Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.56 no.6 Campinas Nov./Dec. 2006
Comparison among three techniques of postoperative regional analgesia with ropivacaine in children*
Comparación entre tres técnicas regionales de analgesia postoperatoria en niños con ropivacaina
Ana Maria Menezes Caetano, TSAI; Gilliatt Hanois FalboII; Luciana Cavalcanti LimaIII
pelo CET/SBA do IMIP
IICirurgião Pediátrico do IMIP
IIIMestre em Saúde Materno-Infantil e Anestesiologista do IMIP
METHODS: Eighty-seven children, all males, ages 1 to 5, who underwent elective unilateral inguinal herniorrhaphy participated in this study. Children were randomly assigned to receive CE, IINB, or ISW. The need for postoperative analgesia, length of time until the first dose, severity of pain, and degree of the motor blockade were evaluated.
RESULTS: The need for analgesia and pain severity in the first two hours were greater for the ISW Group when compared with the CE and IINB Groups. Only the children in the CE Group presented a mild motor blockade. The mean length of time until de 1st dose of analgesic was similar in all groups.
CONCLUSIONS: Ilioinguinal/iliohypogastric nerve block was superior to ISW, especially in the first two hours after the surgery. The three anesthetic techniques can be safely and effectively used to control postoperative pain in inguinal herniorrhaphy in children.
MÉTODO: Se estudiaron 87 niños del sexo masculino, con edad entre 1 y 5 años, sometidos a herniorrafias inguinales electivas unilaterales. Los niños recibieron aleatoriamente la PS, el BIHII o la IFO. Se investigó la necesidad de analgésico en el postoperatorio, el tiempo necesario para su primera dosis, la intensidad de dolor y el grado de bloqueo motor.
RESULTADOS: En el grupo de la IFO se observó una mayor necesidad de analgésicos, y una mayor intensidad de dolor en las 1ª y 2ª horas, cuando se comparó con la PS y el BIHII. Apenas niños sometidos a PS presentaron bloqueo motor de grado moderado. El tiempo promedio de la necesidad de la primera dosis de analgésico fue similar entre los grupos.
CONCLUSIONES: El BIHII presentó una superioridad sobre la IFO, especialmente en las primeras dos horas del postoperatorio. As tres técnicas anestésicas pueden ser utilizadas con seguridad y eficacia en el control de dolor postoperatorio de herniorrafia inguinal en niños.
The development of the conduction of nociceptive stimuli and the response to stress in fetuses, newborns, infants, and children have been recently elucidated. This has led to the widespread acceptance that, for moral, ethical, humanitarian, and physiological reasons, pain should be anticipated, safely and effectively prevented, and controlled in all age Groups 1.
There has been a growing understanding of postoperative pain in children and in its management in the last 15 years. This has led to a great availability of therapeutic modalities to prevent and treat it, as well as a widespread acceptance that the control of postoperative acute pain is a fundamental component of the good practice of pediatric anesthesia 2.
The evaluation of pain in the immediate postoperative period in children is difficult, due to the particularities of this patient population. Health professionals should perform this evaluation frequently looking for evidences that indicate the presence of pain, therefore assuring the efficacy of the treatment instituted 3.
This difficulty to evaluate pain precisely and reliably made it possible the proliferation of different pain scales for the pediatric population. The Children Hospital Eastern Ontario Pain Scale (CHEOPS) and the Objective Pain Scale (OPS) can be used for newborns, infants, and children up to the age of seven. However, the former has a complicated behavioral evaluation system, while the latter is easy to be used 4. The reliability of the OPS was demonstrated in a study in which three different observers evaluated postoperative pain in children ages 8 months to 13 years 5,6.
The popularity of regional block as a complement to general anesthesia in pediatrics has increased significantly due to the acknowledgement of its advantages, which include the reduced need of intraoperative anesthetics, the possibility of using less opioids and, consequently, decreasing the incidence of respiratory depression, and limiting the hormonal answer to stress 7-9. As long as there are no specific contra indications, the routine use of local or regional block in every child is the fundament of an effective postoperative analgesia 10.
Both caudal epidural block and ilioinguinal/iliohypogastric nerve block are well-established techniques to control pain after inguinal surgical procedures in children 11-16.
Local anesthesia with infiltration of the surgical wound, ilioinguinal/iliohypogastric nerve block and other peripheral nerve blocks with bupivacaine or other local anesthetic are highly recommended and can be performed in several areas of the body. These techniques have fewer systemic effects, less motor blockade, and greater family acceptance, besides providing from four to 12 hours of analgesia 12,17.
Although bupivacaine is more widely used than ropivacaine, the latter offers a broad safety margin in regional anesthesia in pediatrics 13.
