Thoracic epidural block performed safely in anesthetized patients: a study of a series of cases

Abstracts

JUSTIFICATIVA E OBJETIVOS: O surgimento de casos de paraplegia seguindo a inserção de cateter peridural em pacientes anestesiados levou a questionamento por parte de alguns autores, mesmo que não se confirme que a lesão tenha ocorrido porque o paciente estava anestesiado. Por esse motivo, idealizamos este estudo, que teve como objetivo avaliar a freqüência de complicações neurológicas e de surgimento de seqüelas após anestesia peridural torácica realizada com os pacientes sob anestesia geral. MÉTODO: Participaram do estudo pacientes submetidos à intervenção cirúrgica torácica no período de 16/02/2004 a 30/05/2006. Após monitoração dos sinais vitais e realização da anestesia geral, os pacientes foram colocados em decúbito lateral e realizada anestesia peridural torácica simples ou contínua. Numa ficha especial foram registradas as intercorrências, complicações e dificuldades na realização da técnica. No pós-operatório os pacientes foram acompanhados em busca de sinais e sintomas de disfunção neurológica. RESULTADOS: Foram avaliados 113 pacientes e em 108 foi inserido cateter peridural torácico. Em 45 pacientes a punção foi considerada traumática, ou seja, sangramento no local da punção e punções múltiplas. Em dois pacientes houve perfuração acidental de dura-máter. No pós-operatório imediato um paciente relatou sensação de formigamento em membros inferiores, outro paciente apresentou dormência em membro superior, desaparecendo com a retirada e tração do cateter. A punção foi única nos dois casos. Nenhum outro paciente apresentou sinais ou sintomas de alterações neurológicas. CONCLUSÕES: Nos casos estudados não houve complicação neurológica. Quando executado com bom senso e cuidados específicos o bloqueio peridural torácico pode ser realizado com segurança no paciente anestesiado.

ANESTESIA, Geral; COMPLICAÇÕES; TÉCNICAS ANESTÉSICAS, Regional

SCIENTIFIC ARTICLE

Thoracic epidural block performed safely in anesthetized patients. A study of a series of cases^*

Anestesia peridural torácica realizada con seguridad en el paciente anestesiado. Estudio de una serie de casos

Paulo Roberto Nunes de Bessa, TSA^I; Verônica Vieira da Costa^I; Érika Carvalho Pires Arci^II; Maria do Carmo Barretto de C. Fernandes^III; Renato Ângelo Saraiva, TSA^IV

^IAnestesiologista do Hospital SARAH

^IIEstatística do Hospital SARAH

^IIIEnfermeira do Hospital SARAH

^IVCoordenador de Anestesiologia da Rede SARAH de Hospitais

Correspondence to

SUMMARY

BACKGROUND AND OBJECTIVES: The development of paraplegia following the insertion of epidural catheter in anesthetized patients raised questions by some authors about the procedure, even without the confirmation that the lesion occurred because the patient was anesthetized. For this reason, we designed this study, with the objective to evaluate the frequency of neurological complications and development of sequelae after thoracic epidural block in patients under general anesthesia.

METHODS: Patients undergoing thoracic surgeries from 02/16/2004 to 05/30/2006 participated in the study. After monitoring vital signs and the installation of general anesthesia, patients were placed in lateral decubitus for simple or continuous thoracic epidural block. Intercurrences, complications, and technical difficulties were recorded on a special form. Patients were followed postoperatively to detect the development of any signs and symptoms of neurological dysfunction.

RESULTS: One hundred and thirteen patients were evaluated and the thoracic epidural catheter was placed in 108 patients. The puncture was considered traumatic, i.e., bleeding at the puncture site and multiple punctures, in 45 patients. Accidental perforation of the dura-mater occurred in two patients. In the immediate postoperative period, a patient complained of tingling in the lower limbs, another patient developed numbness in an upper limb, which resolved after the catheter was removed. Both patients had a single puncture. The other patients did not develop any signs or symptoms of neurologic changes.

CONCLUSIONS: The cases studied here did not develop any neurologic complications. When performed judiciously and with specific care, thoracic epidural block can be safely done in the anesthetized patient.

Key Words: ANESTHESIA, General: ANESTHETIC TECHNIQUES: Regional: epidural; COMPLICATIONS: neurologic.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: El surgimiento de casos de paraplejia continuando la inserción de catéter peridural en pacientes anestesiados, hizo con que algunos autores se cuestionasen el hecho incluso cuando no se confirmase que la lesión haya ocurrido porque el paciente estaba anestesiado. Por ese motivo, idealizamos este estudio, que tuvo como objetivo evaluar la frecuencia de complicaciones neurológicas y el aparecimiento de secuelas después de la anestesia peridural torácica realizada con los pacientes bajo anestesia general.

