670
ANESTH ANALG 1990:71:670-4
Lidocaine Local Anesthesia for Arthroscopic Knee Surgery Mark R. Dahl, MD, Joseph F. Dasta, Thomas D. McSweeney, BS
MS,
Wilhelm Zuelzer,
MD,
and
-
DAHL MR, DASTA JF, ZUELZER W, McSWEENEY TD. Lidocaine local anesthesia for arthroscopic knee surgery. Anesth Analg 1990;71:670-4.
Forty-five patients were evaluated during knee arthroscopy performed using local anesthesia produced by lidocaine with epinephrine to determine the dose-response relationship for operative analgesia. Serum lidocaine concentrations were also measured. Patients were randomized prospectively to receive 20 mL of 0.5%, 1.070, or 1.5% lidocaine with epinephrine intraarticularly. lntraoperative discomfort was measured by verbal response on an 11-point linear pain scale. Pain scores were significantly higher in patients receiving 0.5% lidocaine during thefirst 45 min of surgery (P = 0.03). After 45 min, pain scores continued to be higher in the 0.5% lidocaine group than in the 1 .O% or 1.5% groups, but the differences were not statistically
Periarticular infiltration and intraarticular (IA) instillation of local anesthetics is a suitable method of anesthesia for arthroscopic knee surgery and may be an alternative to regional or general anesthesia (1-3). Several methods for producing IA anesthesia have been described for knee arthroscopy that differ in volume, concentration, and type of local anesthetic, use of adjuvant epinephrine, and method of local anesthetic instillation (1-10). Although all regimens have a high success rate, dose requirements have been reported only for bupivacaine (5). Lidocaine has been described for use alone or in combination with bupivacaine, but dose requirements have not been reported (2,643). The purpose of this study was to determine the dose-response relationship for lidocaine and to measure serum lidocaine concentra-
This work was performed at the Ohio State University Hospitals in Columbus, Ohio. Presented at the annual meeting of the American Society of Anesthesiologists, New Orleans, Louisiana, October 1989. Received from the Departments of Anesthesiology and Surgery and the College of Pharmacy, The Ohio State University, Columbus, Ohio. Accepted for publication August 3, 1990. Address correspondence to Dr. Dahl, Mount Carmel Medical Center, 793 West State Street, Columbus, OH 43215. 01990 by the International Anesthesia Research Society
significant. Ninety-four percent of patients in the 1.5% lidocaine group were willing to repeat this anesthetic technique for surgery compared with 83% of those in the 1.0% lidocaine group and 75% of those in the 0.5% lidocaine group (P > 0.05). The duration of postoperative analgesia was similar in all groups. Serum lidocaine concentrations before and 15, 30, 60, and 120 min after instillation of lidocaine were highest in the 1.5% lidocaine group with a peak concentration of 278 nglmL. No patient had symptoms of lidocaine toxicity. W e recommend that lidocaine concentrations of 1 .O% or 1.5% be used when 20 mL is instilled intraarticularly for knee arthroscopy based on patient comfort and absence of lidocaine toxicity.
Key Words: ANESTHESIA, ORTHOPEDIC-knee arthroscopy with lidocaine. ANESTHETIC TECHNIQUES, LOCAL-knee arthroscopy.
tions after extraarticular and IA administration in patients undergoing knee arthroscopy.
