Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942002000100005
Brazilian Journal of Anesthesiology
Scientific Article

Avaliação clínica comparativa entre a cetamina e a clonidina por via peridural no tratamento da dor crônica neuropática

Epidural ketamine versus epidural clonidine as therapeutic for refractory neuropathic chronic pain

Gabriela Rocha Lauretti; Alexandre de Menezes Rodrigues; Josenília Maria Alves Gomes; Marlene Paulino dos Reis

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Resumo

JUSTIFICATIVA E OBJETIVOS: A dor crônica resulta em resposta aumentada dos neurônios do corno dorsal da medula espinhal, devido à ação de diferentes mediadores liberados pelas terminações neuronais, incluindo agonistas para os receptores N-metil-D-aspartato. Além das vias ascendentes sensitivas, vias descendentes inibitórias modulam a sensação de dor, incluindo a participação de a2-agonistas localizados nos aferentes primários e na medula espinal. Este estudo visou avaliar o efeito antinociceptivo da cetamina (antagonista do receptor N-metil-D-aspartato) e da clonidina (a2-agonista) administrada por via peridural, no tratamento da dor crônica neuropática. MÉTODO: Vinte e seis pacientes adultos com queixa de dor tipo neuropática, não-responsiva aos tratamentos convencionais, foram de forma prospectiva, aleatória e duplamente encoberta, divididos em dois grupos. Todos os pacientes fizeram uso de 50-75 mg de amitriptilina por via oral diariamente. A dor foi avaliada utilizando-se a escala analógica visual (EAV) de 10 cm, em que “zero” correspondeu à “ausência de dor” e “dez” à “pior dor imaginável”. Um cateter peridural foi inserido na região lombar, e as medicações por via peridural foram administradas em intervalos de 8 horas, durante três semanas. O Grupo Cetamina recebeu 0,1 mg.kg-1 de cetamina sem conservante, seguida da administração de 30 mg de lidocaína a 1%, em cada aplicação. O Grupo Clonidina recebeu 30 µg de clonidina sem conservante, seguida da administração de 30 mg de lidocaína a 1%, em cada aplicação. RESULTADOS: Vinte e três pacientes fizeram parte da avaliação final. A administração de cetamina ou clonidina por via peridural, nas doses propostas, resultou em analgesia durante todo o período da manutenção do cateter peridural (EAV inicial 8-10 cm versus EAV final 0-3 cm) (p < 0,002). Após a retirada do cateter peridural, os valores numéricos da EAV mantiveram-se entre 0-3 cm durante 2 a 5 semanas. CONCLUSÕES: A administração de cetamina ou clonidina por via peridural resultou em ação antinociceptiva em pacientes com dor crônica neuropática, não-responsiva aos tratamentos convencionais, representando alternativas eficazes, quando o tratamento convencional não obteve sucesso.

Palavras-chave

ANALGÉSICOS, DOR, Crônica, HIPNÓTICOS, TÉCNICAS ANESTÉSICAS, Regional

Abstract

BACKGROUND AND OBJECTIVES: Chronic pain results in an increased response of spinal cord dorsal horn neurons due to the action of several mediators released by neuronal terminals, including the agonists of N-methyl-D-aspartate receptors. In addition to sensory ascending pathways, inhibitory descending pathways modulate pain, including a2-adrenoceptors located on primary afferent terminals and on the spinal cord. This study was designed to investigate the anti-noxious effects of epidural ketamine (N-methyl-D-aspartate antagonist) or epidural clonidine (a2-adrenergic agonist) in the treatment of neuropathic chronic pain. METHODS: Twenty-six adult patients, with neuropathic chronic pain not responsive to conservative therapy, were randomly divided into two groups in this prospective double-blind study. All patients were regularly taking 50-75 mg oral amitriptyline at bedtime. Pain was evaluated through a 10 cm visual analog scale (VAS), with “zero” corresponding to “no pain” and 10 to “the worst possible pain”. A lumbar epidural catheter was inserted and test drugs were administered at 8 hour-intervals during 3 weeks. The ketamine group (KG) was given each time 1 mg.kg-1 preservative-free ketamine followed by 30 mg of 1% lidocaine. The clonidine group (Clo G) was given 30 µg preservative-free clonidine followed by 30 mg of 1% lidocaine (3 ml). RESULTS: Twenty-three patients were evaluated (KG-n=10; Clo G-n=13). Epidural administration of ketamine or clonidine in the proposed doses resulted in analgesia during epidural catheter maintenance (initial VAS 8-10 cm versus final VAS 0-3 cm) (p < 0.002). VAS scores remained maintained between 0 and 3 cm from 2 to 5 weeks following epidural catheter removal. CONCLUSIONS: Epidural ketamine or clonidine resulted in analgesia for neuropathic chronic pain refractory to conservative treatment and are effective alternatives when conventional treatment fails.

Keywords

ANALGESICS, ANESTHETIC TECHNIQUES, Regional, HYPNOTICS, PAIN, Chronic

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