Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine: pilot study on outpatient hemorrhoidectomy

Abstracts

JUSTIFICATIVA E OBJETIVOS: A hemorroidectomia pode ser realizada sob várias técnicas anestésicas e em regime ambulatorial. A dor pós-operatória é intensa e pode atrasar o retorno para a residência. O objetivo deste estudo foi avaliar as vantagens e a realização do bloqueio bilateral dos nervos pudendos para analgesia pós-operatória em hemorroidectomias. MÉTODO: O bloqueio bilateral dos nervos pudendos com bupivacaína S75:R25 a 0,25% foi realizado com estimulador de nervos em 35 pacientes submetidos à hemorroidectomia sob raquianestesia. Foram avaliadas intensidade da dor, duração da analgesia, analgesia de demanda e eventuais complicações relacionadas à técnica. Os dados foram avaliados às 6, 12, 18, 24 e 30 horas após o término da intervenção cirúrgica. RESULTADOS: Em todos os pacientes, foi obtido sucesso com a estimulação de ambos os nervos pudendos. Em nenhum momento da avaliação ocorreu dor intensa. Até 12 horas após o bloqueio, todos os pacientes apresentaram anestesia na região perineal; com 18 horas, 17 pacientes e 24 horas; 10 pacientes A analgesia pós-operatória foi ótima em 18 pacientes; satisfatória, em cinco pacientes; e insatisfatória, em sete pacientes. A duração média da analgesia foi de 23,77 horas. Não ocorreram alterações da pressão arterial, da freqüência cardíaca, nem foram observadas náuseas ou vômitos. Todos os pacientes tiveram micção espontânea. Nenhuma complicação local ou sistêmica foi relacionada ao anestésico local. Vinte e sete pacientes classificaram de excelente a técnica de analgesia e apenas três pacientes do sexo masculino ficaram satisfeitos o que foi justificado pela anestesia no pênis. CONCLUSÕES: O bloqueio bilateral dos nervos pudendos, orientado por estimulador de nervos, proporciona a analgesia de excelente qualidade, com baixa necessidade de opióides, sem complicações local ou sistêmica e sem retenção urinária. Estudos controlados permitirão demonstrar se esta técnica deve ser a primeira opção para analgesia em hemorroidectomias. A permanência de anestesia perineal por 20,21 horas deverá induzir novos trabalhos com o bloqueio dos nervos pudendos orientado por estimulador para o ato cirúrgico.

ANESTÉSICOS, Local; ANESTÉSICOS, Local; CIRURGIA, Anorretal; TÉCNICAS ANESTÉSICAS, Regional

SCIENTIFIC ARTICLE

Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine. Pilot study on outpatient hemorrhoidectomy^*

Analgesia pos-operatoria con bloqueo bilateral del nervio pudendo con bupivacaína S75:R25 a 0,25%. Estudio piloto en hemorroidectomia bajo régimen ambulatorial

Luiz Eduardo Imbelloni, TSA, M.D.^I; Lúcia Beato, TSA, M.D.^II; Carolina Beato, M.D.^II; José Antônio Cordeiro, M.D.^III; Dulcimar Donizete de Souza, M.D.^IV

^IDiretor do Instituto de Anestesia Regional, Hospital de Base, São José do Rio Preto, Anestesiologista da Clínica São Bernardo, Rio de Janeiro, RJ

^IIAnestesiologista da Clínica São Bernardo, Rio de Janeiro, RJ

^IIIProfessor Livre Docente em Probabilidade e Estatística da Faculdade de Medicina de São José do Rio Preto, SP

^IVDoutor em Ciências da Saúde; Diretor Adjunto de Pessoal da Faculdade de Medicina de São José do Rio Preto, SP

^{Correspondence to}

SUMMARY

BACKGROUND AND OBJECTIVES: Hemorrhoidectomy may be performed under several anesthetic techniques and in outpatient regimen. Postoperative pain is severe and may delay discharge. This study aimed at evaluating bilateral pundendal nerves block for post- hemorrhoidectomy analgesia.

