion regimens have been studied, varying the dose and/or the speed of administration, in an attempt to establish the most adequate. CONCLUSIONS Due to its wide therapeutic spectrum, oxytocin remains the drug of choice to prevent uterine atony after cesarean sections. Although it has been used for almost 50 years, the adequate infusion regimen in cesarean sections has not been determined yet. The current tendency is to use continual infusion of low doses, and bolus administration should be avoided.JUSTIFICATIVA Y OBJETIVOS: La ocitocina es un uterotonico utilizado en anestesia obstetrica, cuya administracion, tanto profilactica, como terapeutica, se justifica por reducir la incidencia de hemorragia despues del alumbramiento. Sin embargo, todavia no se establecio el regimen ideal de infusion en cesareas electivas. Este estudio tiene la intencion de revisar las principales caracteristicas fisiologicas y farmacologicas de la ocitocina y discutir su uso racional por parte de los anestesiologos, teniendo en cuenta sus efectos colaterales. CONTENIDO: La ocitocina es producida por el hipotalamo y almacenada por la hipofisis posterior. En el utero, hay una contraccion de la musculatura lisa que es bastante importante para el control de la hemorragia despues de la expulsion de la placenta. Actua tambien en otros sistemas, siendo relevante la reduccion de la resistencia vascular periferica con la consecuente hipotension arterial. Las acciones extra-uterinas pasan a ser importantes cuando la ocitocina se crea en altas dosis o en bolus, especialmente en embarazadas bajo anestesia (sea bloqueo espinal o anestesia general) presentando hipovolemia, o con alteracion previa en el sistema cardiovascular. Diversos regimenes de infusion han sido estudiados, variando la dosis y/o la velocidad de infusion en la tentativa de establecer cual es la manera mas adecuada para su utilizacion. CONCLUSIONES: La ocitocina permanece como farmaco de primera eleccion para la prevencion y el tratamiento de la atonia uterina despues de la cesarea, especialmente por su amplio espectro terapeutico. A pesar de estar disponible para la practica clinica hace casi 50 anos, todavia no esta establecido cual es el regimen adecuado de su infusion en cesareas. La tendencia actual es la utilizacion en infusion continua de dosis reducidas, debiendo ser evitada la administracion en bolus.

Fluid preload in obstetric patients. How to do it

BACKGROUND AND OBJECTIVES In has been shown in non-obstetric patients, that a fast acute fluid preload immediately after spinal anesthesia was more effective than a slow preload before regional block to decrease the incidence and severity of arterial hypotension after spinal anesthesia. This study aimed at comparing the incidence of arterial hypotension and vasopressants consumption in parturients submitted to C-section under spinal anesthesia with different fluid preload regimens. METHODS Sixty term pregnant women submitted to C-section under spinal anesthesia. Patients were randomly distributed in three groups receiving acute preload (10 ml kg(-1) lactated Ringers) as follows: Group 1 (n = 20), before spinal anesthesia through 18G catheter; Group 2 (n = 20), after spinal anesthesia through 18G catheter and Group 3 (n = 20), after spinal anesthesia through 16G catheter with pressurizer. Blood pressure (BP) was monitored at 1-minute intervals until delivery and 0.2 mg bolus metaraminol was administered for any BP decrease from baseline values; 0.4 mg was administered for BP decrease >or= 20%. Control blood pressure was defined as the mean of three successive SBP values obtained before acute preload and spinal block. Variables studied were: preload rate, incidence of maternal arterial hypotension, nausea, vomiting, vasopressants consumption, Apgar scores and umbilical artery pH. RESULTS Acute preload was faster in Group 3 as compared to Groups 1 and 2 (201 +/- 61 vs 56 +/- 13 and 59 +/- 21 ml min(-1), p < 0.05). Groups were similar regarding the incidence of arterial hypotension, nausea and vomiting, metaraminol consumption, Apgar scores and umbilical artery pH. CONCLUSIONS Acute preload before or after spinal anesthesia performance, in a slow or fast rate, does not change vasopressants consumption, the incidence of maternal arterial hypotension, nausea and vomiting, as well as fetal wellbeing.JUSTIFICATIVA Y OBJETIVOS: En pacientes no obstetricas, se demostro que la expansion volemica rapida realizada inmediatamente despues de la inyeccion subaracnoidea del anestesico local era mas efectiva que la expansion volemica lenta, realizada previamente a la instalacion del bloqueo para reducir la incidencia y la gravedad de la hipotension arterial despues de raquianestesia. El objetivo del estudio fue comparar la incidencia de hipotension arterial y el consumo de vasopresores en embarazadas sometidas a cesarea bajo raquianestesia con diferentes regimenes de expansion volemica. METODO: Fueron evaluadas prospectivamente 60 embarazadas de termino sometidas a cesarea bajo raquianestesia. Las pacientes recibieron expansion volemica con 10 ml.kg-1 de solucion de Ringer con lactato como sigue: Grupo 1 (n = 20), antes de la raquianestesia a traves de cateter 18G; Grupo 2 (n = 20), despues de raquianestesia y con cateter 18G y Grupo 3 (n = 20) despues de raquianestesia con cateter 16G bajo accion de un presurizador. La presion arterial (PA) fue monitorizada a cada minuto y se administro 0,2 mg de metaraminol para cualquier diminucion de PA, a partir del valor de control y 0,4 mg para diminucion > 20%. La PA control fue definida como la media de tres valores sucesivos de PAS obtenidos antes de la expansion volemica y del bloqueo. Se estudio la velocidad de infusion de fluidos, incidencia de hipotension arterial materna, nausea y vomito, consumo de metaraminol, indice de Apgar y pH de la arteria umbilical. RESULTADOS: La velocidad de administracion de fluidos fue mayor en el Grupo 3 de que en los Grupos 1 y 2 (201 ± 61 vs 56 ± 13 y 59 ± 21 ml.min-1, p < 0,05). Los grupos fueron semejantes en relacion a la incidencia de hipotension arterial, nausea, vomito, consumo de metaraminol, indice de Apgar y pH de la arteria umbilical. CONCLUSIONES: La expansion volemica, realizada antes o despues de la instalacion de la raquianestesia, de manera rapida o lenta, no modifica el consumo de vasopresor, la ocurrencia de hipotension arterial materna, nausea o vomitos, y tampoco el bien estar fetal.

