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Postoperative analgesia and intraoperative inhalational anesthetic requirements during umbilical herniorrhaphy in children: Postincisional local infiltration versus preincisional caudal epidural block
ELSEVIER
Postoperative Analgesia and Intraoperative Inhalational Anesthetic Requirements during Umbilical Herniorrhaphy in Children: Postincisional Local Infiltration versus Preincisional Caudal Epidural Block Joseph D. Tobias, MD* Department
*Associate Professor of Pediatrics and Anesthesiology; Director, Pediatric Critical Care/ Anesthesia Address correspondence to Dr. Tobias at the Department of Child Health, University of Missouri, M658 Health Sciences Center, One Hospital Drive, Columbia, MO 65212, USA. Received for publication August 15, 1995; revised manuscript accepted for publication March 8. 1996.
of Anesthesiology,
The University
of Missouri,
Columbia,
MO.
Study Objective: To determine the postoperative analgesic efjcaq oJ and the effects on, intraoperative inhalational anesthetic requirements of preincisional caudal epidural block versus postincisional infiltration of local anesthetic following umbilical herniovrhaphy in children. Design: Randomized, double-blind, prospective study. Setting: University medical center. Patients: 16 ASA status I and IIpatients (11 males, 5 females), ages 11 to 20 months, weighing up to I7 kg, Interventions: During standard anesthetic care, 16 children were randomized to receive either caudal block with 1.5 ml/kg of 0.2% bup’avacaine (group 1) or local infiltration of the surgical site with up to 1.2 ml/kg of 0.25% bupivacaine (Group 2). Measurements and Main Results: Patients in Group 1 had significantly decreasedpain scores and requirements for supplemental postoperative intravenous (N) fentanyl. Five of eight patients in Group 1 did not require supplemental IVfentanyl during their in-hospital postoperative course, while all eight patients in Group 2 required supplemental IVfentanyl. The patients who received caudal epidural block also had decreased intraoperative requirements for isoflurane, shorter time to extubation (4.1 + 0.8 min vs. 8.4 -+ 1.5 min), and quicker discharge home (129 f 13 min vs. 163 f 22 min). Five of eight patients in Croup 1 were ready for discharge at our usual time of 120 minutes, as opposed to one of eight patients in Group 2. Conclusion: Preincisional caudal epidural block is more effective in controlling pain 0 1996 by following umbilical herniorrhaphy than is postincisional local injltration. Elsevier Science Inc.
Journal of Clinical Anesthesia 8:634-638, 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0952-8180/96/$15.00 PI1 So952-Sl80(96)00171-7
Analgesia and umbilical hazorrhaphy:
Keywords: Analgesia, postoperative; anesthesia, caudal; anesthetics, inhalational; herniorrhaphy, umbilical; pediatrics.
Introduction Regional anesthetic techniques remain a popular means of providing analgesia following lower abdominal procedures in children.‘,’ The efficacy of caudal epidural block has been documented following inguinal herniorrhaphy, penoscrotal surgery, and lower extremity procedures.‘-4 When compared with caudal epidural block, local infiltration with local anesthetics has been shown to provide roughly equivalent analgesia following inguinal herniorrhaphy.2-4 I am unaware of previous reports evaluating the efficacy of caudal epidural block and local infiltration following umbilical herniorrhaphy. My previous clinical practice for caudal epidural block following umbilical herniorrhaphy was to administer up to 1.2 ml/kg of 0.25% bupivacaine. A pilot investigation, using this volume and dose of bupivacaine, demonstrated inadequate analgesia and the need for supplemental intravenous (IV) opioids in four of the first five patients. Therefore, a larger volume (1.5 ml/kg) was used for the current study. I undertook a prospective evaluation comparing caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine versus local infiltration of the surgical site with 0.25% bupivacaine.
Materials
and Methods
This study was approved by the Institutional Review Board and the Committee for the Protection of Human Subjects of Vanderbilt University, and written, informed consent was obtained from one parent of each child. ASA physical status I or II patients, weighing less than 17 kg, presenting for repair of an umbilical hernia, were considered eligible for this study. Patients weighing greater than 17 kg were excluded because there are limited data in the pediatric population concerning the upper limits of volume that should be used for caudal epidural blockade. Our current clinical practice limits the volume to 25 ml. In patients weighing more than 1‘i kg, the volume based on 1.5 ml/kg of 0.2% bupivacaine would have exceeded this limit. Patients undergoing other procedures (eg, circumcision, inguinal herniorrhaphy) in addition to umbilical herniorrhaphy were not included. All patients were fasted for at least 4 hours. Oral premedication (midazolam 0.7 mg/kg) was followed by inhalational induction with halothane in 70% nitrous oxide/ oxygen (N,O/O,). Following anesthetic induction, IV access was obtained and an infusion of 5% dextrose in lactated Ringer’s solution was started. No analgesic drugs were administered preoperatively or intraoperatively. Tracheal intubation was facilitated with vecuronium 0.1 mg/ kg, and anesthesia was maintained with isoflurane (concentration adjusted according to clinical neeid) in 50% N,O and 50% 0,. The expired concentration of isoflurane was recorded every 15 minutes during the procedure. All patients received IV glycopyrrolate 5.0 mcg/kg.
