Pain relief in day care arthroscopic knee surgery: A comparison between intra-articular ropivacaine and levobupivacaine: A prospective, double-blinded, randomized controlled study.

BACKGROUND: Post-operative pain frequently hampers implementation of day care arthroscopic knee surgery in spite of so many analgesic, local anesthetic drugs and routes of administration. AIMS: The aim of the present study was carried out to compare the efficacy of ropivacaine and levobupivacaine when administered through intra-articular route in controlling pain after day care arthroscopic knee surgery. SETTING AND
DESIGN: It was a prospective, double-blinded and randomized controlled study.
MATERIALS AND METHODS: April 2008-December 2008, 60 patients of both sex, of American Society of Anesthesiologists physical status I and II, undergoing day care arthroscopic knee surgery were randomly assigned into two groups (R, L). Group R received 10 ml of 0.75% ropivacaine, whereas group L received 10 ml of 0.50% levobupivacaine through intra-articular route at the end of the procedure. Pain assessed using visual analog scale (VAS) and diclofenac sodium given as rescue analgesia when VAS >3. Time of first analgesic request and total rescue analgesic were calculated. STATISTICAL ANALYSIS AND
RESULTS: based on comparable demographic profiles; time for the requirement of first post-operative rescue analgesia (242.16 ± 23.86 vs. 366.62 ± 24.42) min and total mean rescue analgesic requirement was (104.35 ± 18.96 vs. 76.82 ± 14.28) mg in group R and L respectively. Group R had higher mean VAS score throughout the study period. No side effects found among the groups. These two results were clinically and statistically significant (P < 0.05).
CONCLUSION: Hence, it was evident that intra-articular levobupivacaine give better post-operative pain relief, with an increase in time of first analgesic request and decreased need of total post-operative analgesia compared with ropivacaine.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Arthroscopic knee surgery is the one of the most common minimally invasive surgical procedure in modern orthopedic setup. It is commonly performed as an outpatient procedure and is associated with variable amount of post-operative pain, which is caused by irritation of free nerve endings of synovial tissue, anterior fat pad and joint capsule during surgical excision and resection.[1] Undoubtedly, post-operative pain has a negative impact on patient's early mobilization and discharge as well as it causes unanticipated hospital admission particularly in a day care setting.[2] Thus Pain frequently hampers implementation of ambulatory surgery in spite of so many analgesic drugs and regimens. Adequate pain relief reduces surgical stress response, so reduces patient's morbidity and improve post-operative recovery. Several analgesic strategies such as systemic medication (narcotic, non-steroidal anti-inflammatory drugs),[3] central or peripheral nerve block[45] and intra-articular drug administration such as ketorolac,[6] α2 -agonists,[7] opioids,[89] local anesthetics[1011] have been used to interrupt the pain pathway, which is called multimodal approach. However, none is free from limitations such as needs for special equipments, monitoring and risks of complications. Optimal post-operative pain control for day-care surgery should be effective and safe, producing minimal side-effects, facilitating recovery and be easily managed by patients at home.[12]

Utilizing the peripheral receptors for post-operative pain management is an important mode of such approach. Intra-articular route of drug administration is an example for management of pain after joint surgery utilizing the peripheral receptors. It provides analgesia locally with minimal systemic side effects.

Different authors in their previous studies with intra-articular ropivacaine,[1314] fentanyl,[15] dexmedetomidine,[16] levobupivacaine[17] and morphine[17] had proved their efficacy in providing post-operative analgesia in arthroscopic knee surgery.

Ropivacaine is an amino-amide local anesthetic that blocks the peripheral afferents acting on voltage dependent Na+ channels. It is less cardiac and central nervous system (CNS) toxic[18] than other long acting local anesthetics like bupivacaine. It has been used intraarticularly in day-case arthroplasty with varied success rate.[19]

Levobupivacaine, the S-enantiomer of bupivacaine is a comparatively newer local anesthetic agent introduced into clinical practice and it also possesses less cardiac and neural toxicity. Levobupivacaine has been shown to be safe and effective for epidural and spinal anesthesia[20] and blockade of the brachial plexus.[202122]

No direct comparative trials have been performed between these two agents, used intraarticularly at the end of arthroscopic surgery, in a day care set up.

