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Effectiveness of bupivacaine administered via femoral nerve catheter for pain control after anterior cruciate ligament repair
ELSEVIER
Effectiveness of Bupivacaine Administered via Femoral Nerve Catheter for Pain Control after Anterior Cruciate Ligament Repair John E. Tetzlaff, MD,* Jack Andrish, MD,? Jerome O’Hara, Jr., MD,* John Dilger, MD,* Helen J. Yoon, MD* Department of General Anesthesiology and Department Cleveland Clinic Foundation, Cleveland, OH.
of Orthopedic
Surgery,
Address correspondence to Dr. Tetzlaff at the Department of General Anesthesiology, E-31, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA.
Study Objective: To evaluate the quality of p ain control achieved with continuous local anesthetic infusion via a femoral nerve catheter, and to determine the optimum concentration of bupivacaine necessary to maintain pain control after full surgical anesthesia is established with 0.5 % bupivacaine. Design: Randomized, prospective study. Setting: Tertiary care teaching center. Patients: 25 ASA physical status I and II patients scheduled to undergo arthroscopicallyaided anterior crmciate ligament (ACL) reconstruction by one surgeon, and who were willing to accept a femoral nerve catheter for postoperative pain control. Interventions: All patients received general anesthesia with propofol/alfentanil (10 ml/l ml} mixture and nitrous oxide/oxygen (60 %/40 o/o) mixture via endotracheal tube. After induction of general anesthesia, a femoral nerve catheter was inserted with the aid of a nerve stimulator, and 20 ml of 0.5% bupivacaine was administered. The surgeq was completed in a standard manner and the patients were randomized into three groups for the concentration of local anesthetic to continue the pain relief into the recovery phase. On awakying, all patients were determined to have a functioning femoral nerve catheter. Group’1 received 0.0625 % (n = 8) bup zvacaine, Group 2 0.125 % (n = 9) bupivacaine, and Group 3 0.25% (n = 8) bupivacaine; all doses were initiated in a blinded manner at 0.12 ml/kg/hr. Patients also received intravenous patient-controlled analgesia with morphine via demand mode only, with a 1.0 mg dose and a 6 minute lock-out interval. Measurements and Main Results: Pain was determined at &fined intervals by visual analog scale (VAS). Data collected included demographics, VAS scores, and total mmphine administered. All patients were pain-j?ee on emergencefrom general anesthesia. No patient required parenteral opioid for pain control while in the postanesthesia care unit. There were no significant difsences in pain scores among groups, and average pain scores (2.5 to 4.0) indicate good pain control throughout the entire hospitalization. There were no complications. Conclusions: Low concentrations of bupivacaine delivered via femoral nerve catheter after an established femoral nerve block can provide excellent postoperative pain control a&r ACL reconstruction.
Received for publication January 20, 1997; revised manuscript accepted for publication May 19, 1997.
Keywords: Analgesia: orthopedics: anterior
*Staff Anesthesiologist torthopedic
Surgeon
Journal of Clinical Anesthesia 9:542-545, 1997 D 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
acute pain; anesthesia, regional: cruciate ligament repair.
femoral
nerve block;
0952~8180/97/$17.00 PI1 s0952-8180(97)00141-4
Femoral nerve catheter for postoperative pain:
Introduction The length of hospitalization for anterior cruciate ligament (ACL) reconstruction has been steadily decreasing with the increasing use of arthroscopic assistance. Because of the recent trend toward decreasing hospitalization and performing the surgery on an outpatient basis, control of postoperative pain becomes a vital issue. Parenteral analgesics can be effective in pain control, but the residual sedation, urinary retention, and respiratory depression can decrease the progress toward discharge and can be associated with complications. These limitations have led to the search for alternatives to conventional “on-demand” parenteral opioids. The use of patient-controlled analgesia (PCA) with opioids delivered intravenously (IV) by pump improves pain control but does not eliminate sedation, respiratory depression, or the other minor complications of parenteral opioids, and it cannot be applied to the outpatient setting. Using regional anesthesia to control postoperative pain has many applications in lower extremity surgery. Conduction block of the femoral nerve provides good control of pain for surgery of the knee region, as well as the anterior and lateral surfaces of the thigh. Even major knee surgery is mainly within the dermatomes of the femoral nerve, except for the posterior capsule. Because the femoral nerve is contained within a fascial sheath, it is possible to inject a bolus of long-acting local anesthetic and achieve proximal spread to the origin of the lumbosacral plexus or insert a catheter into this sheath and provide continuous anesthesia with infusion of any local anesthetic. This action achieves the additional benefit of blockade of the obturator and lateral femoral cutaneous nerves, further improving analgesia for procedures of the thigh and knee. Effective pain control with this approach has been described by intermittent injection for ACL repair,’ and with a catheter for total knee replacement.*a3 The use of regional anesthesia, or any analgesic intervention, prior to surgical incision may improve postoperative pain control. This decrease in acute postoperative pain is referred to as ‘preemptive analgesia.“4 In addition to the actual surgical stimulus, acute pain is accentuated by the peripheral release of mediators of tissue injury that increase the sensitivity of peripheral receptors, alteration in the receptor fields of dorsal column cells, as well as recruitment of normal receptors to nociceptive transmission, both peripherally and centrally. Interventions that interrupt this cycle may decrease the amount of postoperative pain experienced within the first 24 hours. We wanted to determine whether dense femoral nerve block established prior to surgery would provide the preemptive basis for good postoperative pain control after ACL reconstruction, and, if so, the minimum necessary dose of bupivacaine required to maintain this analgesia.
