Prevalence of diaphragmatic paralysis after brachial plexus blockade by the posterior approach with 0.2% ropivacaine

Abstracts

JUSTIFICATIVA E OBJETIVOS: O bloqueio de plexo braquial pela via interescalênica descrita por Winnie é uma das técnicas mais eficazes para promover analgesia pós-operatória de intervenções cirúrgicas no ombro. Uma de suas conseqüências é a paralisia diafragmática. Esta paralisia pode levar, em pacientes com algum grau de disfunção pulmonar prévia, à insuficiência respiratória. A abordagem do plexo braquial por via posterior tem conquistado espaço. O objetivo deste estudo foi determinar a prevalência de paralisia diafragmática, após o bloqueio de plexo braquial interescalênico pela via posterior com o uso de ropivacaína a 0,2%. MÉTODO: Vinte e dois pacientes submetidos ao bloqueio do plexo braquial interescalênico pela via posterior com ropivacaína a 0,2%, foram avaliados no pós-operatório com o objetivo de identificar sinais radiológicos de elevação da cúpula diafragmática sugestivos de paralisia hemidiafragmática. Em 20 pacientes utilizou-se 40 mL de ropivacaína a 0,2%, nestes foi realizada radiografia de tórax em inspiração. Em dois foram utilizados 20 mL de ropivacaína a 0,2%, com subseqüente avaliação fluoroscópica. RESULTADOS: Não houve complicações relacionadas à realização do bloqueio. Em todos os pacientes, o bloqueio foi efetivo e proporcionou boa analgesia pós-operatória. Foi observada elevação da cúpula diafragmática compatível com paralisia hemidiafragmática em todos os casos estudados. CONCLUSÕES: Nas condições deste estudo observou-se que o bloqueio do plexo braquial pela via posterior é uma técnica que está associada à alta prevalência de paralisia diafragmática, mesmo utilizando-se baixas concentrações de anestésico local.

ANESTÉSICOS, Local; CIRURGIA, Ortopédica; COMPLICAÇÕES; TÉCNICAS ANESTÉSICAS, Regional

SCIENTIFIC ARTICLE

Prevalence of diaphragmatic paralysis after brachial plexus blockade by the posterior approach with 0.2% ropivacaine^*

Prevalencia de parálisis diafragmática después del bloqueo del plexo braquial por la vía posterior con ropivacaína a 0,2%

Marcos Guilherme Cunha Cruvinel, TSA, M.D.^I; Carlos Henrique Viana de Castro, TSA, M.D.^II; Yerkes Pereira Silva, M.D.^III; Roberto Cardoso Bessa Júnior, TSA, M.D.^IV; Flávio de Oliveira França, M.D.^V; Flávio Lago, M.D.^V

^IAnestesiologista do Hospital Lifecenter, Especialista em Clínica Médica, Certificado de Área de Atuação em Dor pela SBA

^IIAnestesiologista do Hospital Lifecenter, Especialista em Clínica Médica e Terapia Intensiva

^IIIAnestesiologista do Hospital Lifecenter, Especialista, Mestre e Doutorando em Pediatria pela UFMG

^IVAnestesiologista do Hospital Lifecenter, Especialista em Terapia Intensiva, Certificado de Área de Atuação em Dor pela SBA

^VOrtopedista do Hospital Lifecenter

^{Correspondence to}

SUMMARY

BACKGROUND AND OBJECTIVES: Brachial plexus blockade by the interscalene approach, described by Winnie, is one of the most effective techniques in promoting postoperative analgesia in surgeries of the shoulder. Diaphragmatic paralysis is one of the consequences of this technique. This paralysis can cause respiratory failure in patients with prior lung dysfunction. Brachial plexus blockade by the posterior approach has become increasingly more popular. The objective of this study was to determine the prevalence of diaphragmatic paralysis after interscalene brachial plexus blockade by the posterior approach with 0.2% ropivacaine.

METHODS: Twenty-two patients who underwent interscalene brachial plexus blockade by the posterior approach with 0.2% ropivacaine were evaluated in the postoperative period to identify radiological signs of elevation of the hemidiaphragm that could suggest hemidiaphragmatic paralysis. Forty mL of 0.2% ropivacaine were used in 20 patients; inspiratory chest X-rays were done in these patients. Twenty mL of 0.2% ropivacaine were used in two patients, with posterior fluoroscopic evaluation.

