BERKELEY, CA (UroToday.com) - Caudal epidural-morphine or epidural-local administration has been used for postoperative pain relief in lower abdominal surgery, thoracotomy, liver transplantation, and many outpatient urologic procedures such as hypospadias and laparoscoppic orchiopexy. It has also been suggested that stress response hormone levels can be used as an objective method to assess the analgesic efficacy of the anesthetic techniques used in children, as the assessment of pain in children can be difficult and nonobjective. Bispectral index analysis (BIS) is a widely used monitor of the hypnotic component of anesthesia. This study by Teyin et al was the first to include BIS for obtaining a constant level of intraoperative anesthesia depth and the effect of regional anesthesia on surgical stress response.

Twenty-eight children between 4 and 16 years of age and with ASA physical status I and II, who were undergoing elective inguinal herniorrhaphy or orchidopexy, were randomly assigned to two groups. The patients, their parents and the anesthesiologist who evaluated pain scores in the postanesthesia care unit (PACU) and laboratory staff who performed the plasma hormone level analysis were blinded to which drug had been used for caudal anesthesia. The same senior pediatric anesthesiologist performed all the caudal blocks. After the end of surgery, patients were transferred to the PACU where HR, respiratory rate, SpO2 and systolic, diastolic and mean pressures were recorded every 15 min and any changes were recorded immediately. In addition, during the postoperative observation period, sedation scores (1: awake, 2: sleeping but easily arousable with verbal stimulation, 3: sleeping and unarousable with verbal stimulation), rating pain scores (0: comfortable and no reaction, 1: minimal face mimics or complaint of pain when asking, 2: crying or negative reactions, 3: severe reactions or crying without rest) were recorded every 30 min by another anesthesiologist who was trained to evaluate pain scores.

The children in both groups were comparable in terms of age, weight, height, and duration of operation (P > 0.05). There were slight increases in bispectral index scores for both groups at 10th and 35th min after starting the surgery (P < 0.05). But these changes were within our predetermined BIS values limits (40 60). There were no statistically significant differences in BIS values and mean arterial pressure values between the two groups or mean arterial pressure changes with time in either group compared with baseline values. There were no statistical differences between the two groups for serum cortisol values measured DI. During surgery, at 40th min, measured cortisol increased in group M, and decreased in group B (P < 0.001). Postoperatively, blood cortisol levels increased from baseline values in both groups, but there were no significant differences between groups M and B. The intra-operative increase of glucose level in group M was significantly higher than group B (P < 0.05). Postoperative serum glucose level in group M was higher than serum glucose value in group B (P < 0.05). Postoperative Rating Pain Scores and Postoperative Sedation Scores were comparable in both groups.

They speculate that the increases in postoperative cortisol levels might be due to emotional factors such as anxiety, stay in PACU, or being separated from parents. The study concluded that both caudal epidural-morphine and caudal epidural-bupivacaine provide effective postoperative pain relief. It also concluded that caudal administration of bupivacaine is more effective than caudal epidural-morphine for attenuating intraoperative and postoperative stress responses associated with lower abdominal and genitourinary surgery in children.

Pediatric Anesthesia, October 2005