Materials
and Methods
After Cleveland Clinic Foundation Institutional Review Board approval and written, informed consent, 25 ASA physical status I and II patients who were scheduled for
Tetzlasf et al.
ACL reconstruction with general anesthesia, and who were willing to accept a femoral nerve catheter for postoperative pain control, were randomized, by envelope selection from a random number table, into three groups. All patients received general anesthesia with induction of propofol-alfentanil mixture 0.2 ml/kg (10 ml of propofol at a concentration of 10 mg/ml, to which is added 1 ml of alfentanil at a concentration of 500 mcg/ml), intubation of the trachea facilitated by succinylcholine, and maintenance of anesthesia with nitrous oxide, oxygen, and propofol-alfentanil at 0.4 ml/kg/hr. After the anesthesia was established and prior to surgical preparation, a femoral nerve catheter was inserted. A sterile field was created, and the femoral pulse was identified. At a site 1 cm lateral to the pulse at the level of the inguinal ligament, the catheter was inserted using a modified Seldinger technique, facilitated by a nerve stimulator. The catheter was a Burron 19-gauge Teflon catheter over a needle, through which a 22-gauge soft, polyvinyl chloride (PVC) catheter was threaded, prior to removal of the stiffer 19-gauge catheter. The catheter was advanced 8 to 10 cm cephalad within the sheath and secured in place with benzoin and sterile adhesive dressing. Once in place, the catheter was injected with 20 ml of 0.5% bupivacaine in incremental doses, and after the surgical prep was completed, the surgery was begun with a standard technique. One surgeon (JA) performed all surgical procedures. At the conclusion of the surgical procedure, the patient was awakened from general anesthesia and the function of the femoral nerve was evaluated. The patient did not enter the study phase unless there was evidence of complete femoral nerve block. Complete block was defined as inability to move the quadriceps muscle and lack of sensation over the anterior thigh. Once the femoral nerve catheter function was verified, the three groups were determined by random card draw. The anesthesia team and those collecting pain scores were blinded to the solutions being used. The concentrations included Group 1: 0.0625% b u p ivacaine, Group 2: 0.125%, and Group 3: 0.25%; doses were infused at 0.12 ml/kg/hr. Pain scores were collected at 1,4, 8, 12, 16, and 24 hours after surgery in the postanesthesia care unit (PACU) and pain intensity was determined using a visual analog scale (VAS) from 0 to 10, with 10 being the worst pain possible. The patients also received IV PC4 with morphine, via demand mode only, with 1.0 mg dose and 6 minute lockout interval, and they were encouraged to medicate themselves for any pain experienced. PCA pumps were discontinued at 24 hours postoperatively. Total morphine received was recorded. An average hourly rate was calculated. Because of the absence of a control group, without treatment, the PCA morphine usage was collected from ten historically matched patients for comparison of morphine usage. The PCA device was initiated with the same dose, demand mode, and lockout interval, and adjusted when pain control required additional intervention. Data were evaluated with Fisher’s exact and Kruskal Wallis tests. A p-value less than 0.05 was considered significant. J. Clin.
Anesth.,
vol. 9, November
1997
543
Original Contributions Table
1
Demographics (means ? SD) Gender
Age b-4
(male/female)
Group 1 Group 2
28.4 (2.1) 24.5 (3.1)
5/3 z/4
Group 3 Significant differences
27.1 (2.1) none
Height
(cm)
Weight
(kg)
ASA Physical Status
6/2
177.7 (9) 175.2 (6) 174.6 (10)
81.8 (10) 73.0 (9) 77.6 (14)
1.1 1.2 1.1
none
none
none
none
Group 1 = 0.0625% bupivacaine; Group 2 = 0.125% bupivacaine; Group 3 = 0.25% bupivacaine.