The aim of this study was to compare caudal epidural block with ilioinguinal/iliohypogastric nerve block and infiltration into the surgical wound regarding postoperative analgesia, motor blockade, and complications related with the technique in children who underwent inguinal herniorrhaphy using ropivacaine as the local anesthetic. The parameters studied were pain severity, duration of analgesia, and the need for analgesics. Motor blockade was evaluated according to its severity and duration.
After approval by the Ethics and Research Committee of the Instituto Materno Infantil Professor Fernando Figueira (IMIP) and informed consent was signed by the parents, 87 children, all boys, physical status ASA I and II, 1 to 5 years old, undergoing elective unilateral inguinal herniorrhaphy were evaluated. Exclusion criteria included disease or malformation that presented a contra indication to the use of any one of the techniques, allergy to the drugs used, and parents not allowing the child to participate in the study. The children were randomly divided in 3 groups, composed of 29 patients each, to receive inhalational general anesthesia with halothane associated with caudal epidural block (CE), or iliohypogastric/ilioinguinal nerve block (IINB), or infiltration of the surgical wound (ISW) by the surgeon at the end of the procedure. The following doses of 0.2% ropivacaine were used: 1 mL.kg-1 for CE, 0.6 mL.kg-1 for IINB, and 0.5 mL.kg-1 for ISW 9. At the end of the surgery, the children were transferred to the posthanestetic recovery unit and, afterwards, to a regular ward.
The parameters evaluated were age, weight, height, physical status, duration of the surgical procedure, and length of hospital stay. Postoperative analgesia, according to the need of the 1st and 2nd dose of analgesic and the mean length of time until the 1st dose, the severity of the pain, and the frequency of the motor blockade were compared in the three groups.
These parameters were evaluated and recorded by an examiner unaware of the anesthetic technique used. The OPS was used to evaluate pain 18,19. This scale is composed of five parameters: crying, movement, agitation, posture, and verbal complaints of pain; each parameter is attributed a value between 0 and 2, with total values between 0 and 10.
If the result of the evaluation were 0, it indicated absence of pain. Values between 1 and 3 corresponded to mild pain and the child did not need analgesics. Values between 4 and 6 (inclusive) corresponded to moderate pain and the child received dypirone (1 drop.kg-1 = 25 mg.kg-1). Values between 7 and 10 (inclusive) corresponded to severe pain and the child received the same dose of dypirone.
Pain was evaluated again 20 minutes after the treatment with dypirone and, if the child presented values equal or greater than 4, it was medicated with codeine (1 mg.kg-1). The observer recorded every pain score, as well as the need for analgesics.
The modified Bromage scale, with values between 0 and 3, in which zero is considered absence of motor blockade and 3 a complete motor blockade, was used to evaluate the motor blockade of the lower limbs 20. If the child did not understand the verbal command to raise the legs, the examiner was oriented to apply pressure on the soles of its feet and evaluate the movement of the legs.
Pain was evaluated every 30 minutes in the first 2 hours, and every hour from then on. The degree of the motor blockade was evaluated every hour.
The intercurrences in the surgical room, posthanestetic recovery unit, or in the ward, such as hemodynamic or heart rate changes, allergic reactions, nausea, vomiting, irritation or hematoma at the puncture site, and/or others were recorded on the appropriate form.
The data bank and the statistical analysis were done with the Epi-Info 2002, a public domain software, and a bivariate analysis was performed to compare the three Groups (CE, IINB, ISW) regarding duration of the analgesia, the need for complimentary doses of analgesics, pain severity, motor blockade, and perioperative intercurrences. The association among the categorical parameters was evaluated by the Chi-square test and the Fisher-Freeman-Halton Exact test. The test t Student was used to compare the means and quantitative parameters. In every test a level of 5% was considered significant.
There were no significant differences among the Groups regarding age, weight, height, duration of the surgical procedure, and length of hospital stay (Table I).
The use of the 1st dose of analgesics in the postoperative period was greater among children in the ISW Group (31%), while the IINB Group had the lower usage (3.4%) of this 1st dose (p = 0.020) (Table II).
Only 2 children in the ISW Group (6,9%) needed a 2nd dose of analgesic in the postoperative period. There were no differences among the groups (Table III).
There were no statistical differences regarding the mean length of time until the 1st dose of dypirone between the SE and ISW Groups (324.2 ± 237.2 min and 190 ± 153.4 min, respectively). Only one patient in the IINB Group needed dypirone (260 min) and codeine (300 min) after the surgical procedure.
The majority of the children experienced no pain or had mild pain in the 1st hour. However, there was a statistically significant difference among the groups regarding moderate pain, since only children in the ISW Group (13.8%) experienced this degree of pain (p= 0.049) (Figure 1). There were no reports of severe pain in the 1st hour.