Tobias
Patients were randomized to either caudal epidural block or local infiltration. The caudal epidural block was placed after the induction of anesthesia and prior to the surgical procedure. Caudal epidural block included 1.5 ml/kg of 0.2% bupivacaine with epinephrine (Group I). This dosage was prepared by drawing up 1.2 ml/kg of 0.25% bupivacaine with epinephrine 1:200,000 and diluting the solution with preservative-free saline to a total volume of 1.5 ml/kg. Group 2 received local infiltration of the fascia, subcutaneous tissue, and skin with 0.25% bupivacaine with epinephrine 1:200,000 (maximum volume 1.2 ml/kg). The local infiltration was performed following the surgical procedure prior to closure of the surgical wound. Following the surgical procedure, residual neuromuscular blockade was reversed with neostigmine 0.07 mg/kg and glycopyrrolate 0.01 mg/kg, the trachea was extubated, and the child was transported to the postanesthesia care unit (PACU). The time from completion of the surgical procedure to tracheal extubation was noted. In the PACU, recovery from anesthesia was assessed using the Aldrete score.” The efficacy of analgesia was assessed by a nurse using the scoring system described by Casey et a16and Hannallah et aL3 The scoring system assigns a score of 0, 1, or 2 to five variables including blood pressure, crying, movement, posture, and agitation (maximum score of 10). The score was assigned in the PACU (5 and 30 minutes after arrival). The nurse assigning the score was blinded to the analgesic technique. Intravenous fentanyl 0.5 mcg/kg was available for children who were judged to be in pain (score of 3 or greater). If the child achieved a score of 3 or greater, the evaluation was repeated in 5 minutes and, if the score were 3 or greater again, the fentanyl was administered. Patients were observed for 60 minutes in the PACU and then transferred to the holding area. Pain scores were also assigned at 5 and 30 minutes after arrival in the holding area. All patients were kept in the holding area until the following discharge criteria were achieved: normal mental status, stable vital signs, ability to ambulate with minimal assistance, and ability to tolerate clear liquids. The patients were not required to void prior to discharge. Time for admission to the PACU until discharge home was recorded. A follow-up telephone call was made the following day to check on the status of the patient. Demographic data were analyzed using an unpaired t-test and are expressed as means _+SD. A Mann-Whitney two-sample comparison was used to analyze the length of the surgical procedure, anesthesia time, expired isoflurane concentration, time from completion of the surgical procedure until extubation, and time from admission to the PACU until discharge home. These data are also presented as means + SD. Nonarithmetic data (pain scores, Aldrete scores) are presented as medians with the range. Chi-square analysis with Yates’ correction was used to analyze the pain scores and the number of doses of supplemental IV fentanyl required in the PACU. To allow for the use of chi-square analysis for the pain scores, a contingency table was constructed with the pain scores grouped into three ranges, O-2, 3-5, and 6-10. J. Gin. Anesth., vol. 8, December
1996
635
Original
Contributions
Results
Table 2. Intraoperative Groups 1 and 2
A total of 16 patients were randomized via sealed envelope assignment, with 8 patients in Group 1 (caudal epidural block) and 8 patients in Group 2 (local infiltration). The demographic and intraoperative data are summarized in Table 1. There were no statistically significant differences between the two groups in regard to age, weight, gender, duration of surgical procedure, or total anesthesia time. All patients had recovered to the same degree from their general anesthetic as assessed by the Aldrete score at the assignment of the 5-minute pain score. Intraoperative requirements for isoflurane were decreased in Group 1 when compared with Group 2. The expired concentration of isoflurane was significantly less at 15, 30, 45, and 60 minutes into the surgical procedure (Table 2). Time to extubation was 4.1 f 0.8 minutes in Group 1 and 8.4 i 1.5 minutes in Group 2 (p = 0.0002). The time from arrival in the PACU until discharge home was 129 c 13 minutes in Group 1 and 163 + 22 minutes in Group 2 (p = 0.0041). Five of eight patients in Group 1 were ready for discharge at our routine time of 120 minutes as opposed to one of eight patients in Group 2. The pain scores and need for supplemental analgesics Group 1 and 2 patients are summarized in Table 3. The pain scores were significantly lower at the first two evaluation points in Group 1 when compared with Group 2 (Table 3). No difference was noted at evaluation points 3 and 4. Patients in Group 1 had a significantly (p = 0.01) decreased requirement for supplemental IV fentanyl. Five of eight patients in Group 1 did not require supplemental IV fentanyl during their in-hospital postoperative course and had pain scores of 2 or less at all four evaluation points. All eight patients in Group 2 required supplemental IV fentanyl. There were no major complications related to either type of block. Transient motor weakness of the lower extremities was noted in one patient who received caudal epidural block. The motor weakness resolved in 60 minutes and discharge was not delayed. Seven of eight patients who received a caudal epidural block voided prior to discharge. Follow-up telephone conversation 24 hours after discharge did not reveal other adverse effects from caudal epidural block.