RESULTS: There were no complications related to the procedure. The anesthesia was effective in every patient, providing good postoperative analgesia. Every patient in this study presented elevation of the diaphragm compatible with hemidiaphragmatic paralysis.

CONCLUSIONS: We observed that brachial plexus blockade by the posterior approach is associated with a high prevalence of diaphragmatic paralysis, even with low concentrations of local anesthetics.

Key Words: ANESTHETICS, Local: ropivacaine; ANESTHETIC TECHNIQUES, Regional: brachial plexus; COMPLICATIONS: diaphragmatic paralysis; SURGERY, Orthopedic.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: El bloqueo de plexo braquial por vía interescalénica descrita por Winnie es una de las técnicas más eficaces para promover la analgesia postoperatoria de intervenciones quirúrgicas en el hombro. Una de sus consecuencias es la parálisis diafragmática. En pacientes con algún grado de disfunción pulmonar previa, esa parálisis puede conllevar a la insuficiencia respiratoria. El abordaje del plexo braquial por vía posterior ha conquistado espacio. El objetivo de este estudio fue el de determinar la prevalencia de parálisis diafragmática, después del bloqueo de plexo braquial interescalénico por vía posterior con el uso de ropivacaína a 0,2%.

MÉTODO: Veinte y dos pacientes sometidos al bloqueo del plexo braquial interescalénico por vía posterior con ropivacaína a 0,2% fueron evaluados en el postoperatorio con el objetivo de identificar señales radiológicas de elevación de la cúpula diafragmática sugestivas de parálisis hemidiafragmática. En 20 pacientes se utilizó 40 mL de ropivacaína a 0,2%, en ellos fue realizada la radiografía de tórax en inspiración. En dos fueron utilizados 20 mL de ropivacaína a 0,2%, con la siguiente evaluación fluoroscópica.

RESULTADOS: No hubo complicaciones relacionadas con la realización del bloqueo. En todos los pacientes, el bloqueo fue efectivo y proporcionó una buena analgesia postoperatoria. Se observó una elevación de la cúpula diafragmática compatible con la parálisis hemidiafragmática en todos los casos estudiados.

CONCLUSIONES: En las condiciones de este estudio se pudo observar que el bloqueo del plexo braquial por vía posterior es una técnica que está asociada a la alta prevalencia de parálisis diafragmática, incluso cuando se utilizan bajas concentraciones de anestésico local.

INTRODUCTION

Surgical procedures in the shoulder present severe postoperative pain ^1,2. An adequate analgesia allows for a faster recovery. Among the main postoperative analgesia techniques for surgeries in the shoulder, and the one that presents the best results, is the brachial plexus blockade by the interscalene approach ^1-19. The brachial plexus can be anesthetized in the interscalene groove using several approaches, such as the anterolateral, described by Winnie, lateral, modified lateral, and posterior. Recently, several authors have shown interest in the posterior approach, which can also be called cervical paravertebral block ^20-23.

Phrenic nerve block, with subsequent diaphragmatic paralysis, is one of the main side effects of the brachial plexus blockade above the clavicle. This has been well documented when is secondary to Winnie's technique ^24-34. Diaphragmatic paralysis may have severe consequences for the patient with previous respiratory deficiency, being a relative contraindication in this group of patients.

The objective of this study was to determine the prevalence of diaphragmatic paralysis after interscalene brachial plexus blockade by the posterior approach using 0.2% ropivacaine.

METHODS

After approval by the Ethics Committee and signing of the informed consent, 22 patients, physical status ASA I and II, who underwent arthroscopic surgeries of the shoulder, participated in this study. Twenty of those patients received 40 mL of 0.2% ropivacaine, while two received 20 mL of 0.2% ropivacaine for the brachial plexus blockade by the posterior approach. Every patient received premedication procedure. They were monitored with an EEG, derivations leads D_II and V5, pulse oxymeter, and noninvasive blood pressure. They did not receive premedication. Patients were placed in lateral decubitus, lying on the opposite shoulder, their head flexed over the neck and placed on a pillow. Oxygen was administered through a nasal catheter (3 L.min^-1). Patients were sedated with IV sufentanil 0.1 µg.kg^-1, so they would remain calm, cooperative, and able to answer verbal commands. If the response were not satisfactory, up to 3 mg of midazolam would be administered. After evaluating the effectiveness of the anesthesia (30 min), patients underwent balanced general anesthesia, and also received 100 mg of ketoprophen and 2 g of dipyrone.