[Post-cesarean section analgesia with low spinal morphine doses and systemic nonsteroidal anti-inflammatory drug: diclofenac versus ketoprofen.].

BACKGROUND AND OBJECTIVES The association of low spinal morphine doses and muscular diclofenac is effective to control postoperative pain after Cesarean section under spinal anesthesia. Ketoprofen, also an NSAID, may be advantageous over diclofenac because it may be intravenously administered. This study aimed at comparing the analgesic efficacy of diclofenac and ketoprofen in association to low spinal morphine doses in the immediate postoperative period of patients submitted to Cesarean section under spinal anesthesia. METHODS Participated in this prospective study 44 healthy parturients, physical status ASA I or II, submitted to Cesarean section under spinal anesthesia with 15 mg hyperbaric bupivacaine and 28 microg morphine. Patients were randomly allocated into two groups, 90 minutes after anesthetic induction: Group D (n = 22): 75 mg muscular diclofenac; and Group K (n = 22): 100 mg intravenous ketoprofen diluted in 100 ml of 5% glucose in 20 minutes. Pain was evaluated immediately before NSAID administration and then every hour for six hours, using the Visual Analog Scale of Pain (VAS - 0 cm meaning no pain and 10 cm the worst possible pain). Rescue analgesia was provided by intravenous PCA pump (1mg bolus morphine with 7 minutes lockout interval, without basal infusion and maximum 20 mg morphine dose in 4 hours). The following parameters were evaluated: pain intensity, need for rescue analgesia, cumulative morphine consumption in the first 6 hours following NSAID administration, and the incidence of pruritus, nausea, vomiting and respiratory depression. RESULTS Both groups were similar in pain intensity, cumulative morphine doses and incidence of pruritus, nausea and vomiting in the first six hours following NSAID administration. CONCLUSIONS When associated to low spinal morphine doses, ketoprofen was similar to diclofenac in providing postoperative analgesia in the first six hours following Cesarean section under spinal anesthesia.BACKGROUND AND OBJECTIVES: The association of low spinal morphine doses and muscular diclofenac is effective to control postoperative pain after Cesarean section under spinal anesthesia. Ketoprofen, also an NSAID, may be advantageous over diclofenac because it may be intravenously administered. This study aimed at comparing the analgesic efficacy of diclofenac and ketoprofen in association to low spinal morphine doses in the immediate postoperative period of patients submitted to Cesarean section under spinal anesthesia. METHODS: Participated in this prospective study 44 healthy parturients, physical status ASA I or II, submitted to Cesarean section under spinal anesthesia with 15 mg hyperbaric bupivacaine and 28 µg morphine. Patients were randomly allocated into two groups, 90 minutes after anesthetic induction: Group D (n = 22): 75 mg muscular diclofenac; and Group K (n = 22): 100 mg intravenous ketoprofen diluted in 100 ml of 5% glucose in 20 minutes. Pain was evaluated immediately before NSAID administration and then every hour for six hours, using the Visual Analog Scale of Pain (VAS - 0 cm meaning no pain and 10 cm the worst possible pain). Rescue analgesia was provided by intravenous PCA pump (1mg bolus morphine with 7 minutes lockout interval, without basal infusion and maximum 20 mg morphine dose in 4 hours). The following parameters were evaluated: pain intensity, need for rescue analgesia, cumulative morphine consumption in the first 6 hours following NSAID administration, and the incidence of pruritus, nausea, vomiting and respiratory depression. RESULTS:Both groups were similar in pain intensity, cumulative morphine doses and incidence of pruritus, nausea and vomiting in the first six hours following NSAID administration. CONCLUSIONS: When associated to low spinal morphine doses, ketoprofen was similar to diclofenac in providing postoperative analgesia in the first six hours following Cesarean section under spinal anesthesia.

