Brazilian Journal of Anesthesiology
Brazilian Journal of Anesthesiology
Original Investigation

Effectiveness and safety of ultra-low-dose spinal anesthesia versus perineal blocks in hemorroidectomy and anal fistula surgery: a randomized controlled trial

Eficácia e segurança da raquianestesia com dose ultrabaixa versus bloqueios perineais em hemorroidectomia e cirurgia de fístula anal: um ensaio clínico randomizado

Rafael Peterson Soares Santos, Alfredo Dias de Oliveira-Filho, Manoel Álvaro de Freitas Lins Neto, Lucas Correia Lins, Fabiano Timbó Barbosa, Sabrina Joany Felizardo Neves

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Ultra-low-dose Spinal Anesthesia (SA) is the practice of employing minimal doses of intrathecal agents so that only the roots that supply a specific area are anesthetized. The aim of this study was to compare the effectiveness and safety of ultra-low-dose spinal anesthesia with that of Perineal Blocks (PB).

A two-arm, parallel, double-blind randomizes controlled trial comparing two anesthetic techniques (SA and PB) for hemorrhoidectomy and anal fistula surgery was performed. The primary outcomes were postoperative pain, complementation and/or conversion of anesthesia, and hemodynamic changes.

Fifty-nine patients were included in the final analysis. The mean pain values were similar in the first 48 h in both groups (p > 0.05). The individuals allocated to the SA group did not need anesthetic complementation; however, those in the PB group required it considerably (SA group, 0% vs. PB group, 25%; p = 0.005). Hemodynamic changes were more pronounced after PB: during all surgical times, the PB group showed lower MAP values and higher HR values (p < 0.05). Postoperative urinary retention rates were similar between both groups (SA group 0% vs. PB group 3.1%, p = 0.354).

SA and PB are similarly effective in pain control during the first 48 h after hemorrhoidectomy and anal fistula surgery. Although surgical time was shorter among patients in the PB group, the SA technique may be preferable as it avoids the need for additional anesthesia. Furthermore, the group that received perineal blocks was under sedation with a considerable dose of propofol.


Anal fistula; Outpatient surgery; Hemorrhoidectomy; Spinal anesthesia; Urinary retention



A anestesia espinhal (AE) com dose ultrabaixa é a prática de empregar doses mínimas de agentes intratecais para que apenas as raízes que irrigam uma área específica sejam anestesiadas. O objetivo deste estudo foi comparar a eficácia e segurança da raquianestesia com dose ultrabaixa com a dos bloqueios perineais (BP).


Foi realizado um ensaio clínico randomizado, duplo-cego, paralelo, de dois braços, comparando duas técnicas anestésicas (AE e BP) para hemorroidectomia e cirurgia de fístula anal. Os desfechos primários foram dor pós-operatória, complementação e/ou conversão da anestesia e alterações hemodinâmicas.


Cinquenta e nove pacientes foram incluídos na análise final. Os valores médios de dor foram semelhantes nas primeiras 48 horas em ambos os grupos (p > 0,05). Os indivíduos alocados no grupo AE não necessitaram de complementação anestésica; no entanto, aqueles no grupo BP necessitaram consideravelmente (grupo AE, 0% vs. grupo BP, 25%; p = 0,005). As alterações hemodinâmicas foram mais pronunciadas após o BP: durante todos os tempos cirúrgicos, o grupo BP apresentou menores valores de PAM e maiores valores de FC (p < 0,05). As taxas de retenção urinária pós-operatória foram semelhantes entre os dois grupos (grupo AE 0% vs. grupo BP 3,1%, p = 0,354).


AE e BP são igualmente eficazes no controle da dor durante as primeiras 48 horas após hemorroidectomia e cirurgia de fístula anal. Embora o tempo cirúrgico tenha sido menor entre os pacientes do grupo BP, a técnica AE pode ser preferível, pois evita a necessidade de anestesia adicional. Além disso, o grupo que recebeu bloqueios perineais estava sob sedação com dose considerável de propofol.


Fístula anal; Cirurgia ambulatória; Hemorroidectomia; Raquianestesia; Retenção urinária


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