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Single-injection lumbar epidural morphine for postoperative analgesia in children
Regional Anesthesia 22(3):212-217, 1997
Single-Injection Lumbar Epidural Morphine for Postoperative Analgesia in Children A Report of 175 Cases t
Pervin Bozkurt, M.D., Gtiner Kaya, M.D., and Y/Jksel Yeker, M.D.
Background and Objectives. Since the first report of epidural opioid administration to pediatric patients, several studies have described the quality of analgesia, doses, pharmacokinetics, and side effects of this procedure. A pediatric series using an easy and cheap single-injection technique of epidural morphine administration for postoperative analgesia is presented. Methods. Postoperative analgesia was achieved with a single lumbar epidural morphine injection (0.1 mg/kg in 0.2 mL/kg saline), which was given via a 22-gauge intramuscular needle to 153 pcdiatric patients (aged 4 months-17 years) following 175 lower abdominal or urologic operations. Injections were given by 43 anesthesiology residents under the supervision of pediatric anesthesiologists, after termination of surgery performcd under general ancsthcsia. Resttlts. The success rate of epidural puncture on the first at.tempt was 92%. Pain control was considered excellent in 76% of patients for 24 hours. The remaining patients had analgesia lasting 10.9 -+ 5.5 hours after epidural morphine administration. No alterations in hemodynamic parameters were observed. "IXvo patients (1.1%) developed respiratory depression during early postoperative care and one, with a history of apneic spclls, had an episode of apnea 5 hours after morphine administration. The inddences of minor side effects were: nausea, 33.9%; vomiting, 42.9%; pruritis 9%; and urinary retention 12.5%. Conclusions. This technique is easy to perform, even for trainees in anesthesiology. With appropriate patient selection and avoidance of the concomitant use of narcotics and sedatives, epidural morphine provides protnpt, effective, safe, and prolonged analgesia in child ren. Regional Anesthesia 1997: 22:212-21Z Key words: pediatric surgery, postoperative analgcsia, epidural analgesia, morphine.
Following tile first publication in 1979 regarding epidural opioid administration (1), interest in postoperative pain control greatly increased. The first pediatric report (2) was published i n 1981, and subsequently several studies described quality of analgesia, doses, pharmacokinetics, and side effects (3-12). tlowever, these all involved relatively small series of patients, and local anesthetics were often
given in combination with m o r p h i n e via an epidural catheter. The frequency of complications and side effects also varied widely a m o n g these studies. Since the first use of epidural narcotics for postoperative analgesia in o u r clinic, we have found a single lumbar epidural injection of m o r p h i n e to be an easy and inexpensive m e t h o d of providing postoperative analgesia in pediatric patients undergoing lower abdominal or urologic surgery. In this prospective study, 175 single lumbar epidural morphine injections were administered by 43 anesthesiology residents, and tile frequency of adverse effects and complications, as well as the qttality of analgesia, was evaluated.
From the Department of Anesthesiology, Istanbul University,
Cerrahpa~a Medical Faculty, Istanbul, Turkey. Accepted for publication April 8, 1996. Reprint requests: Pervin Bozkurt, M.D., Atak6y 5. Kisim A7 Blok, D 40, 34750 Istanbul, Turkey.
212
Postoperative Epidural Morphine in Children
Materials and Methods Patient Population The study was approved by the institutional ethics committee, and informed consent was obtained from the parents. Between November 1988 and December 1994, epidural morphine was used for analgesia after 175 major urologic or lower abdominal surgical procedures in 153 pediatric patients, 138 of whom were boys (Table 1). Twenty-one patients underwent more than one operation. The patients' ages ranged from 4 months to 17 years (mean, 6.43 • 3.4 years, median, 6 years) and their weights from 6.4 kg to 75 kg.
Anesthetic Management Nonpremedicated children were admitted to the operating room following a 4-hour fasting period. Anesthesia was induced in children younger than 6 years with 3% halothane and in children 6 years and older with 5 mg/kg intravenous thiopentone. Endotracheal intubation was facilitated by administration of atracurium 0.5 mg/kg, and anesthesia was maintained with 1.5% isoflurane (49 procedures, 28%) or 1% halothane (126 procedures, 72%) and nitrous oxide in oxygen (50% inspired oxygen fraction). Thirty-five patients received 0.05 mg/kg morphine intravenously following induction of anesthesia.
Epidural Technique The children were turned to a lateral position at the end of their surgical .procedures, and lumbar epidural injections were performed by anesthesiology residents rotating on the pediatric anesthesia service under the supervision of a pediatric anesthesiologist. For children younger than 13 years, a standard 20- to 22-gauge, 35 mm long intramuscular needle was used, and for children 13 and older a 20-gauge spinal needle was used. From a midline approach, the epidural space at the L3-4 level was found by the loss of resistance method with the use of a saline-filled syringe. Morphine 0.1 mg/kg in 0.2 mL/kg saline was injected. Inhalation anesthesia was discontinued, and residual paralysis from muscle relaxant was antagonized. Patients were extubated in the operating room and taken to the recovery room, where they remained for 1 hour and were then transported to the surgical ward. Study parameters were recorded following 24 hours in the ward.