Sistemas respiratórios com absorção de CO2, circulares, valvulares: comparação do comportamento térmico entre sistema coaxial e convencional com diferentes fluxos de gás fresco

BACKGROUND AND OBJECTIVES The adequate maintenance of inhaled gases temperature during anesthetic procedures is critical to prevent perioperative respiratory complications. This study aimed at comparing the ability to warm up inhaled gases of coaxial breathing system and conventional system, by varying fresh gas flows (FGF). METHODS Breathing systems were tested in a lung simulator ventilated with 600 mL tidal volume and respiratory frequency of 10 bpm. The model simulated human CO2 production by delivering 250 mL.min-1 of CO2 flow. Then, exhaled gas from the model was directed to a pre-warmed humidifier to simulate human exhaled gas. Both systems were classified as circle, valve circuits with CO2 absorption. In the coaxial system (model A), the inspiratory branch was enveloped by the expiratory branch, whereas the conventional one (model B) presented separated respiratory branches. Inhaled gas temperature was measured at the following moments: 0, 5, 10, 20, 30, 40, 50, 60 and 90 minutes, with low (0.5 and 1 L.min-1) and high (3 and 6 L.min-1) FGF. RESULTS Model A presented significant thermal variation between beginning and end of experiment (22.47 +/- 1.77 masculineC and 24.27 +/- 3.52 masculineC respectively, p < 0.05). Both models A and B produced similar temperatures at the end of the study (24.27 +/- 3.52 masculineC and 23.61 +/- 1.93 masculineC respectively). There was no difference between final temperatures of both models and environmental temperature (21.25 +/- 1.20 masculineC and 21.81 +/- 1,87 masculineC respectively). Low FGF has produced similar temperatures to those observed at the end of the study with higher flows in both models (A: 25.53 +/- 4.78 masculineC and 23.02 +/- 0.80 masculineC; B: 24.50 +/- 0.85 masculineC and 22.72 +/- 2.36 masculineC, respectively). CONCLUSIONS The coaxial system presented significant thermal variation between beginning and end of experiment, while this was not observed in the conventional one. No difference was observed in final temperatures when comparing both systems, regardless of the FGF.JUSTIFICATIVA E OBJETIVOS: A manutencao da temperatura do gas inalado pelo paciente durante o procedimento anestesico e fundamental para evitar complicacoes respiratorias durante o peri-operatorio. O objetivo deste estudo e comparar a capacidade de aquecimento dos gases inalados em sistemas respiratorios com absorcao de CO2, circulares, valvulares, coaxial e convencional, variando o fluxo de gas fresco (FGF). METODO: Foram estudados dois sistemas respiratorios em um simulador de pulmao, que foi ventilado com volume corrente de 600 mL e frequencia de 10 bpm. O modelo simulava a producao de CO2, atraves da administracao de fluxo de 250 mL.min-1 de CO2, e o gas exalado do pulmao-teste passava por um umidificador aquecido para simular o gas expirado. Os dois sistemas foram classificados como circulares, valvulares, com absorcao de CO2. No sistema A (coaxial), o ramo inspiratorio passava pelo interior do ramo expiratorio, enquanto que o sistema B foi o convencional. As medidas de temperatura do gas inalado foram realizadas nos momentos 0, 5, 10, 20, 30, 40, 50, 60 e 90 minutos, sendo empregados FGF baixos (0,5 e 1 L.min-1) e altos (3 e 6 L.min-1). RESULTADOS: O sistema A apresentou variacao termica significativa entre o inicio e o final dos ensaios (22,47 ± 1,77 oC e 24,27 ± 3,52 oC p < 0,05, respectivamente). Os sistemas A e B produziram temperaturas semelhantes ao final do estudo (24,27 ± 3,52 oC e 23,61 ± 1,93 oC, respectivamente), e nao houve diferenca entre as temperaturas finais dos sistemas e a temperatura ambiental (21,25 ± 1,20 oC e 21,81 ± 1,87 oC, respectivamente). A utilizacao de baixos FGF produziu temperaturas semelhantes as temperaturas observadas ao final do estudo com fluxos mais elevados nos dois sistemas (A: 25,53 ± 4,78 oC e 23,02 ± 0,80 oC; B: 24,50 ± 0,85 oC e 22,72 ± 2,36 oC, respectivamente). CONCLUSOES: O sistema coaxial apresentou variacao termica significativa entre o inicio e o final do experimento, o que nao foi observado no sistema convencional. Nao houve diferenca das temperaturas finais quando comparados os dois sistemas entre si, independentemente do FGF empregado.