Therefore, the purpose of this clinical investigation was to compare the analgesic efficacy of ropivacaine (0.75%) and levobupivacaine (0.5%) in intra-articular route following day care arthroscopic knee surgery.

MATERIALS AND METHODS

After obtaining permission from Institutional Ethics Committee, written informed consent was taken. A total of 60 adult patients were randomly allocated to two equal groups (n = 30 in each group) using computer generated random number list. American Society of Anesthesiologists physical status I and II, aged between 18 and 60 years of both sexes undergoing elective arthroscopic knee surgery (such as meniscectomy, chondral debridement, loose body removal, diagnostic arthroscopy and lavage, Synovectomy) under spinal anesthesia are included in this study. Selected patients (N = 60) are randomly allocated in two groups (30 patients in each groups). Patients in Group R received 10 ml of 0.75% Ropivacaine. Group L received 10 ml of 0.50% levobupivacaine total volume of the drug was 10 ml in each group.

Exclusion criteria

Patient refusal, any known allergy or contraindication to ropivacaine, levobupivacaine, pregnancy, lactating mothers, hepatic, renal or cardiopulmonary abnormality, alcoholism, diabetes, long-term analgesic therapy, spinal cord deformities, bleeding diathesis, local skin site infections were excluded from the study. As we were dealing with day care surgery patients having no assistance in home and dwelling at more than 10 km from our institution were also excluded from this study.

In pre-operative assessment the patients were enquired about any history of drug allergy, previous operations or prolonged drug treatment. General examination, systemic examinations and assessment of the airway were done. Pre-operative fasting of minimum 6 h was ensured before operation in all day care cases. All patients received premedication of tablet diazepam 10 mg orally the night before surgery as per pre-anesthetic check-up direction to allay anxiety, apprehension and for sound sleep. The patients also received tablet ranitidine 150 mg in the previous night and in the morning of operation with sips of water.

All patients were clinically examined in the pre-operative period, when whole procedure was explained. 10 cm visual analogue scale (VAS) (0, no pain and 10, worst pain imaginable) was also explained during the pre-operative visit. All patients are investigated for Hb%, total leukocyte count, differential leukocyte count, erythrocyte sedimentation rate, platelet count, blood sugar, blood urea, serum creatinine and liver function tests. A 12 lead electrocardiography (ECG) and chest X-ray were also taken. On entering the patient in the operative room standard intra-operative monitors such as ECG, pulse oximeter, non-invasive blood pressure (NIBP) were attached and baseline parameter were recorded. Philips IntelliVue MP20 monitor used for this purpose.

The anesthetic technique was standardized for all patients. Lumber puncture done in a sitting position at L3 and L4 inter-vertebral space in median approach with 26 Gauge spinal needle. Then maintaining sitting position 3 ml of 0.5% hyperbaric Bupivacaine given in the subarachnoid space and placed the patient in the supine position immediately. After 5 min of subarachnoid injection arthroscopic procedure is allowed to start confirming the level of block. During the procedure if any patient needed further dose of analgesia, that patient was excluded from the study. At the end of surgery before skin closure, study drug was administered by the surgeon through port site in the intra-articular space. Tourniquet was kept inflated for another 20 min. Drain put by the surgeon was clamped before administering the study drug and remain clamped for another 15 min. Heart rate, NIBP, respiratory rate, SpO2, ECG and pain VAS were recorded at 1st, 2nd, 4th, 6th,9th, 12th, 16th, 18th and 20th post-operative hours. Injection diclofenac sodium (75 mg IM) was given as rescue analgesia if the pain VAS >3. First post-operative analgesia request time, total diclofenac used in first 20 h were recorded. All data will be collected by an observer who is unaware of patients’ group assignment.

