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Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.56 no.6 Campinas Nov./Dec. 2006
Postoperative analgesia for orthopedic surgeries of the hip and femur: a comparison between psoas compartment and inguinal paravascular blocks*
Analgesia postoperatoria para procedimientos quirúrgicos ortopédicos de cadera y fémur: comparación entre bloqueo del compartimiento del psoas y bloqueo perivascular inguinal
Luiz Eduardo Imbelloni, TSAI; Lúcia Beato, TSAII; Carolina BeatoII; José Antônio CordeiroIII
do Instituto de Anestesia Regional, Hospital de Base da FAMERP
IIAnestesiologista da Clínica São Bernardo, Rio de Janeiro, RJ
IIICoordenador de Ensino da FAMERP
METHODS: One hundred patients who had a lumbar plexus block through the psoas compartment were compared to 100 patients who had an inguinal paravascular block, using a peripheral nerve stimulator, with 40 mL of 0.25% bupivacaine. The analgesia of the ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves was assessed 4, 8, 12, 16, 20, and 24 hours after the end of the surgical procedure. Pain severity was also evaluated in the same period. The amount of opioids administered in the postoperative period was recorded. A radiological study with non-ionic contrast was done in five patients in each group to evaluate the dispersion of the anesthetic.
RESULTS: The ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves were blocked in 92% of the patients with psoas compartment block versus 62% in those with inguinal paravascular block. Lumbar plexus block reduced the need for opioids, and 42% of the patients who underwent psoas compartment block and 36% of the patients who underwent inguinal paravascular block did not need additional analgesics in the postoperative period. Analgesia lasted for approximately 21 hours in the psoas compartment block and 15 hours in the inguinal paravascular block.
CONCLUSIONS: Psoas compartment block and inguinal paravascular block are excellent techniques for postoperative analgesia in orthopedic surgeries, decreasing the need for opioids. This study showed that the injection in the psoas compartment was easier and more effective in blocking the five nerves of the lumbar plexus.
MÉTODO: Cien pacientes recibieron bloqueo del plexo lumbar a través del compartimiento del psoas y fueron comparados con 100 pacientes que recibieron bloqueo del plexo lumbar vía perivascular inguinal, identificados por el estimulador de nervios periféricos con la inyección de 40 mL bupivacaína a 0,25% sin epinefrina. La analgesia en los nervios ilioinguinal, genitofemoral, cutáneo femoral lateral, femoral y obturatorio fue evaluada a las 4, 8, 12, 16, 20 y 24 horas después del final de la intervención quirúrgica. La intensidad del dolor también fue medida en el mismo período. La cantidad de opioides administrada en el postoperatorio fue anotada. En cinco pacientes de cada grupo, un estudio radiográfico con contraste no iónico se realizó para medir la dispersión de la solución anestésica.
RESULTADOS: Los nervios ilioinguinal, genitofemoral, cutáneo femoral lateral, femoral y obturatorio fueron bloqueados en 92% de los pacientes en el compartimiento del psoas versus 62% en el bloqueo perivascular inguinal. El bloqueo del plexo lumbar redujo la necesidad de opioides y 42% de los pacientes sometidos al bloqueo del compartimiento del psoas y 36% de los pacientes en el bloqueo inguinal no necesitaron analgésico adicional en el postoperatorio. La duración de la analgesia fue de aproximadamente 21 horas con el bloqueo del compartimiento del psoas y 15 horas en el bloqueo perivascular inguinal.
CONCLUSIONES: El bloqueo del compartimiento del psoas y perivascular inguinal es una excelente técnica para la analgesia postoperatoria en intervenciones quirúrgicas ortopédicas reduciendo la necesidad de opioides. Ese estudio mostró que la inyección en el compartimiento del psoas fue más fácil y más efectiva en el bloqueo de los cinco nervios del plexo lumbar.
The anesthesiologist must have keen anatomy knowledge in order to perform any regional block, and the lumbar plexus block is not an exception. Winnie is responsible for describing the two known techniques of lumbar plexus block. The "3 in 1 block", described in 1973 1, while the posterior approach identified by paresthesia was described one year later 2. Recently, several studies reported the use of the blockade trough the inguinal approach 3-6 or through the psoas compartment for postoperative analgesia of orthopedic surgeries of the hip and femur. Computed tomography of the lumbosacral region of four cadavers demonstrated that, at the L5 level, the femoral nerve is located between the lateral femoral cutaneous and the obuturator nerves 7 and, although the former is at the same level as the femoral nerve, the latter might be with it or in its own fascia 7.