9
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213
Table 1. Types of Surgery Operation
No.
Operation
Hypospadias(Duckett, MAGPI,Mathieu procedures)
87
Uretroplasty
5
Epispadias Bladder augmentation Repair of various fistulae ol urinary system Vesicoureteral reflux (Lich Greguar, Cohen) Nephrectomy
12 12 6
Penile plasty Splenectomy Colostomy closure
2 4 3
10
Colostomy
2 8
4
Colorectal operations (Duhamel, PENA, PSARP) Cyst dermoid sacral
3 1
Cloaca Condyloma accuminata
1 1
1 1
Vaginoplasty 2 Extirpation of tumors (Wilms, neuroblastoma) 3
Bladder neck reconstruction Nephrolithiasis Ambiguous genitalia Rupture of corpus cavernosum Urinoma
6
No.
Study data were obtained from data forms prospectively completed o n each patient. These data forms were completed by anesthesiologists and nursing staff during the first 24 hours of the postoperative period. These data, recorded by the attending anesthesiologist and the blinded ward nurse, included: age; weight; type of surgery; anesthetic technique; use of intraoperative narcotics; number of attempts; incidence of dural puncture; dose of morphine; duration and adequacy of analgesia as directly observed by nurses or anesthesiologists; time to first supplemental analgesic administration; side effects and their time of occurrence and treatment. Adequacy of analgesia was rated as follows: 0, no pain, comfortable patient; 1, mild pain, soothed by affection; 2, patient crying with full lung capacity or complaining of unbearable pain requiring specific treatment. Side effects encountered were pruritis; nausea (as reported by the child); vomiting; urinary retention of more than 8 hours duration or requiring bladder catheterization; respiratory depression; apnea; episodes of desaturation (65% of patients were monitored with pulse oximetry or decreased respiratory rate); and hemo: dynamic alterations, including tachycardia, bradycardia, or change in arterial pressure of more than 10% as compared with initial measurements. All values were expressed as means and standard deviations. Correlations were obtained of analgesia duration with age and intraoperative narcotic use; of incidence of vomiting with the inhalation anesthetic used, intraoperative narcotic use, age, and type of operation; and of incidence of ventilatory depression with age.
214
Regional Anesthesia Vol. 22 No. 3 May-June 1997 100%
Results
i
9O%
Most patients were toddlers and young children, but 5.7% of patients were 1 year old or younger and 22.3% were older than 10 years (Fig. 1). Placement of the needle in the epidural space was successful in all cases, with success on the first attempt in 92%. In 8% of patients, a second attempt was performed by a pediatric anesthesiology consultant. Dural punctures occurred in five cases (2.9%); in these, a second injection was performed at the next lower intervertebral level. No headaches or neurologic complications were observed.
6O% M.
O5O%
p.
,.=, 4o~ tM
=-20% 10% O% HOURS L
B ,Score 0
III Scoce 1
OSc~e 2
[ i
Fig. 2. Postoperative pain scores versus time.
Analgesia The onset of analgesia after epidural morphine was quite rapid. The patients awoke from general anesthesia within 10-20 minutes after the epidural injections were given, and all patients except one were pain-free in the recovery room. Pain control was considered excellent for 24 hours in 76% of patients. In 5% of children, mild pain requiring no treatment (score 1) for 10 hours after epidural morphine administration was recorded. One patient had severe pain (score 2) starting at 4 hours, and 18% had severe pain starting at 10 hours (Fig. 2). This pain was managed With narcotics or nonsteroidal analgesics, In patients with pain scores of 1 and 2 in the first 24 hours, the time to first pain perception was 10.9 + 5.5 hours after epidural morphine administration. Following induction, 20% of patients received 0.05 mg/kg intravenous morphine. However, there was no correlation between pain-free hours and
35% 30%
2s%
H U
15% 10%
., 0-1 year
~so~ =E
I!I11 t-5 y~ar
,
IN! 5-10 year
, 10-17. year
Fig. 1. Age distribution of study group. More than half of the patients were toddlers and young children.
intraoperative intravenous narcotic use (r = .11, P = .13) Also, duration of analgesia did not correlate with age (r = .08, P = .28).
