Blood levels of bupivacaine after arthroscopy of the knee joint

Systemic Ropivacaine Concentrations Following Local Infiltration Analgesia and Femoral Nerve Block in Older Patients Undergoing Total Knee Arthroplasty

Purpose

The study examined the pharmacokinetic profile of fixed formulation mixtures comprising 225 mg of ropivacaine for local infiltration analgesia with or without epinephrine, and femoral nerve block in older patients presenting for orthopedic surgery and explored potential influences of block type, age, and body weight on this profile.

Patients and Methods

Twenty four patients scheduled for total knee arthroplasty were randomly assigned to three groups: femoral nerve block, local infiltration analgesia with epinephrine and local infiltration analgesia without epinephrine. Blood samples were collected at 10, 30, 60, and 120 min following the block and total plasma concentrations of ropivacaine were quantified by high performance liquid chromatography.

Results

The mean individual peak total plasma concentrations of ropivacaine in local infiltration analgesia with and without epinephrine, and femoral nerve block group were 0.334, 0.490 and 0.545 μg mL-1 (p = 0.16). Local infiltration with epinephrine group had significantly lower plasma ropivacaine concentrations at 30, 60 and 120 minutes. The plasma ropivacaine concentrations exceeded 2.2 μg mL-1 in one patient. Age, but not body weight, had a moderate correlation with peak plasma ropivacaine concentration (r = 0.37, p = 0.08).

Conclusion

Administration of a fixed 225 mg dose of ropivacaine for local infiltration analgesia with epinephrine and femoral nerve block results in plasma ropivacaine concentrations below the toxicity threshold, indicating their safety. The use of local infiltration analgesia with epinephrine provides a greater safety margin, as local infiltration analgesia without epinephrine may lead to ropivacaine concentrations associated with symptoms of local anesthetic toxicity.

Local infiltration analgesia in knee and hip arthroplasty efficacy and safety

Background

This is a secondary publication of a PhD thesis. Local infiltration analgesia (LIA) is a new multimodal wound infiltration method for treating postoperative pain after knee and hip arthroplasty. This method is based on systematic infiltration of a mixture of ropivacaine, a long acting local anaesthetic, ketorolac, a cyclooxygenase inhibitor (NSAID), and adrenalin around all structures subject to surgical trauma in knee and hip arthroplasty.

Aims

Paper I: to assess whether pain relief after LIA in total knee arthroplasty (TKA) is as effective as femoral block. Paper II: to assess whether the plasma concentration of ropivacaine and ketorolac after LIA in TKA reaches levels linked to toxicity. Paper III: to assess whether the plasma concentration of unbound ropivacaine after LIA in THA reaches levels linked to toxicity and if it is higher in THA as compared to TKA. Paper IV: to assess whether the plasma concentration of ketorolac after LIA in THA reaches levels linked to toxicity, and whether administration of ketorolac in LIA is safer as compared to the intramuscular route.

Methods

Two patient cohorts of 40 patients scheduled for elective total knee arthroplasty (TKA) and 15 patients scheduled for total hip arthroplasty (THA) contributed to this work. In a randomized trial the efficacy of LIA in TKA with regard to pain at rest and upon movement was compared to femoral block.

Results

Both methods result in a high quality pain relief and similar morphine consumption during the 24 h monitoring period. In the same patient cohort the maximal total plasma concentration of ropivacaine was below the established toxic threshold for most patients. All patients in the THA cohort were subjected to the routine LIA protocol. In these patients both the total and unbound plasma concentration of ropivacaine was determined. The concentration was below the established toxic threshold. As ropivacaine binds to α–1 acid glycoprotein (AAG) we assessed the possibility that increased AAG may decrease the unbound concentration of ropivacaine. A 40% increase in AAG was detected during the first 24 h after surgery, however the fraction of unbound ropivacaine remained the same. There was a trend towards increased C max of ropivacaine with increasing age and decreasing creatinine clearance but the statistical power was too low to draw any conclusion. Administration of 30 mg ketorolac according to the LIA protocol both in TKA and THA resulted in a similar C max as previously reported after 10 mg intramuscular ketorolac. Neither age, nor body weight or BMI, nor creatinine clearance, correlates to maximal ketorolac plasma concentration or total exposure to ketorolac (AUC).