The lumbar plexus is formed by the anterior divisions of the first four spinal lumbar nerves, being located in front of the transverse processes of the lumbar vertebrae. It is within the psoas muscle, being formed by the following nerves: iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, and femoral. A study of the motor function of the lumbar plexus nerves in 80 patients demonstrated that the posterior approach (psoas compartment) is more effective than the 3 in 1 block, resulting in a greater number of nerves blocked 8.
The objective of this study was to compare the efficacy of the lumbar plexus block through the posterior approach (psoas compartment) with the inguinal paravascular block, using a neurostimulator, regarding the quality of analgesia in major orthopedic surgeries of the hip and femur, assessing the effectivity of the branches blocked and the dispersion of the anesthetics in the different nerves of the lumbar plexus by means of a radiological exam with contrast.
After approval by the Clinic's Board of Directors for Publication and Divulgation and signing of an informed consent, 200 patients who were to be submitted to orthopedic surgeries of the hip and femur participated in this prospective study. Exclusion criteria included hypovolemia, coagulation disorders, severe cardiopulmonary problems, infection, refusal of the method proposed, and hospital discharge less than 24 hours after the surgery (evaluation period).
Every patient underwent standard anesthesia. Premedication was not administered in the ward. Intravenous administration of Ringer's lactate was initiated after venous cannulation with a 16G or 18G catheter. In the surgical room, patients were monitored with continuous ECG in the CM5 derivation, non-invasive blood pressure, and pulse oxymeter. Vesical catheterization was not done. After sedation with 1 to 1.5 mg.kg-1 fentanyl, spinal anesthesia was done with the patient in the left lateral decubitus with 2 to 3 mL isobaric 0.5% bupivacaine, via the paramedian approach, in the L2-L3 or L3-L4 space, with a 27G Quincke needle. Midazolam, 0.5 to 1 mg, and ketamine, 5 to 15 mg, were administered before the anesthesia in patients with a fractured femur. Sedation during the surgical procedure was done with fractioned doses of midazolam. Dypirone, 30 mg.kg-1, and tenoxicam, 40 mg, were added to the last crystalloid solution administered before the end of the procedure.
At the end of the surgery, patients were separated in two groups. Group 1 = Psoas Compartment: patient in lateral decubitus during the surgery, psoas compartment block was done with the limb that was operated on top. Anatomical references were the iliac crest and a point 5 cm away on a line passing through the spinal processes of L4-L6. It was done with a 100-mm needle (B. Braun Mesungen AG, 21G needle, 0.8x100 mm) connected to a peripheral nerve stimulator (Stimuplex®, B. Braun Melsungen AG) set to discharge a 1 mA square pulsatile current with 1 Hz. The needle was inserted perpendicularly, 7 to 10 cm deep, aiming at obtaining a contraction of the femoral quadriceps. Once the contraction was achieved, the current was decreased to 0.5 mA, maintaining a sustained contraction, and 40 mL 0.25% bupivacaine were injected after making sure there was no blood return. Group 2 = Inguinal paravascular: patient in dorsal decubitus during the surgery; the inguinal paravascular block was done 1 cm lateral to the femoral artery in the inguinal fold. Using a 50-mm needle (B. Braun Meslungen AG, 22G needle, 0.70x50 mm) connected to a peripheral nerve stimulator (Stimuplex®, B. Braun Melsungen AG) set to discharge a 1 mA square pulsatile current with 1 Hz. It was inserted perpendicularly, 2 to 5 cm deep, aiming at obtaining a contraction of the femoral quadriceps muscle. Once the contraction was achieved, the current was decreased to 0.5 mA, maintaining a sustained contraction, and 40 mL 0.25% bupivacaine were injected, after making sure there was no blood return.