Methods Forty-five outpatients (ASA physical status I or 11) scheduled for arthroscopic knee surgery participated in this institutionally approved, randomized, doubleblind study. Written informed consent was obtained before patients entered the study. All patients were offered inhalation of nitrous oxide and oxygen (50/50 mixture) by mask before lidocaine injection; no other premedication was administered. With the patient supine, the operative knee was shaved, the skin was cleansed with povidone-iodine solution, and the knee draped. In all patients, 20 mL of 0.5% lidocaine (Astra Pharmaceutical Products Inc., Westborough, Mass.) with freshly added epinephrine (Elkins-Sinn Inc., Cherry Hill, N.J.) (1:200,000) was injected into the skin, subcutaneous tissue, and capsule in three peripatellar portals. Entry portals were located medial to the patellar tendon, lateral to the patellar tendon, and off the superolateral corner of the patella (1). The IA injec-
ARTHROSCOPY UNDER LOCAL ANESTHESIA
tion was made through an anesthetized skin portal. Patients were randomized to receive 20 mL intraarticularly of 0.5%, 1.0%, or 1.5% preservative-free lidocaine with freshly added epinephrine (1:200,000). Spread of IA lidocaine was encouraged by flexion and extension of the knee joint. Throughout surgery the joint was flushed continuously by gravity with lactated Ringer’s solution. At the end of surgery, the arthroscope (4-mm Storz, 30-degree lens) and surgical instruments were removed, and the joint was flushed with copious amounts of lactated Ringer’s solution. Patients returned to the ambulatory surgery unit until discharge. Pain was measured by verbal response to an 11point pain scale, consisting of a 10-cm horizontal line labeled ”no pain” at 0 and “agonizing pain” at 10. The line was divided into 11 equal segments and numbered. Patients were shown the pain scale before each measurement. If a pain score greater than 3 was reported and not relieved by repositioning the leg or injecting lidocaine into the skin, patients were first offered inhalation of nitrous oxide and oxygen (50/50 or 60/40 mixture by mask). If the pain was not diminished after nitrous oxide and oxygen, patients were offered intravenous fentanyl(50 pg); likewise, if the pain was not diminished after nitrous oxide and oxygen and fentanyl, patients were offered general anesthesia. Pain was measured after IA injection and arthroscope insertion and at 15-min intervals during surgery. Patients were also asked to record the time and pain score when the first postoperative oral analgesic was taken and the highest pain score during the night after surgery. Patients were later interviewed by telephone. Venous blood was collected immediately before extraarticular injection and 15, 30, 60, and 120 min after the IA lidocaine injection. No patient received supplemental injections of lidocaine. The blood was centrifuged and the serum harvested and stored at -80°C. Lidocaine concentrations were determined in duplicate by gas-liquid chromatography with a nitrogen phosphorous detector, with a sensitivity of 5 ng/mL and a coefficient of variation less than 10% (11)Statistical analyses were performed using Statistical Analysis System (SAS, version 5.11, 1988) computer programs (12,13). Patient characteristics were compared using one-way analysis of variance. The Mantel-Haenszel ?-test was used to compare gender, the type of surgery, and patient data as appropriate. The Kruskal-Wallis rank sum test was used to compare washout times and the duration of surgery and postoperative analgesia. A nonparametric re-
671
ANESTH ANALG 1990;71:67&4
Table 1. Patient and Operative Data Groups ~
Age (yr) Weight (kg) Gender (MIF) Washout (min) Surgery duration (min) Opera tive/diagnostic
0.5%“
1.0%
1.5%
37 t 16 82 ? 12 814 28 ? 8 73 t 23 1012
12 14 1015 28 2 8 69 ? 20 1411
28 ? 7 74 ? 12 11/5 29 5 7 67 ? 26 1412
36 78
? ?
Values listed are mean ? SD, except for gender and surgical procedure, which are patient counts. Surgical procedures are grouped as operative (resectionor repair of intraarticular tissue) and diagnostic (visualizationwith or without biopsy). Differences between groups were not statistically significant. “These values refer to the intraarticular lidocaine concentration administered.
peated measures analysis of variance test compared pain scores (14). Differences were considered statistically significant if the exact probability test value was less than 0.05.
Results The groups were similar with respect to age, weight, and gender. The duration of IA lidocaine (listed as washout), duration of surgery, and type of surgical procedure were not statistically different between groups (Table 1). The 0.5% lidocaine group had significantly higher pain scores through the first 45 min of surgery than either the 1.0% or 1.5%lidocaine groups (Figure 1). Pain scores through the last intraoperative measurement were not statistically different among groups. Power analysis of combined pain scores from incision to 30 min (n = 43) and from incision to 45 min ( n = 38) revealed that our sample size and variability was such that we could detect group differences with 0.89 and 0.73 power, respectively (aerror of 0.05). More patients in the 1.5% lidocaine group were given nitrous oxide and oxygen before lidocaine injection than patients in either the 0.5% or 1.0% group. The number of patients in each group that inhaled nitrous oxide and oxygen intraoperatively was similar (Table 2). Only one of the patients who reported a pain score of 3 or less intraoperatively requested inhalation of nitrous oxide and oxygen. The duration of postoperative analgesia was similar among groups (Table 2). Eighty-five percent of all patients interviewed by telephone said they would be willing to repeat this anesthetic technique. The number of patients willing to repeat this anesthetic technique was greatest in the 1.5% lidocaine group (94%),
672
DAHL ET AL.