Side Effects Systolic blood pressure remained within the normal range for the observation period in all patients. Nine patients (9.1%) developed tachycardia, and seven of these had fever. Respiratory. Two patients aged 2 and 8 years (1.1%) developed ventilatory depression during the first postoperative hour. Each had arterial desaturation (SaO2 85-90%) and bradypnea for few minutes. These two cases were handled by maintaining the airway with slight head extension and administering supplemental oxygen via face mask while repeatedly stimulating breathing. Blood gases drawn at this time showed carbon dioxide tension as 42 m m Hg and 45 m m Hg, respectively. Ventilatory parameters normalized without requiring naloxone treatment or intubation. A 2-year-old patient with a history of apneic spells had another apnea episode 5 hours after morphine administration and was admitted to the intensive care unit for observation. Another 3-year-old patient developed bradypnea and sweating 12 hours after epidural morphine but had no signs of pain or fever. There was no correlation between incidence of respiratory depression and age. None of the other patients had significant changes in SaO2 or respiratory rate during the follow-up period. The mean + SD values of SaO2 and respiratory rate for all patients are plotted in Figure 3, N o n r e s p i r a t o r y , The incidence of nonrespiratory side effects is listed in Table 2. Pruritis usually occurred on the face and most often was not an annoyance to the patients. Six children were treated
Postoperative Epidural Morphine in Children
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Bozkurt et al.
215
100 90 8O 70
Fig. 3. Changes in oxygen saturation (SpO2) (top) and respiratory rate (bottom) with time. All data are mean --. SD.
6O 50
IT,
4O 3O 20
,,++!!II.I
T-
HOURS
with hydroxyzine HCI or propofol. Nausea occurred in 34% of children, and vomiting was observed in 75 children (42.9%). These symptoms started approximately 4-5 hours after morphine administration. Nausea and vomiting were treated in 22 occurrences, 13 with metoclopramide, and 9 with trimethobenzamide. There was no correlation between vomiting and the use of isoflurane as an inhalation anesthetic (r = . 17, P = .02), intraoperative narcotic use (r = .14, P = .03), patient age, (r = .1, P = .14), and type of operation (r = .16, P = .028). The majority of operations (n = 143; 82%) required urinary bladder catheters. Of the remaining 32 patients, 4 (12.5%) had voiding problems postoperatively and required urinary catheterization. In 69 children (39.4%), postoperative analgesia was excellent for the first 24-hour period, and no side effects occurred. Discussion
Genitourinary and lower abdominal operations are often associated with moderate to severe postoperative pain in children. Recognition of this Table 2. Incidence of Nonrespiratory Side Effects Effect Nausea Vomiting Pruritis Urinary retention
No.
%
60 76 16 4 of 32 uncatheterized
33.9 42.9 9.0 12.5
problem has made it desirable to find safe ways of administering perioperative opioids. Epidural morphine provides selective analgesia with the advantage of longer duration of effect as compared with other routes of morphine administration (10,13). In order to apply these advantageous aspects of epidural morphine in children in our country, we introduced this inexpensive and easy method. The lack of appropriately sized epidural catheters for pediatric use in Turkey forced us to perform a single injection. The study group searched for an appropriate needle for epidural injection. A 20-gauge spinal needle is too long for manipulation in children up to 8 years old, in w hom the epidural space lies 0.7-2 cm under the skin (14-17). Use of needles longer than 25 mm is unnecessary and may increase the risk of inadvertent penetration into the subarachnoid space (18). Our epidural injections were performed by 43 different anesthesiology residents, who had been trainees in anesthesiology for 1 or 2 years. Penetration of ligamentum flavum and the loss of resistance w hen the epidural space is entered are quite obvious, as attested by the fact that our trainees perforated the dura in only five cases. In the case of unrecognized dural or vascular puncture, direct subarachnoid or intravenous injection of morphine would occur. However, doses up to 0.2 mg/kg have been injected into the subarachnoid space and reported as a safe dose (19). Nevertheless, more cautious postoperative monitoring is required, owing to the potential for respiratory depression. Our technique is cost-
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Regional Anesthesia Vol. 22 No. 3 May-June 1997
effective because the price of an intramuscular needle is 1/30th the cost of a spinal needle and 1/150th that of an epidural needle. The reported duration of analgesia following epidural inorphine ranges from 4 to 24 flours (2,9,14). In our series, tile follow-up time ended 24 hours after surgery, and 76% of patients had no pain during this interval. Morplfine pharmacokinetics are similar for adults and children (7). In adults, morphine half-lives are similar in cerebrospinal fluid and plasma after epidural administration. The main factor governing the long duration of analgesia is the very high morphine concentration in the vicinity of the receptors (20). Children receiving epidural morphine did not have pain in tile early postoperative period, in which they would have been disoriented, frightened, and anxious. This early pain relief may have helped them to cope with the subsequent pain. Analgesia and side effects resulting from epidural morphine can be explained by actions on tile spinal cord and rostral nfigration of the drug in cerebrospinal fluid (13,20,21 ). The most serious complication noted is ventilatory depression (4,9,22-24), with incidences of 0-9% in studies in which