METHODS: Bilateral pundendal nerves block with 0.25% S75:R25 bupivacaine was performed with nerve stimulator in 35 patients submitted to hemorrhoidectomy under spinal anesthesia. Evaluated parameters were pain severity, duration of analgesia, demand analgesia and possible technique-related complications. Data were evaluated 6, 12, 18, 24 and 30 hours after surgery completion.

RESULTS: Successful pudendal nerves stimulation was achieved in all patients. There has been no severe pain in all evaluated moments. At 12 hours after blockade, all patients had perineal anesthesia; at 18 hours, 17 patients and at 24 hours, 10 patients still presented perineal anesthesia. Postoperative analgesia was optimal for 18 patients; satisfactory, for 5 patients; and unsatisfactory, for 7 patients. Mean analgesic duration was 23.77 hours. There were no changes in blood pressure, heart rate, no nausea and vomiting were observed. All patients had spontaneous micturition. No local anesthetic-related local or systemic complications were observed. Technique was considered excellent by 27 patients and only 3 male patients considered it satisfactory due to penile anesthesia.

CONCLUSIONS: Bilateral pudendal nerves block oriented by nerve stimulator provides excellent analgesia with low need for opioids, without local or systemic complications and without urinary retention. Controlled studies might be able to show whether this should be the first analgesic option for hemorrhoidectomies. Perineal anesthesia lasting 20.21 hours shall induce further studies with stimulator-oriented pudendal block.

Key words: ANESTHETICS, Local: bupivacaine, enantiomeric mixture (S75:R25); ANESTHETIC TECHNIQUES, Regional: pudendal block; SURGERY, Anorectal: hemorrhoidectomy

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: La hemorroidectomia puede ser realizada bajo varias técnicas anestésicas y en régimen ambulatorial. El dolor pos-operatorio es intenso y puede atrasar el retorno para el hogar. El objetivo de este estudio fue evaluar las ventajas y la realización del bloqueo bilateral de los nervios pudendos para analgesia pos-operatoria en hemorroidectomias.

MÉTODO: El bloqueo bilateral de los nervios pudendos con bupivacaína S75:R25 a 0,25% fue realizado con estimulador de nervios en 35 pacientes sometidos a la hemorroidectomia bajo raquianestesia. Fueron evaluadas intensidad del dolor, duración de la analgesia, analgesia de demanda y eventuales complicaciones relacionadas a la técnica. Los datos fueron evaluados a las 6, 12, 18, 24 y 30 horas después del término de la intervención quirúrgica.

RESULTADOS: En todos los pacientes, fue logrado éxito con la estimulación de ambos los nervios pudendos. En ningún momento de la evaluación ocurrió dolor intenso. Hasta 12 horas después del bloqueo, todos los pacientes presentaron anestesia en la región perineal; con 18 horas, 17 pacientes y 24 horas, 10 pacientes A analgesia pos-operatoria fue óptima en 18 pacientes; satisfactoria, en cinco pacientes; e insatisfactoria, en siete pacientes. La duración media de la analgesia fue de 23,77 horas. No ocurrieron alteraciones de la presión arterial, de la frecuencia cardiaca, ni fueron observados náuseas o vómitos. Todos los pacientes tuvieron micción espontánea. Ninguna complicación local o sistémica fue relacionada al anestésico local. Veintisiete pacientes clasificaron de excelente la técnica de analgesia y apenas tres pacientes del sexo masculino quedaron satisfechos, justificado por la anestesia en el pene.

CONCLUSIONES: El bloqueo bilateral de los nervios pudendos, orientado por estimulador de nervios proporciona una analgesia de excelente calidad, con baja necesidad de opioides, sin complicaciones local o sistémica y sin retención urinaria. Estudios controlados permitirán demostrar si esta técnica debe ser la primera opción para la analgesia en hemorroidectomias. La permanencia de anestesia perineal por 20,21 horas deberá inducir nuevos trabajos con el bloqueo de los nervios pudendos orientado por estimulador para el acto quirúrgico.

