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Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.56 no.4 Campinas Set./Aug. 2006
Catheters and anesthetic solutions in regional peripheral anesthesia: Quo Vadis? case reports*
Catéteres y soluciones anestésicas en anestesia regional periférica: ¿Quo Vadis? relato de casos
Karl Otto Geier
Anestesiologista do Hospital Municipal de Pronto-socorro de Porto Alegre/RS; Anestesiologista Colaborador da Clindor do Hospital São Lucas da PUC/RS; Certificado na Área de Atuação em Dor pela AMB; Membro Efetivo (Life Member) da Sociedade Européia de Anestesia Regional (ESRA); Mestre em Cirurgia pela UFRGS
OBJECTIVES: The clinical results of regional peripheral blockades are not
always what we hope for. Sometimes the results are short of our intent and sometimes
are exaggerated. To understand and learn those phenomena, radioimaging techniques
are very helpful. The objective of this study is to demonstrate the different
trajectories and distribution of catheters and anesthetics (local anesthetic
with contrast), respectively, used in regional blockades of the upper and lower
CASE REPORTS: Three cases of peripheral regional blockade, in which unexpected clinical effects were solved using contrast X-rays, are presented.
CONCLUSIONS: Contrast X-rays are very useful to verify the position of catheters and solve unexpected anesthetic effects, because they are able to relate the unpredictable dispersion of anesthetics to the signs and symptoms of peripheral blockades.
Key Words: ANESTHETIC TECHNIQUES, Regional: peripheral block; THERAPY AND DIAGNOSIS PROCEDURES: radiology.
Y OBJETIVOS: Los desenlaces clínicos de bloqueos anestésicos
regionales periféricos no siempre son los esperados. A veces resultan
insuficientes, a veces lo valoran demasiado. Para el entendimiento y aprendizaje
de esos fenómenos, los medios de radio imagen son más eficientes.
El objetivo de este estudio fue el de demostrar los diferentes trayectos y distribuciones,
respectivamente, de catéteres y de soluciones anestésicas (anestésico
local con contraste), utilizados en bloqueos regionales de los miembros.
RELATO DE LOS CASOS: Se presentan tres casos de bloqueos regionales periféricos, en que los efectos clínicos inesperados fueron aclarados por imágenes radiográficas contrastadas.
CONCLUSIONES: Con el interés de certificar la posición de catéteres y de aclarar los efectos anestésicos inesperados, los estudios de radio imágenes contrastadas son de gran utilidad, ya que correlacionan dispersiones imprevisibles de soluciones anestésicas, con síntomas y señales de bloqueos periféricos.
Even though the introduction of catheters and the pharmacokinetics of anesthetics are fundamental for a successful anesthetic blockade, anatomical barriers do not always guarantee the adequate positioning of these devices or the predictability of the drug's dispersion. Consequently, the clinical results of the blockades are not always what we expect. Sometimes the results are short of our intent1 and sometimes they are exaggerated2. Radioimaging has become an indispensable complement to the anesthesiologist's arsenal to help us understand and learn whatever possible about those phenomena3.
The objective of this study is to demonstrate the different trajectories and distributions of catheters and anesthetics (local anesthetic with contrast), respectively, used in regional blockades of the limbs.
Male patient, 10 years old, 30 kg, 1.22 m, physical status ASA I, fasting, with a grade II exposed fracture of the left hand and the distal third of the left forearm more than 8 hours old, with a peripheral venous access, was admitted to the operating room for cleaning of the wound. ECG by cardioscope using the DII derivation, non-invasive blood pressure, and pulse oximeter were monitored. General anesthesia was induced with increasing concentrations of sevoflurane up to 7%, and the patient was intubated. During the anesthetic-surgical procedure, sevoflurane was replaced by 1.5% isoflurane. Blockade of the brachial plexus was done through the axilla, using the transarterial technique, with 1.3% lidocaine with epinephrine 1:200,00, corresponding to 10% of his height in centimeters4.