Results All three groups were comparable for age, gender, and ASA physical status (Table I). All patients entered into the study had a full femoral nerve block on emergence from general anesthesia. All femoral nerve catheters were functioning properly on arrival to the PACU. No patient required treatment for pain while in the PAW. Pain scores were evaluated at 1, 4, 8, 12, 16, and 24 hours after the end 0f.surger-y and were not significantly different among groups (Table 2). Morphine usage was also not different among groups. The historical control group consisted of ten healthy patients who received ACL repair with general anesthesia and who refused regional anesthesia. Their morphine PCA usage was 6.5 mg/hr over the first 24 hours, which was 50% greater than the average in the three treatment groups. Good pain control (pain score <4) was achieved postoperatively in all groups. There were no complications (infection, sheared catheter, local anesthetic toxicity, nerve injury) associated with the use of the femoral nerve catheters in the cohort of patients used for this study.
Discussion Our results confirm the efficacy of femoral nerve catheter use for postoperative pain control after ACL reconstruction in young patients. Establishment of surgical anesthesia with a lumbar plexus block and general anesthesia prior to incision resulted in excellent pain control with very dilute solutions (0.0625% bupivacaine). Each of the patients in this study had good pain control on emergence from general anesthesia and continued to have analgesia, with no significant difference in morphine use via the PCA device. This finding is not surprising, considering the primary innervation for pain in the knee and upper leg is via the femoral nerve. Thus, femoral nerve blockade should be an effective analgesic intervention. A previous
Table 2
Pain Score and Total Morphine
study has established the efficacy of intermittent femoral nerve block for pain control after knee surgery.’ At the time this study was designed, postoperative pain control via peripheral nerve catheters was being maintained with higher concentrations of bupivacaine. This was the result of a lack of awareness of the equivalent efficacy of very low concentrations of bupivacaine and the luxury of admitting patients to the hospital for the night. The transition to outpatient status for ACL repair, combined with the increasing experience with very low concentrations of bupivacaine (0.03% and less) having analgesic properties with minimum or no motor block, has advanced the use of 0.0625% bupivacaine as a therapeutic choice, as opposed to the control status it was given in this study. Although there is no formal control group (saline) to compare the pain control from the other study groups, comparison to historical control reveals a 50% reduction in PCA morphine usage with a comparable general anesthetic technique. Any preemptive analgesic influence of the general anesthetic drugs would have been equally present in the historical control, and reductions in pain scores and morphine usage would have to be attributed to the pain control achieved with the femoral catheter. That the analgesia was sustained over a 24hour period, even in the lowest concentration group (0.0625%), suggests that the combination of preoperative nerve block and general anesthesia contributes to decreasing the subsequent pain. PCA morphine during the first 24 hours seemed to be required only for that portion of the pain that originates from sciatic innervation (ie, the posterior capsule of the knee). Even this issue would probably not have the same result if this study were repeated in the same operating room now, because refinement in surgical techniques, including the source of the allograft tendon and the means of securing the graft, are much less invasive to
Used (means t SD) Pain Scores
Group
N
Bupivacaine per hour (mg)
0.0625% 0.125% 0.25% p-value
8 9 8
4.2 4.4 4.3
PACU = postanesthesia 544
PACU
1 hour
4 hours
8 hours
12 hours
16 hours
24 hours
2.63 (1.4) 2.67 (1.3) 3.71 (1.1) 0.384
4.57 (2.5) 3.11 (1.1) 5.13 (3.0) 0.210
3.14 (2.7) 3.00 (1.0) 4.50 (2.3) 0.302
2.43 (2.2) 3.11 (1.7) 4.00 (2.0) 0.316
3.00 (2.6) 3.11 (0.8) 4.00 (1.5) 0.448
2.75 (2.9) 2.4 (1.9) 4.5 (1.9) 0.193
1.5 (0.7) 1.0 (1.0) 3.5 (1.4) 0.191
care unit.
