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Revista Brasileira de Anestesiologia

Print version ISSN 0034-7094On-line version ISSN 1806-907X

Rev. Bras. Anestesiol. vol.52 no.2 Campinas Mar./Apr. 2002 



Patient controlled analgesia with fentanyl or sufentanil in the postoperative period of knee ligament reconstruction: comparative study*


Analgesia controlada por el paciente con fentanil o sufentanil en el pós-operatorio de reconstrucción de ligamentos de la rodilla: estudio comparativo



Marcelo Negrão Lutti, TSA, M.D.I; João Lopes Vieira, TSA, M.D.II; Dante Roberto Eickhoff, M.D.III; Daniel de Carli, M.D.III; Marcelo Antônio de Carvalho, M.D.III

IInstrutor do CET/SBA
IICo-responsável pelo CET/SBA





BACKGROUND AND OBJECTIVES: Epidural opioids, associated or not to local anesthetics, have been used for postoperative analgesia in continuous infusion and/or patient controlled boluses. The aim of this study was to compare postoperative analgesia provided by epidural fentanyl or sufentanil, in bolus or continuous infusion, in patients submitted to knee ligament reconstruction.
METHODS: Seventy ASA I - II patients, aged 16 to 47 years, were randomly distributed in two groups. All patients were submitted to epidural anesthesia with 0.5% bupivacaine (100 mg) with epinephrine 1:200,000 associated to fentanyl (100 mg). At the end of the procedure, patients received epidural fentanyl (Group F) or sufentanil (Group S) in continuous infusion plus patient controlled boluses. Group F infusion solution was made of saline (85 ml), 500 µg fentanyl (10 ml) and 0.5% bupivacaine (5 ml). Group S solution was made of saline (92 ml), 150 µg sufentanil (3 ml) and 0.5% plain bupivacaine (5 ml). Infusion pump´s flow was initially programmed to 5 ml.h-1, with 2 ml patient controlled bolus doses every 15 minutes at most, for both groups. The following parameters were compared: pain, number of patient controlled boluses, opioid consumption, motor block, sedation and side-effects.
RESULTS: There have been no statistically significant difference in analgesia quality between groups, being in most cases rated good (AVS 0 to 2). There has been a significant difference in the number of patient controlled boluses, with Group F needing more boluses than Group S. There has been no difference in total infused solution volume and total infusion time. There has been no motor block after beginning of patient-controlled analgesia. Vomiting and urine retention incidences were higher in Group S and there have been no significant differences in sedation and pruritus between groups.
CONCLUSIONS: Epidural fentanyl or sufentanil in continuous epidural infusion and patient-controlled boluses in the doses used in this study have induced excellent postoperative analgesia. However, sufentanil caused more severe side effects than fentanyl.

Key words: ANALGESIA, Postoperative: patient controlled analgesia; ANALGESICS, Opioids: fentanyl, sufentanil; ANESTHETIC TECHNIQUES, Regional: continuous epidural


JUSTIFICATIVA Y OBJETIVOS: Los opioides han sido utilizados por vía peridural asociados o no a anestésicos locales para analgesia pós-operatoria de forma continua y/o en bolus controlado por el paciente. El objetivo de este estudio fue comparar la analgesia pós-operatoria entre el fentanil y sufentanil en infusión continua y en bolus por vía peridural, en pacientes sometidos a la reconstrucción de ligamento de la rodilla.
MÉTODO: Participaron del estudio 70 pacientes con edad entre 16 y 47 anos, estado físico ASA I y II, divididos aleatoriamente en dos grupos: Grupo F (fentanil) y Grupo S (sufentanil). Todos los pacientes fueron sometidos a anestesia peridural con bupivacaína a 0,5% (100 mg) con epinefrina 1:200.000 asociada a fentanil (100 mg). Al final de la cirugía, los pacientes recibieron fentanil (Grupo F) o sufentanil (Grupo S) por vía peridural en régimen de infusión continua más bolus liberados por el paciente. En el Grupo F fue utilizada solución fisiológica (85 ml) conteniendo fentanil 500 µg (10 ml) y bupivacaína (5 ml a 0,5%). En el Grupo S fue utilizada solución fisiológica (92 ml) conteniendo sufentanil 150 µg (3 ml) y bupivacaína (5 ml a 0,5%). Para los dos grupos la bomba de infusión fue programada inicialmente en 5 ml.h-1, con dosis de 2 ml en bolus liberado por el paciente en un intervalo de 15 minutos. Fueron comparados los siguientes parámetros: dolor, número de bolus accionados, consumo de opioides, bloqueo motor, sedación y efectos colaterales.
RESULTADOS: No hubo diferencia significativa entre los grupos cuanto la calidad de la analgesia, siendo la mayoría de buena calidad (EAV 0 a 2). Hubo diferencia significativa cuanto al número de bolus liberados. En el Grupo F  fue mayor que el Grupo S. No hubo diferencia cuanto al volumen total de la solución infundida y tiempo de infusión total. No hubo bloqueo motor después de la institución de la analgesia controlada por el paciente (ACP). La incidencia de vómitos y retención urinaria fue mayor en el Grupo S y cuanto a la sedación y al prurito, no hubo diferencia entre los grupos.
CONCLUSIONES: El fentanil y el sufentanil continuos y en bolus accionados por el paciente, por vía peridural, en las dosis utilizadas en este estudio, presentaron excelente analgesia pós-operatoria. No obstante, el sufentanil presentó efectos colaterales mas intensos que el fentanil.