Conclusion

LIA provides good postoperative analgesia which is similar to femoral block after total knee arthroplasty. The plasma concentration of ropivacaine seems to be below toxic levels in most TKA patients. The unbound plasma concentration of ropivacaine in THA seems to be below the toxic level.

Implication

The use of ketorolac in LIA may not be safer than other routes of administration, and similar restrictions should be applied in patients at risk of developing side effects.

The in vitro effects of bupivacaine on articular chondrocytes

We have studied the effects of bupivacaine on human and bovine articular chondrocytes in vitro. Time-lapse confocal microscopy of human articular chondrocytes showed > 95% cellular death after exposure to 0.5% bupivacaine for 30 minutes. Human and bovine chondrocytes exposed to 0.25% bupivacaine had a time-dependent reduction in viability, with longer exposure times resulting in higher cytotoxicity. Cellular death continued even after removal of 0.25% bupivacaine. After exposure to 0.25% bupivacaine for 15 minutes, flow cytometry showed bovine chondrocyte viability to be 41% of saline control after seven days. After exposure to 0.125% bupivacaine for up to 60 minutes, the viability of both bovine and human chondrocytes was similar to that of control groups. These data show that prolonged exposure 0.5% and 0.25% bupivacaine solutions are potentially chondrotoxic.

Serum and wound drain ropivacaine concentrations after wound infiltration in joint arthroplasty

Ropivacaine blood and drain levels were measured in 20 hip and 15 total knee arthroplasties after intraoperative wound infiltration with 150 to 200 mL (360-400 mg) of ropivacaine, followed by a 48-hour intra-articular pain pump infusion of 1000 mg (knees) and 300 mg (hips) commencing 12 hours postoperatively. Concentrations were below 2 microg/mL over the first 12 hours before the pain pump increased levels. Peak total ropivacaine concentration ranged from 0.65 to 4.36 microg/mL with the pain pump. The high infiltration doses produced levels below or within the safe threshold of 1 to 3 microg/mL. Pain pump infusion produced some C(max) levels above 3.0 microg/mL, but there was no clinical evidence of toxicity. Wound drain amounts (0.53-26.69 mg) indicate reinfusion should be safe, although further study is needed to confirm this.

Efficacy of continuous intra-articular bupivacaine infusion for postoperative analgesia after anterior cruciate ligament reconstruction: a double-blinded, placebo-controlled, prospective, and randomized study

BACKGROUND

The increasing trend toward outpatient surgery has stimulated the development of techniques focused on decreasing perioperative and postoperative pain. Pain control infusion pumps are gaining in popularity in orthopaedic procedures to control postoperative pain.

HYPOTHESIS

Continuous infusion of bupivacaine via a catheter placed intra-articular into the knee after anterior cruciate ligament reconstruction using ipsilateral autograft quadrupled semitendinosus will decrease postoperative pain scores and narcotic and NSAID consumption.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Three randomized study groups of 21 subjects were evaluated: group I, 0.25% bupivacaine infused intra-articular at 4 mL/hour for 72 hours (study); Group II, 0.9% saline infused intra-articular at 4 mL/hr for 72 hours (placebo); Group III, no intra-articular infusion catheter (control). Each subject received general anesthesia and preemptive intra-articular anesthesia. Visual analog scale pain scores and analgesic use were compiled for the 96-hour study period.

RESULTS

With the exception of significantly higher total narcotic usage in the control group compared with the study group only for the time period of 48 to 72 hours, there were no other statistically significant differences between each of the study groups with respect to pain and narcotic and NSAID use for the entire study period.