J. Clin. Anesth., vol. 9, November
1997
Femoral nerve catheter forpostoperatzvepain:
sciatic dermatomes than was the surgical technique performed in this study. The technical ease of femoral nerve catheter insertion results from the anatomy of the femoral nerve and the lumbosacral plexus. Although they are distinct nerves at the inguinal ligament, the femoral, obturator, and lateral femoral cutaneous nerves have a common site of origin at the lumbosacral plexus, just lateral to the lumbar transverse processes. The modification of the femoral nerve block to achieve lumbosacral plexus block was described by Winnie el al.,5 and is based on the fact that the nerve is located within a fascial sheath, ultimately reaching the lumbosacral plexus. The local anesthetic solution is injected into the sheath with pressure applied distal to the site of injection, and the solution moves proximal within the sheath. The additional blockade of obturator and lateral femoral cutaneous nerves is an added benefit to surgical anesthesia, because separate procedures to block these nerves are not necessary. The existence of a sheath will allow placement of a catheter via Seldinger technique into this sheath, which can be threaded proximally for a considerable distance into the area near the origin of the femoral, lateral femoral cutaneous, and obturator nerves in the iliopsoas compartment. The advantage of proximal placement of the catheter tip is that low concentrations of local anesthetic should be capable of achieving analgesia in all three nerves with low continuous infusion.336 This theory has been confirmed after total knee replacement and various open and arthroscopic procedures.1-3,7*8 Very low concentrations of bupivacaine have established efficacy for pain control in this setting.7zs The timing of the local anesthetic intervention in this study may have made a difference in the quality of postoperative pain control. Interrupting pain signals before the surgical insult and/or the patient’s first perception of excruciating pain may have decreased the amount of postoperative pain perceived and the amount of analgesic required by “preemptive” anaIgesia. 4,‘JThe nociceptive surgical stimulus sends a signal to dorsal horn spinal cord cells, which have a cumulative effect, resulting in an increasing amount of pain perceived. I0 If analgesic intervention precedes the nociceptive stimulus, the summation effect may be less, and the effect of accumulated signals in the dorsal column will be decreased.” Surgical conduction anesthesia would be effective in blocking this transmission and may be the most effective way to achieve the “preemptive analgesic effect.“12,‘3 Once surgical conduction anesthesia is established, it may be easier to maintain with the use of very low concentrations of local anesthetic, thus minimizing systemic effects and the risk of toxicity. It could be speculated that the primary source of pain control was the preemptive effect of the block administered prior to the patient’s first experience of pain, with minimal contribution from the continued infusion. Arguing against this idea would be the assumption that, with fml resolution of the block, there would be first acute, and then hyperacute, pain, which would be prevented by the low concentration infusions and the well known analgesic properties of bupivacaine, even at very low concentrations.14 Theoretically, complete peripheral nerve block
Tetzlaffet
al.
may be the most effective approach to prevention of hypersensitivity, because all nociceptive transmission is completely interrupted.” In conclusion, very low concentrations of bupivacaine maintain analgesia for at least 24 hours via femoral nerve catheter after a surgical block has been established with bupivacaine prior to surgical incision. A preemptive analgesic effect is thought to be responsible.
Addendum The Burron Contiplex kit costs approximately $9.50, the catheter $2.00, and a vial of bupivacaine 0.5% $1.12.
References J, Trojan S, Arhelger S, Krings-Ernst I: Intermittent femoral nerve blockade for anterior cruciate ligament repair. Use of a catheter technique in 208 patients. Acta Anaestlzesiol Belg 1991;42:207-12. Edwards ND, Wright EM: Continuous low-dose 3-n-l nerve blockade for postoperative pain relief after total knee replacement. An&h Analg 1992;75:265-7. Serpell MG, Millar FA, Thomson MF: Comparison of lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 1991;46:275-7. Katz J, Kavanagh BP, Sandler AN, et al: Preemptive analgesia. Clinical evidence of neuroplasticity contributing to postoperative pain. Anesthesiology 1992;77:439-46. Winnie Al?, Ramamurthy S, Durrani 2: The inguinal paravascular technique of lumbar plexus anesthesia: The “3-m-l Block.” Anesth Analg 1973;52:989-96. De Andres J, Bellver J, Barrera L, Febre E, Bolinches R: A comparative study of analgesia after knee surgery with intraartitular bupivacaine, intraarticular morphine, and lumbar plexus block. An&h Analg 1993;77:727-30. Dahl JB, Christiansen CL, Daugaard JJ, Schultz P, Carlsson P: Continuous blockade of the lumbar plexus after knee surgerypostoperative analgesia and bupivacaine plasma concentrations. A controlled clinical trial. Anaesthesia 1988;43:1015-8. Anker-Moller E, Spansberg N, Dahl JB, Christensen EF, Schultz P, Carlsson P: Continuous blockade of the lumbar plexus after knee surgery: a comparison of the plasma concentrations and analgesic effect of bupivacaine 0.250% and 0.125%. Acta Anaesthesiol &and 1990;34:468-72. Ejlersen E, Andersen HB, Eliasen KR, Mogensen TS: A comparison between preincisional and postincisional lidocaine infiltration and postoperative pain. Anesth Analg 1992;74:495-8. Yamamoto T, Shimoyama N, Mizuguchi T: Role of the injury discharge in the development of thermal hyperestbesia after sciatic nerve constriction injury in the rat. Anesthesiolo~ 1993;79:993-1002. Woolf CJ, Chong MS: Preemptive analgesia-treating postoperative pain by preventing the establishment of central sensitiration. Anestlr Analg 1993;77:362-79. Solomon RE, Gebhart GF: Synergistic antinociceptive interactions among drugs administered to the spinal cord. Anesth Analg 1994;78:1164-12. Kehlet H, Dahl JB: The value of “multi-modal” or “balanced analgesia” in postoperative pain treatment. Anesth Analg 1993; 77:1048-56. Bleyaert A, Soetens M, Vaes L, Van Steenberge AL, Van der Donck A: Bupivacaine, 0.125 percent, in obstetric epidural anaigesia: experience in three thousand cases. AnesthesioZoa 1979;51:435-8.