Analgesia was evaluated by a nurse, trained previously for this task, with the pin pick and sensitivity to cold tests to determine the extension of the sensitive blockade in the areas supplied by the ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, and femoral nerves 4, 8, 12, 16, 20, and 24 hours after the administration of the anesthetic. Pain was assessed according to the following scale: 0 = absence of pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain. The patient was transferred to the regular ward and, if he/she complained of pain, a solution containing 30 mg meperidine and 300 mg dypirone was administered intravenously. The total number of doses of the analgesic solution during the first 24 hours was recorded, as well as any cardiovascular changes. The presence of analgesia of the feet was also evaluated to determine whether there was dissemination to the sciatic nerve. The patient was followed-up for 48 hours to determine whether there were any complications at the site of the block. Five patients in each group underwent contrast X-ray with 1 mL of iohexol with 300 mg.mL-1, to determine needle placement, followed by 20 mL, to study the dispersion of the local anesthetic, immediately and 30 minutes later.
Age, weight, height, duration of the surgical procedure, and duration of the analgesia were evaluated by the test t Student for two samples; the number of doses was evaluated by the Mood test for medians; pain severity, considered an ordinal quantitative parameter, was evaluated by the Fisher Exact test. Percentages were compared by the Chi-square test or Fisher Exact test, when appropriate. A p = 0.05 was considered significant.
Table III shows the level of pain in the first 24 hours. Severe pain (grade 3) was not observed during the study. The successful blockade of the five nerves (complete sensitive block of the ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, and femoral nerves) was achieved in 92% of the patients in Group 1 and in 68% of the patients in Group 2. In the first 12 hours of evaluation, 76 patients in Group 1 showed analgesia of the five nerves versus only 2 patients in Group 2, which was statistically significant (p < 0.001) (Table IV). At the end of the evaluation (24 h), 11 patients in Group 1 had a blockade of the five nerves versus zero patients in Group 2. Table IV shows the number of patients that presented blockade in the different nerves in 24 hours.
It was necessary to remove a bone graft from the iliac crest in seven patients in each group. The duration of the analgesia in Group 1 varied from 18 to 24 hours, with a mean of 21.3 ± 2.4, and in Group 2 varied from 6 to 13 hours, with a mean of 8.9 ± 2.4 hours (p < 0.001).
The mean duration of the surgeries was 2.11 ± 0.73 hours in Group 1 and 2.13 ± 0.75 hours in Group 2. In every patient the first evaluation (4 hours) was done without residual blockade from the epidural block. The mean duration of the analgesia was 20.6 ± 5.7 hours in Group 1 and 15.8 ± 6.4 hours in Group 2, and this difference was statistically significant (p < 0.001). Forty-two patients in Group 1 and 36 patients in Group 2 did not need analgesics in the first 24 hours. Table V shows the number of patients in both groups who received 1, 2, or 3 doses of analgesics; the difference between the groups was not statistically significant (p = 0.38). There were no cases of bradycardia or hypotension in the first 24 hours.
There were no complications at the puncture site during the evaluation period. There were no cases of intravascular injection or accidental puncture of the subarachnoid space. We did not observe any cases of hypotension or unilateral or bilateral epidural block. There were no complaints of analgesia of the feet. There were no neurological complications. Vesical catheterization was not necessary. One patient had loss of sensitivity in the thigh that lasted 36 hours. There were no complaints of paresthesia after 48 hours. There was cephalad and caudal dispersion of the anesthetic immediately after the injection in the psoas compartment (Figure 1) and after 1 minute (Figure 2), and the same occurred with the injection in the inguinal region.
Lumbar plexus block in the psoas compartment or in the inguinal region with the aid of a peripheral nerve stimulator is easy to perform and has few side effects. This technique blocked the five nerves in 92% of the patients in the psoas compartment approach and in only 68% in the inguinal region approach. The resulting analgesia was effective to the point that 42% of the patients in the psoas compartment group and 36% in the inguinal region group did not need extra analgesics in the first 24 hours. These results are different than those obtained for the postoperative analgesia, in children, with the psoas compartment block (more than 90%) compared to the "3 in 1" block (20%) 9.
The upper portion of the leg is innervated by the lumbosacral plexus: the lateral femoral cutaneous nerve (L2-L3), laterally; the femoral nerve (L2-L4), anteriorly; the obturator (L2-L4) and genitofemoral nerves (L1-L2), medially; and by the sciatic nerve (L4-S3), posteriorly. The ilioinguinal nerve (L1) innervates mainly the iliac crest and its blockade is important when a graft is removed, what was done in seven patients in each group. The duration of the analgesia varied from 18 to 24 hours, with a mean of 20 hours, in Group 1 versus 6 to 13 hours, with a mean of 8 hours, in Group 2, suggesting that the posterior approach is better when a graft is to be removed from the iliac crest.