Table 1.
Demographic
Data of Patients in Groups Group
Age (months) Weight (kg) Gender (male/female Surgical time (min) Anesthesia time (min) Extubation time (min) Discharge time (min)
1
15.9 f 4.1 12.1 + 3.3
6’2 69 i: 6 77~~6 4.1 i 0.8 129 f 13
Group
1 and 2” 2
p-value
14.6 or 3.3 12.8 f 2.5 5/3 68 t 7 82 + 5 8.4 f 1.5 163 f 22
NS NS NS NS 0.08 0.0002 0.0047
*Group 1 patients received a caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine while Group 2 patients received local infiltration of the wound and subcutaneous tissues with 0.25% bupivacaine. 636
J. Clin. Anesth., vol. 8, December
1996
Expired
Isoflurane
Concentrations
of
Group 15 30 45 60
minutes minutes minutes minutes
0.7 0.6 0.5 0.4
1
+ 0.2 t 0.1 f 0.1 * 0.1
Group 1.1 1.1 1.3 0.8
f f + t
2
p-value
0.2 0.2 0.3 0.3
0.0019 0.0002 0.0002 0.02
Discussion Various techniques are available to provide postoperative analgesia in children, including regional anesthetic techniques such as caudal epidural block, IV opioids, and nonsteroidal antiinflammatory drugs (NSAIDs). Although recent studies have demonstrated equal efficacy of both local infiltration and caudal epidural block following inguinal herniorrl~aphy,2,4 the current study demonstrates the superiority of caudal epidural block following umbilical herniorrhaphy. Graham and Wandless’ compared local infiltration with local infiltration plus intramuscular ketorolac (0.5 mg/kg) to provide analgesia following umbilical herniorrhaphy. They noted that with local infiltration alone, many patients experienced a diffuse discomfort in the abdomen, possibly related to peritoneal traction. No significant difference was noted between the groups. Twenty percent of patients (an equal number in both groups) experienced what was judged to be moderate pain. The authors concluded that the addition of the NSAID provided no additional benefit. Our usual routine for providing postoperative analgesia following lower abdominal or lower extremity procedures is caudal epidural block. During a pilot investigation, it was noted that 1.2 ml/kg of 0.25% bupivacaine did not provide acceptable analgesia following repair of an umbilical hernia. It is probable that the volume of 1.2 ml/kg did not achieve a high enough sensory level to provide analgesia for this surgical procedure. While volumes of 1.2 ml/kg will reliably produce sensory levels of T,,, it may be that higher levels are needed following this surgical procedure. Subsequently, we found that children who received caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine had decreased postoperative opioid requirements and decreased pain scores when compared with local infiltration of the surgical site. Sensory levels were not measured and, therefore, I cannot comment on the level of blockade that was achieved. When compared with local infiltration, the patients who received caudal blocks had decreased pain scores (at 5 and 30 minutes after arrival in the PACU) and required fewer doses of IV fentanyl. Additionally, a greater number of patients who received caudal block required no postoperative analgesic drugs (five of eight patients us. 0 of eight patients). I also noted intraoperative advantages of caudal epidural block when compared with local infiltration. The decreased requirements for inhalational decreased time to extubation were
anesthetic drug and not unexpected find-
Analgesia and umbilical hemioruha&: Table 3.
Tobias
Pain Scores and Keed for Supplemental Fentanyl in Groups 2 and 2” 2
p-value
1 (0 to 4) 1 (0 to 2) 0 (0 to 1)
4 (3 to 6) 3 (2 to 3) 1 (0 to 2)
0.007
O(Oto1)
1 (0 to 1)
NS
Group 1 0 (0 to 2)
Group 2 2 (1 to 3)
p-value 0.01
Pain score.9
Group
1 (PACE, 5 minutes) 2 (PACU, 30 minutes) 3 (Holding area, 5 minutes) 4 (Holding area, 30 minutes) Supplemental fentanyl (doses)
Group
1
0.03 NS
Note: Data are presented as the medians, ltith ranges in parentheses. PACU = postanesthesia care unit.