CONCLUSION

The continuous infusion of intra-articular bupivacaine via pain control infusion pumps after anterior cruciate ligament reconstruction using ipsilateral autograft quadrupled semitendinosus cannot be supported when postoperative visual analog scale pain scores and analgesic use are the rationale for justification.

In vitro exposure to 0.5% bupivacaine is cytotoxic to bovine articular chondrocytes

PURPOSE

Intra-articular use of 0.5% bupivacaine is common in arthroscopic surgery. This study was conducted to test the hypotheses that (1) 0.5% bupivacaine is toxic to articular chondrocytes, and (2) the intact articular surface protects chondrocytes from the effects of short-term exposure to 0.5% bupivacaine.

METHODS

Freshly isolated bovine articular chondrocytes were prepared into alginate bead cultures and were treated with 0.5% bupivacaine solution or 0.9% saline for 15, 30 or 60 minutes, washed, and returned to growth media. Chondrocytes were recovered from alginate 1 hour, 1 day, and 1 week after bupivacaine exposure; they were fluorescently labeled to identify apoptotic and dead cells and were analyzed by flow cytometry. Twelve osteochondral cores were harvested from bovine knees. The superficial 1 mm of cartilage was removed from 6 cores (top-off). Intact and top-off cores were submerged in 0.9% saline or 0.5% bupivacaine solution for 30 minutes and then maintained in chondrocyte growth media for 24 hours. Live-cell/dead-cell fluorescent imaging was assessed using confocal microscopy.

RESULTS

Greater than 99% chondrocyte death/apoptosis was observed in all bupivacaine-exposed alginate bead cultures compared with 20% cell death in saline-treated controls (P < .05). Osteochondral cores with intact surfaces treated with 0.5% bupivacaine showed 42% dead chondrocytes. When the articular surface was removed, 0.5% bupivacaine resulted in increased cell death, with 75% dead chondrocytes (P < .05).

CONCLUSIONS

Results show that 0.5% bupivacaine solution is cytotoxic to bovine articular chondrocytes and articular cartilage in vitro after only 15 to 30 minutes' exposure. The intact bovine articular surface has some chondroprotective effects.

CLINICAL RELEVANCE

Because healthy chondrocytes are important for maintenance of the cartilage matrix, chondrocyte loss may contribute to cartilage degeneration. This study shows a cytotoxic effect of 0.5% bupivacaine solution on bovine articular chondrocytes in vitro. Although these results cannot be directly extrapolated to the clinical setting, the data suggest that caution should be exercised in the intra-articular use of 0.5% bupivacaine.

A prospective randomized comparison of spinal versus local anesthesia with propofol infusion for knee arthroscopy

PURPOSE

Knee arthroscopy is the most common orthopaedic procedure performed in the United States, and there are few randomized studies comparing local anesthesia, in conjunction with propofol, with regional anesthesia for knee arthroscopy. The purpose of the study was to test the hypothesis that patients receiving local anesthesia combined with propofol infusion (LAP) will recover from anesthesia faster and experience less postoperative headache and back pain compared with spinal anesthesia (SA).

TYPE OF STUDY

Randomized trial.

METHODS

A randomized trial was used to compare SA and LAP in adults undergoing knee arthroscopy. A simple randomization scheme in sealed envelopes was used. An independent observer collected data the day of surgery and contacted patients by telephone on the first postoperative day to inquire about back pain or headaches, and to have them rate their anesthesia (excellent, good, fair, or poor).

RESULTS

Eighteen patients (average age, 53 years) received LAP and 14 received SA. Baseline assessment of the 2 groups was similar. The mean time spent in the postoperative anesthesia care unit (PACU) was 2.8 hours for the LAP group and 4.0 hours for the SA group (P < .0001). Spinal anesthesia was associated with back pain in 5 of 14 patients in the SA group compared with none in the LAP group (P = .004). There were no statistically significant differences between the 2 groups with respect to headache (P = .5) or overall patient satisfaction (P = .3). The amount of time required to administer anesthesia was similar between the 2 groups (P = .2). The number of patients requiring additional sedation intraoperatively was higher in the LAP group compared with the SA group, 9 of 18 and 1 of 14, respectively (P = .02).

