Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.54 no.4 Campinas July/Aug. 2004
Epidural caudal block: evaluation of length of analgesia with the association of lidocaine, fentanyl and clonidine*
Bloqueo peridural sacral: evaluación de la duración de la analgesia con el uso asociado de lidocaína, fentanil y clonidina
Carlos Alberto de Souza Martins, TSA, M.D.I; Pedro Wanderley de Aragão, M.D.II; João de Oliveira Prazeres, M.D.III; Mahiba Mattar Rahbani de Souza Martins, M.D.IV
Serviço de Anestesiologia da Clínica São Marcos, São Luís
MA; Professor Adjunto da Disciplina de Farmacologia da UFMA; Mestre em Ciências
da Saúde pela UFMA
IIProfessor Adjunto da Disciplina de Farmacologia da UFMA; Coordenador do Centro de Estudos da Clínica São Marcos; Mestre em Ciências da Saúde pela UFMA; Membro Ativo da Associação Médica Brasileira; Membro da Sociedade Brasileira de Farmacologia e de Terapêutica Experimental; Membro da Sociedade Brasileira para o Progresso da Ciência; Membro da Sociedade Brasileira para o Estudo da Dor
IIProfessor Adjunto da Disciplina de Anatomia da UFMA; Mestre em Ciências da Saúde pela UFMA
IVProfessor Adjunto da Disciplina de Farmacologia da UFMA; Mestre em Ciências da Saúde pela UFMA
BACKGROUND AND OBJECTIVES:
The association of different substances to local anesthetics aims to improve
the blockade quality and prolonging analgesia. The aims of this study were to
compare the effectiveness of the association of clonidine, clonidine and fentanyl,
and fentanyl, to lidocaine for postoperative analgesia.
METHODS: Participated in this study 64 patients aged 23 years or above, physical status ASA I or II, undergoing to orificial proctologic surgery under epidural caudal anesthesia. Patients were distributed in 4 groups of 16: group I (lidocaine alone); group II (lidocaine and fentanyl); group III (lidocaine, fentanyl and clonidine); and group IV (lidocaine and clonidine). The quality of sensory and motor blockade were compared.
RESULTS: There has been no difference in onset and maximum block level among groups. Absence of motor block was the most frequent result, found in about 64% of patients. Analgesia length was different among groups, being more significant in group III.
CONCLUSIONS: Clonidine, associated or not to fentanyl, has prolonged postoperative analgesia after epidural caudal blockade with lidocaine.
Key Words: ANALGESICS, Opioids: fentanyl; ANESTHETIC TECHNIQUES, Regional: epidural caudal block; POSTOPERATIVE ANALGESIA: clonidine, lidocaine, regional block
JUSTIFICATIVA Y OBJETIVOS: La asociación
de diferentes substancias a los anestésicos locales es hecha con el objetivo
de mejorar la cualidad del bloqueo y prolongar la duración de la analgesia.
El objetivo de este trabajo fue comparar la eficacia de la asociación de
clonidina, clonidina y fentanil y de fentanil a la lidocaína, en el tiempo
de analgesia pós-operatoria.
MÉTODO: El estudio envolvió 64 pacientes con edad igual o superior a 23 años, estado físico I ó II (ASA), escalados para cirugía proctológica orificial, sometidos a anestesia peridural sacral. Los pacientes fueron distribuidos en 4 grupos de 16: grupo I (lidocaína aislada), grupo II (lidocaína y fentanil), grupo III (lidocaína, fentanil y clonidina) y grupo IV (lidocaína y clonidina). Se compararon las características de los bloqueos sensitivo y motor.
RESULTADOS: No hubo diferencia entre la latencia, bien como en el nivel máximo de bloqueo entre los grupos. La ausencia de bloqueo motor fue el resultado más frecuente, encontrado en cerca de 64% de los pacientes. El intervalo de analgesia fue diferente entre los grupos, siendo más significativo en el grupo III.
CONCLUSIONES: El uso de la clonidina, asociada o no al fentanil, prolongó el tiempo de analgesia pós-operatoria en la anestesia peridural sacral con lidocaína.
Regional anesthesia for short procedures should be limited to surgery length, thus preventing its effects to go beyond the time needed for the procedure itself. On the other hand, it is desirable for analgesia to be maintained in the postoperative period. The search for higher quality when the aim is to reversibly intervene with nervous action potential conduction, has led to the use of associations of substances such as opioids and a2 agonists to local anesthetics for different blockades, be them peripheral1,2, spinal or epidural3-7, to increase postoperative analgesia length and shorten onset after anesthetic administration. Caudal epidural space has been used as anesthetic route since Sicard and Cathelin, working independently, have used the sacrococcigeal hiatus for this aim in 19018. The technique has become popular in 1940 when it was used for labor analgesia. It is an easy route, which can be used for orificial proctologic surgeries. Morphine has been associated to local anesthetics in epidural and spinal anesthesia, but its major inconvenient is to induce respiratory depression. One alternative has been more liposoluble opioids, such as fentanyl and sufentanil.