ings and can be explained by the placement of the caudal block prior to the start of the surgical procedure, while the infiltration in Group 2 was performed at the completion of the surgical procedure. While one might critici.ze the study design for the different methodology of the two groups, this is in keeping with our standard practice, which is to place the caudal block prior to the procedure and thereby limit the need for inhalational drugs. Our surgical colleagues are hesitant to use local infiltration prior to the procedure in younger patients because it may distort the anatomy. While this may eliminate some of the scientific validity of the study, it does adhere to current clinical practice. While the differences in time to extubation were statistically significant, the average difference of 4.3 minutes is not a clinically significant event. However, the earlier discharge home by an average of 34 minutes may be a more clinically significant finding. Furthermore, I noted that five of eight patients who received caudal epidural block were ready for discharge at 120 minutes (our minimum allowable discharge time), as compared with one of eight patients who received local infiltration. Various factors necessitated longer stays in the group that received local infiltration including sedation related to IV opioids as well as nausea/vomiting (three patients). Considering the methodology of the current study, it is possible that the differences in pain scores may be attributed to the preemptive effect of the caudal block and not a true difference in analgesic efficacy between the two techniques. While the placement of an epidural block prior to surgical incision may have a preemptive effect on postoperative pain and decrease postoperative analgesic requirements, the preemptive effects of local infiltration are not as convincing.’ Local infiltration of the wound does not block visceral pain and therefore maly not effectively block nociceptive input into the spinal cord or provide preemptive analgesia. The efficacy of caudal epidural block depends on both the volume and the concentration of local anesthetic used. In the current study, I chose to use the maximum allowable dose of bupivacaine (3 mg/kg) to eliminate the possibility that inadequate analgesia was the result of an inadequate dose. Previous studies following inguinal herniorrhaphy have demonstrated equal analgesic efficacy with either 0.25% or 0.125% bupivacaine and a lower in-
cidence of residual lower extremity motor weakness with the 0.125% solution.g Future studies are needed to determine if lower concentrations of bupivacaine provide equivalent analgesia following this procedure. The current study was limited to patients who weighed 17 kg or less. Our current clinical practice is to limit the maximum volume for caudal epidural block to 25 ml. Therefore, to eliminate an additional confounding factor (different volumes of the local anesthetic when calculated on a ml/kg basis), I decided to limit the current study to patients who would qualify for a dose of 1.5 ml/kg. Future studies are needed to define the efficacy of the 25 ml dose for patients weighing more than 17 kg. Various formulas based on age, weight, or the distance from the sacral hiatus to C, have been used to calculate the volume of local anesthetic for caudal block.” However, the majority of these formulas have been developed for use in infants and toddlers. Volumes in excess of 25 ml are not generally recommended due to concerns of excessive spread of the sensory level and increases in cerebrospinal fluid pressure.” It has been suggested that if such large volumes are needed to provide satisfactory analgesia, another epidural approach should be chosen.” Despite its efficacy, the discussion of caudal epidural block must include some mention of possible adverse effects including inadvertent intravascular or intraosseous injection. These complications are not a concern with local infiltration and remain the primary advantage of the latter technique. Dalens and Hasnaoui” reported their experience with caudal blocks with no major adverse effects in a consecutive series of 750 patients. Minor adverse effects included motor blockade and urinary retention. Despite the reported safety of caudal block, calculation of the total dose, use of a test dose, and slow injection are recommended to prevent local anesthetic toxicity. Given these concerns, the current study demonstrates that cauda1 epidural block provides more effective analgesia, limits postoperative opioid requirements, and results in earlier discharge home when compared with local infiltration of the wound.
References 1. Payne KA, Hendrix MR, Wade WJ: Caudal bupivacaine for postoperative analgesia in pediatric lower limb surgery. JPediab Surg 1993;28:155-7.
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1996
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Original Contrihltions 2. Conroy JM, Othersen HB Jr, Dot-man BH, Gottesman JD, Wallace CT, Brahen NH: A comparison of wound instillation and caudal block for analgesia following pediatric inguinal herniorrhaphy. J Pediatr Surg 1993;28:565-7. 3. Hannallah RS, Broadman LM, Belman AB, Abramowitz MD, Epstein BS: Comparison of caudal and ilioinguinal/iliohypogastric nerve blocks for control of post-orchiopexy pain in pediatric ambulatory surgery. Anesthesiology 1987;66:832-4. 4. Splinter WM, Bass J, Komocar L: Regional anaesthesia for hernia repair in children: local vs. caudal anaesthesia. Can J Anaesth 1995;42:197-200. 5. Aldrete JA, Kroulik D: A postanesthetic recovery score. Anesth Analg 1970;49:92&34. 6. Casey WF, Rice LJ, Hannallah RS, Broadman LM, Norden JM, Guzzetta P: A comparison between bupivacaine instillation versus ilioinguinal/iliohypogastric nerve block for postoperative analgesia following inguinal herniorrhaphy in children. Anesthesiology 1990;72:637-9. 7. Graham SG, Wandless JG: The effect of ketorolac as an adjuvant
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1996
to local anaesthetic infiltration for analgesia in paediatric umbilical hernia surgery. Paediatr Am&h 1995;5:161-3. 8. Ure BM, Troidl H, Spangenberger W, et al: Preincisional local anesthesia with bupivacaine and pain after laparoscopic cholecystectomy. A double-blind randomized clinical trial. Surg Endosc 1993;7:482-8. 9. Wolf AR, Valley RD, Fear DW, Roy WL, Lerman J: Bupivacaine for caudal analgesia in infants and children: the optimal effective concentration. Anesthesiology 1988;69:102-6. 10. Dalens BJ: Blocks along the neuraxis. In: Dalens BJ (ed): Pediatric Regional Anesthesia. Boca Raton, FL: CRC Press, Inc., 1990:349436. 11. Burn JMB, Langdon L, Semple AJ, Bisset WI: Transient loss of consciousness after therapeutic caudal block [Letter]. Anaesthesia 1985;40:380. 12. Dalens B, Hasnaoui A: Caudal anesthesia in pediatric surgery: success rate and adverse effects in 750 consecutive patients. Anesth Analg 1989;68:83-9.