CONCLUSIONS

Although subjects receiving LAP were more likely to require additional sedation intraoperatively compared with the SA group, LAP was associated with significantly less time to home readiness as measured by time in the PACU.

LEVEL OF EVIDENCE

Level I.

Short-term analgesic effects of intra-articular injections after knee arthroscopy

PURPOSE

To study the effects of 3 different intra-articular analgesic combinations on postoperative pain, and whether the timing of the injection, either preoperative or postoperative, had an effect on postoperative analgesia.

TYPE OF STUDY

Prospective, randomized, double-blind clinical trial.

METHODS

Patients undergoing knee arthroscopy performed by a single surgeon under general anesthesia were randomized into 6 study groups. Each patient received an intra-articular injection 20 minutes before incision and at the end of the procedure. One injection contained the study medications, and the other contained normal saline solution (placebo). The patients, surgeon, and data collection personnel were blinded to the contents of the injections. Outcome measures included visual analogue pain scores at 0, 60, and 120 minutes after the procedure, and total recovery room fentanyl consumption.

RESULTS

Fifty patients successfully completed the study protocol. Patients receiving combinations of morphine, bupivacaine, and epinephrine or bupivacaine and epinephrine yielded lower pain scores and narcotics consumption than patients receiving epinephrine alone, which was statistically significant irrespective of the timing of injection (P < .0001). Patients receiving the study medication preoperatively had significantly lower pain scores at the first measurement (t = 0) than those receiving the study medication postoperatively (P = .0343). There was no statistically significant effect of timing of the treatment medication administration at either 60 or 120 minutes postoperatively. Comparison of fentanyl consumption between groups receiving the treatment medication preoperatively versus postoperatively showed no significant difference.

CONCLUSIONS

The combination of morphine, bupivacaine, and epinephrine, as well as the combination of bupivacaine and epinephrine provide excellent postoperative pain control when used either preoperatively or postoperatively in knee arthroscopy. There was a trend that patients receiving preoperative analgesic injections experienced superior pain control than did those injected postoperatively.

LEVEL OF EVIDENCE

Level I, Randomized Controlled Trial.

Analgesic effect of intra-articular ketorolac in knee arthroscopy: comparison of morphine and bupivacaine

This prospective study assessed the postoperative analgesic effect of intra-articular ketorolac, morphine, and bupivacaine during arthroscopic outpatient partial meniscectomy. Group 1 patients (n=20) received postoperative injection of 60 mg intra-articular ketorolac, group 2 patients (n=20) 10 cc intra-articular bupivacaine 0.25%, group 3 patients (n=20) 1 mg intra-articular morphine diluted in 10 cc saline, and group 4 patients (n=20, controls) only 10 cc saline. We evaluated the postoperative analgesic effect (period measured from the end of the surgery until further analgesia was demanded), the level of postoperative pain (by visual analog scale 1, 2, 3, 12, and 24 h after surgery), and the need for additional pain medication (during the first 24 h after surgery). The best analgesic effect was in patients treated with intra-articular ketorolac, and this was statistically significant in: postoperative analgesic effect and the need for additional pain medication immediately after surgery, and after 24 h. No complications were found related to the intra-articular treatment. We conclude that 60 mg intra-articular ketorolac provides better analgesic effect than 10 cc intra-articular bupivacaine 0.25% or 1 mg intra-articular morphine.

