Eduardo Jun Sadatsune

Determination of the minimum effective volume of 0.5% bupivacaine for ultrasound-guided axillary brachial plexus block

BACKGROUND AND OBJECTIVE The use of ultrasound for needle correct placement and local anesthetic spread monitoring helped to reduce the volume of local anesthetic required for peripheral nerve blocks. There are few studies of the minimum effective volume of local anesthetic for axillary brachial plexus block. The aim of this study was to determine the minimum effective volume (VE90) of 0.5% bupivacaine with epinephrine (1:200,000) for ultrasound guided ABPB. METHOD Massey and Dixons up-and-down method was used to calculate the minimum effective volume. The initial dose was 5 mL per nerve (radial, median, ulnar, and musculocutaneous). In case of blockade failure, the volume was increased to 0.5 mL per nerve. A successful blockade resulted in decreased volume of 0.5 mL per nerve to the next patient. Successful blockade was defined as a motor block ≤2, according to the modified Bromage scale; lack of thermal sensitivity; and response to pinprick. The achievement of five cases of failure followed by success cases was defined as criterion to complete the study. RESULTS 19 patients were included in the study. The minimum effective volume (VE90) of 0.5% bupivacaine with 1:200,000 epinephrine was 1.56 mL (95% CI, 0.99-3.5) per nerve. CONCLUSION This study is in agreement with some other studies, which show that it is possible to achieve surgical anesthesia with low volumes of local anesthetic for ultrasound-guided peripheral nerve blocks.

Minimum effective concentration of bupivacaine for axillary brachial plexus block guided by ultrasound

INTRODUCTION The use of ultrasound in regional anesthesia allows reducing the dose of local anesthetic used for peripheral nerve block. The present study was performed to determine the minimum effective concentration (MEC90) of bupivacaine for axillary brachial plexus block. METHODS Patients undergoing hand surgery were recruited. To estimate the MEC90, a sequential up-down biased coin method of allocation was used. The bupivacaine dose was 5 mL for each nerve (radial, ulnar, median, and musculocutaneous). The initial concentration was 0.35%. This concentration was changed by 0.05% depending on the previous block; a blockade failure resulted in increased concentration for the next patient; in case of success, the next patient could receive or reduction (0.1 probability) or the same concentration (0.9 probability). Surgical anesthesia was defined as driving force ≤ 2 according to the modified Bromage scale, lack of thermal sensitivity and response to pinprick. Postoperative analgesia was assessed in the recovery room with numeric pain scale and the amount of drugs used within 4h after the blockade. RESULTS MEC90 was 0.241% [R(2): 0.978, confidence interval: 0.20-0.34%]. No patient, with successful block, reported pain after 4h. CONCLUSION This study demonstrated that ultrasound guided axillary brachial plexus block can be performed with the use of low concentration of local anesthetics, increasing the safety of the procedure. Further studies should be conducted to assess blockade duration at low concentrations.

Concentração mínima efetiva de bupivacaína para o bloqueio do plexo braquial via axilar guiado por ultrassom

INTRODUCTION The use of ultrasound in regional anesthesia allows reducing the dose of local anesthetic used for peripheral nerve block. The present study was performed to determine the minimum effective concentration (MEC90) of bupivacaine for axillary brachial plexus block (ABPB). METHODS Patients undergoing hand surgery were recruited. To estimate the MEC90, a sequential up-down biased coin method of allocation was used. The bupivacaine dose was 5mL for each nerve (radial, ulnar, median, and musculocutaneous). The initial concentration was 0.35%. This concentration was changed by 0.05% depending on the previous block: a blockade failure resulted in increased concentration for the next patient; in case of success, the next patient could receive or reduction (0.1 probability) or the same concentration (0.9 probability). Surgical anesthesia was defined as driving force ≤ 2 according to the modified Bromage scale, lack of thermal sensitivity and response to pinprick. Postoperative analgesia was assessed in the recovery room with numeric pain scale and the amount of drugs used within 4hours after the blockade. RESULTS MEC90 was 0.241% [R2: 0.978, confidence interval: 0.20%-0.34%]. No successful block patient reported pain after 4hours. CONCLUSION This study demonstrated that ultrasound guided ABPB can be performed with the use of low concentration of local anesthetics, increasing the safety of the procedure. Further studies should be conducted to assess blockade duration at low concentrations.