Postoperative Analgesia and Intraoperative Inhalational Anesthetic Requirements during Umbilical Herniorrhaphy in Children: Postincisional Local Infiltration versus Preincisional Caudal Epidural Block Joseph D. Tobias, MD* Department
*Associate Professor of Pediatrics and Anesthesiology; Director, Pediatric Critical Care/ Anesthesia Address correspondence to Dr. Tobias at the Department of Child Health, University of Missouri, M658 Health Sciences Center, One Hospital Drive, Columbia, MO 65212, USA. Received for publication August 15, 1995; revised manuscript accepted for publication March 8. 1996.
of Anesthesiology,
The University
of Missouri,
Columbia,
MO.
Study Objective: To determine the postoperative analgesic efjcaq oJ and the effects on, intraoperative inhalational anesthetic requirements of preincisional caudal epidural block versus postincisional infiltration of local anesthetic following umbilical herniovrhaphy in children. Design: Randomized, double-blind, prospective study. Setting: University medical center. Patients: 16 ASA status I and IIpatients (11 males, 5 females), ages 11 to 20 months, weighing up to I7 kg, Interventions: During standard anesthetic care, 16 children were randomized to receive either caudal block with 1.5 ml/kg of 0.2% bup’avacaine (group 1) or local infiltration of the surgical site with up to 1.2 ml/kg of 0.25% bupivacaine (Group 2). Measurements and Main Results: Patients in Group 1 had significantly decreasedpain scores and requirements for supplemental postoperative intravenous (N) fentanyl. Five of eight patients in Group 1 did not require supplemental IVfentanyl during their in-hospital postoperative course, while all eight patients in Group 2 required supplemental IVfentanyl. The patients who received caudal epidural block also had decreased intraoperative requirements for isoflurane, shorter time to extubation (4.1 + 0.8 min vs. 8.4 -+ 1.5 min), and quicker discharge home (129 f 13 min vs. 163 f 22 min). Five of eight patients in Croup 1 were ready for discharge at our usual time of 120 minutes, as opposed to one of eight patients in Group 2. Conclusion: Preincisional caudal epidural block is more effective in controlling pain 0 1996 by following umbilical herniorrhaphy than is postincisional local injltration. Elsevier Science Inc.
Journal of Clinical Anesthesia 8:634-638, 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0952-8180/96/$15.00 PI1 So952-Sl80(96)00171-7
Analgesia and umbilical hazorrhaphy:
Keywords: Analgesia, postoperative; anesthesia, caudal; anesthetics, inhalational; herniorrhaphy, umbilical; pediatrics.
Introduction Regional anesthetic techniques remain a popular means of providing analgesia following lower abdominal procedures in children.‘,’ The efficacy of caudal epidural block has been documented following inguinal herniorrhaphy, penoscrotal surgery, and lower extremity procedures.‘-4 When compared with caudal epidural block, local infiltration with local anesthetics has been shown to provide roughly equivalent analgesia following inguinal herniorrhaphy.2-4 I am unaware of previous reports evaluating the efficacy of caudal epidural block and local infiltration following umbilical herniorrhaphy. My previous clinical practice for caudal epidural block following umbilical herniorrhaphy was to administer up to 1.2 ml/kg of 0.25% bupivacaine. A pilot investigation, using this volume and dose of bupivacaine, demonstrated inadequate analgesia and the need for supplemental intravenous (IV) opioids in four of the first five patients. Therefore, a larger volume (1.5 ml/kg) was used for the current study. I undertook a prospective evaluation comparing caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine versus local infiltration of the surgical site with 0.25% bupivacaine.
Materials
and Methods
This study was approved by the Institutional Review Board and the Committee for the Protection of Human Subjects of Vanderbilt University, and written, informed consent was obtained from one parent of each child. ASA physical status I or II patients, weighing less than 17 kg, presenting for repair of an umbilical hernia, were considered eligible for this study. Patients weighing greater than 17 kg were excluded because there are limited data in the pediatric population concerning the upper limits of volume that should be used for caudal epidural blockade. Our current clinical practice limits the volume to 25 ml. In patients weighing more than 1‘i kg, the volume based on 1.5 ml/kg of 0.2% bupivacaine would have exceeded this limit. Patients undergoing other procedures (eg, circumcision, inguinal herniorrhaphy) in addition to umbilical herniorrhaphy were not included. All patients were fasted for at least 4 hours. Oral premedication (midazolam 0.7 mg/kg) was followed by inhalational induction with halothane in 70% nitrous oxide/ oxygen (N,O/O,). Following anesthetic induction, IV access was obtained and an infusion of 5% dextrose in lactated Ringer’s solution was started. No analgesic drugs were administered preoperatively or intraoperatively. Tracheal intubation was facilitated with vecuronium 0.1 mg/ kg, and anesthesia was maintained with isoflurane (concentration adjusted according to clinical neeid) in 50% N,O and 50% 0,. The expired concentration of isoflurane was recorded every 15 minutes during the procedure. All patients received IV glycopyrrolate 5.0 mcg/kg.