Bupivacaine bolus injection versus placebo for pain management following total knee arthroplasty

Following surgery, total knee arthroplasty (TKA) patients experience considerable pain. All available effective analgesia agents produce some unwanted side effects. Sixty consenting elective TKA patients were randomized to receive bupivacaine 20 mL 0.5% (100 mg) or 20 mL normal saline injected into the joint space after capsule closure. Patients were interviewed up to 24 hours after surgery for pain and pain relief. Narcotic usage was recorded. The bupivacaine group had lower pain scores and reduced narcotics during the 24-hour period, with a 23-minute shorter time to discharge from the postanesthesia care unit than the placebo group (P =.02). Although a bupivacaine bolus injected at capsule closure results in decreased pain levels (P =.07) and narcotic consumption (P =.09), it is not statistically significantly better than placebo.

Efficacy and uptake of ropivacaine and bupivacaine after single intra-articular injection in the knee joint

The efficacy of ropivacaine 100 mg (5 mg ml(-1)), 150 mg (7.5 mg ml(-1)) and 200 mg (10 mg ml(-1)) and bupivacaine 100 mg (5 mg ml(-1)) given by intra-articular injection into the knee after the end of surgery was studied in 72 ASA I-II patients scheduled for elective knee arthroscopy under general anaesthesia in a randomized, double-blind study. Kapake (paracetamol 1 g and codeine 60 mg) was given as a supplementary analgesic. Pain scores were assessed 1-4 h after surgery and a verbal rating scale of overall pain severity was assessed on second postoperative day. Ropivacaine or bupivacaine concentrations were determined in peripheral venous plasma up to 3 h after injection in eight patients in each group. Verbal rating pain scores were lower with ropivacaine 150 mg compared with bupivacaine 100 mg (P<0.05). There was a tendency for lower analgesic consumption and pain scores with all doses of ropivacaine (not significant). The mean (SD) maximum total plasma concentrations of ropivacaine were 0.64 (0.25), 0.78 (0.43), and 1.29 (0.46) mg litre(-1) after 100, 150 and 200 mg. The corresponding unbound concentrations were 0.018 (0.009), 0.024 (0.020) and 0.047 (0.022) mg litre(-1). Both were proportional to the dose. The maximum total concentration after bupivacaine 100 mg was 0.57 (0.36) mg litre(-1). The time to reach maximum plasma concentration was similar for all doses and varied between 20 and 180 min. All concentrations were well below the threshold for systemic toxicity.

Combined pre- and post-surgical bupivacaine wound infiltrations decrease opioid requirements after knee ligament reconstruction

PURPOSE

To test the efficacy of a combination of selective pre- and post-surgical local anesthetic infiltrations of the knee, compared with standard intra-articular injection at the end of surgery alone, to reduce postoperative opioid requirements following arthroscopic cruciate ligament reconstruction (ACLR).

METHODS

In a double-blind, randomized, controlled trial, we studied 23 patients (ASA I or II) scheduled for elective ACLR under general anesthesia. The treatment group (n = 12) received infiltrations with bupivacaine 0.25% with epinephrine 1:200,000 presurgically (10 ml into the portals, 10 ml at the medial tibial incision site, 10 ml at the lateral femoral incision site, and 10 ml intra-articularly) and postsurgically (5 ml at the medial tibial incision and 10 ml at the lateral femoral incision). The control group (n = 11) received infiltrations with saline 0.9% in the same manner. All patients received a standard intra-articular local anesthetic instillation of the knee (25 ml of bupivacaine 0.25% with epinephrine 1:200,000) at the completion of surgery.

RESULTS

Postoperative opioid requirements were lower in the treatment group (5.8 +/- 2.9 mg morphine equivalent) than in the control group ( 13.7 +/- 5.8 mg; P = 0.008). Treatment patients were ready for discharge approximately 30 min earlier than control patients (P = 0.046). There were no adverse events in the treatment group. In the control group, 2/11 patients vomited and a third experienced transient postoperative diaphoresis, dizziness and pallor.

CONCLUSION

We conclude that a combination of selective pre- and post-surgical wound infiltration with bupivacaine 0.25% provides superior analgesia compared with a standard post-surgical intra-articular injection alone.