ANESTH ANALG 1990;71:67M
:i
La. Lidocaine 0 0.5% 1.0% 1.5%
= eza
5
't i.
5
1
n n
p(0.05
3
1
INJ
INC
50
15
45
60
75
90
Groups 0.5%" = 12)
1.0% (n = 15)
1.5% (n = 16)
2 6
2 3
6
6.0 2 3.3 75
5.9 2 2.9 83
(n
'p
0
Y
TM(MIN) Table 2. Clinical Summary
105 120
B
Figure 1 . Median pain scores plotted by group at each measurement period. Pain scores are significantly higher in the 0.5% lidocaine group through 45 min of surgery. The number of patients remainingat each time period is listed above the bar. INJ,injection; INC, incision; and POSTOP, postoperative.
~~~
N,O before lidocaine (n) Intraoperative N,O (n) Duration of analgesia (h) Repeat local anesthesia (%)
5 5.5 t 2.3 94
a
$ v
The duration of analgesia was the time from intraarticular injection until the onset of pain after surgery. Patient willingness to repeat local anesthesia for this procedure is listed as "repeat local anesthesia." One patient from the 0 . 5 2 and three from the 1.0% lidocaine group were lost to follow-up. There were no statistically significant differences between groups. "These values refer to the intraarticular lidocaine concentration administered.
but the differences among the three groups were not statistically significant (Table 2). Two patients in the 0.5% lidocaine group required general anesthesia because of knee pain. No patient required pneumatic tourniquet inflation for intraoperative control of bleeding in the knee joint. The surgeon reported satisfactory visualization and access to IA structures. Serum lidocaine concentrations in 17 patients ranged from undetectable to 278 ng/mL. Peak concentrations occurred 60 and 120 min after IA injection. The 1.5%lidocaine group had the highest concentrations (Figure 2). No patient reported symptoms of lidocaine toxicity.
"T
i.0. Lidocaine
250t 0-0 A-A
1.5% 1.0%
2ooi 0-0
150
,
0.5%
1
1
I
A
/
TIME (MIN) Figure 2. Venous serum concentrations of lidocaine versus time after IA lidocaine instillation.
Discussion In the present study the level of patient satisfaction with local anesthesia was similar to other reports and comparable to different anesthetic techniques (3). Eriksson et al. (3) surveyed 278 patients who had arthroscopic knee surgery using spinal, general, or
ARTHROSCOPY UNDER LOCAL ANESTHESIA
ANESTH ANALG 1990;71:670-4
local anesthesia. Ninety-seven percent of patients given general anesthesia reported satisfaction, as compared with 77% of patients having local anesthesia and 64% of those given spinal anesthesia. In 11% the spinal anesthetics were not sufficient and general anesthesia was required. In the present study 14% of patients in the 0.5% lidocaine group were given general anesthesia because of insufficient anesthesia. The desire for an adequate duration of intraoperative analgesia and prolonged postoperative analgesia may have prompted other investigators to combine lidocaine with a longer acting local anesthetic, such as bupivacaine (2,7,8), or to irrigate the joint intraoperatively with a dilute lidocaine solution (6). The results of the present study suggest that a single IA dose of lidocaine with epinephrine provides satisfactory analgesia for arthroscopic procedures on the knee. Both 1.0% and 1.5% lidocaine provide significantly better analgesia than 0.5% lidocaine through 45 min of surgery. The trend in pain scores remained constant after 45 min, but differences were not statistically significant. This may be due in part to the fact that fewer subjects remained in the analysis. The duration of postoperative analgesia, however, was not prolonged with the higher concentrations of lidocaine, perhaps because similar amounts of lidocaine remain in the knee after joint irrigation, regardless of the initial dose, or because the maximal effect occurs with the lowest concentration studied. The techniques described for IA instillation of local anesthetic include an initial injection of local anesthetic with subsequent washout by continuous irrigation, either with an isotonic crystalloid solution (2,7,8) or with a dilute concentration of local anesthetic (3,4,6,10). Other authors anesthetize the skin portals and continuously irrigate the joint with a dilute solution of local anesthetic without an initial IA injection (4,lO). The joint can be irrigated by gravity infusion (3,6,7,9) or