INTRODUCTION

Hemorrhoidal diseases are common throughout the world and are symptomatic in 4.4% of the population ¹. Approximately 90% of anorectal procedures may be performed in outpatient regimen ². Among all treatments for hemorrhoidal diseases, surgical resection seems to be the best to eliminate symptoms and improve quality of life ³. However, severe postoperative pain may prolong hospital stay ⁴. Postoperative pain is a major outpatient regimen problem ⁵. A retrospective study with 1100 patients submitted to outpatient procedures has shown that 35% of patients had moderate to severe pain at home, in spite of analgesic therapy ⁶. Several analgesic methods have been proposed for post-hemorrhoidectomy pain relief, such as subcutaneous morphine with infusion pump ⁷, transcutaneous electric stimulation ⁸, dexametazone ⁹, perianal infiltration with bupivacaine ¹⁰, posterior perineal block ¹¹ and of the ischiorectal fossa ¹².

The pudendal nerve is formed by posterior S₂, S₃ and S₄ branches and is divided in four branches: inferior anal nerves, perineal nerves, posterior labial nerves (females), posterior scrotal nerves (males), clitoris dorsal nerve (females) and penile dorsal nerve (male) ¹³. In theory, pudendal nerve block may provide perineal analgesia or anesthesia being often used by surgeons and obstetricians. Peripheral nerve stimulator, which is an excellent teaching method for regional anesthesia, helps the anesthesiologist in this type of blockade due to location monitored by perineal muscles contracture.

Different animal and human studies have shown that levogyrous local anesthetics are less toxic for central nervous and cardiovascular systems as compared to racemic or dextrogyrous bupivacaine, with intrinsic ability to promote vasoconstriction and less intense motor block ^14,15. A comparison of racemic and bupivacaine with levogyrous enantiomeric excess of 50% (S75;R25) for brachial plexus block, has not shown differences in observed parameters ¹⁶. Authors concluded suggesting that S75:R25 is a safer alternative as compared to racemic bupivacaine due to lower toxicity ¹⁶.

This study aimed at evaluating post-hemorrhoidectomy analgesia with 0.25% S75:R25 bupivacaine bilaterally injected in pudendal nerves located with the aid of electrical stimulation.

METHODS

After the Ethics Committee approval and their informed consent, participated in this study 35 patients physical status ASA I and II, aged 20 to 60 years, submitted to spinal anesthesia with 50 mg of 2% isobaric lidocaine for hemorrhoidectomy in outpatient regimen. Spinal anesthesia was induced in the left lateral position in L₃-L₄ interspace, by the paramedial route with 27G Quincke needle (B. Braun Melsungen S.A.). Monitoring consisted of noninvasive blood pressure, heart rate and pulse oximetry. Patients were not premedicated. Venoclysis was installed in the operating room with lactated Ringer's and 50 to 100 µg fentanyl were intravenously administered. Minimum intraoperative fluids were administered, always below 500 mL.

Bilateral pudendal nerves block was performed at surgery completion with patients in lithotomy position and under spinal anesthesia effect. The needle access was transperineal and medial to ischial tuberosity on both sides, using beveled insulated needle with 100 mm (B. Braun Melsungen AG, 21G 0.8 x 100 mm needle) connected to peripheral nerve stimulator (Stimuplex^®, B. Braun Melsungen AG) set to release a square pulsatile current of 1 mA, with 2 Hz frequency, perpendicularly inserted to a depth of approximately 7 cm, trying to obtain anal sphincter contraction. After perineal contraction, 20 mL of 0.25% bupivacaine (S75:R25) were injected in each side.

Patients were followed for six hours in the hospital and then at 12, 18, 24 and 30 hours by telephone when they were questioned about pain severity, which was classified as: absent (level 0), mild (level 1), moderate (level 2) or severe (level 3). Patients were also asked whether the operated region was insensitive (anesthesia). Pain at first evacuation was evaluated with the same scale and time between blockade and first evacuation was recorded. Patients were asked about postoperative analgesia, which should be classified as excellent, satisfactory or poor.

