Control of pain through epidural block and incidence of cardiac dysrhythmias in postoperative period of thoracic and major abdominal surgical procedures: a comparative study.

BACKGROUND AND OBJECTIVES: Upper abdomen and thorax surgeries cause intense pain. Some of postoperative pain main complications are cardiocirculatory complications. The objective of this study was to test the hypothesis that postoperative analgesia with employment of local anesthetics plus spinal opioids may reduce the incidence of cardiovascular complications in postoperative period of patients in these conditions, comparing with classical methods of postoperative analgesia, opioids and NSAIDs, administered upon patient's demand. METHOD: Eighty adult patients, ASA I and II, without ECG alterations, were allocated into two groups of 40: Group A, patients under general anesthesia with propofol, cisatracurium and isoflurane, associated with epidural anesthesia with catheter and control of postoperative analgesia with bupivacaine and epidural morphine; and Group B, patients under general anesthesia with the same drugs and doses of A, plus postoperative analgesia carried out with NSAIDs and intravenous morphine at the end of surgery and in regular intervals. In both groups Holter was applied for 24 hours. Pain evaluation was carried out through visual analog scale. RESULTS: In pain evaluation, an evident predominance of 0 score (p<0.001) was observed in Group A and there was also reduction of blood pressure levels in postoperative period in a more accentuated way. Ventricular and supraventricular dysrhythmias were five times more frequent in Group B (p=0.00001), in which a tendency to a higher frequency of ventricular extrasystoles in age>50 years (22.2% versus 0.0%. p=0.26) was also detected. No significative difference of heart rate among groups (p>0.05) was observed. CONCLUSIONS: The best quality of analgesia in postoperative period, carried out in Group A, reduced the incidence of cardiovascular complications.

Assessing the use of 50% enantiomeric excess bupivacaine-loaded microspheres after sciatic nerve block in rats.

BACKGROUND AND OBJECTIVES: To achieve better therapeutic benefits of local anesthetics in the control of postoperative pain through controlled-release carrier. The objective of this study was to compare the characteristics of sensory and motor blockade between microspheres without local anesthetic: racemic bupivacaine-loaded microspheres; 50% enantiomeric excess bupivacaine-loaded microspheres; and free 50% enantiomeric excess bupivacaine. METHODS: Wistar rats were distributed into four groups: A (Microsphere); B (S50-R50 bupivacaine-loaded microsphere); C (50% enantiomeric excess bupivacaine-loaded microsphere); and D (50% enantiomeric excess bupivacaine). Inhalation anesthesia was performed before the sciatic nerve block (2% halothane and 100% O(2)). Sensorial blockade was measured by the time required for each rat to withdraw its paw from a hot plate at 56°C (positive>4 sec). Motor blockade was measured by the time between drug injection until recovery of a motor score of 2 on the established criterion. RESULTS: The sensory response was significantly more frequent in groups B, C, and D than in group A (p<0.001). There were no statistically significant differences in the response to the sensory test in groups B, C, and D (p>0.05). The response to the motor test was also significantly more frequent in groups B, C, and D than in group A (p=0.02). A tendency to greater positivity in the motor test was more frequently found in groups B and D than in group C (p=0.10). CONCLUSIONS: Controlled-release of 50% enantiomeric excess bupivacaine-loaded microspheres showed similar results regarding analgesia and less motor blockade when compared to other anesthetic formulations.