by a pressure-controlled inflow device (1,4,8,10). Pressurized irrigation is thought to decrease IA bleeding, to provide better joint distention, and to evacuate debris efficiently (8,lO). However, periarticular extravasation has resulted in leg swelling (4,lO) and systemic absorption of local anesthetic (10). In our study irrigation by gravity inflow provided satisfactory operative conditions (3,6,7,9) and functioned without complication. The serum lidocaine concentrations in the 1.5% lidocaine group were higher than those in the 0.5%or 1.0% lidocaine groups. All lidocaine concentrations were at least an order of magnitude lower than those associated with systemic toxicity, which is usually greater than 5 pg/mL (15). Although we sampled blood for only 120 min, it is unlikely that further
673
absorption of lidocaine would be significant because the joint was flushed with lactated Ringer’s solution during and after surgery. Lidocaine concentrations in the present study are comparable to those reported by Massey et al. (6), who used a similar IA dose but then irrigated with a 0.2% lidocaine solution. Although absorption of extraarticular lidocaine contributed to the total venous concentration, the dose was constant for all three groups. Epinephrine will slow local anesthetic absorption from the knee after periarticular and IA injection. Yoshiya et al. (7) reported mean venous lidocaine concentrations of 900-1000 ng/mL and a maximum value of 2400 ng/mL after administering an IA lidocaine and bupivacaine solution without epinephrine. A similar IA lidocaine dose with epinephrine in our study resulted in mean concentrations of 100-200 ng/mL and a maximum value of 278 ng/mL. Epinephrine also decreases serum concentrations of bupivacaine when injected into the knee (16). Epinephrine may act to decrease IA bleeding during surgery and to negate the need for tourniquet inflation. If tourniquet inflation is part of the surgical technique, a different anesthetic technique may be necessary. In conclusion, arthroscopy of the knee under lidocaine local anesthesia can be performed in many patients who desire to remain awake. The frequent use of systemic analgesics intraoperatively, however, points out the need for an appropriate level of anesthesiological vigilance. We recommend the use of 1.0% or 1.5% lidocaine with epinephrine based on patient comfort intraoperatively and the absence of lidocaine toxicity in any of our patients. The authors thank Cathy L. Chambersand Richard I. Cook, MD, for their help in the preparation of this manuscript.
References 1. McGuire DA, Forst JD, Floerchinger SL. Local anesthesia and arthroscopic surgery of the knee. Alaska Med 1986;28:20-4. 2. Ngo IV, Hamilton WG, Wichern WA, Andree RA. Local anesthesia with sedation for arthroscopic knee surgery of the knee: a report of 100 consecutive cases. Arthroscopy 1985;l: 237-41. 3. Eriksson E, Haggmark T, Saartok T, Sebik A, Ortengren B. Knee arthroscopywith local anesthesia in ambulatory patients. Orthopedics 1986;9:186-8. 4. Debruyne D, Moulin MA, Carmes C, Beguin JA, Locker 8. Monitoring serum bupivacaine levels during arthroscopy. Eur J Clin Pharmacol 1985;27:73>5. 5. Gerber H, Censier K, Gacht AA, Romppainen J. Intra-articular absorption of bupivacaine during arthroscopy-comparison of 0.25%, 0.5% and 0.75% solution. Anesthesiology 1985;64: A217.
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ANESTH ANALG 1990;71:67C-4
6. Massey T, Huang TL, Malinick R, Zell M. Serum lidocaine
levels during arthroscopy using continuous irrigation with lidocaine. Clin Orthop 1988;229:1824. 7. Yoshiya S, Kurosaka M, Hirohata K, Andrish JT. Knee arthroscopy using local anesthetic. Arthroscopy 1988;4:86-9. 8. Halperin N, Anatol A, Hirschberg E, Agasi M. Arthroscopy of the knee under local anesthesia and controlled pressureirrigation. Clin Orthop 1978;134:176-9. 9. Meining RP, Holtgrewe JL, Wiedel JD, Christie DB, Kestin KJ. Plasma bupivacaine levels following single dose intraarticular instillation for arthroscopy. Am J Sports Med 1988;16:295-300. 10. Wedmark T, Lundh R. Arthroscopy under local anaesthesia using controlled pressure-irrigation with prilocaine. J Bone Joint Surg [Br] 1982;64:58>5. 11. Abernethy DR, Greenblatt DJ. Lidocaine determination in
12. 13. 14.