MÉTODO: Participaron en el estudio pacientes sometidos a la intervención quirúrgica torácica en el período de 16/02/2004 a 30/05/2006. Después de la monitorización de las señales vitales y de la anestesia general, los pacientes fueron puestos en decúbito lateral y fue realizada la anestesia peridural torácica simple o continua. En una ficha especial se registraron las intercurrencias, complicaciones y dificultades en la realización de la técnica. En el postoperatorio los pacientes tuvieron acompañamiento en busca de señales y de síntomas de disfunción neurológica.

RESULTADOS: Se evaluaron 113 pacientes y a 108 de ellos se les insertó catéter peridural torácico. En 45 pacientes la punción fue considerada traumática, o sea, hubo sangramiento en el local de la punción y punciones múltiples. En dos pacientes hubo perforación accidental de duramadre. En el postoperatorio inmediato, un paciente relató una sensación de hormigueo en los miembros inferiores, otro paciente presentó adormecimiento en miembro superior, desapareciendo con la retirada y la tracción del catéter. La punción fue única en los dos casos. En ningún otro paciente hubo señales o síntomas de alteraciones neurológicas.

CONCLUSIONES: En los casos estudiados no hubo complicación neurológica. Cuando se efectúa con sentido común y con los cuidados específicos, el bloqueo peridural torácico puede ser realizado con seguridad en el paciente anestesiado.

INTRODUCTION

Simple or continuous epidural block under general anesthesia has been the center of controversies ¹.

Reports of paraplegia after the insertion of epidural catheters ^2,3 raised concerns in some authors, even though in none of the cases reported the cause-effect relationship between the lesion and performing the blockade under general anesthesia had been confirmed. In most cases, other factors were associated, such as comorbidities, intraoperative hypotension, technical difficulty, and lack of experience by the anesthesiologist ⁴.

Epidural thoracic block under general anesthesia has been a routine for 10 years at the hospital where the study was conducted to provide comfort to patients, considering that most of them are oncologic patients.

The objective of this study was to evaluate the frequency of complications, the presence of technical difficulties, and the development of neurological sequelae of thoracic epidural block in patients under general anesthesia.

METHODS

This study was approved by the Ethics and Research Committee of the Hospital SARAH Brasília - Centro.

This study consisted of a series of cases of patients undergoing thoracic surgery from 02/16/2004 to 05/30/2006.

Adult patients received diazepam (10 mg per os) the night before the surgery, and midazolam (15 mg per os) 40 minutes before the surgery. Children only received 0.6 mg.kg^-1 of midazolam 40 minutes before the surgery. When they arrived to the anesthesia induction room, patients were monitored with continuous ECG, non-invasive blood pressure, and SpO₂ (peripheral hemoglobin oxygen saturation). Balanced general anesthesia was then performed and invasive blood pressure, esophageal temperature, and gas analyzer and capnography were added to the monitoring.

Patients were placed in lateral decubitus and simple or continuous epidural block was performed. In the cases of continuous epidural block, the catheter was secured at the puncture site with a semi-permeable, sterile bandage, and along the course of the catheter in the dorsal region of the patient with non-sterile, semi-permeable bandage. The bandages were changed in case of visible bleeding or if it were getting lose. Aseptic technique was used to change the bandage using NS and sterile pads to clean the site of catheter insertion.

The anesthesiologist responsible for the case recorded the following data on a standardized form: puncture site, number of attempts, number of intervertebral spaces that were punctured, if it was a traumatic puncture, the reason for the trauma, presence of technical difficulties, the type of needle used, anesthetic used, and the type of postoperative analgesia.

The epidural analgesic solution consisted of 1 mg.kg^-1 bupivacaine with adrenaline and 3 to 5 µg.mL^-1 of fentanyl without preservatives.

Analgesia consisted of a continuous epidural infusion associated with the dose requested by the patient, with a fixed interval of 60 minutes between requests.

Postoperatively, patients were followed-up by a nurse and an anesthesiologist who evaluated and recorded the presence of signs and symptoms of neurologic dysfunction in the immediate and late (30 days later) postoperative periods, as well as the conditions of the epidural catheter at the time of removal, the day it was removed, and the reason for removal.

A descriptive analysis of the data was done in the statistical evaluation.

RESULTS

One-hundred and thirteen patients, of both genders, 40 (F) and 73 (M), ages varying from 2 to 78 years, were included in the study (Table I).

The mean weight of the patients was 60.2 kg. Most patients were ASA II (98) (Table I).

One-hundred and seven patients underwent thoracotomy, four videothoracoscopy, one a minithoracotomy, and one a thymectomy.