Ocitocina em cesarianas. O que há de novo

Oxytocin is the uterotonic agent of choice in the prevention and treatment of postpartum uterine atony. Nevertheless, there is no consensus on the optimal dose and rate for use in cesarean sections. The use of high bolus doses (e.g., 10 IU of oxytocin) can determine deleterious cardiovascular changes for the patient, especially in situations of hypovolemia or low cardiac reserve. Furthermore, high doses of oxytocin for prolonged periods may lead to desensitization of oxytocin receptors in myometrium, resulting in clinical inefficiency.

Oxytocin in cesarean sections: what is the best way to use it?

BACKGROUND AND OBJECTIVES Oxytocin is the uterotonic used in obstetric anesthesia, and its prophylactic and therapeutic administration is justified because it reduces the incidence of post-partum hemorrhage. However, the ideal infusion regimen in elective cesarean sections has not been determined yet. The objective of this study was to review the main physiological and pharmacological characteristics of oxytocin and to discuss its rational use by anesthesiologists in view of its side effects. CONTENTS Oxytocin is produced by the hypothalamus and stored in the posterior lobe of the pituitary gland. In the uterus, is causes contraction of the smooth muscle, which is very important to control hemorrhage after uterine emptying. It also affects other systems, and the reduction in peripheral vascular resistance with consequent hypotension is very important. The extra-uterine actions of oxytocin are important when administered in high doses or in bolus, especially in parturients under anesthesia (spinal block or general anesthesia) with hypovolemia or preexistent alterations in the cardiovascular system. Several infusion regimens have been studied, varying the dose and/or the speed of administration, in an attempt to establish the most adequate. CONCLUSIONS Due to its wide therapeutic spectrum, oxytocin remains the drug of choice to prevent uterine atony after cesarean sections. Although it has been used for almost 50 years, the adequate infusion regimen in cesarean sections has not been determined yet. The current tendency is to use continual infusion of low doses, and bolus administration should be avoided.JUSTIFICATIVA Y OBJETIVOS: La ocitocina es un uterotonico utilizado en anestesia obstetrica, cuya administracion, tanto profilactica, como terapeutica, se justifica por reducir la incidencia de hemorragia despues del alumbramiento. Sin embargo, todavia no se establecio el regimen ideal de infusion en cesareas electivas. Este estudio tiene la intencion de revisar las principales caracteristicas fisiologicas y farmacologicas de la ocitocina y discutir su uso racional por parte de los anestesiologos, teniendo en cuenta sus efectos colaterales. CONTENIDO: La ocitocina es producida por el hipotalamo y almacenada por la hipofisis posterior. En el utero, hay una contraccion de la musculatura lisa que es bastante importante para el control de la hemorragia despues de la expulsion de la placenta. Actua tambien en otros sistemas, siendo relevante la reduccion de la resistencia vascular periferica con la consecuente hipotension arterial. Las acciones extra-uterinas pasan a ser importantes cuando la ocitocina se crea en altas dosis o en bolus, especialmente en embarazadas bajo anestesia (sea bloqueo espinal o anestesia general) presentando hipovolemia, o con alteracion previa en el sistema cardiovascular. Diversos regimenes de infusion han sido estudiados, variando la dosis y/o la velocidad de infusion en la tentativa de establecer cual es la manera mas adecuada para su utilizacion. CONCLUSIONES: La ocitocina permanece como farmaco de primera eleccion para la prevencion y el tratamiento de la atonia uterina despues de la cesarea, especialmente por su amplio espectro terapeutico. A pesar de estar disponible para la practica clinica hace casi 50 anos, todavia no esta establecido cual es el regimen adecuado de su infusion en cesareas. La tendencia actual es la utilizacion en infusion continua de dosis reducidas, debiendo ser evitada la administracion en bolus.