Half of the anesthetic was injected posteriorly to the axillary artery and the remainder anteriorly. After the neurovascular sheath was dilated by the anesthetic without any resistance, a 10 cm long 18G Perifix® (B. Braun) catheter was introduced through a short catheter, with a compatible diameter, placed beforehand as a guide, using the catheter through catheter technique6, to achieve prolonged postoperative analgesia and to be used in possible future surgical interventions. The catheter was secured in place with transparent adhesive material (Loban®-3M). Surgery began approximately five minutes after the brachial blockade was confirmed (peripheral vasodilation and increased temperature) in the entire upper limb. No anesthetic was injected intravenously during the intraoperative period. Since in the postoperative period the patient presented loss of sensibility in the superior thoracic metameres (T1 to T3-T4), an anteroposterior radiographic study with contrast was done with the patient supine with cervical lateralization and slight elevation of the trunk. It identified the catheter close to the thoracic spine and probable distribution of the contrast in the paravertebral and epidural spaces (?). The catheter was kept in situ. The analgesia by demand with the patient in bed with a slight elevation of the head was satisfactorily reached with 8 mL to 12 mL of 0.25% bupivacaine during the six-day hospital stay. Although during the periods between doses of 0.25% bupivacaine the patient moved around the ward on a wheelchair with a nurse's aid, no clinical complaints were reported. His vital signs from the immediate postoperative period until the radiographic diagnosis showed no significant changes in blood pressure, heart rate, and respiratory dynamics. A clinical test to assess the respiratory difficulty was done 30 minutes after the same dose of bupivacaine during 4 to 5 successive deep breaths. The test was asymptomatic, although there was a discrete reduction in the expansion of the left hemithorax that, when compared to the radiographic imaging, showed elevation of the left diaphragm, suggesting paresis of the left phrenic nerve (Figure 1). This was not noticed initially since the priority was the positioning of the catheter and the distribution of the anesthetic solution injected.
Male patient, 42 years old, physical status ASA II, with a grade II exposed fracture of the forearm, monitoring was similar to case 1, and with a peripheral venous access, underwent surgical intervention in the right upper limb under blockade of the brachial plexus through the axilla, by the transarterial and catheter through catheter techniques described previously. After dilation of the neurovascular sheath by the anesthetic solution, a 20 cm long 18G PerifixÒ catheter (B. Braun) was inserted for the postoperative analgesia and complementary surgical procedures. The patient had no complaints regarding the blockade. An AP X-ray was done with 6 mL IopamironÒ contrast (Schering, Brazil) and 14 mL anesthetic solution injected through the catheter. There was distribution of the solution in the mid third supraclavicular area, the catheter's trajectory was linear and its distal end was at the intervertebral C6 foramen, with diffusion of the contrast to the cervical epidural space (Figure 2). The anesthetic did not affect the diaphragm.
Male patient, 28 years old, weighing 73 kg, measuring 1.72 m, physical status ASA I, underwent medial fasciotomy of the left leg due to a compartment syndrome in this region secondary to severe trauma. The anesthetic procedure proposed was the blockade of the internal saphenous nerve at the medial and distal region of the thigh with the placement of a catheter using the transartorial approach and the loss of air resistance technique. Monitoring was the same as for cases 1 and 2, with the intravenous administration of normal saline. The patient was in a supine position and the lower limbs were abducted; the internal epicondyle of the femur and the sartorius muscle were palpated. After the infiltration of the superficial planes with 1 to 2 mL of 1% lidocaine, an 18G venous catheter (NiproÒ, Brazil), 55 mm long, was connected to a 5 mL syringe containing air, puncturing the muscle sartorius at a 30° angle. After loss of resistance, the syringe was disconnected, the needle was secured in place, and the catheter was introduced distally with clockwise and counter clockwise movements. A 20 cm extension was connected to the catheter and secured against the skin as previously described. 7 mL Lopamidol® (Schering, Brazil) was injected (Figure 3). The result was the effective anesthetic blockade with increase in the temperature in the medial aspect of the leg, which is innervated by the internal saphenous nerve.