15.
16.
human plasma with application to single-dose pharmacokinetic studies. J Chromatogr 1982;232:180-5. Ray AA, Sall JP, Saffer M. SAS user’s guide: statistics. Cary, N.C.: SAS Institute Inc., 1982:139-200, 205-12, and 381-96. Allen A, Council KA, Sall JP. SAS user’s guide: basics. Cary, N.C.: SAS Institute Inc., 1982527-32 and 575-86. Tandon PK, Moeschberger ML. SAS Macros for nonparametric analysis of repeated measures designs, SAS Users Group, International. New Orleans: SAS Institute Inc., 198380b17. Pieper JA, Rodman JH. Lidocaine. In: Evans WE, Schentag JJ, Jusko WJ, eds. Applied pharmacokinetics. Spokane, Wash.: Applied Therapeutics Inc., 1986639431. Carnes RS, Butterworth IV, Poehling GS, Samuels MP. Safety and efficacy of intra-articular bupivacaine and epinephrine anesthesia for knee arthroscopy. Anesthesiology 1989;71:A729.
ANESTH ANALG 1990:71:670-4
Lidocaine Local Anesthesia for Arthroscopic Knee Surgery Mark R. Dahl, MD, Joseph F. Dasta, Thomas D. McSweeney, BS
MS,
Wilhelm Zuelzer,
MD,
and
-
DAHL MR, DASTA JF, ZUELZER W, McSWEENEY TD. Lidocaine local anesthesia for arthroscopic knee surgery. Anesth Analg 1990;71:670-4.
Forty-five patients were evaluated during knee arthroscopy performed using local anesthesia produced by lidocaine with epinephrine to determine the dose-response relationship for operative analgesia. Serum lidocaine concentrations were also measured. Patients were randomized prospectively to receive 20 mL of 0.5%, 1.070, or 1.5% lidocaine with epinephrine intraarticularly. lntraoperative discomfort was measured by verbal response on an 11-point linear pain scale. Pain scores were significantly higher in patients receiving 0.5% lidocaine during thefirst 45 min of surgery (P = 0.03). After 45 min, pain scores continued to be higher in the 0.5% lidocaine group than in the 1 .O% or 1.5% groups, but the differences were not statistically
Periarticular infiltration and intraarticular (IA) instillation of local anesthetics is a suitable method of anesthesia for arthroscopic knee surgery and may be an alternative to regional or general anesthesia (1-3). Several methods for producing IA anesthesia have been described for knee arthroscopy that differ in volume, concentration, and type of local anesthetic, use of adjuvant epinephrine, and method of local anesthetic instillation (1-10). Although all regimens have a high success rate, dose requirements have been reported only for bupivacaine (5). Lidocaine has been described for use alone or in combination with bupivacaine, but dose requirements have not been reported (2,643). The purpose of this study was to determine the dose-response relationship for lidocaine and to measure serum lidocaine concentra-
This work was performed at the Ohio State University Hospitals in Columbus, Ohio. Presented at the annual meeting of the American Society of Anesthesiologists, New Orleans, Louisiana, October 1989. Received from the Departments of Anesthesiology and Surgery and the College of Pharmacy, The Ohio State University, Columbus, Ohio. Accepted for publication August 3, 1990. Address correspondence to Dr. Dahl, Mount Carmel Medical Center, 793 West State Street, Columbus, OH 43215. 01990 by the International Anesthesia Research Society
significant. Ninety-four percent of patients in the 1.5% lidocaine group were willing to repeat this anesthetic technique for surgery compared with 83% of those in the 1.0% lidocaine group and 75% of those in the 0.5% lidocaine group (P > 0.05). The duration of postoperative analgesia was similar in all groups. Serum lidocaine concentrations before and 15, 30, 60, and 120 min after instillation of lidocaine were highest in the 1.5% lidocaine group with a peak concentration of 278 nglmL. No patient had symptoms of lidocaine toxicity. W e recommend that lidocaine concentrations of 1 .O% or 1.5% be used when 20 mL is instilled intraarticularly for knee arthroscopy based on patient comfort and absence of lidocaine toxicity.