1. Lynch
2.
3.
4.
5.
6.
7.
8.
9.
10.
11
12.
13.
14.
J. Clin. Anesth., vol. 9, November
1997
545
Effectiveness of Bupivacaine Administered via Femoral Nerve Catheter for Pain Control after Anterior Cruciate Ligament Repair John E. Tetzlaff, MD,* Jack Andrish, MD,? Jerome O’Hara, Jr., MD,* John Dilger, MD,* Helen J. Yoon, MD* Department of General Anesthesiology and Department Cleveland Clinic Foundation, Cleveland, OH.
of Orthopedic
Surgery,
Address correspondence to Dr. Tetzlaff at the Department of General Anesthesiology, E-31, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA.
Study Objective: To evaluate the quality of p ain control achieved with continuous local anesthetic infusion via a femoral nerve catheter, and to determine the optimum concentration of bupivacaine necessary to maintain pain control after full surgical anesthesia is established with 0.5 % bupivacaine. Design: Randomized, prospective study. Setting: Tertiary care teaching center. Patients: 25 ASA physical status I and II patients scheduled to undergo arthroscopicallyaided anterior crmciate ligament (ACL) reconstruction by one surgeon, and who were willing to accept a femoral nerve catheter for postoperative pain control. Interventions: All patients received general anesthesia with propofol/alfentanil (10 ml/l ml} mixture and nitrous oxide/oxygen (60 %/40 o/o) mixture via endotracheal tube. After induction of general anesthesia, a femoral nerve catheter was inserted with the aid of a nerve stimulator, and 20 ml of 0.5% bupivacaine was administered. The surgeq was completed in a standard manner and the patients were randomized into three groups for the concentration of local anesthetic to continue the pain relief into the recovery phase. On awakying, all patients were determined to have a functioning femoral nerve catheter. Group’1 received 0.0625 % (n = 8) bup zvacaine, Group 2 0.125 % (n = 9) bupivacaine, and Group 3 0.25% (n = 8) bupivacaine; all doses were initiated in a blinded manner at 0.12 ml/kg/hr. Patients also received intravenous patient-controlled analgesia with morphine via demand mode only, with a 1.0 mg dose and a 6 minute lock-out interval. Measurements and Main Results: Pain was determined at &fined intervals by visual analog scale (VAS). Data collected included demographics, VAS scores, and total mmphine administered. All patients were pain-j?ee on emergencefrom general anesthesia. No patient required parenteral opioid for pain control while in the postanesthesia care unit. There were no significant difsences in pain scores among groups, and average pain scores (2.5 to 4.0) indicate good pain control throughout the entire hospitalization. There were no complications. Conclusions: Low concentrations of bupivacaine delivered via femoral nerve catheter after an established femoral nerve block can provide excellent postoperative pain control a&r ACL reconstruction.
Received for publication January 20, 1997; revised manuscript accepted for publication May 19, 1997.
Keywords: Analgesia: orthopedics: anterior
*Staff Anesthesiologist torthopedic
Surgeon
Journal of Clinical Anesthesia 9:542-545, 1997 D 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
acute pain; anesthesia, regional: cruciate ligament repair.
femoral
nerve block;
0952~8180/97/$17.00 PI1 s0952-8180(97)00141-4
Femoral nerve catheter for postoperative pain:
Introduction The length of hospitalization for anterior cruciate ligament (ACL) reconstruction has been steadily decreasing with the increasing use of arthroscopic assistance. Because of the recent trend toward decreasing hospitalization and performing the surgery on an outpatient basis, control of postoperative pain becomes a vital issue. Parenteral analgesics can be effective in pain control, but the residual sedation, urinary retention, and respiratory depression can decrease the progress toward discharge and can be associated with complications. These limitations have led to the search for alternatives to conventional “on-demand” parenteral opioids. The use of patient-controlled analgesia (PCA) with opioids delivered intravenously (IV) by pump improves pain control but does not eliminate sedation, respiratory depression, or the other minor complications of parenteral opioids, and it cannot be applied to the outpatient setting. Using regional anesthesia to control postoperative pain has many applications in lower extremity surgery. Conduction block of the femoral nerve provides good control of pain for surgery of the knee region, as well as the anterior and lateral surfaces of the thigh. Even major knee surgery is mainly within the dermatomes of the femoral nerve, except for the posterior capsule. Because the femoral nerve is contained within a fascial sheath, it is possible to inject a bolus of long-acting local anesthetic and achieve proximal spread to the origin of the lumbosacral plexus or insert a catheter into this sheath and provide continuous anesthesia with infusion of any local anesthetic. This action achieves the additional benefit of blockade of the obturator and lateral femoral cutaneous nerves, further improving analgesia for procedures of the thigh and knee. Effective pain control with this approach has been described by intermittent injection for ACL repair,’ and with a catheter for total knee replacement.*a3 The use of regional anesthesia, or any analgesic intervention, prior to surgical incision may improve postoperative pain control. This decrease in acute postoperative pain is referred to as ‘preemptive analgesia.“4 In addition to the actual surgical stimulus, acute pain is accentuated by the peripheral release of mediators of tissue injury that increase the sensitivity of peripheral receptors, alteration in the receptor fields of dorsal column cells, as well as recruitment of normal receptors to nociceptive transmission, both peripherally and centrally. Interventions that interrupt this cycle may decrease the amount of postoperative pain experienced within the first 24 hours. We wanted to determine whether dense femoral nerve block established prior to surgery would provide the preemptive basis for good postoperative pain control after ACL reconstruction, and, if so, the minimum necessary dose of bupivacaine required to maintain this analgesia.