The development of new postoperative analgesic techniques has allowed for anesthetic planning aiming at a pain-free postoperative period with patients early recovery and discharge 1. So, depending on the surgery, the use of long lasting anesthetics associated or not to opioids in peripheral, continuous epidural and spinal blocks, makes possible to improve postoperative analgesia 2-6.

Opioids associated to long-lasting local anesthetics improve epidural and spinal block quality, allowing for the maintenance of a more superficial anesthesia with less drug and inhalational anesthetics consumption, when combined epidural/general anesthesia is used 5-7.

Epidural fentanyl or morphine associated to local anesthetics have been used in single doses or through catheter’s, in intermittent boluses or continuous infusion by programmed infusion pump’s 8.

These pumps allow analgesia to be patient-controlled, not only bringing more comfort and safety but also creating a higher interactivity of patients with their recovery 8-14. There are pumps designed for intravenous infusion of drugs too, though its use is related to higher opioid consumption 5,6.

Side-effects of opioids infusion techniques are sedation, nausea, vomiting, pruritus and urine retention. Another more severe effect is respiratory depression, usually related to morphine analgesia 5,6,21-24.

Knee anterior cruciate ligament reconstruction with arthroscopic patellar tendon transposition is very painful, especially during the first postoperative day. It increases time for hospital discharge and makes difficult early physiotherapy. A recent study 8 has shown the efficacy of fentanyl or morphine associated to low bupivacaine concentrations in continuous infusion to control postoperative pain in a patient-controlled analgesia system (PCA), which allowed early physiotherapy and patients discharge in 24 hours 8. It has also shown a low incidence of side-effects (sedation, nausea, vomiting and pruritus), specially with fentanyl 8. Moreover, continuous infusion and bolus doses were lower than those administered by other authors 8,15-17.

Sufentanil has also been used in PCA with good results in controlling postoperative pain 18,19.

The aim of this study was to compare fentanyl and sufentanil in patient-controlled epidural analgesia with continuous infusion pump, in patients submitted to knee ligament reconstruction. Besides analgesia, other parameters were also evaluated, like opioid consumption and side-effects, such as sedation, pruritus, urine retention and respiratory depression.



After the Centro Médico de Campinas Ethics Committee approval, 70 patients aged 16 to 47 years, physical status ASA I and II, scheduled to undergo knee ligament reconstruction under epidural anesthesia gave their written informed consent to be included in this study.

All patients were premedicated with oral diazepam (10 mg) 60 minutes before surgery.

Venous puncture was performed in the operating room with an 18 or 16G catheter in an upper limb vein, followed by lactated Ringer’s infusion (500 ml). Monitoring included a cardioscope in DII lead, pulse oximetry and non-invasive automatic blood pressure. Before epidural block, patients received mild intravenous sedation with titrated fractions of midazolam (5 mg) and fentanyl (50 µg) in sufficient doses to keep patients relaxed and cooperative. Then, lumbar epidural puncture was performed with a 16G Tuohy needle. After a negative test dose with 2% lidocaine with epinephrine 1:200,000 (60 mg), 0.5% bupivacaine (100 mg) with epinephrine 1:200,000 plus 100 µg fentanyl were injected. Next, a catheter was inserted in the epidural space in the cephalad direction aiming at postoperative patient controlled analgesia with an infusion pump, which was connected to the epidural catheter after surgery.

In the immediate postoperative period, patients were randomly distributed in two groups: Group F (n = 35) and Group S (n = 35), which received solutions and schedules shown in table I and table II.

If more or less analgesia was required, infusion rate was up or down adjusted in 20% of the initial dose. In the presence of undesirable side effects, doses would also be reset to less 20% of previous ones. In the persistence of undesirable effects, they would be treated as follows: for severe pruritus - 1) muscular diphenydramine (50 mg); 2) 2 ml naloxone + 8 ml distilled water intravenously titrated. Respiratory depression with respiratory rate equal to or less than 9 ipm would be treated with the same kind of naloxone administration. Intravenous metoclopramide (10 mg) would be administered for nausea and vomiting.

Sedation was evaluated through the following parameters: 0 = no sedation; 1 = mild sedation (occasionally sleepy, awakens when called); 2 = moderate sedation (often sleepy, awakens when called); 3 = deep sedation (sleepy, awakens with painful stimulus). Bromage’s scale was used to evaluate motor block: 0 = no motor block; 1 = unable to raise stretched legs; 2 = unable to bend knees; 3 = unable to bend feet.