Key Words: ANESTHESIA, ORTHOPEDIC-knee arthroscopy with lidocaine. ANESTHETIC TECHNIQUES, LOCAL-knee arthroscopy.
tions after extraarticular and IA administration in patients undergoing knee arthroscopy.
Methods Forty-five outpatients (ASA physical status I or 11) scheduled for arthroscopic knee surgery participated in this institutionally approved, randomized, doubleblind study. Written informed consent was obtained before patients entered the study. All patients were offered inhalation of nitrous oxide and oxygen (50/50 mixture) by mask before lidocaine injection; no other premedication was administered. With the patient supine, the operative knee was shaved, the skin was cleansed with povidone-iodine solution, and the knee draped. In all patients, 20 mL of 0.5% lidocaine (Astra Pharmaceutical Products Inc., Westborough, Mass.) with freshly added epinephrine (Elkins-Sinn Inc., Cherry Hill, N.J.) (1:200,000) was injected into the skin, subcutaneous tissue, and capsule in three peripatellar portals. Entry portals were located medial to the patellar tendon, lateral to the patellar tendon, and off the superolateral corner of the patella (1). The IA injec-
ARTHROSCOPY UNDER LOCAL ANESTHESIA
tion was made through an anesthetized skin portal. Patients were randomized to receive 20 mL intraarticularly of 0.5%, 1.0%, or 1.5% preservative-free lidocaine with freshly added epinephrine (1:200,000). Spread of IA lidocaine was encouraged by flexion and extension of the knee joint. Throughout surgery the joint was flushed continuously by gravity with lactated Ringer’s solution. At the end of surgery, the arthroscope (4-mm Storz, 30-degree lens) and surgical instruments were removed, and the joint was flushed with copious amounts of lactated Ringer’s solution. Patients returned to the ambulatory surgery unit until discharge. Pain was measured by verbal response to an 11point pain scale, consisting of a 10-cm horizontal line labeled ”no pain” at 0 and “agonizing pain” at 10. The line was divided into 11 equal segments and numbered. Patients were shown the pain scale before each measurement. If a pain score greater than 3 was reported and not relieved by repositioning the leg or injecting lidocaine into the skin, patients were first offered inhalation of nitrous oxide and oxygen (50/50 or 60/40 mixture by mask). If the pain was not diminished after nitrous oxide and oxygen, patients were offered intravenous fentanyl(50 pg); likewise, if the pain was not diminished after nitrous oxide and oxygen and fentanyl, patients were offered general anesthesia. Pain was measured after IA injection and arthroscope insertion and at 15-min intervals during surgery. Patients were also asked to record the time and pain score when the first postoperative oral analgesic was taken and the highest pain score during the night after surgery. Patients were later interviewed by telephone. Venous blood was collected immediately before extraarticular injection and 15, 30, 60, and 120 min after the IA lidocaine injection. No patient received supplemental injections of lidocaine. The blood was centrifuged and the serum harvested and stored at -80°C. Lidocaine concentrations were determined in duplicate by gas-liquid chromatography with a nitrogen phosphorous detector, with a sensitivity of 5 ng/mL and a coefficient of variation less than 10% (11)Statistical analyses were performed using Statistical Analysis System (SAS, version 5.11, 1988) computer programs (12,13). Patient characteristics were compared using one-way analysis of variance. The Mantel-Haenszel ?-test was used to compare gender, the type of surgery, and patient data as appropriate. The Kruskal-Wallis rank sum test was used to compare washout times and the duration of surgery and postoperative analgesia. A nonparametric re-
671
ANESTH ANALG 1990;71:67&4
Table 1. Patient and Operative Data Groups ~
Age (yr) Weight (kg) Gender (MIF) Washout (min) Surgery duration (min) Opera tive/diagnostic
0.5%“
1.0%
1.5%
37 t 16 82 ? 12 814 28 ? 8 73 t 23 1012
12 14 1015 28 2 8 69 ? 20 1411
28 ? 7 74 ? 12 11/5 29 5 7 67 ? 26 1412
36 78
? ?