Tobias
Patients were randomized to either caudal epidural block or local infiltration. The caudal epidural block was placed after the induction of anesthesia and prior to the surgical procedure. Caudal epidural block included 1.5 ml/kg of 0.2% bupivacaine with epinephrine (Group I). This dosage was prepared by drawing up 1.2 ml/kg of 0.25% bupivacaine with epinephrine 1:200,000 and diluting the solution with preservative-free saline to a total volume of 1.5 ml/kg. Group 2 received local infiltration of the fascia, subcutaneous tissue, and skin with 0.25% bupivacaine with epinephrine 1:200,000 (maximum volume 1.2 ml/kg). The local infiltration was performed following the surgical procedure prior to closure of the surgical wound. Following the surgical procedure, residual neuromuscular blockade was reversed with neostigmine 0.07 mg/kg and glycopyrrolate 0.01 mg/kg, the trachea was extubated, and the child was transported to the postanesthesia care unit (PACU). The time from completion of the surgical procedure to tracheal extubation was noted. In the PACU, recovery from anesthesia was assessed using the Aldrete score.” The efficacy of analgesia was assessed by a nurse using the scoring system described by Casey et a16and Hannallah et aL3 The scoring system assigns a score of 0, 1, or 2 to five variables including blood pressure, crying, movement, posture, and agitation (maximum score of 10). The score was assigned in the PACU (5 and 30 minutes after arrival). The nurse assigning the score was blinded to the analgesic technique. Intravenous fentanyl 0.5 mcg/kg was available for children who were judged to be in pain (score of 3 or greater). If the child achieved a score of 3 or greater, the evaluation was repeated in 5 minutes and, if the score were 3 or greater again, the fentanyl was administered. Patients were observed for 60 minutes in the PACU and then transferred to the holding area. Pain scores were also assigned at 5 and 30 minutes after arrival in the holding area. All patients were kept in the holding area until the following discharge criteria were achieved: normal mental status, stable vital signs, ability to ambulate with minimal assistance, and ability to tolerate clear liquids. The patients were not required to void prior to discharge. Time for admission to the PACU until discharge home was recorded. A follow-up telephone call was made the following day to check on the status of the patient. Demographic data were analyzed using an unpaired t-test and are expressed as means _+SD. A Mann-Whitney two-sample comparison was used to analyze the length of the surgical procedure, anesthesia time, expired isoflurane concentration, time from completion of the surgical procedure until extubation, and time from admission to the PACU until discharge home. These data are also presented as means + SD. Nonarithmetic data (pain scores, Aldrete scores) are presented as medians with the range. Chi-square analysis with Yates’ correction was used to analyze the pain scores and the number of doses of supplemental IV fentanyl required in the PACU. To allow for the use of chi-square analysis for the pain scores, a contingency table was constructed with the pain scores grouped into three ranges, O-2, 3-5, and 6-10. J. Gin. Anesth., vol. 8, December
1996
635
Original
Contributions
Results
Table 2. Intraoperative Groups 1 and 2
A total of 16 patients were randomized via sealed envelope assignment, with 8 patients in Group 1 (caudal epidural block) and 8 patients in Group 2 (local infiltration). The demographic and intraoperative data are summarized in Table 1. There were no statistically significant differences between the two groups in regard to age, weight, gender, duration of surgical procedure, or total anesthesia time. All patients had recovered to the same degree from their general anesthetic as assessed by the Aldrete score at the assignment of the 5-minute pain score. Intraoperative requirements for isoflurane were decreased in Group 1 when compared with Group 2. The expired concentration of isoflurane was significantly less at 15, 30, 45, and 60 minutes into the surgical procedure (Table 2). Time to extubation was 4.1 f 0.8 minutes in Group 1 and 8.4 i 1.5 minutes in Group 2 (p = 0.0002). The time from arrival in the PACU until discharge home was 129 c 13 minutes in Group 1 and 163 + 22 minutes in Group 2 (p = 0.0041). Five of eight patients in Group 1 were ready for discharge at our routine time of 120 minutes as opposed to one of eight patients in Group 2. The pain scores and need for supplemental analgesics Group 1 and 2 patients are summarized in Table 3. The pain scores were significantly lower at the first two evaluation points in Group 1 when compared with Group 2 (Table 3). No difference was noted at evaluation points 3 and 4. Patients in Group 1 had a significantly (p = 0.01) decreased requirement for supplemental IV fentanyl. Five of eight patients in Group 1 did not require supplemental IV fentanyl during their in-hospital postoperative course and had pain scores of 2 or less at all four evaluation points. All eight patients in Group 2 required supplemental IV fentanyl. There were no major complications related to either type of block. Transient motor weakness of the lower extremities was noted in one patient who received caudal epidural block. The motor weakness resolved in 60 minutes and discharge was not delayed. Seven of eight patients who received a caudal epidural block voided prior to discharge. Follow-up telephone conversation 24 hours after discharge did not reveal other adverse effects from caudal epidural block.
Table 1.