The efficacy of intra-articular morphine for postoperative knee arthroscopy analgesia

This article describes two prospective, randomized, double-blind clinical trials designed to investigate this. Trial 1 compared a conventional local anaesthetic agent (100 mg bupivacaine) injected intra-articularly (i.a.) with a control (normal saline) and 1 mg of i.a. morphine. No significant difference was noted in the first 4 hours between the groups with respect to visual analogue pain (VAS) scores. However, at 6 and 24 hours, the group of patients who received 1 mg i.a. morphine recorded lower pain scores and required less supplementary analgesia. Trial 2 assessed the dose response relationship for i.a. morphine comparing 5 mg intravenous (i.v.) morphine (control) with 1 mg and 5 mg i.a. morphine. At early time points (1, 2, and 4 hours) similar VAS pain scores were recorded for both 5 mg i.v. morphine and 5 mg i.a. morphine, both significantly lower than the group receiving 1 mg i.a. morphine. At 6 and 24 hours, 5 mg of i.a. morphine produced significantly lower pain scores, less analgesic requirement, and less sleep disturbance on the first postoperative night than the other groups. It can be concluded from these two studies that 5 mg i.a. was the most effective analgesic following knee arthroscopy.

Local and intra-articular infiltration of bupivacaine before surgery: effect on postoperative pain after anterior cruciate ligament reconstruction

In a double-blind, randomized trial, 40 patients undergoing open anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone autograft were randomly allocated to two groups: group A (n = 20) received an intra-articular instillation of 20 mL bupivacaine (0.25%) and a local infiltration of 20 mL bupivacaine (0.5%) 15 minutes before surgery. Group B (n = 20) received an injection of saline solution in the same manner. Patient-controlled on-demand analgesia (PCA) with intravenous piritramid was used for postoperative pain control. A significant decrease in pain scores on a visual analog scale (VAS scale, 0 to 10) was found in the bupivacaine group (group A) at bedrest on the day of surgery only (pain score, 5.5 v 7.3 (scale, 0 to 10), P < .05). At all other times, no significant differences were found. The overall supplemental opioid requirements were not different between the study groups (63.9 v 62.6 mg piritramid/72 hours). A long-lasting, clinically relevant, pain-reducing effect with infiltration of bupivacaine before surgery could not be shown with this study.

Local anesthesia in outpatient knee arthroscopy: a comparison of efficacy and cost

This study was performed to compare the efficacy, cost-effectiveness, and safety of general, regional, and local anesthesia when performing outpatient knee arthroscopy. The study consisted of two portions. A retrospective review of 256 outpatient knee arthroscopies was performed. The types of anesthesia used were general endotracheal, regional (epidural or spinal), and local. Comparisons were made between operative procedure, anesthesia procedure time, need for supplemental anesthesia, recovery room time and cost, pharmaceutical cost, and complications. A prospective study consisted of 100 consecutive outpatient knee arthroscopies performed using local anesthesia. Data identical to the retrospective portion were obtained. Visual analog scales were used in a patient questionnaire completed at the first postoperative visit to assess patient satisfaction with local anesthesia. The retrospective data showed similar demographics and operative procedures performed in the three study groups. The difference between operative time and total anesthetic time for the local group was 35 minutes less than for regional, and 23 minutes less than for the general group. These differences were statistically significant (P < or = .05). Total pharmaceutical cost was significantly less for the local group (P < or = .05). Recovery room cost for the local anesthesia group averaged $134 compared with $450 for regional and $527 for general. This difference was significant (P < or = .05). There were 19 complications with general anesthesia, 16 with regional anesthesia, and 2 with local. There were two regional and two local cases that needed subsequent general anesthesia. The prospective data showed nearly identical time and cost data. The patient questionnaire showed nearly universal acceptance and satisfaction with the use of local anesthesia. The use of local anesthesia for outpatient knee arthroscopy is safe, effective, and well accepted. The use of local anesthesia was shown to save a minimum of $400 per case compared with the other anesthetic methods studied.