Values listed are mean ? SD, except for gender and surgical procedure, which are patient counts. Surgical procedures are grouped as operative (resectionor repair of intraarticular tissue) and diagnostic (visualizationwith or without biopsy). Differences between groups were not statistically significant. “These values refer to the intraarticular lidocaine concentration administered.
peated measures analysis of variance test compared pain scores (14). Differences were considered statistically significant if the exact probability test value was less than 0.05.
Results The groups were similar with respect to age, weight, and gender. The duration of IA lidocaine (listed as washout), duration of surgery, and type of surgical procedure were not statistically different between groups (Table 1). The 0.5% lidocaine group had significantly higher pain scores through the first 45 min of surgery than either the 1.0% or 1.5%lidocaine groups (Figure 1). Pain scores through the last intraoperative measurement were not statistically different among groups. Power analysis of combined pain scores from incision to 30 min (n = 43) and from incision to 45 min ( n = 38) revealed that our sample size and variability was such that we could detect group differences with 0.89 and 0.73 power, respectively (aerror of 0.05). More patients in the 1.5% lidocaine group were given nitrous oxide and oxygen before lidocaine injection than patients in either the 0.5% or 1.0% group. The number of patients in each group that inhaled nitrous oxide and oxygen intraoperatively was similar (Table 2). Only one of the patients who reported a pain score of 3 or less intraoperatively requested inhalation of nitrous oxide and oxygen. The duration of postoperative analgesia was similar among groups (Table 2). Eighty-five percent of all patients interviewed by telephone said they would be willing to repeat this anesthetic technique. The number of patients willing to repeat this anesthetic technique was greatest in the 1.5% lidocaine group (94%),
672
DAHL ET AL.
ANESTH ANALG 1990;71:67M
:i
La. Lidocaine 0 0.5% 1.0% 1.5%
= eza
5
't i.
5
1
n n
p(0.05
3
1
INJ
INC
50
15
45
60
75
90
Groups 0.5%" = 12)
1.0% (n = 15)
1.5% (n = 16)
2 6
2 3
6
6.0 2 3.3 75
5.9 2 2.9 83
(n
'p
0
Y
TM(MIN) Table 2. Clinical Summary
105 120
B
Figure 1 . Median pain scores plotted by group at each measurement period. Pain scores are significantly higher in the 0.5% lidocaine group through 45 min of surgery. The number of patients remainingat each time period is listed above the bar. INJ,injection; INC, incision; and POSTOP, postoperative.
~~~
N,O before lidocaine (n) Intraoperative N,O (n) Duration of analgesia (h) Repeat local anesthesia (%)
5 5.5 t 2.3 94
a
$ v
The duration of analgesia was the time from intraarticular injection until the onset of pain after surgery. Patient willingness to repeat local anesthesia for this procedure is listed as "repeat local anesthesia." One patient from the 0 . 5 2 and three from the 1.0% lidocaine group were lost to follow-up. There were no statistically significant differences between groups. "These values refer to the intraarticular lidocaine concentration administered.
but the differences among the three groups were not statistically significant (Table 2). Two patients in the 0.5% lidocaine group required general anesthesia because of knee pain. No patient required pneumatic tourniquet inflation for intraoperative control of bleeding in the knee joint. The surgeon reported satisfactory visualization and access to IA structures. Serum lidocaine concentrations in 17 patients ranged from undetectable to 278 ng/mL. Peak concentrations occurred 60 and 120 min after IA injection. The 1.5%lidocaine group had the highest concentrations (Figure 2). No patient reported symptoms of lidocaine toxicity.
"T
i.0. Lidocaine
250t 0-0 A-A
1.5% 1.0%
2ooi 0-0
150
,
0.5%
1
1
I
A
/
TIME (MIN) Figure 2. Venous serum concentrations of lidocaine versus time after IA lidocaine instillation.