Demographic
Data of Patients in Groups Group
Age (months) Weight (kg) Gender (male/female Surgical time (min) Anesthesia time (min) Extubation time (min) Discharge time (min)
1
15.9 f 4.1 12.1 + 3.3
6’2 69 i: 6 77~~6 4.1 i 0.8 129 f 13
Group
1 and 2” 2
p-value
14.6 or 3.3 12.8 f 2.5 5/3 68 t 7 82 + 5 8.4 f 1.5 163 f 22
NS NS NS NS 0.08 0.0002 0.0047
*Group 1 patients received a caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine while Group 2 patients received local infiltration of the wound and subcutaneous tissues with 0.25% bupivacaine. 636
J. Clin. Anesth., vol. 8, December
1996
Expired
Isoflurane
Concentrations
of
Group 15 30 45 60
minutes minutes minutes minutes
0.7 0.6 0.5 0.4
1
+ 0.2 t 0.1 f 0.1 * 0.1
Group 1.1 1.1 1.3 0.8
f f + t
2
p-value
0.2 0.2 0.3 0.3
0.0019 0.0002 0.0002 0.02
Discussion Various techniques are available to provide postoperative analgesia in children, including regional anesthetic techniques such as caudal epidural block, IV opioids, and nonsteroidal antiinflammatory drugs (NSAIDs). Although recent studies have demonstrated equal efficacy of both local infiltration and caudal epidural block following inguinal herniorrl~aphy,2,4 the current study demonstrates the superiority of caudal epidural block following umbilical herniorrhaphy. Graham and Wandless’ compared local infiltration with local infiltration plus intramuscular ketorolac (0.5 mg/kg) to provide analgesia following umbilical herniorrhaphy. They noted that with local infiltration alone, many patients experienced a diffuse discomfort in the abdomen, possibly related to peritoneal traction. No significant difference was noted between the groups. Twenty percent of patients (an equal number in both groups) experienced what was judged to be moderate pain. The authors concluded that the addition of the NSAID provided no additional benefit. Our usual routine for providing postoperative analgesia following lower abdominal or lower extremity procedures is caudal epidural block. During a pilot investigation, it was noted that 1.2 ml/kg of 0.25% bupivacaine did not provide acceptable analgesia following repair of an umbilical hernia. It is probable that the volume of 1.2 ml/kg did not achieve a high enough sensory level to provide analgesia for this surgical procedure. While volumes of 1.2 ml/kg will reliably produce sensory levels of T,,, it may be that higher levels are needed following this surgical procedure. Subsequently, we found that children who received caudal epidural block with 1.5 ml/kg of 0.2% bupivacaine had decreased postoperative opioid requirements and decreased pain scores when compared with local infiltration of the surgical site. Sensory levels were not measured and, therefore, I cannot comment on the level of blockade that was achieved. When compared with local infiltration, the patients who received caudal blocks had decreased pain scores (at 5 and 30 minutes after arrival in the PACU) and required fewer doses of IV fentanyl. Additionally, a greater number of patients who received caudal block required no postoperative analgesic drugs (five of eight patients us. 0 of eight patients). I also noted intraoperative advantages of caudal epidural block when compared with local infiltration. The decreased requirements for inhalational decreased time to extubation were
anesthetic drug and not unexpected find-
Analgesia and umbilical hemioruha&: Table 3.
Tobias
Pain Scores and Keed for Supplemental Fentanyl in Groups 2 and 2” 2
p-value
1 (0 to 4) 1 (0 to 2) 0 (0 to 1)
4 (3 to 6) 3 (2 to 3) 1 (0 to 2)
0.007
O(Oto1)
1 (0 to 1)
NS
Group 1 0 (0 to 2)
Group 2 2 (1 to 3)
p-value 0.01
Pain score.9
Group
1 (PACE, 5 minutes) 2 (PACU, 30 minutes) 3 (Holding area, 5 minutes) 4 (Holding area, 30 minutes) Supplemental fentanyl (doses)
Group
1
0.03 NS
Note: Data are presented as the medians, ltith ranges in parentheses. PACU = postanesthesia care unit.