Although the lumbosacral plexus may occasionally be blocked through the posterior approach, sciatic nerve block is necessary for complete analgesia of the lower limb. It was demonstrated in a postoperative evaluation, in children, that the posterior approach of the lumbar plexus using the Winnie technique could be effective blocking both the lumbar and the sacral plexus 10. In this study, the posterior approach did not promote analgesia of the region innervated by the sciatic nerve (determined by evaluating the foot). The block performed in L3 or L4 could result in a bilateral blockade, may it be epidural, subarachnoid, or by dispersion of the local anesthetic that is close to the paravertebral space. This happens frequently, depending on the technique used. Dalens 9, using the technique described by Chayen 10, reported an incidence of 88% of bilateral blockade, while with the Winnie technique 2 there were no reports of bilateral blockade. In this study, using the peripheral nerve stimulator there were no cases of bilateral blockade using the posterior approach.
The femoral access to the lumbar plexus, according to most authors, is effective in blocking the femoral and lateral femoral cutaneous nerves, but its blockade of the obturator nerve is questionable. Some authors believe that the inguinal paravascular approach blocks more than the three nerves and should be called "4 in 1" or "3.5 in 1" 11,12, while other authors, based on the motor assessment, defend a "2 in 1" block 4. Parkinson et al. 8, using the posterior and the anterior approach, and Geier 4, using the anterior approach, evaluated the ability to produce motor blockade. Parkinson's results differed from the results of other authors. Geier found a complete 3 in 1 block in 20% of the patients. We did not find any studies comparing the posterior approach with the inguinal approach regarding postoperative analgesia in the five components of the lumbar plexus. This study demonstrated that in order to achieve a blockade of the five components of the lumbar plexus, the posterior approach is better than the inguinal approach. It also showed that when it is necessary to remove bone graft form the iliac crest, the posterior approach should be used, because pain relief was better in the seven patients in Group 1.
The recommended dose of bupivacaine is 2 mg.kg-1, but one might use up to 3 mg.kg-1 of 0.5% bupivacaine, in patients undergoing sciatic nerve or "3 in 1" block 13. Adding epinephrine to 0.5% bupivacaine did not influence the plasma concentration of the local anesthetic, the time necessary to achieve maximum plasma concentration, or the duration of the analgesia 13. In this study we used 0.25% bupivacaine and doses below those recommended and we did not observe any complications caused by its absorption. The number of patients that needed analgesics in the first 12 hours was very low, since the mean duration of the analgesia was 18 hours, similar to the analgesia obtained with 0.5% bupivacaine, 17 hours 13. Using the lower concentration of the anesthetic, there was a difference in the duration of the analgesia that lasted longer with the psoas compartment approach (21 hours) compared to the inguinal approach (16 hours). This was probably related to the bone graft removed in both groups. Forty two patients (42%) did not need analgesics in the first 24 hours in the psoas approach versus 36 patients (36%) in the inguinal approach. The doses of the analgesics in the postoperative period were significantly higher in the anterior approach when compared to the posterior, and this can be explained by the removal of the bone graft.
The posterior approach was effective in blocking the five nerves of the lower limb derived from the lumbar plexus (ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, and femoral), but it did not block the nerves from the sacral plexus (common fibular and tibial nerves). The anterior approach was less effective in blocking the five nerves and it did block the sacral plexus. The knowledge of the extension of the blockades of the different nerves of the lumbar plexus allows the anesthesiologist to choose the best access to provide a better analgesia in surgeries of the hip and femur.
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Dr. Luiz Eduardo Imbelloni
Av. Epitácio Pessoa, 2.356/203 Lagoa
22.471-000 Rio de Janeiro, RJ
Submitted for publication
07 de fevereiro de 2006
Accepted for publication 29 de agosto de 2006
* Received from Instituto de Anestesia Regional do Hospital de Base da Faculdade de Medicina de São José do Rio Preto (FAMERP), São José do Rio Preto, SP