RESUMO
OBJECTIVE: In this prospective randomized controlled study, we aimed to evaluate the effects of the administration of equal doses of bupivacaine and morphine (BM) at high volume and low concentration (HV-LC) or low volume and high concentration (LV-HC) on the number of drugs consumed, pain scores and side effects. PATIENTS AND METHODS: We randomized 64 patients who underwent thoracotomy into two groups. Group 1 received a solution prepared with 0.12% bupivacaine and 0.05 mg/cc morphine, administered with a basal infusion rate of 4 cc/h, a 2-cc bolus dose, and a 30-minute lockout time. Group 2 received a solution prepared with 0.48% bupivacaine and 0.2 mg/cc morphine, administered with a basal infusion rate of 1 cc/h, a 0.5-cc bolus dose, and a 30-minute lockout time. We compared patient-controlled epidural analgesia (PCEA) usage doses, pain scores, sensory and motor block, hemodynamic effects, side effects, and patient satisfaction in the postoperative periods. RESULTS: An increase in drug consumption with PCEA was found in the first 24 hours postoperatively in Group 2 (p<0.05). Resting visual analog scale (VAS) scores were statistically significantly higher at hours 2, 28, 32, 36, 44 and coughing VAS scores were also higher at hours 2 and 20 in Group 2. Heart rates in Group 2 were lower than in Group 1 at hours 16, 24, 44 and 48 (p<0.05). The cephalic spread of the sensory block in Group 1 was more extensive (p<0.05). The groups demonstrated no significant differences regarding side effects and patient satisfaction (p>0.05). CONCLUSIONS: The HV-LC approach resulted in better analgesia, less drug consumption, and greater cephalic spread of sensory block than the LV-HC approach. Both applications were effective and safe in terms of analgesia and side effects.