Statistical analysis

Sample size was estimated using time of first analgesic request as the main primary variable. On the basis of previous study assuming within group standard deviation (SD) of 15 min and the true difference in the meantime to the requirement of the first dose rescue analgesic to be 120 min, we needed to study at least 26 patients per group to be able to reject the null hypothesis that the population means of the groups are equal with probability (power) 0.80. Raw data were entered into a MS Excel spreadsheet and analyzed using standard statistical software SPSS® statistical package version 18.0 (SPSS Inc., Chicago, IL, USA). Categorical variables were analyzed using the Pearson's Chi-square test. Normally distributed continuous variables were analyzed using the independent sample t-test and P < 0.05 was considered to be statistically significant.

RESULTS AND ANALYSIS

There were no significant differences between the two groups with regard to demographic data such as age, sex, weight, height and duration of surgery and tourniquet time [Table 1]. Majority of the patient had undergone meniscectomy and other indications of arthroscopy were in Table 2. Time for the request of first post-operative rescue analgesia in Group R (242.16 ± 23.86 min) was shorter compared to Group L (366.62 ± 24.42 min) (P < 0.05) [Table 3, Figure 1]. Total amount of rescue analgesia requirement in first 24 h in the post-operative period was also significantly less in Group L (76.82 ± 14.28) compared to Group R (104.35 ± 18.96) (P < 0.05) [Table 4, Figure 2]. The VAS score was 0 in all the groups at 1st post-operative hour. Compared with Group L, Group R had higher mean VAS score at all the readings up to 9th post-operative hours [Figure 3] which equalized at 12th h. At 16th h reading in group L had higher VAS score. Thereafter VAS increased in group R than L gradually. No incidence of adverse effects such as nausea, vomiting, urinary retention, itching or sedation was observed in any one in the study population.

Table 1

Comparison of demographic data between the two study groups

Table 2

Indications of arthroscopy for randomized patient groups

Table 3

Mean, standard deviation and significance level of duration of post-operative analgesia in minutes

Figure 1

Time of first post-operative analgesia request in Group R (ropivacaine) and Group L (levobupivacaine)

Table 4

Mean, standard deviation and significance level of rescue analgesia required in 20 h (mg)

Figure 2

Total amount of mean rescue analgesia in 20 h as diclofenac sodium IM in Group R (ropivacaine) and Group L (levobupivacaine)

Figure 3

The comparison of visual analog scale score at 1st, 2nd, 4th, 6th, 9th, 12th, 16th, 18th and 20th post-operative hours in Group R (ropivacaine) and Group L (levobupivacaine)

DISCUSSION

Day care surgery has proven over the years as the best method to reduce the burden on the health care resources as well as achievement of extreme patient satisfaction.[23] In developing countries like India, most of the patients avoid bearing expenses of prolonged hospital stay. At the same time infrastructure in our country is not organized uniformly to smoothly deliver the day care procedures. In the present day scenario, pain is the most common medical cause of delayed recovery and discharge after ambulatory surgery and a frequent cause of unplanned admission and subsequently delayed return to work.[24]

Arthroscopic surgical procedures are also associated with variable amount of post-operative pain. Intra-articular route of drug administration has an innovative but important role to provide post-operative analgesia after arthroscopic procedure. Different author in their study have proved the analgesic efficacy of intra-articular ropivacaine,[1314] fentanyl,[15] dexmedetomidine,[16] morphine,[17] levobupivacaine[17] and pethidine.[25] Prolonged post-operative analgesia and decreased requirement of rescue analgesia in intra-articular drug administration may be due to a slower rate of absorption through poorly vascular intra-articular surface. In our prospective double-blinded randomized comparative study we have compared the analgesic efficacy of intra-articular ropivacaine and levobupivacaine following arthroscopic knee surgery.