In the 2nd postoperative hour, the majority of children did not experience pain, with an incidence of 100%, 100%, and 82.8% in the CE, IINB, and ISW Groups. Only children in the ISW Group experienced mild (13.8%) and moderate (3.4%) pain, and this difference was statistically significant (p = 0.010) (Figure 2).
Pain severity in the third and forth postoperative hours was similar in all three groups, but the majority experienced no pain or mild pain.
There were no differences among the groups in the evaluation of postoperative analgesia in the fifth and sixth hours. Only two children in the ISW Group (8.3%) and one in the CE Group (4.3%) experienced moderate pain in the fifth hour.
In the sixth hour, only one child (4.5%) in the CE Group experienced moderate pain. There were no differences among the groups in the eighth and 12th hours. Only one child in the ISW Group experienced moderate pain.
After the 12th hour all patients in the three groups were pain free.
There were no differences among the groups regarding postoperative motor blockade. Only children in the CE Group presented motor blockade grade I in the Bromage Scale (6.9%, 10.3%, and 3.4% in the first, second, and third hours, respectively).
There were no cases of motor blockade from the forth hour on.
Two children in the IINB Group (6.9%) presented bradycardia, five in the ISW Group (17.2%) and four in the CE Group (13.8%) presented tachycardia, and one child in the CE Group (3.4%) presented hypoxia. There were no statistically significant differences among the groups, only a higher tendency for tachycardia in the ISW Group.
The intercurrences observed in the ward included nausea and vomiting, with an incidence of 6.9% in the CE Group, 6.9% in the ISW Group, and 10.3% in the IINB Group, with no statistically significant differences among the groups.
In the postoperative analgesia of inguinal herniorrhaphy in children, caudal epidural anesthesia was not superior to ilioinguinal/iliohypogastric nerve block regarding pain scores. However, these techniques were superior to infiltration of the surgical wound, especially in the first two postoperative hours. One hypothesis to justify these results is that there might have been a technical flaw in the administration of the caudal epidural anesthesia, whose frequency of expected flaws, according to the literature, is about 4% 21-23.
The mean length of time until the 1st dose of analgesic was similar to the results of a few studies, suggesting that the addition of a local anesthetic through a central or peripheral block or infiltration into the surgical wound, before or after the surgery, decreases significantly the severity of the postoperative pain. Note that when the infiltration of the surgical wound is performed by the surgeon, it should be done under the muscular fascia, because it is less effective when the infiltration is done only under the skin 24-28. It is possible that some of the infiltration in this study were done only in the more superficial planes, resulting in reduced efficacy of the technique.
The results of several studies comparing different concentrations of ropivacaine and bupivacaine in caudal epidural block were similar to ours, suggesting that caudal ropivacaine in children provides an effective sensitive block of similar duration as bupivacaine. Ropivacaine, in the concentration of 0.2%, causes a motor blockade of shorter duration, which represents an advantage for its use in children, who have a lower tolerance to the feeling of immobilization of the lower limbs 29-33.
The frequency of intercurrences observed in the operative period did not differ among the three techniques. Bradycardia, tachycardia, and hypoxia should be considered as common perioperative events during pediatric anesthesia 34-37. Since the ISW showed a greater tendency for tachycardia, one can assume that it happened because infiltration was performed only at the end of the surgical procedure; therefore, the surgical stimulus was greater in this group that did not have access to analgesia before the procedure.
In the ward, nausea and vomiting were the only events observed. The mean frequency among the techniques was 8%, which is the rate expected for the number of anesthesias performed, and does not seem to be related to a specific technique 38-40. The ilioinguinal/iliohypogastric nerve block seems to be a safe and effective anesthetic technique to control postoperative pain in children undergoing inguinal herniorrhaphy. However, further studies are necessary to better establish the efficacy and safety of the technique.
Although pain severity in the first two hours showed higher scores in the infiltration of the surgical wound group, the results of this study suggest that the three techniques are effective in promoting postoperative analgesia in children undergoing inguinal herniorrhaphy. However, IINB was slightly superior to CE and significantly superior to ISW in promoting postoperative analgesia, especially in the first two hours, a period that is very important in outpatient procedures that require early hospital discharge.
Even though the present study did not show a great superiority of IINB over CE, it is important to emphasize that the IINB is easy to perform, does not need special equipment, did not cause motor blockade and, unlike caudal epidural block, is not done inside the central nervous system, being less invasive.
Under the conditions this study was performed, the three techniques using ropivacaine allowed for postoperative pain control with a low incidence of side effects in children undergoing inguinal herniorrhaphy.
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Dra. Ana Maria Menezes Caetano
Rua Feliciano José de Farias, 160/1101
51030-450 Recife, PE
Submitted for publication
07 de junho de 2005
Accepted for publication 22 de agosto de 2006
* Received from Instituto Materno-Infantil Professor Fernando Figueira (IMIP), Recife, PE