children received epidural morphine via caudal or lumbar injection of 0.05-0.10 mg/kg morphine (3,10, 11). This study began in 1988 and was based on early published studies (2,3). The decision of the study team was to use a 0.1 mg/kg morphine dose. In the first 2 years, there were no episodes of respiratory depression and the initial protocol was continued. We observed two patients with early ventilatory depression who had also received morphine during surgery. Positioning so as to maintain an open airway resolved the respiratory obstruction (without naloxone use) in these two patients. We attributed the ventilatory depression (obstruction) to residual effects of anesthetics or additive effects of intraoperative morphine. Other authors have also suggested that ventilatory depression may increase with the concomitant use of sedatives and narcotics (4,22,25). One patient with late bradypnea may actually represent our only case of late ventilatory depression due to rostral spread of morphine (4). In the patient with a history of apneic spells, the preoperative visit was inadequate and did not identify the history of underlying apneic events, which may have been exaggerated by use of epidural morphine. Atria et al, reported that the ventilatory response to carbon dioxide remains depressed at least 22 hours after epidural morphine, indicating that pediatric patients should be closely monitored in an intensive care unit setting (7). We think that postoperative observation in the ward with monitoring of respira-
tory rate and arterial oxygen saturation and avoidance of concomitant sedative use of narcotics, as well as suitable patient selection, could be sufficient to handle this problem. Adverse postoperative responses other than nausea and vomiting were infrequent after epidural morphine administration. For reasons that remain unclear, the incidence of postoperative vomiting, as reported in the literature, varies widely from 8.9% to 47% (3,7,8,11). The lack of correlation with age, type of operation, intraoperative narcotic use, or choice of inhalation anesthetic forces us to believe that morphine is the main cause, as suggested by Weinstein et al. (26) Despite the high incidence of vomiting (42.9%), no severe consequences due to vomiting occurred, and patients were fully awake during these episodes. Previous studies report a wide range in incidence of pruritis (0-100%) in children (3, 6-9,11). In our group, the incidence was 9%. Our 12% incidence of urinary retention is less than those reported by Krane et al. (9) and Attia et al. (7) and more titan the 7% reported by Deconti et al. (11 ). However, our series is not a suitable one for evaluating the incidence of urinary retention because of the surgical need for routine bladder catheterization. In conclusion, a single injection of epidural morphine with a 20- to 22-gauge intramuscular needle is easy to perform, even by trainees in anesthesiology. The key to the safety of this procedure is knowledge of the anatomy of children and an appreciation of how it differs..ffom that of adults. With appropriate patient selection and choice of injection site, meticulous preparation, and careful aspiration, it is unlikely that a vessel or subarachnoid space will be entered. Epidural morphine provides prompt, effective, and prolonged analgesia after abdominal and urologic surgery in children. Nonrespiratory effects occur in a significant fraction of the patients, while ventilatory depression is rare when concomitant use of narcotics and sedatives is avoided.
Acknowledgment The authors wish to thank tile recovery room and pediatric anesthesia ward nurses for their support and Drs. A. Kiir~ad Bozkurt and Mark A. Warner for reviewing the manuscript.
References 1. Behar M, Olshwang D, Magora F, Davidson JT. Epidural morphine in the treatment of pain. Lancet 1979: I: 527-529.
Postoperative Epidural Morphine in Children 2. Jensen BH. Caudal block for postoperative pain relief in children after genital operations. A comparison between bupivacaine and morphine. Acta Anesthesiol Scand 1981: 25: 373-375. 3. Glenski JA, Warner MA, Dawson B, Kaufman B. Postoperative use of epidurally administered morphine in children and adolescents. Mayo Clin Proc 1984: 59: 530-533. 4. Rawal N, Wattwil M. Respiratory depression after epidural m o r p h i n e - - A n experimental and clinical study. Anesth Analg 1984: 63: 8-14. 5. Finholt DA, Stirt JA, DiFazio CA. Epidural morphine for postoperative analgesia in pediatric patients. Anesth Analg 1985: 64: 304. 6. Dalens B, Tanguy A, Haberer JP. Lumbar epidural anesthesia for operative and postoperative pain relief in infants and young children. Anesth Analg 1986: 65: 1069-1073. 7. Atria J, Ecoffey C, Sandouk E Gross JB, Samii K. Epidural morphine in children: Pharmacokinetics and CO2 sensitivity. Anesthesiology 1986: 65: 590-594. 8. Rosen KR, Rosen DA. Caudal epidural morphine for control of pain following open heart surgery in children. Anesthesiology 1989: 7 0 : 4 1 8 - 4 2 I. 9. Krane EJ, Tyler DC, Jacobson LE. The dose response of caudal morphine in children. Anesthesiology 1989: 71: 48-52. 10. Valley DR, Bailey GA. Caudal morphine for postoperative analgesia in infants and children: A report of 138 cases. Anesth Analg 1991: 72: 120-124. 11. DeConti RW, Diaz JH, Falterman KW. Prolonged postoperative analgesia with lumbar epidural morphine in children undergoing thoradc and upper abdominal surgery. J Pediatr Surg 1992: 27: 392. 12. Lejus C, Roussiere-G, Testa S, Ganansia ME Meignier M, Souron R. Postoperative extradural analgesia in children: Comparison of morphine with fentanyl. Br J Anaesth 1994: 72: 156-159. 13. Dalens BJ. Pediatric regional anesthesia. Ist ed. CRC Press, 1990: 127-149. 14. Ecoffey C, Attia J,~ Safnii K. Analgesia and side effects following epidural morphine in children. Anesthesiology 1985: 63: A470.