The neurovascular sheath in the axilla is formed by the pre-vertebral fascia located at the surface of the spine, extending from the skull to the coccyx. In the cervical region, the pre-vertebral fascia stretches out to cover the anterior, medial, and posterior scalenus muscles, attaching laterally in the transverse processes of the vertebrae, and continuing caudally through the dorsal thoracic fascia. As the spinal nerves emerge between the anterior and medial scalenus muscles, they are covered by an extension of the scalenus pre-vertebral fascia that extends to the axilla and involves the brachial plexus and the subclavian artery and vein, being called vascular sheath or neurovascular sheath. It is known that a successful brachial plexus blockade through the axilla depends on the administration of a single dose6 of large volumes of anesthetic solutions in the neurovascular sheath or on catheters inserted proximally7, leading to dispersions that reach the roots of the brachial plexus and the cervicothoracic sympathetic chain. Horner's syndrome is a consequence of these two factors8. The aim of those strategies is to rupture or dissect the septa, which is similar to papyrus, of the neurovascular sheath that divide the plexus components into compartments, exposing them to the anesthetics. In Case 1, the loss of metameric sensitivity in C7-T1 to T3-T4 related by the patient suggests a communication of the neurovascular sheath with the paravertebral and epidural spaces (Figure 1). This was confirmed in adults, by the interscalene approach9, with the catheterization of 12 cm of the neurovascular sheath. One assumes that the widespread introduction of catheters in the neurovascular sheath through the axilla is possible due to the narrowing and fragile structure of its septa, which do not present twists or folds. It is curious that the ipsilateral metameric sensibility changes manifested by the patient, which was in no way pronounced, only happened after the second dose of 0.25% bupivacaine; it was not precise or was absent on pin prick test in the contralateral side. Actually, one must consider that in this age group the information is not always accurate. According to Urmey et al.10, hemidiaphragmatic paresis is common in brachial plexus blockades using the interscalene, but not the axillary, approach.
In Case 2 we observed a clear communication between the neurovascular sheath and the epidural space. Actually, there is potentially an anatomical relation between the neurovascular sheath, the endothoracic fascia, and the paravertebral and epidural spaces. However, the communication among these anatomic structures depends on mechanical factors that favor it. The contrast IopamironÒ 300 (6 mL) and the anesthetic (14 mL) were distributed through the neurovascular sheath to the epidural space through the C6 root. The contrast X-Ray showing a "double line" or "train track" image at the C6-C7 level is typical of anesthetic deposition in the epidural space11. To explain the X-ray image (Figure 2), it is hypothesized that the catheter dissects and penetrates the cone of the C6 root or there is a small anatomic communication between the neurovascular sheath of the brachial plexus and the epidural space. The insertion of the catheter in this patient apparently did not show any resistance in this trajectory. This is another radiographic anatomic result that can elucidate unexpected consequences of regional blockades.
Another virtual behavior that became real with the administration of air, anesthetic, or contrast was documented in Case 3. This confirmed the reliable dualism between radiographic images and anatomy. Anatomical knowledge is an essential part of the set of basic sciences when learning regional anesthesia. In this case, the AP contrast X-ray of the distal portion of the middle third of the thigh showed the course of the internal saphenous nerve between the adductor magnus muscle and the tendons of the sartorius and gracillis muscles, anatomically deeper. Distally, the contrast becomes narrower and proximally it disperses inside the adductor canal of the thigh.
In conclusion, radioimaging studies are not only increasingly helpful when learning the techniques of regional anesthesia as well as in verifying unexpected locations of catheters and the unpredictable distribution of anesthetic solutions, therefore, allowing the correlation between them and the clinical results of anesthetic blockades.
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Dr. Karl Otto Geier
Rua Coronel Camisão, 172
90540-050 Porto Alegre, RS
Submitted for publication
7 de outubro de 2005
Accepted for publication 19 de abril de 2006
* Received from Hospital Municipal de Pronto Socorro de Porto Alegre, RS