Perineural Dexmedetomidine Reduces the Median Effective Concentration of Ropivacaine for Adductor Canal Block

[A prospective comparative study on effectiveness of single versus continuous adductor canal block combined with local infiltration anesthesia in unicompartmental knee arthroplasty]

Objective

To compare the early analgesic effects and the impact on knee joint function recovery after unicompartmental knee arthroplasty (UKA) between single adductor canal block (SACB) and continuous adductor canal block (CACB) combined with local infiltration anesthesia (LIA) using a prospective study.

Methods

The patients with knee osteoarthritis admitted between April 2022 and December 2023 were enrolled as a subject. Among them, 60 patients met the selection criteria and were enrolled in the study. They were randomly assigned to the SACB group or CACB group in a ratio of 1:1 using a random number table method. There was no significant difference between the two groups ( P>0.05) in terms of age, gender, height, body mass, body mass index, affected side, and preoperative resting visual analogue scale (VAS) score and active VAS score, Oxford knee score (OKS), and American Hospital of Special Surgery (HSS) score. All patients received multimodal analgesia management using LIA combined with SACB or CACB. The operation time, pain related indicators (resting and activity VAS scores, number and timing of breakthrough pain, opioid consumption), joint function related indicators (quadriceps muscle strength, knee range of motion, OKS score, and HSS score), as well as postoperative block complications and adverse events were recorded and compared between the two groups.

Results

There was no significant difference in the operation time between the two groups ( P<0.05). All patients in the two groups were followed up with a follow-up time of (9.70±4.93) months in the SACB group and (12.23±5.05) months in the CACB group, and the difference was not significant ( P>0.05). The CACB group had a significant lower resting VAS score at 24 hours after operation compared to the SACB group ( P<0.05). There was no significant difference in resting and active VAS scores between the two groups at other time points ( P>0.05). The CACB group had a significantly lower incidence of breakthrough pain compared to the SACB group [9 cases (30.00%) vs. 17 cases (56.67%); P<0.05). However, there was no significant difference in the timing of breakthrough pain occurrence and opioid consumption between the two groups ( P>0.05). Four cases in the SACB group and 7 cases in the CACB group experienced adverse events, with no significant difference in the incidence of adverse events between the two groups ( P>0.05). The CACB group had significantly better knee joint mobility than the SACB group at 1 and 2 days after operation ( P<0.05). There was no significant difference between the two groups in knee joint mobility on 0 day after operation and quadriceps muscle strength and OKS and HSS scores at different time points ( P>0.05).

Conclusion

In UKA, the analgesic effects and knee joint function recovery are similar when compared between LIA combined with SACB and LIA combined with CACB. However, SACB is simpler to perform and can avoid adverse events such as catheter displacement and dislocation. Therefore, SACB may be a better choice.

Adductor Canal Block Versus Local Infiltration Analgesia for Postoperative Pain Management in Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a common surgical procedure for patients with knee osteoarthritis, often associated with postoperative pain. Effective pain management strategies are essential for improving patient outcomes and satisfaction. This study aimed to compare the efficacy of two analgesic modalities, local infiltration analgesia (LIA) and adductor canal block (ACB), in providing postoperative pain relief for patients undergoing TKA.

METHODS

This prospective randomized comparative study included 60 patients undergoing TKA for knee osteoarthritis under subarachnoid block (spinal anaesthesia). Patients were divided into two groups: LIA group (local wound infiltration with periarticular injection of bupivacaine 0.125% + dexmedetomidine 1 mcg/kg) and ACB group (ACB with bupivacaine 0.125% + 1 mcg/kg dexmedetomidine). Pain relief was assessed using the Numerical Rating Scale (NRS) score, time to first rescue analgesic requirement (NRS > 3), and total amount of analgesic needed in the first 24 hours post-surgery.

RESULTS

The time to first perception of pain with NRS > 3 was 11.30±0.8 hours in the ACB group and 9.40 ± 1.1 hours in the LIA group, with a statistically significant difference (p < 0.001). Additionally, the total number of rescue analgesic doses given in the first 24 hours post-operatively differed significantly between the two groups (p = 0.046).

CONCLUSION

The study concludes that ACB is an effective postoperative analgesic modality, superior to local infiltration analgesia, for patients undergoing TKA.

Dexmedetomidine as an Adjuvant in Peripheral Nerve Block

Peripheral nerve block technology is important to balanced anesthesia technology. It can effectively reduce opioid usage. It is the key to enhance clinical rehabilitation as an important part of the multimodal analgesia scheme. The emergence of ultrasound technology has accelerated peripheral nerve block technology development. It can directly observe the nerve shape, surrounding tissue, and diffusion path of drugs. It can also reduce the dosage of local anesthetics by improving positioning accuracy while enhancing the block's efficacy. Dexmedetomidine is a highly selective drug α₂-adrenergic receptor agonist. Dexmedetomidine has the characteristics of sedation, analgesia, anti-anxiety, inhibition of sympathetic activity, mild respiratory inhibition, and stable hemodynamics. Numerous studies have revealed that dexmedetomidine in peripheral nerve blocks can shorten the onset time of anesthesia and prolong the time of sensory and motor nerve blocks. Although dexmedetomidine was approved by the European Drug Administration for sedation and analgesia in 2017, it has not yet been approved by the US Food and Drug Administration (FDA). It is used as a non-label drug as an adjuvant. Therefore, the risk-benefit ratio must be evaluated when using these drugs as adjuvants. This review explains the pharmacology and mechanism of dexmedetomidine, the effect of dexmedetomidine on various peripheral nerve block as an adjuvant, and compare it with other types of adjuvants. We summarized and reviewed the application progress of dexmedetomidine as an adjuvant in nerve block and look forward to its future research direction.