Oral tramadol was prescribed in case of pain. Analgesia was classified as optimal if no analgesic (tramadol) was needed; satisfactory (one dose) and unsatisfactory (two or more doses). Demographics data, painless period, pain severity, oral analgesic frequency, total doses and complications, such as urinary retention, were evaluated.

Qualitative variables (presence of pain, pain severity, pain at first evacuation, blockade at 6, 12, 18, 24 and 30 hours and level of satisfaction) were evaluated with regard to gender by Fisher's Exact test. Quantitative variables compared with regard to time were analyzed by paired t test, and with regard to gender by t test for two samples, assuming different variances.

RESULTS

Demographics data are shown in table I. Spinal anesthesia was satisfactory for all patients and no patient needed complementation with general anesthesia. Both pudendal nerves were successfully stimulated in all patients. There were no changes in blood pressure and heart rate, there were no postoperative nausea or vomiting. All patients had spontaneous micturition. No local or systemic complications were related to local anesthetics.

Brazilian Journal of Anesthesiology, 2005; 55: 6: 614-621

Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine.

Pilot study on outpatient hemorrhoidectomy

Luiz Eduardo Imbelloni; Lúcia Beato; Carolina Beato; José Antônio Cordeiro; Dulcimar Donizete de Souza

Pain severity in the first 30 postoperative hours is shown in table II and there has been no maximum pain (severe) throughout the study. All patients presented perineal anesthesia 12 hours after blockade. At 18 hours, 22 patients; at 24 hours, 12 patients and at 30 hours, no patient presented perineal anesthesia (Table II).

Brazilian Journal of Anesthesiology, 2005; 55: 6: 614-621

Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine.

Pilot study on outpatient hemorrhoidectomy

Luiz Eduardo Imbelloni; Lúcia Beato; Carolina Beato; José Antônio Cordeiro; Dulcimar Donizete de Souza

At 6 and 12 postoperative hours no female has referred mild pain and four males have referred it (remaining males did nor refer pain), showing a higher incidence of pain in males in these moments. At 18 hours, one female has referred mild pain as compared to 10 males, with a high incidence of pain among males. At 24 hours, two females have referred moderate pain and no one has referred mild pain, while among males there has been one case of moderate and nine cases of mild pain, showing a higher incidence of mild or moderate pain among males. Two females have referred pain at first postoperative evacuation as compared to eight males. At 12 post-blockade hours, all patients had perineal anesthesia; at 18 hours, 22 patients, being 15 females and 7 males, indicating lower probability of blockade for males in this period. At 24 hours, blockade persisted in 12 patients, being 5 females and 7 males, with no statistically significant difference in this moment.

Analgesia duration was 15 to 20 hours in 10 patients; 21 to 25 hours, in 14 patients; 26 to 30 hours, in 10 patients; and more than 31 hours in 1 patient, with mean duration of 23.77 hours. Postoperative analgesia was optimal for 23 patients; satisfactory, for 5 patients, and unsatisfactory, for seven patients. There has been no need for postoperative analgesia in 23 patients. First evacuation was approximately 30 hours after bilateral pudendal nerves block; 10 patients have referred pain at evacuation, while 25 patients have not. Analgesic technique was considered excellent by 32 patients and only 3 male patients have considered it satisfactory due to penile anesthesia. There has been no difference in level of satisfaction between genders (p = 0.10) (Table III and Table IV).

Brazilian Journal of Anesthesiology, 2005; 55: 6: 614-621

Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine.

Pilot study on outpatient hemorrhoidectomy

Luiz Eduardo Imbelloni; Lúcia Beato; Carolina Beato; José Antônio Cordeiro; Dulcimar Donizete de Souza

Brazilian Journal of Anesthesiology, 2005; 55: 6: 614-621

Bilateral pudendal nerves block for postoperative analgesia with 0.25% S75:R25 bupivacaine.

Pilot study on outpatient hemorrhoidectomy

Luiz Eduardo Imbelloni; Lúcia Beato; Carolina Beato; José Antônio Cordeiro; Dulcimar Donizete de Souza

DISCUSSION

External hemorrhoidal thrombosis is probably one of the most common anorectal emergency diagnoses and surgery is the treatment, of choice. In our study, postoperative analgesia with bilateral pudendal nerves block under spinal anesthesia has resulted in mean 23.77 hours analgesia with low need for opioids and 23 patients without rescue medication.

