Comparison of ropivacaine, bupivacaine, and lignocaine in femoral nerve block to position fracture femur patients for central neuraxial blockade in Indian population

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Acute Crit Care. 2024;39(2):275-281

Publication date (electronic) : 2024 May 2

doi : https://doi.org/10.4266/acc.2023.01606

Manik Seth, Santvana Kohli, Madhu Dayal, Arin Choudhury

Department of Anesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India

Corresponding Author: Santvana Kohli Department of Anesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjung Hospital, 383, Air Force and Naval Officers’ Enclave, Sector-7, Plot-11, Dwarka, New Delhi, India Tel: +91-78-3843-4398 Email: dr.santvana.kohli@gmail.com

Received 2023 December 12; Revised 2024 March 19; Accepted 2024 March 28.

Abstract

INTRODUCTION

One of the common causes of hospital admissions in the elderly is fractures resulting from falls, especially femoral neck fractures. There were an estimated 1.66 million hip fractures worldwide in 1990. According to the epidemiologic projections, this worldwide annual number will rise to 6.26 million by the year 2050 [1]. A study on hip fracture incidence performed in the Rohtak district of north India, the most populous country in the world, reported a crude incidence above the age of 50 years of 129 per 100,000 [2]. The corresponding figures were 105 and 159 per 100,000 men and women, respectively.

The vast majority of femur fractures are treated by surgical repair, which is usually conducted under regional anesthesia. Central neuraxial blockade (CNB) is a widely accepted anesthetic technique for these cases [3]. However, positioning for CNB can be extremely painful for patients, resulting in sympathetic activation and a subsequent increase in cardiac work load that may compromise high risk cardiac patients. Effective management of pain is important for patient comfort and to facilitate the performance of the CNB. Pain management in femur fracture patients has traditionally been based on systemic opioids, which have multiple adverse effects in frail and elderly patients. Blockade of the femoral nerve has been proposed as an alternative [4-8]. Femoral nerve block (FNB) produces good analgesia with very few side effects compared to opioids and non-steroidal anti-inflammatory drugs.

Most studies have reported using lignocaine for FNB. Lignocaine is an intermediate acting local anesthetic (LA) agent. Bupivacaine provides a longer duration of action, but has potentially life-threatening cardiac toxicity. Ropivacaine has emerged as a new and safer alternative to bupivacaine. Ropivacaine has a greater degree of motor sensory differentiation, resulting in a relative reduction in motor blockade and less cardiac toxicity than bupivacaine [9]. Few studies, however, have directly compared the effectiveness of ropivacaine with other LAs in patients with femur fractures in terms of satisfactory analgesia and ease of positioning prior to CNB.

MATERIALS AND METHODS

This prospective, randomized interventional study was conducted in a tertiary care teaching institute (Vardhman Mahavir Medical College and Safdarjung Hospital) over a period of 1 year after approval from the Institutional Ethics Board (IEC/VMMC/SJH/Thesis/October/2017-029, dated 30.10.2017). Informed written consent was obtained.

All American Society of Anesthesiologists grade I and II patients between 18 and 75 years who were scheduled to undergo surgery for fracture neck femur and who consented to be a part of the study were included. Patients excluded from the study were those who had no baseline pain (visual analog scale [VAS] score <4), any contraindications to CNB, known allergy to LA agents, those requiring fixation of multiple fractures and therefore general anesthesia, those with pre-existing peripheral neuropathies, inflammation or infection over the femoral injection site, or those with impaired cognition or dementia making assessment of pain difficult.

After a detailed pre-anesthetic check-up, complete systemic examination and relevant investigations, the purpose and protocol of the study were explained to patients. Patients were told to rate their pain on a scale of 0–10 where 0 denoted no pain and 10 denoted the worst pain imaginable (VAS). No sedative premedications were prescribed. Upon arrival in the premedication room adjoining the operating room (OR), standard monitoring was performed, and an intravenous (IV) line was secured.

Patients were randomized into three groups by a computer-generated randomization algorithm. All patients received ultrasound guided FNB prior to transfer to the main operating theatre. The test drug in group B was 15 ml of 0.25% bupivacaine, while that in group R was 15 ml of 0.5% ropivacaine and in group L was 15 ml of 1.5% lignocaine. Drugs were prepared by a physician other than the one performing the block. Sensory blockade was evaluated at 5-minute intervals after performing the block using loss of perception to pinprick in the anterior and medial parts of the thigh (corresponding to femoral nerve sensory distribution).