[Research progress on analgesic effect of adductor canal block after knee arthroplasty]

Objective

To summarize the research progress of the analgesic effect of adductor canal block (ACB) applied to knee arthroplasty, in order to find the ACB mode that can obtain better effectiveness.

Methods

The research progress of the analgesic effect of ACB after knee arthroplasty was reviewed by widely consulting the related literature on ACB at home and abroad in recent years.

Results

In recent years, multimodal analgesia has become the mainstay of postoperative pain management after knee arthroplasty. Among these, ACB replaces the once "gold standard" femoral nerve block (FNB) by offering comparable and effective analgesia with better preservation of quadriceps function. It is generally safe and efficient to use 0.2% ropivacaine ACB with initial loading doses of 15-30 mL and continual loading doses of less than 8 mL/hour to give analgesia comparable to FNB with minimal impact on lower extremity muscular strength. However, the risk of patient falls must still be taken into consideration by medical staff. Adjuvants like dexmedetomidine and dexamethasone used in ACB can increase the analgesic duration and postoperative analgesic impact. As a perineural adjunct for ACB, 1 µg/kg dexmedetomidine may strike a balance between safety and analgesic efficacy.

Conclusion

ACB is a safe and effective analgesia method after knee arthroplasty. The adductor canal anatomy, the optimum blocking strategy and blocking site of ACB are all hotly debated and still require additional study due to the significant variety of the nerve structures in adductor canal.

Intravenous versus perineural dexmedetomidine in prolongation of analgesia with regional anesthesia: a meta-analysis and systematic review

Background and Objective. It is unclear whether perineural administration offers advantages when compared to intravenous dexmedetomidine in local anesthesia. To compare the efficacy of perineural versus intravenous dexmedetomidine as local anesthetic adjuvant, we conducted the meta analysis and systematic review. Materials and Methods. Two researchers searched MEDLINE, OVID, PubMed, Embase, Cochrane Central, Web of Science and Wanfang data for randomized controlled trials comparing the effect of intravenous versus perineural dexmedetomidine as local anesthetic adjuvant without any language restrictions. Results. We identified 14 randomized controlled trials (801 patients). The results revealed that the duration of analgesia (SMD: -1.76, 95 % CI, [-2.7, -0.83] P = 0.000, I2 = 96 %), the duration of sensory block (SMD:- 3.99, 95 % CI, [-5.88, -2.0], P = 0.000, I2 = 97.6 %), the duration of motor block (SMD: -1.6, 95 % CI, [-2.78, -0.41] P = 0.008, I 2 = 95.5 %) were significantly longer in the perineural group, when compared to systematic dexmedetomidine. The onset time of sensory block (SMD: 1.55, 95 % CI, [0.16, 2.94] P = 0.028, I2 = 96.7 %) and the onset time of motor block (SMD: 0.84, 95 % CI, [0.17, 1.5] P = 0.013, I2 = 88.3 %) were shorter in perineural group compared to intrave nous dexmedetomidine. Meanwhile, analgesic consumption in 24 hours (SMD: 0.37, 95 % CI, [0.05, 0.69] P = 0.023, I 2 = 55.6 %) and the incidence of patients of Ramsay Sedation Scale > 3 (RR: 3.8, 95 % CI, [1.45, 9.97] P = 0.000, I 2 = 26.9 %), hypotension (RR: 1.74, 95 % CI, [1.15, 2.65] P= 0.009, I2 = 32.7 %) and bradycardia (RR: 3.71, 95 % CI, [1.27, 10.86] P = 0.017, I2 = 0 %) were lower in perineural dexmedetomidine compared to the intravenous group. Conclusions. Our meta-analysis generates the evidence that perineural dexmedetomidine is a superior adminstration for prolonging the duration of analgesia. Perineural dexmedetomidine also shows the advantages in duration of sensory block and the onset time of sensory and motor block, when compared to the intravenous administration. Simultaneously, dexmedetomidine as a local anesthetic adjuvant for perineural injection may be much safer than intravenous application because of the lower incidence of patients of Ramsay Sedation Scale > 3 and lower incidence of hypotension and bradycardia.

Ropivacaine as the drug of choice for regional anesthesia: why so?

While writing the article, we analyzed all the studies related to ropivacaine for the first half of 2021, which were published in PubMed. Previous review articles on ropivacaine were also analyzed. Purpose: collection and analysis of the latest research results on ropivacaine. Assessment of the place of ropivacaine in modern regional anesthesia.