Hemorrhoidectomy is a short procedure, however extremely painful, and few studies are directed toward postoperative analgesia ¹⁷. Major pain factors are related to surgical procedure. Milligan-Morgan technique (open) seems to be much more painful as compared to Reis Neto semi-open hemorrhoidectomy or even to the closed procedure ¹⁸. Some authors use posterior perineal block for anesthesia and postoperative analgesia.

There are several variants of initial descriptions ^11,19,20. Differences refer to technical details, equipment and anesthetic drugs. It is also necessary to differentiate pararectal infiltration from perineal block. Pararectal (or perineal) infiltration is a superficial posterior perineal block often used as single technique ²¹. Our study has used bilateral pudendal nerves block oriented by nerve stimulator, resulting in perineal anesthesia for 20.21 hours and showing that blockade may be used as single technique for the proposed procedure. It was not our proposal to evaluate differences in the incidence of pain between genders. However, there has been higher incidence of pain among males as compared to females in all evaluated periods and during first evacuation. These data shall be the object of further studies.

All anesthetic drugs have already been used for posterior perineal block: bupivacaine, lidocaine, mepivacaine, ropivacaine, associated or not, with or without epinephrine, and in volumes varying from 20 to 50 mL. Lidocaine or mepivacaine administered to 400 patients have induced analgesia for 5 hours in 31.5%, for more than 10 hours in 48.5% and for more than 15 hours in 9.2%; 3.2% had no need for analgesics ¹¹. One to three mL of 0.5% bupivacaine injected in the base of each hemorrhoid 10 minutes before incision have allowed a painless period 10 times longer as compared to control group ¹⁰. The injection of 20 mL of 0.25% bupivacaine with levogyrous enantiomeric excess of 50% (S75:R25) in each pudendal nerve has promoted mean 23.77 hours analgesia. A different publication ¹⁶ evaluating the same solution with twice the concentration (0.5%) in the brachial plexus has not evaluated analgesia duration, thus not allowing the comparison of results.

Spinal anesthesia leads to clinical vesical function disorders due to the interruption of micturition reflex. Bladder function remains imperfect until the blockade has regressed to the 3^rd sacral segment in all patients ²². With long lasting anesthetics, accumulated volume may exceed the cystometric capacity of the bladder ¹⁷. For this reason, spinal anesthesia in our study was induced with 50 mg of 2% isobaric lidocaine, in an attempt to prevent urinary retention caused by the anesthetic technique, which was confirmed by spontaneous micturition in all patients. This shows that bilateral pudendal nerves block has resulted in perineal anesthesia for approximately 20 hours without preventing spontaneous micturition.

This pilot study has used bilateral pudendal nerves block with the aid of peripheral nerve stimulator to control postoperative pain of patients submitted to hemorrhoidectomy under spinal anesthesia. The study has its limitations because analgesia results were not compared to a different method.

Based on our results, we consider that bilateral pudendal nerves block with peripheral nerve stimulator for postoperative analgesia with 0.25% S75:R25 bupivacaine may be indicated for all anorectal procedures, provided no previous infection is present. With this technique, analgesia is effective, without local or systemic complications, making first evacuation less painful and without side effects, such as urinary retention. In the future, controlled and comparative studies may show whether this technique should be the first option for hemorrhoidectomy analgesia. Mean perineal anesthesia duration of 21.20 hours shall induce further studies with pudendal nerves block and nerve stimulator.

ACKNOWLEDGMENT

We acknowledge professor Manoel Antônio Pereira Alvarez for suggesting the study.

REFERENCES

Submitted for publication April 28, 2005

Accepted for publication July 6, 2005

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*

Received from Instituto de Anestesia Regional, São José do Rio Preto, SP

Publication Dates

• Publication in this collection
  13 Mar 2006
• Date of issue
  Dec 2005

History

• Received
  28 Apr 2005
• Accepted
  06 July 2005