Materials
and Methods
After Cleveland Clinic Foundation Institutional Review Board approval and written, informed consent, 25 ASA physical status I and II patients who were scheduled for
Tetzlasf et al.
ACL reconstruction with general anesthesia, and who were willing to accept a femoral nerve catheter for postoperative pain control, were randomized, by envelope selection from a random number table, into three groups. All patients received general anesthesia with induction of propofol-alfentanil mixture 0.2 ml/kg (10 ml of propofol at a concentration of 10 mg/ml, to which is added 1 ml of alfentanil at a concentration of 500 mcg/ml), intubation of the trachea facilitated by succinylcholine, and maintenance of anesthesia with nitrous oxide, oxygen, and propofol-alfentanil at 0.4 ml/kg/hr. After the anesthesia was established and prior to surgical preparation, a femoral nerve catheter was inserted. A sterile field was created, and the femoral pulse was identified. At a site 1 cm lateral to the pulse at the level of the inguinal ligament, the catheter was inserted using a modified Seldinger technique, facilitated by a nerve stimulator. The catheter was a Burron 19-gauge Teflon catheter over a needle, through which a 22-gauge soft, polyvinyl chloride (PVC) catheter was threaded, prior to removal of the stiffer 19-gauge catheter. The catheter was advanced 8 to 10 cm cephalad within the sheath and secured in place with benzoin and sterile adhesive dressing. Once in place, the catheter was injected with 20 ml of 0.5% bupivacaine in incremental doses, and after the surgical prep was completed, the surgery was begun with a standard technique. One surgeon (JA) performed all surgical procedures. At the conclusion of the surgical procedure, the patient was awakened from general anesthesia and the function of the femoral nerve was evaluated. The patient did not enter the study phase unless there was evidence of complete femoral nerve block. Complete block was defined as inability to move the quadriceps muscle and lack of sensation over the anterior thigh. Once the femoral nerve catheter function was verified, the three groups were determined by random card draw. The anesthesia team and those collecting pain scores were blinded to the solutions being used. The concentrations included Group 1: 0.0625% b u p ivacaine, Group 2: 0.125%, and Group 3: 0.25%; doses were infused at 0.12 ml/kg/hr. Pain scores were collected at 1,4, 8, 12, 16, and 24 hours after surgery in the postanesthesia care unit (PACU) and pain intensity was determined using a visual analog scale (VAS) from 0 to 10, with 10 being the worst pain possible. The patients also received IV PC4 with morphine, via demand mode only, with 1.0 mg dose and 6 minute lockout interval, and they were encouraged to medicate themselves for any pain experienced. PCA pumps were discontinued at 24 hours postoperatively. Total morphine received was recorded. An average hourly rate was calculated. Because of the absence of a control group, without treatment, the PCA morphine usage was collected from ten historically matched patients for comparison of morphine usage. The PCA device was initiated with the same dose, demand mode, and lockout interval, and adjusted when pain control required additional intervention. Data were evaluated with Fisher’s exact and Kruskal Wallis tests. A p-value less than 0.05 was considered significant. J. Clin.
Anesth.,
vol. 9, November
1997
543
Original Contributions Table
1
Demographics (means ? SD) Gender
Age b-4
(male/female)
Group 1 Group 2
28.4 (2.1) 24.5 (3.1)
5/3 z/4
Group 3 Significant differences
27.1 (2.1) none
Height
(cm)
Weight
(kg)
ASA Physical Status
6/2
177.7 (9) 175.2 (6) 174.6 (10)
81.8 (10) 73.0 (9) 77.6 (14)
1.1 1.2 1.1
none
none
none
none
Group 1 = 0.0625% bupivacaine; Group 2 = 0.125% bupivacaine; Group 3 = 0.25% bupivacaine.