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217
15. Dalens B, Chrysostome Y. Intervertebral epidural anesthesia in pediatric surgery: Success rate and adverse effects in 650 consecutive procedures. Paediatr Anaesth 1991: 1: 107-117. 16. Hasan MA, Howard RE Lloyd-Thomas R. Depth of epidural space in children. Anaesthesia 1994: 49: 1085-1087. 17. Steward DJ. Manual of pediatric anaesthesia. 4th ed. New York, Churchill Livingstone, 1995: 126. 18. Yamashita M. Paediatric epidural needles. Paediatr Anaesth 1992: 2: 343. 19. Chanvin M, Samii K, Schermann JM, Sandouk P, Bourdon R, Viars P. Plasma pharmacokinetics of morphine after intramuscular, extradural and intrathecal administration. Br J Anaesth 1982: 54: 843-847. 20. Dahlstr/~m B. Pharmacokinetics and pharmacodynamics of epidural and intrathecal morphine. Int Anesthesiol Clin 1986: 24: 29--42. 21. Bromage PR, Camporesi EM, Durant PAC, Nielsen CH. Rostral spread of epidural morphine. Anesthesiology 1982: 56: 431-436. 22. Gustafsson LL, Schildt B, Jacobsen KJ. Adverse effects of extradural and intrathecal opiates: Report of a nationwide survey in Sweden. Br J Anaesth 1982: 54: 479-485. 23. Tamsen A, Sj6strom S, Hartwig P, Persson P, Gabrielsson J, Paalzow L. CSF and plasma kinetics of morphine and meperidine after epidural administration. Anesthesiology 1983: 59: A196. 24. Camporesi EM, Nielsen CH, Bromage PR, Durant PA. Ventilatory CO2 sensitivity after intravenous and epidural morphine in volunteers. Anesth Analg 1983: 62: 633-640. 25. Weddel SJ, Ritter RR. Serum levels following epiduL ral administration of morphine and correlation with relief of postsurgical pain. Anesthesiology 1981: 54: 210. 26. Weinstein MS, Nicholson SC, Schreinere MS. A single dose of morphine sulfate increases the incidence of vomiting after outpatient inguinal surgery in children. Anesthesiology 1994: 81: 572-577.
Single-Injection Lumbar Epidural Morphine for Postoperative Analgesia in Children A Report of 175 Cases t
Pervin Bozkurt, M.D., Gtiner Kaya, M.D., and Y/Jksel Yeker, M.D.
Background and Objectives. Since the first report of epidural opioid administration to pediatric patients, several studies have described the quality of analgesia, doses, pharmacokinetics, and side effects of this procedure. A pediatric series using an easy and cheap single-injection technique of epidural morphine administration for postoperative analgesia is presented. Methods. Postoperative analgesia was achieved with a single lumbar epidural morphine injection (0.1 mg/kg in 0.2 mL/kg saline), which was given via a 22-gauge intramuscular needle to 153 pcdiatric patients (aged 4 months-17 years) following 175 lower abdominal or urologic operations. Injections were given by 43 anesthesiology residents under the supervision of pediatric anesthesiologists, after termination of surgery performcd under general ancsthcsia. Resttlts. The success rate of epidural puncture on the first at.tempt was 92%. Pain control was considered excellent in 76% of patients for 24 hours. The remaining patients had analgesia lasting 10.9 -+ 5.5 hours after epidural morphine administration. No alterations in hemodynamic parameters were observed. "IXvo patients (1.1%) developed respiratory depression during early postoperative care and one, with a history of apneic spclls, had an episode of apnea 5 hours after morphine administration. The inddences of minor side effects were: nausea, 33.9%; vomiting, 42.9%; pruritis 9%; and urinary retention 12.5%. Conclusions. This technique is easy to perform, even for trainees in anesthesiology. With appropriate patient selection and avoidance of the concomitant use of narcotics and sedatives, epidural morphine provides protnpt, effective, safe, and prolonged analgesia in child ren. Regional Anesthesia 1997: 22:212-21Z Key words: pediatric surgery, postoperative analgcsia, epidural analgesia, morphine.
Following tile first publication in 1979 regarding epidural opioid administration (1), interest in postoperative pain control greatly increased. The first pediatric report (2) was published i n 1981, and subsequently several studies described quality of analgesia, doses, pharmacokinetics, and side effects (3-12). tlowever, these all involved relatively small series of patients, and local anesthetics were often
given in combination with m o r p h i n e via an epidural catheter. The frequency of complications and side effects also varied widely a m o n g these studies. Since the first use of epidural narcotics for postoperative analgesia in o u r clinic, we have found a single lumbar epidural injection of m o r p h i n e to be an easy and inexpensive m e t h o d of providing postoperative analgesia in pediatric patients undergoing lower abdominal or urologic surgery. In this prospective study, 175 single lumbar epidural morphine injections were administered by 43 anesthesiology residents, and tile frequency of adverse effects and complications, as well as the qttality of analgesia, was evaluated.