With the patient on lateral decubitus, head flexed over the chest and placed on a pillow, the spinal processes of C₆ and C₇ were marked with a dermographic pen. The point to be punctured was set 3 cm laterally to the space between the spinal processes. After cleaning the skin with alcoholic chlorhexidine, the skin was anesthetized with 1% lidocaine without adrenaline using insulin needle and syringe. Afterwards, the course of the puncture needle was anesthetized using a 25 × 7 mm needle and 5 mL of the local anesthetic. A 100 mm, 22G needle (Stimuplex A100 B. Braun – Melsungen, Germany) connected to a neurostimulator (Stimuplex-DIG, B. – Braun Melsungen, Germany), with an intensity of 1 mA, stimulation time of 0.1 µs, and frequency of 1 Hz, was introduced perpendicularly. When the transverse process was touched, the needle was withdrawn, angled laterally, and reintroduced 2 cm deeper than the depth necessary to touch the transverse process, until a motor response was obtained. Motor responses of the levator scapulae, deltoid, and biceps muscles were acceptable. The intensity of the stimulus was decreased until there was no motor response, which, ideally, should occur with a current smaller than 0.5 mA. After making sure blood was not aspirated, 2 mL of 2% lidocaine with 1:200,000 adrenaline was injected. When motor response was interrupted, but without a rise greater than 20 bmp in the heart rate, the local anesthetic was injected in fractionated volumes of 5 mL. When the patient did not present any longer a motor response with a stimulus greater than 0.8 mA, the needle was repositioned.

The 20 patients who received 40 mL of the local anesthetic had a chest X-ray, in deep inspiration, done in the postanesthetic recovery unit. The two patients who received 20 mL of the anesthetic had a fluoroscopic exam done in surgical room. The X-rays were analyzed comparing the position of the hemidiaphragms, while in the fluoroscopic exam their movement was observed. A cephalad position of the right hemidiaphragm, greater than three cm above the left one, was considered abnormal. On the other hand, any cephalad positioning of the left hemidiaphragm in relation to the right was considered abnormal. In the absence of any lung condition that would justify an elevation, the abnormal elevation of the blockade ipsilateral diaphragm was considered to be secondary to diaphragmatic paralysis. The anesthesia was evaluated by determining thermal sensitivity using cotton with alcohol 30 minutes after the anesthesia was administered. In the postanesthetic recovery unit, the quality of the analgesia was evaluated by the patients complaints and the amount of morphine used.

RESULTS

Table I shows the demographic data. Table II shows the effectiveness of the anesthesia, while table III presents postoperative pain in the postanesthetic recovery unit. Patients did not present any adverse effects, such as intravascular injection, hematoma caused by the puncture, dyspnea, or hypoxemia. Every patient presented elevation of the hemidiaphragm, compatible with diaphragmatic paralysis (Figures 1 and 2).

DISCUSSION

Hemidiaphragmatic paresis or paralysis causes important changes in lung function. Urmey and McDonald showed a mean reduction of 27.2% (varying from 21% to 34%) in forced vital capacity (FVC), and 26.4% (varying from 17% to 37%) in the forced expiratory volume in 1 second (FEV1) after interscalene brachial plexus blockade ³³. The authors attributed this change to the decrease in inspiratory strength secondary to hemidiaphragmatic paresis or paralysis. The impossibility of taking a complete inspiration, causing a reduction in FVC, is directly responsible for a reduction, at least in equal proportion, in the measurements of expired volume. Besides this reduction, since the diaphragm has some role in expiration, there can be additional reduction of the expiratory volumes ³³. Besides decreasing the measurements of lung function, phrenic paresis also changes lung mechanics. There are indications of changes in chest wall mechanics and abdominal wall motion (Figure 3). During hemidiaphragmatic paresis, these changes can lead to atelectasis ³⁴, shown in figure 4.