Results All three groups were comparable for age, gender, and ASA physical status (Table I). All patients entered into the study had a full femoral nerve block on emergence from general anesthesia. All femoral nerve catheters were functioning properly on arrival to the PACU. No patient required treatment for pain while in the PAW. Pain scores were evaluated at 1, 4, 8, 12, 16, and 24 hours after the end 0f.surger-y and were not significantly different among groups (Table 2). Morphine usage was also not different among groups. The historical control group consisted of ten healthy patients who received ACL repair with general anesthesia and who refused regional anesthesia. Their morphine PCA usage was 6.5 mg/hr over the first 24 hours, which was 50% greater than the average in the three treatment groups. Good pain control (pain score <4) was achieved postoperatively in all groups. There were no complications (infection, sheared catheter, local anesthetic toxicity, nerve injury) associated with the use of the femoral nerve catheters in the cohort of patients used for this study.
Discussion Our results confirm the efficacy of femoral nerve catheter use for postoperative pain control after ACL reconstruction in young patients. Establishment of surgical anesthesia with a lumbar plexus block and general anesthesia prior to incision resulted in excellent pain control with very dilute solutions (0.0625% bupivacaine). Each of the patients in this study had good pain control on emergence from general anesthesia and continued to have analgesia, with no significant difference in morphine use via the PCA device. This finding is not surprising, considering the primary innervation for pain in the knee and upper leg is via the femoral nerve. Thus, femoral nerve blockade should be an effective analgesic intervention. A previous
Table 2
Pain Score and Total Morphine
study has established the efficacy of intermittent femoral nerve block for pain control after knee surgery.’ At the time this study was designed, postoperative pain control via peripheral nerve catheters was being maintained with higher concentrations of bupivacaine. This was the result of a lack of awareness of the equivalent efficacy of very low concentrations of bupivacaine and the luxury of admitting patients to the hospital for the night. The transition to outpatient status for ACL repair, combined with the increasing experience with very low concentrations of bupivacaine (0.03% and less) having analgesic properties with minimum or no motor block, has advanced the use of 0.0625% bupivacaine as a therapeutic choice, as opposed to the control status it was given in this study. Although there is no formal control group (saline) to compare the pain control from the other study groups, comparison to historical control reveals a 50% reduction in PCA morphine usage with a comparable general anesthetic technique. Any preemptive analgesic influence of the general anesthetic drugs would have been equally present in the historical control, and reductions in pain scores and morphine usage would have to be attributed to the pain control achieved with the femoral catheter. That the analgesia was sustained over a 24hour period, even in the lowest concentration group (0.0625%), suggests that the combination of preoperative nerve block and general anesthesia contributes to decreasing the subsequent pain. PCA morphine during the first 24 hours seemed to be required only for that portion of the pain that originates from sciatic innervation (ie, the posterior capsule of the knee). Even this issue would probably not have the same result if this study were repeated in the same operating room now, because refinement in surgical techniques, including the source of the allograft tendon and the means of securing the graft, are much less invasive to
Used (means t SD) Pain Scores
Group
N
Bupivacaine per hour (mg)
0.0625% 0.125% 0.25% p-value
8 9 8
4.2 4.4 4.3
PACU = postanesthesia 544
PACU
1 hour
4 hours
8 hours
12 hours
16 hours
24 hours
2.63 (1.4) 2.67 (1.3) 3.71 (1.1) 0.384
4.57 (2.5) 3.11 (1.1) 5.13 (3.0) 0.210
3.14 (2.7) 3.00 (1.0) 4.50 (2.3) 0.302
2.43 (2.2) 3.11 (1.7) 4.00 (2.0) 0.316
3.00 (2.6) 3.11 (0.8) 4.00 (1.5) 0.448
2.75 (2.9) 2.4 (1.9) 4.5 (1.9) 0.193
1.5 (0.7) 1.0 (1.0) 3.5 (1.4) 0.191
care unit.