Ropivacaine is structurally closely related to bupivacaine, the difference being a propyl group instead of a butyl group linked to the piperidine ring. Contrary to racemic bupivacaine, ropivacaine is supplied as the pure S-enantiomer. Compared to racemic bupivacaine, ropivacaine has more lipid solubility, differential blockade and a lower systemic toxicity profile.[26]

Ropivacaine seemed to provide similar and effective post-arthroscopy analgesia compared to bupivacaine, showing less CNS and cardiac toxicity.[27] Samoladas et al. found that intra-articular ropivacaine is effective to reduce post-operative pain minimizing the use of systemic analgesia.[13] This study also said that, intra-articular injection of local anesthetic seems to provide an alternative and effective solution in pain control after knee arthroscopy.

In recent years levobupivacaine, the pure S (−)-enantiomer of bupivacaine, emerged as a safer alternative for regional anesthesia than its racemic parent. It demonstrated less affinity and strength of depressant effects onto myocardial and central nervous vital centers in pharmacodynamic studies. Levobupivacaine demonstrated less affinity and strength of the inhibitory effect onto the inactivated state of cardiac sodium channels[28] than the racemic parent or dextrobupivacaine in in vitro animal tissue experimental studies. The mean (SD) convulsive dose after intravenous levobupivacaine in conscious sheep is 103 (18) mg, significantly higher than the convulsive dose of bupivacaine of only 85 (11) mg.[29] Lower volume of distribution and higher plasma protein binding are two integral properties associated with stereoisomerism which are responsible for its lesser toxicity.[30] A study done by Ersan et al. conducted a comparative study[17] using levobupivacaine 0.5%,10 ml and found that the combination of levobupivacaine and lornoxicam is superior to levobupivacaine alone and the addition of morphine does not improve VAS scores.

In our study, demographic profile as well as indications of surgical procedures were almost similar in both groups and has no statistical significance.

Time for the requirement of first post-operative rescue analgesia in Group R was shorter (242.16 ± 23.86 min) than Group L was (366.62 ± 24.42 min) and the results were statistically as well as clinically significant (P < 0.05). While dealing with 48 total knee arthroplasty patients, Rosen et al. found that intra-articular ropivacaine had not produced any significant change in VAS score and narcotic usage when compared with placebo.[31] Here we had found that levobupivacaine produced prolonged analgesia than ropivacaine when used at intra-articular route.

Total mean rescue analgesia requirement was less in Group L (76.82 ± 14.28 mg) when compared to Group R (104.35 ± 18.96 mg). Group L had higher mean VAS score at 16th post-operative hours, otherwise VAS score in group L was always less than group R which signifies pain in levobupivacaine group was significantly (P < 0.05) less than ropivacaine group. During total knee arthroplasty of 60 patients Kazak Bengisun et al. found that use of levobupivacaine and bupivacaine intraarticularly produced lesser rescue analgesic consumption, lower VAS score, shorter hospital stay and higher patient satisfaction score while compared with placebo.[32]

No side-effects were found among the groups.

It was clearly found that analgesic efficacy of intra-articular levobupivacaine is superior to that of intra-articular ropivacaine in reducing the pain over first 20 h post-operative period, for the patients undergoing ambulatory arthroscopic knee surgery under spinal anesthesia. Further clinical studies are also required to define the optimal analgesic dose of intra-articular levobupivacaine, ropivacaine after arthroscopic procedure. A limitation of our study is that we did not follow-up the patients whether any local tissue damage occurred or not in intra-articular space due to study drugs.

CONCLUSION

Intra-articular levobupivacaine increases the duration of analgesia and decreases the need of rescue analgesic in first post-operative 24 h. Hence intra-articular levobupivacaine shows superior analgesic efficacy when compared with intra-articular ropivacaine following day care arthroscopic knee surgery.