Comparison of intraarticular bupivacaine with the addition of morphine or fentanyl for analgesia after arthroscopic surgery

A randomized study on 30 patients undergoing knee arthroscopy was performed. Group I (n = 15) received 50 mg of 0.25% bupivacaine and 1 mg of morphine, and group II (n = 15) received 50 mg of 0.25% bupivacaine and 100 micrograms of fentanyl. The visual analogue scale was recorded at intervals of 1, 2, 3, 4, 6, 12, 24, and 48 hours after the operation. Supplementary analgesia requirements were also recorded. In group I, pain scores were lower than group II (P < .05) during the 1st, 2nd, 3rd, 12th, 24th, and 48th hours. The duration of analgesia on group I was significantly longer than group II. The combination of intraarticular morphine and bupivacaine has a longer analgesic duration and effect than a combination of fentanyl and bupivacaine.

The effect of intraarticular injection of morphine and bupivacaine on postarthroscopic pain control

This study sought to compare the effects of morphine, bupivacaine, and saline injected into the knee after arthroscopic surgery. In a double-blind, randomized trial, 124 patients received either bupivacaine, morphine, bupivacaine and morphine, or saline at the completion of surgery. Postoperative pain was assessed with a 100-mm visual analog pain scale. Analgesic requirements were calculated, and weightbearing status was recorded. We found that morphine alone injected intraarticularly at the completion of arthroscopic knee surgery had no significant effect on postoperative pain, need for supplemental analgesia, or weightbearing status. Patients receiving morphine in combination with bupivacaine did not demonstrate any statistically significant improvement over those receiving bupivacaine alone. Therefore, our results failed to show any beneficial effect of morphine used for postoperative analgesia, either alone or in combination with bupivacaine. The overall pattern in all patients demonstrated decreased pain scores, decreased analgesic use, and increased weightbearing status as the observation period progressed. Finally, preoperative pain was correlated with pain at discharge, indicating that the most significant predictor of postoperative pain was preoperative level of discomfort.

Analgesic effect of intraarticular morphine, bupivacaine, and morphine/bupivacaine after arthroscopic knee surgery

In a double-blind randomized fashion, 38 patients were divided into four groups according to the intraarticular injection received after arthroscopic surgery. Patients in group I (n = 7) received saline, group II (n = 10) morphine, group III bupivacaine, and group IV (n = 11) morphine and bupivacaine. Before surgery and at 0.5, 1, 1.5, 2, 6, and 24 h postoperatively, pain levels were recorded. In addition, postoperative supplemental i.v. morphine requested by the patient was tabulated. Results showed that the mean consumption of supplemental analgesia was lowest in the morphine/bupivacaine group. Although there was a statistically significant difference in pain scores between the saline group and the other three groups during the early postoperative period, there was no significant difference in pain scores between the morphine, bupivacaine, and morphine/bupivacaine groups. We conclude that postoperative, intraarticular injection of analgesics is beneficial in reducing pain levels. The combination of morphine/bupivacaine appears to be the most beneficial analgesic due to its low supplemental analgesic requirements postoperatively.

Serum bupivacaine concentrations after intraarticular injection for pain relief after knee arthroscopy

Intraarticular injection of local anesthetic drugs after arthroscopic knee surgery is used to provide postoperative analgesia. Toxic serum levels of bupivacaine have been reported after its use both in regional anesthesia and for intraarticular injection. The toxicity of the former is related to needle misplacement and the latter is presumed to be absorptive. This study evaluates the effect of tourniquet inflation and the addition of epinephrine on serum concentrations of bupivacaine after intraarticular injection. The results shows that the peak serum bupivacaine concentrations can be reduced by adding epinephrine and injecting it after tourniquet inflation.