Sensory block was graded as follows [10]. Grade 0 (block failure): sharp pin felt even after 30 minutes;

grade 1: analgesia, dull sensation felt; grade 2: anesthesia, no sensation felt. After achieving sensory loss as evaluated by skin pinprick, the patient was moved to the OR where CNB was administered in a sitting position.

VAS scores were noted before the block, after achieving complete block, and during positioning for CNB. If a patient reported VAS score ≥4 during positioning, the procedure was stopped, and IV fentanyl 0.5 μg/kg was given every 5 minutes until the patient’s pain score decreased to <4 or up to a maximum dose of 3 μg/kg (whichever came first). If a pain score <4 could not be achieved, patients were excluded from the study. Positioning was reattempted after reduction of VAS to <4. VAS score during patient positioning and the quality of the position were recorded by the anesthesiologist administering the CNB. Duration of time to achieve VAS was recorded, as was the performance time (defined as the time from the beginning of patient positioning to the end of the performance of CNB). Patient positioning was evaluated as 0 (unsatisfactory) or 1 (satisfactory).

Intraoperative monitoring of relevant parameters such as heart rate, non-invasive blood pressure, and oxygen saturation was done. Any episode of hypotension (decrease in mean arterial pressure, mean arterial pressure more than 20% of the baseline value) or bradycardia (heart rate less than 60/min) were noted and managed. Following surgery, all patients were transferred to the postanesthetic care unit, where standard monitoring was performed. Patient experience with FNB was evaluated 24 hours later, in the orthopedics ward, using a two-point score: 0, bad, I will never repeat it; 1, good, if necessary, I would repeat it.

RESULTS

A total of 75 patients were included in the study: 25 each in groups B, R. and L (Figure 1). The demographic profile of the study population is described in detail in Table 1, along with group-wise distributions. There were no significant differences in patient characteristics among the three groups (P>0.05). Preoperative vital parameters are presented in Table 2; these were also comparable among the three test groups.

Figure 1.

Flowchart for patients selection and division into study groups. FNB: femoral nerve block.

Table 1.

Demographic characteristics of the patient population with group-wise division

Table 2.

Preoperative vitals parameters of the study population with group-wise division

Patients were assessed preoperatively using VAS before FNB intervention and at the time of positioning patients for CNB after FNB. No case of block failure was observed in any test subject. Differences in VAS scores before and after FNB are presented in Table 3 for the three groups. Scores were comparable before FNB; however, after the intervention, statistically significant differences were found in VAS scores between groups (bupivacaine vs. ropivacaine and bupivacaine vs. lignocaine comparisons, but not the ropivacaine vs. lignocaine comparison). Percentage decrease in VAS was highest in group R (82.8%) followed by groups L (81.5%) and B (52.4%). Time to achieve a VAS less than 4 was 26.2±2.4 minutes in group B, 8.5±1.9 minutes in group R, and 4.1±0.7 minutes in group L. Differences among the three groups were statistically significant, as shown in Table 3.

Table 3.

Group-wise comparison of FNB onset, quality, improvement in VAS and time to perform neuraxial block

Grade 1 sensory block was achieved in all patients in all groups. Grade 2 sensory block was achieved in all patients in groups R and L. In group B, it was achieved in only 13 patients (52%). There were statistically significant differences in groups B vs. R and B vs. L. Average time taken to achieve grade 1 sensory block was 11.7±1.8 minutes in group B, 3.9±0.5 minutes in group R, and 2.4±0.3 minutes in group L. Average time for grade 2 sensory block to set in was 26.2±2.4 minutes in group B, 8.7±1.5 minutes in group R, and 4.1±0.7 minutes in group L. These differences among groups were statistically significant (Table 3).