Discussion In the present study the level of patient satisfaction with local anesthesia was similar to other reports and comparable to different anesthetic techniques (3). Eriksson et al. (3) surveyed 278 patients who had arthroscopic knee surgery using spinal, general, or
ARTHROSCOPY UNDER LOCAL ANESTHESIA
ANESTH ANALG 1990;71:670-4
local anesthesia. Ninety-seven percent of patients given general anesthesia reported satisfaction, as compared with 77% of patients having local anesthesia and 64% of those given spinal anesthesia. In 11% the spinal anesthetics were not sufficient and general anesthesia was required. In the present study 14% of patients in the 0.5% lidocaine group were given general anesthesia because of insufficient anesthesia. The desire for an adequate duration of intraoperative analgesia and prolonged postoperative analgesia may have prompted other investigators to combine lidocaine with a longer acting local anesthetic, such as bupivacaine (2,7,8), or to irrigate the joint intraoperatively with a dilute lidocaine solution (6). The results of the present study suggest that a single IA dose of lidocaine with epinephrine provides satisfactory analgesia for arthroscopic procedures on the knee. Both 1.0% and 1.5% lidocaine provide significantly better analgesia than 0.5% lidocaine through 45 min of surgery. The trend in pain scores remained constant after 45 min, but differences were not statistically significant. This may be due in part to the fact that fewer subjects remained in the analysis. The duration of postoperative analgesia, however, was not prolonged with the higher concentrations of lidocaine, perhaps because similar amounts of lidocaine remain in the knee after joint irrigation, regardless of the initial dose, or because the maximal effect occurs with the lowest concentration studied. The techniques described for IA instillation of local anesthetic include an initial injection of local anesthetic with subsequent washout by continuous irrigation, either with an isotonic crystalloid solution (2,7,8) or with a dilute concentration of local anesthetic (3,4,6,10). Other authors anesthetize the skin portals and continuously irrigate the joint with a dilute solution of local anesthetic without an initial IA injection (4,lO). The joint can be irrigated by gravity infusion (3,6,7,9) or by a pressure-controlled inflow device (1,4,8,10). Pressurized irrigation is thought to decrease IA bleeding, to provide better joint distention, and to evacuate debris efficiently (8,lO). However, periarticular extravasation has resulted in leg swelling (4,lO) and systemic absorption of local anesthetic (10). In our study irrigation by gravity inflow provided satisfactory operative conditions (3,6,7,9) and functioned without complication. The serum lidocaine concentrations in the 1.5% lidocaine group were higher than those in the 0.5%or 1.0% lidocaine groups. All lidocaine concentrations were at least an order of magnitude lower than those associated with systemic toxicity, which is usually greater than 5 pg/mL (15). Although we sampled blood for only 120 min, it is unlikely that further
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absorption of lidocaine would be significant because the joint was flushed with lactated Ringer’s solution during and after surgery. Lidocaine concentrations in the present study are comparable to those reported by Massey et al. (6), who used a similar IA dose but then irrigated with a 0.2% lidocaine solution. Although absorption of extraarticular lidocaine contributed to the total venous concentration, the dose was constant for all three groups. Epinephrine will slow local anesthetic absorption from the knee after periarticular and IA injection. Yoshiya et al. (7) reported mean venous lidocaine concentrations of 900-1000 ng/mL and a maximum value of 2400 ng/mL after administering an IA lidocaine and bupivacaine solution without epinephrine. A similar IA lidocaine dose with epinephrine in our study resulted in mean concentrations of 100-200 ng/mL and a maximum value of 278 ng/mL. Epinephrine also decreases serum concentrations of bupivacaine when injected into the knee (16). Epinephrine may act to decrease IA bleeding during surgery and to negate the need for tourniquet inflation. If tourniquet inflation is part of the surgical technique, a different anesthetic technique may be necessary. In conclusion, arthroscopy of the knee under lidocaine local anesthesia can be performed in many patients who desire to remain awake. The frequent use of systemic analgesics intraoperatively, however, points out the need for an appropriate level of anesthesiological vigilance. We recommend the use of 1.0% or 1.5% lidocaine with epinephrine based on patient comfort intraoperatively and the absence of lidocaine toxicity in any of our patients. The authors thank Cathy L. Chambersand Richard I. Cook, MD, for their help in the preparation of this manuscript.
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