ings and can be explained by the placement of the caudal block prior to the start of the surgical procedure, while the infiltration in Group 2 was performed at the completion of the surgical procedure. While one might critici.ze the study design for the different methodology of the two groups, this is in keeping with our standard practice, which is to place the caudal block prior to the procedure and thereby limit the need for inhalational drugs. Our surgical colleagues are hesitant to use local infiltration prior to the procedure in younger patients because it may distort the anatomy. While this may eliminate some of the scientific validity of the study, it does adhere to current clinical practice. While the differences in time to extubation were statistically significant, the average difference of 4.3 minutes is not a clinically significant event. However, the earlier discharge home by an average of 34 minutes may be a more clinically significant finding. Furthermore, I noted that five of eight patients who received caudal epidural block were ready for discharge at 120 minutes (our minimum allowable discharge time), as compared with one of eight patients who received local infiltration. Various factors necessitated longer stays in the group that received local infiltration including sedation related to IV opioids as well as nausea/vomiting (three patients). Considering the methodology of the current study, it is possible that the differences in pain scores may be attributed to the preemptive effect of the caudal block and not a true difference in analgesic efficacy between the two techniques. While the placement of an epidural block prior to surgical incision may have a preemptive effect on postoperative pain and decrease postoperative analgesic requirements, the preemptive effects of local infiltration are not as convincing.’ Local infiltration of the wound does not block visceral pain and therefore maly not effectively block nociceptive input into the spinal cord or provide preemptive analgesia. The efficacy of caudal epidural block depends on both the volume and the concentration of local anesthetic used. In the current study, I chose to use the maximum allowable dose of bupivacaine (3 mg/kg) to eliminate the possibility that inadequate analgesia was the result of an inadequate dose. Previous studies following inguinal herniorrhaphy have demonstrated equal analgesic efficacy with either 0.25% or 0.125% bupivacaine and a lower in-
cidence of residual lower extremity motor weakness with the 0.125% solution.g Future studies are needed to determine if lower concentrations of bupivacaine provide equivalent analgesia following this procedure. The current study was limited to patients who weighed 17 kg or less. Our current clinical practice is to limit the maximum volume for caudal epidural block to 25 ml. Therefore, to eliminate an additional confounding factor (different volumes of the local anesthetic when calculated on a ml/kg basis), I decided to limit the current study to patients who would qualify for a dose of 1.5 ml/kg. Future studies are needed to define the efficacy of the 25 ml dose for patients weighing more than 17 kg. Various formulas based on age, weight, or the distance from the sacral hiatus to C, have been used to calculate the volume of local anesthetic for caudal block.” However, the majority of these formulas have been developed for use in infants and toddlers. Volumes in excess of 25 ml are not generally recommended due to concerns of excessive spread of the sensory level and increases in cerebrospinal fluid pressure.” It has been suggested that if such large volumes are needed to provide satisfactory analgesia, another epidural approach should be chosen.” Despite its efficacy, the discussion of caudal epidural block must include some mention of possible adverse effects including inadvertent intravascular or intraosseous injection. These complications are not a concern with local infiltration and remain the primary advantage of the latter technique. Dalens and Hasnaoui” reported their experience with caudal blocks with no major adverse effects in a consecutive series of 750 patients. Minor adverse effects included motor blockade and urinary retention. Despite the reported safety of caudal block, calculation of the total dose, use of a test dose, and slow injection are recommended to prevent local anesthetic toxicity. Given these concerns, the current study demonstrates that cauda1 epidural block provides more effective analgesia, limits postoperative opioid requirements, and results in earlier discharge home when compared with local infiltration of the wound.
References 1. Payne KA, Hendrix MR, Wade WJ: Caudal bupivacaine for postoperative analgesia in pediatric lower limb surgery. JPediab Surg 1993;28:155-7.
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Original Contrihltions 2. Conroy JM, Othersen HB Jr, Dot-man BH, Gottesman JD, Wallace CT, Brahen NH: A comparison of wound instillation and caudal block for analgesia following pediatric inguinal herniorrhaphy. J Pediatr Surg 1993;28:565-7. 3. Hannallah RS, Broadman LM, Belman AB, Abramowitz MD, Epstein BS: Comparison of caudal and ilioinguinal/iliohypogastric nerve blocks for control of post-orchiopexy pain in pediatric ambulatory surgery. Anesthesiology 1987;66:832-4. 4. Splinter WM, Bass J, Komocar L: Regional anaesthesia for hernia repair in children: local vs. caudal anaesthesia. Can J Anaesth 1995;42:197-200. 5. Aldrete JA, Kroulik D: A postanesthetic recovery score. Anesth Analg 1970;49:92&34. 6. Casey WF, Rice LJ, Hannallah RS, Broadman LM, Norden JM, Guzzetta P: A comparison between bupivacaine instillation versus ilioinguinal/iliohypogastric nerve block for postoperative analgesia following inguinal herniorrhaphy in children. Anesthesiology 1990;72:637-9. 7. Graham SG, Wandless JG: The effect of ketorolac as an adjuvant
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to local anaesthetic infiltration for analgesia in paediatric umbilical hernia surgery. Paediatr Am&h 1995;5:161-3. 8. Ure BM, Troidl H, Spangenberger W, et al: Preincisional local anesthesia with bupivacaine and pain after laparoscopic cholecystectomy. A double-blind randomized clinical trial. Surg Endosc 1993;7:482-8. 9. Wolf AR, Valley RD, Fear DW, Roy WL, Lerman J: Bupivacaine for caudal analgesia in infants and children: the optimal effective concentration. Anesthesiology 1988;69:102-6. 10. Dalens BJ: Blocks along the neuraxis. In: Dalens BJ (ed): Pediatric Regional Anesthesia. Boca Raton, FL: CRC Press, Inc., 1990:349436. 11. Burn JMB, Langdon L, Semple AJ, Bisset WI: Transient loss of consciousness after therapeutic caudal block [Letter]. Anaesthesia 1985;40:380. 12. Dalens B, Hasnaoui A: Caudal anesthesia in pediatric surgery: success rate and adverse effects in 750 consecutive patients. Anesth Analg 1989;68:83-9.