All patients received midazolam as pre-anesthetic medication approximately 40 minutes before the surgery.

Epidural thoracic block was always done with the patient under general anesthesia, and in 108 patients an epidural catheter was inserted.

The median approach to the epidural block was used in 97 patients (85.8%), the paramedian was used in 15 patients (13.3%), and both approaches were used in 1 patient (0.9%).

Thirty-eight patients (33.6%) required only a single attempt, 30 patients (26.5%) required 2 attempts, in 15 patients (13.3%) three attempts were made, and 30 patients (26.5%) required more than 3 attempts (Table II). An 18G Tuohy needle was used in all patients. The failure in the first attempt was the reason for subsequent attempts.

In 67 patients (59.3%) only one intervertebral space was punctured, in 34 (30.1%) 2 spaces were punctured, in 9 patients (8%) 3 spaces, and in 3 patients (2.7%) more than 3 spaces were punctured (Table II).

In 45 patients (39.8%), the anesthesiologist responsible for the case considered the puncture to be traumatic. In 21 (46.7%) of those patients, bleeding at the puncture site was the reason of the trauma, in 21 (46.7%) multiple attempts were made, in 2 patients (4.4%) occurred accidental puncture of the dura-mater, and in 1 patient (2.2%) the puncture was technically difficult (Table II).

The intervertebral spaces accessed were from T₃-T₄ to L₁-L₂; T₆-T₇ was the most frequent, being used in 35 patients (31%), followed by T₅-T₆ in 34 patients (30.1%) (Table II).

At the end of the surgery, the postoperative analgesia schedule was initiated through the epidural catheter and in most cases it was controlled by the patient. Bupivacaine associated with fentanyl via the epidural catheter was used in 108 patients. The mean dose of the continuous epidural infusion was 4.0 ± 0.7 mL.h^-1, and the mean dose given to the patient upon request was 4.1 ± 0.7 mL.h^-1.

All patients in the study were evaluated in the regular ward, and those who remained with the catheter were evaluated until its removal. The rate of infusion of the epidural solution was increased or decreased at the discretion of the anesthesiologist based on pain scores. In the evaluation at the ward, one patient complained of a tingling sensation in the lower limbs in the immediate postoperative period; the catheter was removed and the symptoms subsided. One patient developed numbness on an upper limb with decrease motor strength on the first postoperative day. Traction was applied to the catheter and the rate of infusion was decreased from 5 to 3 mL, with resolution of the symptoms. Puncture in those patients was non-traumatic, and they both required only one attempt.

Hematoma or signs of inflammation or infection at the puncture site or site of insertion of the epidural catheter were not observed in the first three postoperative days. Permanent neurologic complications in the immediate postoperative period were also not observed.

The catheter was removed after a mean of 4.4 days.

Reasons for catheter removal included: removal of the chest tube, which coincided with pain resolution (50 cases), beginning of an inflammatory process at the site of insertion (21 cases), accidental disconnection of the catheter (13 cases), exteriorization of the catheter (10 cases), catheter outside the epidural space (6 cases), patient did not need the infusion of local anesthetic (4 cases), beginning of anticoagulation (2 cases), paresthesia (1 case), and pain at the site of insertion (1 case). The catheter was not used in 5 patients.

Patients were evaluated by the assisting physician 30 days after the surgery and no signs or symptoms of late neurologic sequelae were detected.

DISCUSSION

The present study reflects the routine of the Anesthesiology Service of a rehabilitation hospital, whose main objective is the improvement in the quality of postoperative analgesia of patients undergoing thoracic surgeries. Although epidural analgesia promotes good relief of postoperative pain and, therefore, improves respiratory function, there are still controversies when compared with intravenous or intramuscular analgesia ⁵.

The results of the present study showed a series of patients who received thoracic epidural analgesia after general anesthesia and did not develop postoperative neurologic sequelae. Debates on whether regional block should be done before or after general anesthesia continues to generate controversies, with diverging opinions on the subject ^4,6,7. Several authors consider that performing the epidural block in anesthetized patients provides safety and facilitates the technique, besides increasing patient acceptance of the technique. Others insist that without verbal contact with the patient at the time of the epidural block, the anesthesiologist risks losing signs and symptoms that reflect neurologic compromise. However, there is very few evidence to confirm either side ⁵. There is also a report of a patient who underwent epidural block while awake and still developed spinal cord lesion. This patient did not complain of any symptoms during the blockade ⁸. Other authors also argue that regional blocks under general anesthesia or sedation are, for several reasons including patient safety, increasingly more frequent in the pediatric population ⁹.