From the Department of Anesthesiology, Istanbul University,
Cerrahpa~a Medical Faculty, Istanbul, Turkey. Accepted for publication April 8, 1996. Reprint requests: Pervin Bozkurt, M.D., Atak6y 5. Kisim A7 Blok, D 40, 34750 Istanbul, Turkey.
212
Postoperative Epidural Morphine in Children
Materials and Methods Patient Population The study was approved by the institutional ethics committee, and informed consent was obtained from the parents. Between November 1988 and December 1994, epidural morphine was used for analgesia after 175 major urologic or lower abdominal surgical procedures in 153 pediatric patients, 138 of whom were boys (Table 1). Twenty-one patients underwent more than one operation. The patients' ages ranged from 4 months to 17 years (mean, 6.43 • 3.4 years, median, 6 years) and their weights from 6.4 kg to 75 kg.
Anesthetic Management Nonpremedicated children were admitted to the operating room following a 4-hour fasting period. Anesthesia was induced in children younger than 6 years with 3% halothane and in children 6 years and older with 5 mg/kg intravenous thiopentone. Endotracheal intubation was facilitated by administration of atracurium 0.5 mg/kg, and anesthesia was maintained with 1.5% isoflurane (49 procedures, 28%) or 1% halothane (126 procedures, 72%) and nitrous oxide in oxygen (50% inspired oxygen fraction). Thirty-five patients received 0.05 mg/kg morphine intravenously following induction of anesthesia.
Epidural Technique The children were turned to a lateral position at the end of their surgical .procedures, and lumbar epidural injections were performed by anesthesiology residents rotating on the pediatric anesthesia service under the supervision of a pediatric anesthesiologist. For children younger than 13 years, a standard 20- to 22-gauge, 35 mm long intramuscular needle was used, and for children 13 and older a 20-gauge spinal needle was used. From a midline approach, the epidural space at the L3-4 level was found by the loss of resistance method with the use of a saline-filled syringe. Morphine 0.1 mg/kg in 0.2 mL/kg saline was injected. Inhalation anesthesia was discontinued, and residual paralysis from muscle relaxant was antagonized. Patients were extubated in the operating room and taken to the recovery room, where they remained for 1 hour and were then transported to the surgical ward. Study parameters were recorded following 24 hours in the ward.
9
Bozkurt et al.
213
Table 1. Types of Surgery Operation
No.
Operation
Hypospadias(Duckett, MAGPI,Mathieu procedures)
87
Uretroplasty
5
Epispadias Bladder augmentation Repair of various fistulae ol urinary system Vesicoureteral reflux (Lich Greguar, Cohen) Nephrectomy
12 12 6
Penile plasty Splenectomy Colostomy closure
2 4 3
10
Colostomy
2 8
4
Colorectal operations (Duhamel, PENA, PSARP) Cyst dermoid sacral
3 1
Cloaca Condyloma accuminata
1 1
1 1
Vaginoplasty 2 Extirpation of tumors (Wilms, neuroblastoma) 3
Bladder neck reconstruction Nephrolithiasis Ambiguous genitalia Rupture of corpus cavernosum Urinoma
6
No.
Study data were obtained from data forms prospectively completed o n each patient. These data forms were completed by anesthesiologists and nursing staff during the first 24 hours of the postoperative period. These data, recorded by the attending anesthesiologist and the blinded ward nurse, included: age; weight; type of surgery; anesthetic technique; use of intraoperative narcotics; number of attempts; incidence of dural puncture; dose of morphine; duration and adequacy of analgesia as directly observed by nurses or anesthesiologists; time to first supplemental analgesic administration; side effects and their time of occurrence and treatment. Adequacy of analgesia was rated as follows: 0, no pain, comfortable patient; 1, mild pain, soothed by affection; 2, patient crying with full lung capacity or complaining of unbearable pain requiring specific treatment. Side effects encountered were pruritis; nausea (as reported by the child); vomiting; urinary retention of more than 8 hours duration or requiring bladder catheterization; respiratory depression; apnea; episodes of desaturation (65% of patients were monitored with pulse oximetry or decreased respiratory rate); and hemo: dynamic alterations, including tachycardia, bradycardia, or change in arterial pressure of more than 10% as compared with initial measurements. All values were expressed as means and standard deviations. Correlations were obtained of analgesia duration with age and intraoperative narcotic use; of incidence of vomiting with the inhalation anesthetic used, intraoperative narcotic use, age, and type of operation; and of incidence of ventilatory depression with age.
