Avaliação da eficácia analgésica pós-operatória do bloqueio cervical superficial bilateral para tireoidectomia total por mini-incisão, realizada sob anestesia geral balanceada: estudo aleatório, encoberto, placebo controlado

Abstract

The thyroid disease, most of them are benign. Thyroid nodules are acommon clinical finding, with an estimated prevalence, based on palpation, ranging between 3 and 7% of the U.S. population (1). The bilateral superficial cervical block (BSCB) has proven safe technique of easy execution and low cost, but with inconclusive results regarding the efficacy in improving postoperative pain thyroidectomy. Due to theshortcomings of uncertainties on the subject, it was proposed a prospective randomized placebo-controlled study to help guide future actions. Method: We studied 91 patients with surgical indication for total thyroidectomy surgery by mini-incision technique without neck dissection, in the Hospital Lifecenter in Belo Horizonte, Minas Gerais between July2009 and June 2011. Patients were consecutively and randomly assigned to receive one of three interventions: Placebo - bilateral superficial cervical block (BSCB) using saline (NaCl 0.9% - 20 ml) (n = 28), group Ropi 0.25% - BSCB with the use of ropivacaine 0.25% (20 ml) (n = 31) and group Ropi 0.5% - BSCB with 0.5% ropivacaine (20 ml) (n =32). One patient was excluded in Ropi 0.25% group after receiving the therapy, because surgical wound hematoma in the immediate postoperative, requiring surgical intervention. All patients received balanced general anesthesia after the BSCB. The total thyroidectomywithout neck dissection technique of mini-open incision was performed. To consider miniincision this measure should be between 2.5 and 4.0 cm. Every the 91 surgical procedures were performed by the same surgeon as well as all the BSCB were performed by the sameanesthesiologist. Pain was assessed by numeric rating scale (NRS) in the times: in the post anesthesia recovery room (H0), ward (H1 to H4) and just before hospital discharge (H5). At the end of the study, the painful experience was assessed using the McGill pain questionnaire adapted to the Portuguese language (Br-MPQ). Other variables wereevaluated as morphine consumption, incidence of nausea and vomiting after surgery (PONV). The results were considered statistically significant when the p value was less than 5%. Results: group Ropi 0.5% showed lower pain values by NRS in the ward compared to the placebo group, with no difference between groups in other intervals studied. The group Ropi 0.25% and group Ropi 0,5% showed lower analgesic consumptionin the ward, but unlike the group Ropi 0.5%, the group Ropi 0.25% was not able to decrease the incidence of pain compared to placebo in the times studied. There was no difference in the incidence of PONV between the groups. Conclusions:We conclude that the BCSB with ropivacaine at a concentration of 0.5% was able to reduce not only the percentage of patients who experienced moderate to severe pain during the first 24 hours of post-operative of thyroidectomy for mini-incision, as well as consumption analgesic in this patient population. This decrease was more important in the first 20 hours after surgery. Lower dose of local anesthetic (ropivacaine 0.25%) was also effective in reducing analgesic consumption in the postoperative period of surgery, but did not improve the percentage of patients who experienced moderate to severe pain significantly during this same period, according to the ENV. The incidence of PONV was not influenced by whether or not the BCSB when it was held antiemese prophylactic.