However, diaphragmatic paresis, or even total paralysis, does not cause respiratory failure in healthy individuals ³³. This is confirmed in the series presented here, since not one single patient presented clinical signs of respiratory dysfunction. However, in patients with some degree of prior respiratory dysfunction, diaphragmatic hemiparesis, and especially paralysis, can cause respiratory failure ³³. Patients who cannot recruit the accessory and intercostal muscles to compensate for the loss of the diaphragm, such as patients with ankylosing spondylits, patients with contralateral hemidiaphragmatic paralysis or chronic obstructive pulmonary disease are good examples of this situation ²⁷.

Therefore, hemidiaphragmatic paresis or paralysis has direct implications in the choice of anesthetic technique. Patients who, due to an existing disease, cannot tolerate a potential reduction of 25% in lung function are not good candidates for anesthetic techniques that may change diaphragmatic function ³³. Patients who underwent cardiac surgery may have chronic hemidiaphragmatic paralysis, more often on the left and, therefore, might not tolerate a contralateral block ³⁵. On the other hand, anesthesia ipsilateral to the paralysis has little or no repercussion.

Surgical procedures of the shoulder are associated with severe postoperative pain, which is hard to control ^1,2. Among the analgesic techniques available, brachial plexus blockade is the one that presents the best results ^1-19, and the interscalene approach is used more often ^1-19. The reason is that the shoulder joint is innervated by the axillary and suprascapular nerves, which arise from the highest roots of the brachial plexus, C₅-C₆³⁶. Besides, the skin of the shoulder is innervated by the supraclavicular nerve, originating from the C₃-C₄ roots (cervical plexus) ³⁶. Consequently, the most effective techniques of brachial plexus blockade for shoulder surgery are those that have a more cranial approach, e.g., interscalene ³⁶. Since the phrenic nerve originates from C₃, C₄, and C₅ roots, it is expected that the most effective techniques to promote analgesia in surgical interventions of the shoulder are also those associated more often with its blockade. Winnie ²⁴ demonstrated that, even with the injection of low volumes of local anesthetics, there is dispersion until the cervical roots. Urmey et al. ²⁷, using Winnie's technique and ultrasound demonstrated that the injection of 34 to 52 mL of mepivacaine had an incidence of diaphragmatic paralysis of 100%. The same authors also demonstrated that 20 mL of local anesthetic causes the same pulmonary changes that 45 mL ²⁵. The study of the dispersion of local anesthetics in the brachial plexus blockade by the interscalene approach using contrast X-ray demonstrated that with volumes varying from 10 to 40 mL the involvement of the lower roots of the brachial plexus (C₃-C₄) is constant ³⁷. Our study demonstrated that the pattern of diaphragmatic alteration produced by the posterior approach of the brachial plexus was similar to the one produced when Winnie's technique was used.

In general, lower concentrations of the local anesthetic are associated with a smaller degree of motor block, especially ropivacaine, which produces differential sensitive and motor block ³⁸. Even though 0.33% ropivacaine presents the same incidence of hemidiaphragmatic paresis as bupivacaine in equivalent concentrations when Winnie's approach was used, it did not produced as much changes in respiratory volumes ³⁹. This study demonstrated that, even with a concentration of 0.2% there was phrenic block, but the functional consequences of this mechanical block were not evaluated. One would assume that, with these low concentrations, pulmonary changes would be less significant and, consequently, the probability of respiratory failure would be smaller. This hypothesis has to be verified.

This study concluded that brachial plexus blockade by the posterior approach is associated with a high prevalence of diaphragmatic paralysis, even when low concentrations of local anesthetics are used. Therefore, when the patient cannot tolerate a reduction in lung function, this technique should not be used.

REFERENCES

Submitted for publication 05 de janeiro de 2006

Accepted for publication 30 de junho de 2006

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*

Received from Departamentos de Anestesiologia e Ortopedia do Hospital Lifecenter, Belo Horizonte, MG

Publication Dates

• Publication in this collection
  22 Sept 2006
• Date of issue
  Oct 2006

History

• Accepted
  30 June 2006
• Received
  05 Jan 2005