Assessment of the effect of ketamine in combination with remifentanil on postoperative pain

BACKGROUND AND OBJECTIVES The combination of ketamine and remifentanil seems to be associated with better analgesia and duration. The aim of this study was to evaluate whether a ketamine-remifentanil combination promotes improved postoperative analgesia. METHODS Prospective, randomized, double blind study of 40 patients undergoing video laparoscopic cholecystectomy. Anesthesia was performed with remifentanil, propofol, atracurium, and 50% oxygen. Group 1 (GI) patients received remifentanil (0.4 mcg.kg(-1).min(-1)) and ketamine (5 mcg.kg(-1).min(-1)) and Group 2 (G2) received remifentanil (0.4 mcg.kg(-1).min(-1)) and saline solution. Morphine 0.1mg.kg(-1) was administered at the end of the procedure, and postoperative pain was treated with morphine via PCA. We evaluated the severity of postoperative pain by a numerical scale from zero to 10 during 24 hours. We registered the time to the first analgesic supplementation, amount of morphine used in the first 24 hours, and adverse effects. RESULTS There was a decrease in pain severity between extubation and other times evaluated in G1 and G2. There was no significant difference in pain intensity between the groups. There was no difference between G1 (22±24.9 min) and G2 (21.5±28.1min) regarding time to first dose of morphine and dose supplement of morphine consumed in G1 (29±18.4mg) and G2 (25.1±13.3mg). CONCLUSION The combination of ketamine (5 mcg.kg(-1).min(-1)) and remifentanil (0.4mcg.kg(-1).min(-1)) for cholecystectomy did not alter the severity of postoperative pain, time to first analgesic supplementation or dose of morphine in 24hours.

Avaliação do efeito da cetamina associada à remifentanila na dor pós-operatória

JUSTIFICATIVA Y OBJETIVOS: La asociacion de la cetamina con el Remifentanilo parece estar asociada con una analgesia de mejor calidad y duracion. El objetivo de este estudio fue evaluar si la cetamina asociada al Remifentanilo genera una mejoria de la analgesia postoperatoria. METODO: Se hizo un estudio prospectivo, aleatorio y doble ciego en 40 pacientes sometidos a la colecistectomia videolaparoscopica. La anestesia se realizo con de Remifentanilo, propofol, atracurio y 50% de oxigeno. Los pacientes del G1 recibieron Remifentanilo (0,4 mcg.kg-1.min-1) y cetamina (5 mcg.kg-1.min-1); los del G2, Remifentanilo (0,4 mcg.kg-1.min-1) y solucion salina. Fue administrado 0,1 mg.kg-1 de morfina al final de la operacion y el dolor postoperatorio se trato con morfina por medio de analgesia controlada por el paciente (PCA). La intensidad del dolor postoperatorio fue mensurada por la escala numerica de 0 a 10, durante 24h. Se anoto el tiempo para la primera complementacion analgesica, la cantidad de morfina utilizada durante 24 h y los efectos adversos. RESULTADOS: Ocurrio una reduccion de la intensidad del dolor entre el momento de la desentubacion y los otros momentos calculados en el G1 y en el G2. No fue observada ninguna diferencia significativa en la intensidad del dolor entre los grupos. No hubo diferencia entre G1 (22 ± 24,9 min.) y G2 (21,5 ± 28,1 min.) en el tiempo para la primera dosis de morfina y dosis complementaria de morfina consumida en el G1 (29 ± 18,4 mg) y en el G2 (25,1 ± 13,3 mg). CONCLUSIONES: La asociacion de la cetamina (5 mcg.kg-1.min-1) con el Remifentanilo (0,4 mcg.kg-1.min-1) para la colecistectomia no altero la intensidad del dolor postoperatorio, el tiempo para la primera complementacion o la dosis de morfina en 24h.

Postoperative persistent chronic pain: what do we know about prevention, risk factors, and treatment

BACKGROUND AND OBJECTIVES Postoperative persistent chronic pain (POCP) is a serious health problem, disabling, undermining the quality of life of affected patients. Although more studies and research have addressed the possible mechanisms of the evolution from acute pain to chronic postoperatively, there are still no consistent data about the risk factors and prevention. This article aims to bring what is in the panorama of the current literature available. CONTENT This review describes the definition, risk factors, and mechanisms of POCD, its prevention and treatment. The main drugs and techniques are exposed comprehensively. CONCLUSION Postoperative persistent chronic pain is a complex and still unclear etiology entity, which interferes heavily in the life of the subject. Neuropathic pain resulting from surgical trauma is still the most common expression of this entity. Techniques to prevent nerve injury are recommended and should be used whenever possible. Despite efforts to understand and select risk patients, the management and prevention of this syndrome remain challenging and inappropriate.

Takayasus's Arteritis in Pregnancy. Case Report and Literature Review

BACKGROUND AND OBJECTIVES Takayasuss Arteritis (TA) is a chronic, inflammatory, progressive, idiopathic disease that causes narrowing, occlusion, and aneurysms of systemic and pulmonary arteries affecting especially the aorta and its branches. During pregnancy, one should pay special attention to these patients. The objective of this report was to present the peripartum anesthetic care of a patient with TA and a review of the literature. CASE REPORT This is a 31-year old gravida who underwent exchange of the aortic arch and placement of a metallic aortic valve for TA four years ago. She had no complications during pregnancy, and she was admitted at 34 weeks of pregnancy for anticoagulation management. Elective cesarean section was performed at 39 weeks with continuous epidural anesthesia. Fractionated doses of local anesthetic were administered to guarantee slow installation of the blockade. The patient remained hemodynamically stable and was transferred to the ICU in the postoperative period. CONCLUSIONS Several complications can affect gravidas with TA. Careful patient evaluation, treatment of TA complications, and anestheticsurgical planning are fundamental. Maintenance of perfusion is the main concern in these patients, and neuraxial blocks may be used without harming the mother and fetus. In patients with compensated TA complications, monitoring does not differ from that routinely used in cesarean sections. Continuous epidural anesthesia with slow installation maintains hemodynamic stability and allows monitoring cerebral perfusion through the level of consciousness. To avoid postoperative hypoperfusion or hypertensive complications patients should be monitored in an intensive or semi-intensive care unit for 24 hours.