214
Regional Anesthesia Vol. 22 No. 3 May-June 1997 100%
Results
i
9O%
Most patients were toddlers and young children, but 5.7% of patients were 1 year old or younger and 22.3% were older than 10 years (Fig. 1). Placement of the needle in the epidural space was successful in all cases, with success on the first attempt in 92%. In 8% of patients, a second attempt was performed by a pediatric anesthesiology consultant. Dural punctures occurred in five cases (2.9%); in these, a second injection was performed at the next lower intervertebral level. No headaches or neurologic complications were observed.
6O% M.
O5O%
p.
,.=, 4o~ tM
=-20% 10% O% HOURS L
B ,Score 0
III Scoce 1
OSc~e 2
[ i
Fig. 2. Postoperative pain scores versus time.
Analgesia The onset of analgesia after epidural morphine was quite rapid. The patients awoke from general anesthesia within 10-20 minutes after the epidural injections were given, and all patients except one were pain-free in the recovery room. Pain control was considered excellent for 24 hours in 76% of patients. In 5% of children, mild pain requiring no treatment (score 1) for 10 hours after epidural morphine administration was recorded. One patient had severe pain (score 2) starting at 4 hours, and 18% had severe pain starting at 10 hours (Fig. 2). This pain was managed With narcotics or nonsteroidal analgesics, In patients with pain scores of 1 and 2 in the first 24 hours, the time to first pain perception was 10.9 + 5.5 hours after epidural morphine administration. Following induction, 20% of patients received 0.05 mg/kg intravenous morphine. However, there was no correlation between pain-free hours and
35% 30%
2s%
H U
15% 10%
., 0-1 year
~so~ =E
I!I11 t-5 y~ar
,
IN! 5-10 year
, 10-17. year
Fig. 1. Age distribution of study group. More than half of the patients were toddlers and young children.
intraoperative intravenous narcotic use (r = .11, P = .13) Also, duration of analgesia did not correlate with age (r = .08, P = .28).
Side Effects Systolic blood pressure remained within the normal range for the observation period in all patients. Nine patients (9.1%) developed tachycardia, and seven of these had fever. Respiratory. Two patients aged 2 and 8 years (1.1%) developed ventilatory depression during the first postoperative hour. Each had arterial desaturation (SaO2 85-90%) and bradypnea for few minutes. These two cases were handled by maintaining the airway with slight head extension and administering supplemental oxygen via face mask while repeatedly stimulating breathing. Blood gases drawn at this time showed carbon dioxide tension as 42 m m Hg and 45 m m Hg, respectively. Ventilatory parameters normalized without requiring naloxone treatment or intubation. A 2-year-old patient with a history of apneic spells had another apnea episode 5 hours after morphine administration and was admitted to the intensive care unit for observation. Another 3-year-old patient developed bradypnea and sweating 12 hours after epidural morphine but had no signs of pain or fever. There was no correlation between incidence of respiratory depression and age. None of the other patients had significant changes in SaO2 or respiratory rate during the follow-up period. The mean + SD values of SaO2 and respiratory rate for all patients are plotted in Figure 3, N o n r e s p i r a t o r y , The incidence of nonrespiratory side effects is listed in Table 2. Pruritis usually occurred on the face and most often was not an annoyance to the patients. Six children were treated
Postoperative Epidural Morphine in Children
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100 90 8O 70
Fig. 3. Changes in oxygen saturation (SpO2) (top) and respiratory rate (bottom) with time. All data are mean --. SD.
6O 50
IT,
4O 3O 20
,,++!!II.I
T-
HOURS
with hydroxyzine HCI or propofol. Nausea occurred in 34% of children, and vomiting was observed in 75 children (42.9%). These symptoms started approximately 4-5 hours after morphine administration. Nausea and vomiting were treated in 22 occurrences, 13 with metoclopramide, and 9 with trimethobenzamide. There was no correlation between vomiting and the use of isoflurane as an inhalation anesthetic (r = . 17, P = .02), intraoperative narcotic use (r = .14, P = .03), patient age, (r = .1, P = .14), and type of operation (r = .16, P = .028). The majority of operations (n = 143; 82%) required urinary bladder catheters. Of the remaining 32 patients, 4 (12.5%) had voiding problems postoperatively and required urinary catheterization. In 69 children (39.4%), postoperative analgesia was excellent for the first 24-hour period, and no side effects occurred. Discussion
Genitourinary and lower abdominal operations are often associated with moderate to severe postoperative pain in children. Recognition of this Table 2. Incidence of Nonrespiratory Side Effects Effect Nausea Vomiting Pruritis Urinary retention
No.