Regarding the requirement of fentanyl for positioning for CNB, there were statistically significant differences in groups B vs. R and B vs. L; 12 (48%) patients in group B required additional fentanyl, while no patients in groups R or L required fentanyl. Average time required to perform CNB was 9.9±1.3 minutes in group B, 8.8±0.8 minutes in group R, and 8.3±0.7 minutes in group L (Table 3). There were significant differences in groups B vs.. R (P=0.002), B vs. L (P<0.001), and R vs. L (P=0.038). Patient positioning was satisfactory in all patients in groups R and L, while in group B it was satisfactory only in 13 patients. There were significant differences between groups B and R, as well as B and L. Patient acceptance of FNB was 100% in groups R and L, while in group B only 16 patients (64%) considered the experience to be good. This difference in acceptance was statistically significant (B vs. R, P=0.002 and B vs. L, P=0.002). No vascular punctures occurred nor were there any indications of systemic toxicity such as seizures, arrhythmias, cardiovascular collapse, hypotension, or bradycardia among patients in our study.

DISCUSSION

Advancements in the field of healthcare have increased the average life expectancy worldwide. The incidence of hospital visits by geriatric patients with health problems such as fractures resulting from falls is increasing along with the increase in size world-wide of the geriatric population. Analgesia during positioning of femur fracture patients has traditionally relied on systemic opioids. Blockade of the femoral nerve was proposed as an alternative method of pain control in such situations to avoid the side effects of opioids as early as 1977 [6]. The benefits of femoral nerve blockade have been corroborated in multiple studies. Sia et al. [7] conducted a randomized study in femur fracture patients undergoing surgery under neuraxial blockade. They compared the ease and comfort of positioning during spinal anesthesia of FNB versus IV fentanyl and concluded that FNB was more advantageous. Similarly, Jadon et al. [8] reported significantly better patient satisfaction and lower VAS scores when lignocaine-based FNB was given prior to positioning during spinal anesthesia in fracture femur patients as compared to IV fentanyl.

Many researchers have compared various LA agents in FNB performed for primary surgery. Fanelli et al. [11] conducted a double-blind study comparing 0.75% ropivacaine, 0.5% bupivacaine, and 2% mepivacaine for sciatic and femoral block for elective hallux valgus repair. The authors concluded that 0.75% ropivacaine was the most suitable choice of LA, with an onset similar to that of mepivacaine and postoperative analgesia intermediate between bupivacaine and mepivacaine. Similar to our study findings, the onset of sensory and motor blockade with ropivacaine was significantly shorter than with bupivacaine. However, the duration of postoperative analgesia was longer with both bupivacaine and ropivacaine, which may be due to both sciatic and femoral block in their study versus FNB only in our study, as well as the nature of the surgery. Similar findings were reported in a multicenter study conducted by the Italian Society of Anesthesia [12] of patients undergoing foot and ankle surgery under sciatic-femoral block with increasing doses of ropivacaine (0.5%, 0.75%, and 1%) and 2% mepivacaine. The authors concluded that 0.75% ropivacaine was the most suitable choice of LA for sciatic-femoral block, with an onset similar to mepivacaine and prolonged postoperative analgesia.

Kuthiala and Chaudhary [13] published a review article in which they reported that ropivacaine was a well-tolerated regional anesthetic agent, effective for surgical anesthesia as well as the relief of postoperative and labor pain. The efficacy of ropivacaine was similar to that of bupivacaine and levobupivacaine for peripheral nerve blocks. Clinically adequate doses of ropivacaine appear to be associated with a lower incidence or grade of motor block than bupivacaine. Thus, ropivacaine, with its efficacy, lower propensity for motor block, and reduced potential for CNS toxicity and cardiotoxicity, appears to be a favorable option for regional anesthesia and management of postoperative pain.

The power of our study lies in its novelty. There is a paucity of literature comparing different LA agents in FNB given prior to positioning for CNB of painful fractures. Previous studies [11,12] have compared LA agents for lower limb blocks performed for surgical procedures. Second, our outcome measures included objective criteria such as VAS score and time to performance of block, as well as subjective criteria such as patient feedback. This allowed for comprehensive comparison of LAs as described above. There are certain limitations to our study that should be taken into consideration. The sample size was small due to the limited duration of the study. The anesthesiologist performing the FNB could not be kept constant due to staffing reasons and rotational postings. Studies with different concentrations of each drug need to be conducted to determine the ideal concentration for sensory blockade.

Based on our findings, we conclude that FNB with 0.5% ropivacaine before positioning for CNB provides good pain management and facilitates performance of CNB with excellent patient acceptance, hence improving overall quality and efficiency of care. Ropivacaine exhibits a faster onset of action than bupivacaine and a longer duration of action than both lignocaine and bupivacaine, with a better safety profile than bupivacaine.

KEY MESSAGES

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