Effect of preoperative gabapentin on pain intensity and development of chronic pain after carpal tunnel syndrome surgical treatment in women: randomized, double-blind, placebo-controlled study

CONTEXT AND OBJECTIVES Effective postoperative analgesia is important for reducing the incidence of chronic pain. This study evaluated the effect of preoperative gabapentin on postoperative analgesia and the incidence of chronic pain among patients undergoing carpal tunnel syndrome surgical treatment. DESIGN AND SETTINGS Randomized, double-blind controlled trial, Federal University of São Paulo Pain Clinic. METHODS Forty patients aged 18 years or over were randomized into two groups: Gabapentin Group received 600 mg of gabapentin preoperatively, one hour prior to surgery, and Control Group received placebo. All the patients received intravenous regional anesthesia comprising 1% lidocaine. Midazolam was used for sedation if needed. Paracetamol was administered for postoperative analgesia as needed. Codeine was used additionally if the paracetamol was insufficient. The following were evaluated: postoperative pain intensity (over a six-month period), incidence of postoperative neuropathic pain (over a six-month period), need for intraoperative sedation, and use of postoperative paracetamol and codeine. The presence of neuropathic pain was established using the DN4 (Douleur Neuropathique 4) questionnaire. Complex regional pain syndrome was diagnosed using the Budapest questionnaire. RESULTS No differences in the need for sedation, control over postoperative pain or incidence of chronic pain syndromes (neuropathic or complex regional pain syndrome) were observed. No differences in postoperative paracetamol and codeine consumption were observed. CONCLUSIONS Preoperative gabapentin (600 mg) did not improve postoperative pain control, and did not reduce the incidence of chronic pain among patients undergoing carpal tunnel syndrome surgery.

Dor crônica persistente pós-operatória: o que sabemos sobre prevenção, fatores de risco e tratamento?

BACKGROUND AND OBJECTIVES Postoperative persistent chronic pain (POCP) is a serious health problem, disabling, undermining the quality of life of affected patients. Although more studies and research have addressed the possible mechanisms of the evolution from acute pain to chronic postoperatively, there are still no consistent data about the risk factors and prevention. This article aims to bring what is in the panorama of the current literature available. CONTENT This review describes the definition, risk factors, and mechanisms of POCD, its prevention and treatment. The main drugs and techniques are exposed comprehensively. CONCLUSION Postoperative persistent chronic pain is a complex and still unclear etiology entity, which interferes heavily in the life of the subject. Neuropathic pain resulting from surgical trauma is still the most common expression of this entity. Techniques to prevent nerve injury are recommended and should be used whenever possible. Despite efforts to understand and select risk patients, the management and prevention of this syndrome remain challenging and inappropriate.

SCIENTIFIC ARTICLEAssessment of the Effect of Ketamine in Combination with Remifentanil on Postoperative Pain

BACKGROUND AND OBJECTIVES The combination of ketamine and remifentanil seems to be associated with better analgesia and duration. The aim of this study was to evaluate whether a ketamine- remifentanil combination promotes improved postoperative analgesia. METHODS Prospective, randomized, double blind study of 40 patients undergoing video laparoscopic cholecystectomy. Anesthesia was performed with remifentanil, propofol, atracurium, and 50% oxygen. Group 1 (GI) patients received remifentanil (0.4 mcg.kg(-1).min(-1)) and ketamine (5 mcg.kg(-1).min(-1)) and Group 2 (G2) received remifentanil (0.4 mcg.kg(-1).min(-1)) and saline solution. Morphine 0.1 mg.kg(-1) was administered at the end of the procedure, and postoperative pain was treated with morphine via PCA. We evaluated the severity of postoperative pain by a numerical scale from zero to 10 during 24 hours. We registered the time to the first analgesic supplementation, amount of morphine used in the first 24 hours, and adverse effects. RESULTS There was a decrease in pain severity between extubation and other times evaluated in G1 and G2. There was no significant difference in pain intensity between the groups. There was no difference between G1 (22 ± 24.9 min) and G2 (21.5 ± 28.1 min) regarding time to first dose of morphine and dose supplement of morphine consumed in G1 (29 ± 18.4 mg) and G2 (25.1 ± 13.3 mg). CONCLUSION The combination of ketamine (5 mcg.kg(-1).min(-1)) and remifentanil (0.4 mcg.kg(-1).min(-1)) for cholecystectomy did not alter the severity of postoperative pain, time to first analgesic supplementation or dose of morphine in 24 hours.