Analgesia was evaluated through the 0 to 10 Analog Visual Scale (AVS) where 0 means no pain and 10 the worst possible pain. Analgesia was evaluated in two periods: 12 hours after surgery and then until patients discharge. The following parameters were measured: total infused solution volume, total opioid dose, infusion time, number of requested boluses and number of released boluses. Side-effects, such as nausea, vomiting, pruritus, urine retention, sedation and respiratory depression were recorded.

Student’s t test for Two Independent Groups was used for statistical analysis of age, height, weight, nausea, vomiting, total epidural infusion volume, number of requested boluses, number of released boluses and infusion time. Mann-Whitney non-parametric test was used for statistical analysis of physical status (ASA), gender, pruritus, sedation, urine retention and pain Analog Visual Scale (AVS) scores. Significance level was established to 5% (p < 0.05).



There were no statistically significant differences in age, weight, height, gender and physical status between groups (Table III). There was no statistical evidence that treatments were different regarding pain intensity rated by the Analog Visual Scale (AVS) during the first 12 postoperative hours and, in the subsequent hours until patients’ discharge. The same is true for the number of released boluses. However, a significant difference was seen in the number of bolus requests: Group F (fentanyl) has requested more boluses (Table IV).

Considering the scores 0 (no pain), 1 and 2 (mild-tolerable pain), there has been a good response to postoperative pain treatment in both groups (Table V and Table VI). There was no case of unbearable pain in any group, and only 2 cases in Group F where pain reached score 8. Urine retention was seen in 5 sufentanil group patients, demanding a vesical catheter placement (Table VII).

Sedation was scored zero for most patients (34 patients in each group) with no significant difference. Two mild sedation cases were recorded (1 in each group) (Table VIII). Pruritus had a similar behavior, requiring no treatment (Table IX).

Although low, the incidence of vomiting was higher in sufentanil group (Table X).

No motor block was observed during infusions after lower limbs movement recovery in the PACU.



Knee ligament reconstruction is highly prevalent among young males and its postoperative period is very painful, especially during the first 24 hours when the operated knee is initially moved aiming early physiotherapy.

According to some authors 1,8,25-28, epidural anesthesia with long-lasting local anesthetics associated to opioids and an epidural catheter for postoperative analgesia is the best choice for such procedure. We have used 0.5% bupivacaine with epinephrine 1:200,000 associated to fentanyl (100 µg) to promote intraoperative analgesia. This fentanyl dose used in the beginning of epidural anesthesia has not interfered with the results of postoperative analgesia due to its short-duration effect.

PCA pump was installed before anesthetic blockade recovery with patients still in the operating room. Patients’ discharge from PACU, however, was only authorized after total motor block recovery.

Fentanyl is a lipophilic drug with higher analgesic potency than morphine, which is hydrophilic. Some authors, however, have shown an analgesic similarity between both drugs 2,6,8, but morphine showing more side-effects (nausea, vomiting and sedation). In our study, the comparison between epidural fentanyl and sufentanil associated to low concentration bupivacaine in PCA has shown efficient postoperative analgesia, with a minimum of side-effects statistical analysis of Analog Visual Scale results has shown no difference between groups in the treatment of postoperative pain until patients’ discharge. However, two fentanyl group patients presented with AVS score 8 during movement, demanding a 20% increase in infusion rate. The number of released boluses, total volume and infusion time presented no significant differences, showing a similar analgesic efficacy of fentanyl and sufentanil in treating postoperative pain.

With low bupivacaine concentration (0.025%), we had no motor block case, showing that higher bupivacaine concentrations are needed for that. Patients were kept totally awaken in the postoperative period with only 1 patient in each group with score 1 in the sedation scale. No respiratory depression was seen, showing that patients were protected against this fearful side-effect with those doses of both opioids. Few patients had nausea or vomiting in both groups (GF = 3 and GS = 5), with statistically significant difference favoring fentanyl. Just one patient in each group referred mild pruritus. Urine retention was seen in 5 sufentanil group patients demanding a vesical catheter. No case was observed in fentanyl group.

Analgesia quality and the low incidence of complications have shown that both fentanyl and sufentanil are better than morphine for PCA postoperative analgesia in patients submitted to knee ligament reconstruction. This is ratified by a different study comparing morphine and fentanyl with the same method 8.

The conclusion was that, in the conditions of this study, postoperative analgesia with opioids continuous epidural infusion associated to patient controlled boluses through a PCA pump is an excellent method for treating pain in patients submitted to knee ligament reconstruction, especially when low concentration of long lasting local anesthetics are associated to opioids such as fentanyl and sufentanil. Both fentanyl and sufentanil were effective in promoting analgesia. However, sufentanil had slightly more intense side-effects as compared to fentanyl.



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Correspondence to
Dr. Marcelo Negrão Lutti
R. Dr. José Ferreira de Camargo 1280 - Jardim Planalto
13092-001 Campinas, SP

Submitted for publication June 26, 2001
Accepted for publication October 10, 2001



* Received from CET/SBA do Instituto Penido Burnier, Campinas, SP

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