Spinal sufentanil associated to hyperbaric bupivacaine: Is it possible to decrease opioid dose?

BACKGROUND AND OBJECTIVES The association of isobaric bupivacaine to lower spinal sufentanil dose provides satisfactory analgesia and lower incidence of side effects. This study aimed at evaluating quality of analgesia and incidence of side effects of decreased spinal sufentanil doses associated to hyperbaric bupivacaine for labor analgesia. METHODS Participated in this study 69 healthy term pregnant patients in active labor. Patients were randomly allocated in three groups receiving spinal combination of 2.5 mg hyperbaric bupivacaine and 1 mL saline solution (Control Group); 2.5 mg hyperbaric bupivacaine and 2.5 microg sufentanil (S2.5 Group) or 2.5 mg hyperbaric bupivacaine and 5 microg sufentanil (S5 Group). Pain, using a visual analogue scale (VAS), and side effects were evaluated at 5-minute intervals for the first 15 minutes and then at 15-minute interval until delivery. Study would end with delivery or when patient requested rescue analgesia (VAS > 3 cm). RESULTS Groups S2.5 and S5 presented longer analgesia duration (67.2 +/- 38.6 and 78.9 +/- 38.7 minutes, respectively) and a larger number of patients with effective analgesia (100% and 95.6%, respectively) as compared to Control group where mean analgesia duration was 35.9 +/- 21.6 minutes (p < 0.05) with 69.6% of patients with effective analgesia (p < 0.05). CONCLUSIONS The association of sufentanil to hyperbaric bupivacaine improves quality and prolongs analgesia duration. When associated to 2.5 mg hyperbaric bupivacaine, there is no benefit in administering more than 2.5 microg of sufentanil for labor pain relief.JUSTIFICATIVA Y OBJETIVOS: La adicion de bupivacaina isobarica a dosis menores de sufentanil por via subaracnoidea promueve analgesia de cualidad satisfactoria, con menor incidencia de efectos colaterales. El objetivo del estudio fue evaluar la calidad de la analgesia y la incidencia de efectos colaterales de dosis reducidas de sufentanil subaracnoideo asociados a bupivacaina hiperbarica en analgesia de parto. METODO: Fueron estudiadas prospectivamente 69 embarazadas de termino en trabajo de parto. Las embarazadas fueron aleatoriamente divididas en tres grupos que recibieron, en el espacio subaracnoideo, la combinacion de 2,5 mg de bupivacaina hiperbarica y 1 mL de solucion fisiologica (Grupo Control); 2,5 mg de bupivacaina hiperbarica y 2,5 µg de sufentanil (Grupo S2,5) o 2,5 mg de bupivacaina hiperbarica y 5 µg de sufentanil (Grupo S5). El dolor, de acuerdo con la escala analogico visual (EAV) de dolor y la incidencia de efectos colaterales fueron evaluadas a cada 5 minutos en los primeros quince minutos y a seguir a cada 15 minutos hasta el nacimiento. El estudio terminaba con el nacimiento, o cuando la paciente solicitaba medicacion analgesica de rescate (EAV > 3 cm). RESULTADOS: Los grupos S2,5 y S5 presentaron mayor duracion de analgesia (67,2 ± 38,6 y 78,9 ± 38,7 minutos, respectivamente) y mayor porcentaje de pacientes con analgesia efectiva (100% y 95,6%, respectivamente) que el grupo Control, en el cual la duracion media de analgesia fue de 35,9 ± 21,6 minutos (p < 0,05) y el porcentaje de pacientes con analgesia efectiva fue de 69,6% (p < 0,05). CONCLUSIONES: La adicion de sufentanil a la bupivacaina hiperbarica mejora la calidad y prolonga la duracion de la analgesia. Cuando asociado a 2,5 mg de bupivacaina hiperbarica, no hay ventaja de administrar dosis superior a 2,5 µg de sufentanil para alivio del dolor del trabajo de parto.