In a study similar to ours, the author evaluated a large number of patients undergoing abdominal and thoracic surgeries in whom continuous regional block was performed with the patient under general anesthesia. There were no reports of neurologic complications but, despite this result, he discusses the difficulty to evaluate the relative risks and benefits of this approach ¹⁰. The results of the present study are similar, and one should stress the importance of god judgment and training of the anesthesiology team in each case, always taking into consideration the benefits for the patient at the time of the procedure.

Lesions of the spinal cord might result from trauma caused by the needle or catheter, toxicity of the local anesthetics, epidural hematoma, arterial ischemia, or severe hypotension ⁸. In this study, the puncture was considered traumatic by the anesthesiologist in 39.8% of the patients. The two factors mentioned more often as the cause of trauma include: multiple attempts (48.9%) and bleeding at the site of the puncture (46.7%), factors that, in reality, are interconnected. Although those complications affected a small proportion of patients, they would have been important if the spinal cord had been affected. There are reports that the incidence of complications of regional blocks is greater when multiple attempts are made ^9,10. In the present study, only a single, non-traumatic attempt was made in the two patients who complained of postoperative tingling and numbness.

It has been reported that performing regional blocks in anesthetized patients increases, in theory, the perioperative risk of neurologic complications because they cannot complain of paresthesia at the time of needle or catheter placement or pain in cases of intraneural injection ¹¹. There is also a report of a case of paraplegia in which the authors concluded that if the patient were able to talk during the performance of the regional block the spinal cord lesion could have been avoided ². On the other hand, there is a report of the case of a similar case in an awake patient who did not complain of paresthesia or pain at the time of the spinal block ⁸. Although anesthetized patients cannot complain of pain or paresthesia, other signs can prevent contact with the nerve: reflex muscular movement, increased resistance to the needle, and some resistance to the injection of the local anesthetic ⁴. It has been reported that paresthesia with spinal cord lesion does not occur only during the introduction of the needle, but also during the injection of local anesthetics or secondary to irritation, edema, or hematoma ^12,13. In the present study, the blockade was technically difficult in 48.9% of the cases, since all cases of multiple attempts were so classified. The Anesthesiology team has a considerable experience, with each member having more than 10 years of clinical practice. Despite all this, patients were followed-up closely. Frequent postoperative evaluations contributed to the success of the anesthetic technique and are also extremely important to detect possible neurologic deficits and paresthesia and, consequently, their diagnosis. This conduct is a pattern in our department; it begins in the recovery room and continues for a few days until catheter removal. The patient is evaluated twice a day by a nurse and by an anesthesiologist allowing the early detection of any signs or symptoms of spinal cord damage or ischemia.

It has been described in the literature that post-anesthetic complications after regional blocks ¹⁴ as well as the incidence of neurologic damage, even though possible, are rare and the severity and complexity of the neurologic complications or sequelae vary. Moen et al. ¹⁵ determined that the frequency of severe neurologic complications is approximately 1.6:10,000, while Auroy et al. reported in 1994 ¹¹ an incidence of 3.9:10,000 of severe or extensive neurologic complications and 0.3:10,000 in a study done between 1998 and 1999 ¹⁶. After a survey, another author concluded that radiculopathy or peripheral neuropathy after epidural block has an incidence of 2.19:10,000 (95% CI: 0.88-5.44:10,000). The frequency of permanent neurologic damage after epidural block reported varied from 0 to 7.6:10,000 ¹⁴. There is yet a prospective study on the low prevalence of neurologic complications after regional blocks in pediatric patients in which cases of permanent neurologic sequelae were not observed ¹⁷.

The most important factors to prevent neurologic sequelae include the experience and skillfulness of the anesthesiologist, supervised training, knowledge of preexisting vascular and neurologic disorders, avoidance of repeated attempts when facing technical difficulties, and recognize and treat the complications to avoid permanent lesions ⁴. It is important to reinforce this preventive care because, although rare, neurologic sequelae affect the entire medical team, it is wearying and costly to the patient.

This study has some limitations. It was conceived as a series of cases, with a relatively small study population, but it documented the absence of permanent neurologic complications in patients undergoing epidural thoracic block under general anesthesia, reflecting the daily routine of our department.

It was possible to conclude that there is a low incidence of mild complications, such as bleeding at the site of puncture and perforation of the dura-mater, and that, despite the presence of cases of multiple attempts and technical difficulties, severe or permanent neurologic complications were not observed. When one takes the proper precautions and standard techniques are followed, regional block in a patient under general anesthesia is safe and can be indicated.

REFERENCES

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*

Recebido do Hospital SARAH, Brasília, DF

Publication Dates

• Publication in this collection
  14 Oct 2011
• Date of issue
  Aug 2008

History

• Received
  13 June 2007
• Accepted
  14 Apr 2008