%
60 76 16 4 of 32 uncatheterized
33.9 42.9 9.0 12.5
problem has made it desirable to find safe ways of administering perioperative opioids. Epidural morphine provides selective analgesia with the advantage of longer duration of effect as compared with other routes of morphine administration (10,13). In order to apply these advantageous aspects of epidural morphine in children in our country, we introduced this inexpensive and easy method. The lack of appropriately sized epidural catheters for pediatric use in Turkey forced us to perform a single injection. The study group searched for an appropriate needle for epidural injection. A 20-gauge spinal needle is too long for manipulation in children up to 8 years old, in w hom the epidural space lies 0.7-2 cm under the skin (14-17). Use of needles longer than 25 mm is unnecessary and may increase the risk of inadvertent penetration into the subarachnoid space (18). Our epidural injections were performed by 43 different anesthesiology residents, who had been trainees in anesthesiology for 1 or 2 years. Penetration of ligamentum flavum and the loss of resistance w hen the epidural space is entered are quite obvious, as attested by the fact that our trainees perforated the dura in only five cases. In the case of unrecognized dural or vascular puncture, direct subarachnoid or intravenous injection of morphine would occur. However, doses up to 0.2 mg/kg have been injected into the subarachnoid space and reported as a safe dose (19). Nevertheless, more cautious postoperative monitoring is required, owing to the potential for respiratory depression. Our technique is cost-
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effective because the price of an intramuscular needle is 1/30th the cost of a spinal needle and 1/150th that of an epidural needle. The reported duration of analgesia following epidural inorphine ranges from 4 to 24 flours (2,9,14). In our series, tile follow-up time ended 24 hours after surgery, and 76% of patients had no pain during this interval. Morplfine pharmacokinetics are similar for adults and children (7). In adults, morphine half-lives are similar in cerebrospinal fluid and plasma after epidural administration. The main factor governing the long duration of analgesia is the very high morphine concentration in the vicinity of the receptors (20). Children receiving epidural morphine did not have pain in tile early postoperative period, in which they would have been disoriented, frightened, and anxious. This early pain relief may have helped them to cope with the subsequent pain. Analgesia and side effects resulting from epidural morphine can be explained by actions on tile spinal cord and rostral nfigration of the drug in cerebrospinal fluid (13,20,21 ). The most serious complication noted is ventilatory depression (4,9,22-24), with incidences of 0-9% in studies in which children received epidural morphine via caudal or lumbar injection of 0.05-0.10 mg/kg morphine (3,10, 11). This study began in 1988 and was based on early published studies (2,3). The decision of the study team was to use a 0.1 mg/kg morphine dose. In the first 2 years, there were no episodes of respiratory depression and the initial protocol was continued. We observed two patients with early ventilatory depression who had also received morphine during surgery. Positioning so as to maintain an open airway resolved the respiratory obstruction (without naloxone use) in these two patients. We attributed the ventilatory depression (obstruction) to residual effects of anesthetics or additive effects of intraoperative morphine. Other authors have also suggested that ventilatory depression may increase with the concomitant use of sedatives and narcotics (4,22,25). One patient with late bradypnea may actually represent our only case of late ventilatory depression due to rostral spread of morphine (4). In the patient with a history of apneic spells, the preoperative visit was inadequate and did not identify the history of underlying apneic events, which may have been exaggerated by use of epidural morphine. Atria et al, reported that the ventilatory response to carbon dioxide remains depressed at least 22 hours after epidural morphine, indicating that pediatric patients should be closely monitored in an intensive care unit setting (7). We think that postoperative observation in the ward with monitoring of respira-
tory rate and arterial oxygen saturation and avoidance of concomitant sedative use of narcotics, as well as suitable patient selection, could be sufficient to handle this problem. Adverse postoperative responses other than nausea and vomiting were infrequent after epidural morphine administration. For reasons that remain unclear, the incidence of postoperative vomiting, as reported in the literature, varies widely from 8.9% to 47% (3,7,8,11). The lack of correlation with age, type of operation, intraoperative narcotic use, or choice of inhalation anesthetic forces us to believe that morphine is the main cause, as suggested by Weinstein et al. (26) Despite the high incidence of vomiting (42.9%), no severe consequences due to vomiting occurred, and patients were fully awake during these episodes. Previous studies report a wide range in incidence of pruritis (0-100%) in children (3, 6-9,11). In our group, the incidence was 9%. Our 12% incidence of urinary retention is less than those reported by Krane et al. (9) and Attia et al. (7) and more titan the 7% reported by Deconti et al. (11 ). However, our series is not a suitable one for evaluating the incidence of urinary retention because of the surgical need for routine bladder catheterization. In conclusion, a single injection of epidural morphine with a 20- to 22-gauge intramuscular needle is easy to perform, even by trainees in anesthesiology. The key to the safety of this procedure is knowledge of the anatomy of children and an appreciation of how it differs..ffom that of adults. With appropriate patient selection and choice of injection site, meticulous preparation, and careful aspiration, it is unlikely that a vessel or subarachnoid space will be entered. Epidural morphine provides prompt, effective, and prolonged analgesia after abdominal and urologic surgery in children. Nonrespiratory effects occur in a significant fraction of the patients, while ventilatory depression is rare when concomitant use of narcotics and sedatives is avoided.
Acknowledgment The authors wish to thank tile recovery room and pediatric anesthesia ward nurses for their support and Drs. A. Kiir~ad Bozkurt and Mark A. Warner for reviewing the manuscript.
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