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1997
Femoral nerve catheter forpostoperatzvepain:
sciatic dermatomes than was the surgical technique performed in this study. The technical ease of femoral nerve catheter insertion results from the anatomy of the femoral nerve and the lumbosacral plexus. Although they are distinct nerves at the inguinal ligament, the femoral, obturator, and lateral femoral cutaneous nerves have a common site of origin at the lumbosacral plexus, just lateral to the lumbar transverse processes. The modification of the femoral nerve block to achieve lumbosacral plexus block was described by Winnie el al.,5 and is based on the fact that the nerve is located within a fascial sheath, ultimately reaching the lumbosacral plexus. The local anesthetic solution is injected into the sheath with pressure applied distal to the site of injection, and the solution moves proximal within the sheath. The additional blockade of obturator and lateral femoral cutaneous nerves is an added benefit to surgical anesthesia, because separate procedures to block these nerves are not necessary. The existence of a sheath will allow placement of a catheter via Seldinger technique into this sheath, which can be threaded proximally for a considerable distance into the area near the origin of the femoral, lateral femoral cutaneous, and obturator nerves in the iliopsoas compartment. The advantage of proximal placement of the catheter tip is that low concentrations of local anesthetic should be capable of achieving analgesia in all three nerves with low continuous infusion.336 This theory has been confirmed after total knee replacement and various open and arthroscopic procedures.1-3,7*8 Very low concentrations of bupivacaine have established efficacy for pain control in this setting.7zs The timing of the local anesthetic intervention in this study may have made a difference in the quality of postoperative pain control. Interrupting pain signals before the surgical insult and/or the patient’s first perception of excruciating pain may have decreased the amount of postoperative pain perceived and the amount of analgesic required by “preemptive” anaIgesia. 4,‘JThe nociceptive surgical stimulus sends a signal to dorsal horn spinal cord cells, which have a cumulative effect, resulting in an increasing amount of pain perceived. I0 If analgesic intervention precedes the nociceptive stimulus, the summation effect may be less, and the effect of accumulated signals in the dorsal column will be decreased.” Surgical conduction anesthesia would be effective in blocking this transmission and may be the most effective way to achieve the “preemptive analgesic effect.“12,‘3 Once surgical conduction anesthesia is established, it may be easier to maintain with the use of very low concentrations of local anesthetic, thus minimizing systemic effects and the risk of toxicity. It could be speculated that the primary source of pain control was the preemptive effect of the block administered prior to the patient’s first experience of pain, with minimal contribution from the continued infusion. Arguing against this idea would be the assumption that, with fml resolution of the block, there would be first acute, and then hyperacute, pain, which would be prevented by the low concentration infusions and the well known analgesic properties of bupivacaine, even at very low concentrations.14 Theoretically, complete peripheral nerve block
Tetzlaffet
al.
may be the most effective approach to prevention of hypersensitivity, because all nociceptive transmission is completely interrupted.” In conclusion, very low concentrations of bupivacaine maintain analgesia for at least 24 hours via femoral nerve catheter after a surgical block has been established with bupivacaine prior to surgical incision. A preemptive analgesic effect is thought to be responsible.
Addendum The Burron Contiplex kit costs approximately $9.50, the catheter $2.00, and a vial of bupivacaine 0.5% $1.12.
References J, Trojan S, Arhelger S, Krings-Ernst I: Intermittent femoral nerve blockade for anterior cruciate ligament repair. Use of a catheter technique in 208 patients. Acta Anaestlzesiol Belg 1991;42:207-12. Edwards ND, Wright EM: Continuous low-dose 3-n-l nerve blockade for postoperative pain relief after total knee replacement. An&h Analg 1992;75:265-7. Serpell MG, Millar FA, Thomson MF: Comparison of lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 1991;46:275-7. Katz J, Kavanagh BP, Sandler AN, et al: Preemptive analgesia. Clinical evidence of neuroplasticity contributing to postoperative pain. Anesthesiology 1992;77:439-46. Winnie Al?, Ramamurthy S, Durrani 2: The inguinal paravascular technique of lumbar plexus anesthesia: The “3-m-l Block.” Anesth Analg 1973;52:989-96. De Andres J, Bellver J, Barrera L, Febre E, Bolinches R: A comparative study of analgesia after knee surgery with intraartitular bupivacaine, intraarticular morphine, and lumbar plexus block. An&h Analg 1993;77:727-30. Dahl JB, Christiansen CL, Daugaard JJ, Schultz P, Carlsson P: Continuous blockade of the lumbar plexus after knee surgerypostoperative analgesia and bupivacaine plasma concentrations. A controlled clinical trial. Anaesthesia 1988;43:1015-8. Anker-Moller E, Spansberg N, Dahl JB, Christensen EF, Schultz P, Carlsson P: Continuous blockade of the lumbar plexus after knee surgery: a comparison of the plasma concentrations and analgesic effect of bupivacaine 0.250% and 0.125%. Acta Anaesthesiol &and 1990;34:468-72. Ejlersen E, Andersen HB, Eliasen KR, Mogensen TS: A comparison between preincisional and postincisional lidocaine infiltration and postoperative pain. Anesth Analg 1992;74:495-8. Yamamoto T, Shimoyama N, Mizuguchi T: Role of the injury discharge in the development of thermal hyperestbesia after sciatic nerve constriction injury in the rat. Anesthesiolo~ 1993;79:993-1002. Woolf CJ, Chong MS: Preemptive analgesia-treating postoperative pain by preventing the establishment of central sensitiration. Anestlr Analg 1993;77:362-79. Solomon RE, Gebhart GF: Synergistic antinociceptive interactions among drugs administered to the spinal cord. Anesth Analg 1994;78:1164-12. Kehlet H, Dahl JB: The value of “multi-modal” or “balanced analgesia” in postoperative pain treatment. Anesth Analg 1993; 77:1048-56. Bleyaert A, Soetens M, Vaes L, Van Steenberge AL, Van der Donck A: Bupivacaine, 0.125 percent, in obstetric epidural anaigesia: experience in three thousand cases. AnesthesioZoa 1979;51:435-8.
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