This study aimed at determining whether there are differences in analgesia length after the association of clonidine and fentanyl to lidocaine.
After the Ethics Committee approval, participated in this randomized double-blind study 64 patients aged 23 years or above, physical status ASA I or II, scheduled for orificial proctologic surgeries. In addition to patients' refusal, exclusion criteria were neurological, cardiopulmonary, liver-kidney and psychiatric diseases. Patients were randomly distributed in four groups of 16, namely group I (lidocaine alone), group II (lidocaine and fentanyl), group III (lidocaine, fentanyl and clonidine), and group IV (lidocaine and clonidine).
Patients were monitored in the operating room with mercury column sphygmomanometer (Omron, model 12-605), periodically tested and duly gaged (noninvasive method) for systolic (SBP) and diastolic (DBP) blood pressure measurement, pulse oximetry for SpO2 measurement and continuous ECG at CM5 lead. Then, they were placed in the prone position with a pad under the pubic region. After venoclysis with 20G catheter, lactated Ringer's infusion was started and caudal epidural block was induced after sacral hiatus identification, with 25 x 7 needle without previous skin and subcutaneous infiltration. Administered volume after aspiration was always 20 mL, being 16 mL of 2% lidocaine with vasoconstrictor to all groups and the remaining solution being completed as follows: group I - 4 mL distilled water; group II - 2 mL distilled water and 2 mL = 100 µg fentanyl; group III - 2 mL = 100 µg fentanyl and 2 mL = 150 µg clonidine; group IV - 2 mL distilled water and 2 mL = 150 µg clonidine.
Solutions were prepared by one anesthesiologist and administered by a different anesthesiologist blind to the association. A third anesthesiologist blind to the group patients belonged to evaluated data.
Surgical analgesia length was defined as time elapsed between epidural injection and first spontaneous pain complaint leading to non steroid analgesic prescription.
Onset was defined as time elapsed between end of epidural injection and lack of pain evaluated by pinprick in the sensory area corresponding to S4, S5.
Blockade level was defined as the highest level with no response to pinprick after three successive stimulations at 2-minute intervals.
Motor block intensity was evaluated on lower limbs at surgery completion by modified Bromage's scale:
0 - no blockade;
1 - partial blockade - active leg bending;
2 - partial blockade - active feet bending only;
3 - total blockade - no limb movement.
Analysis of Variance followed by Newman-Kels test was used for statistical comparison of means of all groups. Non-parametric measurements were compared by Mode for maximum sensory block level.
Demographics data are shown in table I.
Analgesia onset evaluated by pinprick and highest sensory block level are shown in table II. There have been no differences in onset and maximum sensory block among groups.
Figure 1 shows that 0 blockade level has been the most frequent, found in approximately 64% of patients.
Table III shows that there were differences among groups in analgesic length. Group III has shown prolonged analgesia as compared to other groups. Groups II and IV were not significantly different as compared to group I.
There were no statistically significant differences among groups in onset, different from other studies where epidural fentanyl associated to lidocaine has shortened blockade onset9. Lack of motor block was the most frequent result, found in approximately 64% of patients. Analgesia duration was longer when clonidine and fentanyl were associated to lidocaine, but this increase was not significant for the group receiving lidocaine and fentanyl, in disagreement with some results found in the literature where there has been prolonged analgesia5,10. Our results have shown that clonidine, associated or not to fentanyl, prolongs epidural lidocaine effects, being however statistically significant only for group III. Clonidine associated to local anesthetics has been increasingly used to improve blockade quality and manage pain. Clonidine induces spinal and supraspinal analgesia11 via a2-adrenergic receptors, in addition to a direct inhibitory effect on pain peripheral conduction pathways (A delta and C). There have been no side effects, such as hypotension, bradycardia and sedation in all groups.
With the methodology used in this study the authors concluded that clonidine associated or not to fentanyl, has prolonged postoperative analgesia after caudal epidural blockade with lidocaine.
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Dr. Carlos Alberto de Souza Martins
Address: Avenida Grande Oriente, nº 23 Quadra 47
ZIP: 65075-180 City: São Luís, Brazil
Submitted for publication May 30,
Accepted for publication November 6, 2003
* Received from Clínica de Proctologia da Universidade Federal do Maranhão (UFMA), São Luís, MA