|Year : 2018 | Volume
| Issue : 2 | Page : 86-90
Efficacy of dexmedetomidine as an adjuvant to ropivacaine in femoral nerve block for acute pain relief in patients with fracture of femoral shaft and neck
Hemant Kumar, Archana Tripathi, Mukesh Somvanshi
Department of Anaesthesiology and Critical Care, Government Medical College and Attached Hospitals, Kota -324001, Rajasthan, India
|Date of Web Publication||31-Aug-2018|
Dr. Archana Tripathi
Professor, Department of Anaesthesiology and Critical Care, Government Medical College and Attached Hospitals, Kota - 324001 Rajasthan
Source of Support: None, Conflict of Interest: None
Background: The patients admitted to the emergency department with the fracture of femoral shaft and neck have severe pain, and these patients require adequate analgesia to allow radiological, orthopedic, and other procedures to be performed. Femoral nerve block (FNB) has proved to be effective in providing satisfactory analgesia. Dexmedetomidine has analgesic and sedative property when used as an adjuvant in regional anesthesia. The aim of this study was to evaluate the efficacy of dexmedetomidine added to ropivacaine in FNB with regard to onset, duration, efficacy of analgesia, and patient acceptance. Materials and Methods: Sixty patients of American Society of Anesthesiologists grade I and II of either sex, aged 18–60 years, who presented with the fracture of femoral shaft and neck in the emergency department were randomly divided into two groups of 30 patients each: group D (n = 30): patients were administered 15 mL ropivacaine (0.5%) plus dexmedetomidine 1 μg/kg body weight (total volume, 16 mL) and group R (n = 30): patients were administered 15 mL ropivacaine (0.5%) plus 1 mL saline. Results: The onset of analgesia was much earlier in group D (3.77 ± 0.84 min) than that in group R (4.6 ± 1.1 min). The mean duration of analgesia was prolonged in group D (744.33 ± 179.6 min) than that in group R (263 ± 67 min). The fall in visual analog scale score was significantly higher in group D in comparison to group R. The patient acceptance after 24 h of the procedure was better in group D. Conclusion: We concluded that the addition of dexmedetomidine to ropivacaine in FNB provides early onset of analgesia, prolongs the duration of analgesia, improves the quality of analgesia, and has better patient acceptance.
Keywords: Dexmedetomidine, femoral nerve block, ropivacaine, visual analog scale scores
|How to cite this article:|
Kumar H, Tripathi A, Somvanshi M. Efficacy of dexmedetomidine as an adjuvant to ropivacaine in femoral nerve block for acute pain relief in patients with fracture of femoral shaft and neck. Indian J Pain 2018;32:86-90
|How to cite this URL:|
Kumar H, Tripathi A, Somvanshi M. Efficacy of dexmedetomidine as an adjuvant to ropivacaine in femoral nerve block for acute pain relief in patients with fracture of femoral shaft and neck. Indian J Pain [serial online] 2018 [cited 2020 May 28];32:86-90. Available from: http://www.indianjpain.org/text.asp?2018/32/2/86/240281
| Introduction|| |
In this era of trauma and increasing mechanization, a significant number of patients are encountered with the fracture of femoral shaft and neck, and they have severe pain, anxiety, and agony. These patients require adequate analgesia to allow radiological, orthopedic, and other procedures to be performed.
The patients with the fracture of femoral shaft and neck present special problems to the physician. The fracture of femoral shaft is subjected to major muscle forces that can deform the thigh and angulate the bone fragment, which in turn can lead to difficulty in reduction of the fracture. Therefore, complete paralysis of all the muscles acting on the femur is mandatory for the reduction of fracture. Pain causes spasm of the thigh muscles, leading to the displacement of the broken bone ends, and so adds on to a vicious cycle of more pain and consequent spasms. This produces a state of neurogenic shock, which might aggravate an already existing hypovolemic shock from occult blood loss into the thigh at the fracture site.
An ideal analgesic technique should provide relief of pain without any change in consciousness. It should have localized effect, that is, only at the site where actual analgesia is required and should not produce systemic side effects such as nausea, vomiting, hypotension, and respiratory depression. Femoral nerve block (FNB) is reported to provide good analgesia in the patients with the fracture of femoral shaft and neck.
Dexmedetomidine (alpha-2 adrenergic agonist) has analgesic and sedative property when used as an adjuvant to ropivacaine in regional anesthesia. The faster onset of action of local anesthetics, rapid establishment of both sensory and motor blockades, prolonged duration of analgesia, and stable cardiovascular parameters make this agent a very effective adjuvant in regional anesthesia.
The purpose and aim of this study was to evaluate the efficacy of dexmedetomidine added to ropivacaine in FNB with regard to onset, duration and efficacy of analgesia, degree of sedation, hemodynamic variations, patient acceptance after 24 h, and side effects.
| Materials and Methods|| |
This study was conducted on 60 patients of American Society of Anesthesiologists (ASA) grade I and II of either sex, aged 18–60 years, who presented with the fracture of femoral shaft and neck in the emergency department, after obtaining approval from the institutional ethics committee and written informed consent from the patients. Random sampling was carried out for the distribution of patients into two groups of 30 patients each: group D (n = 30)–patients were administered 15 mL ropivacaine (0.5%) plus dexmedetomidine 1 μg/kg body weight (total volume, 16 mL) and group R (n = 30)–patients were administered 15 mL ropivacaine (0.5%) plus 1 mL saline (total volume, 16 mL). The study solutions looked identical and were prepared by an anesthesiologist who did not participate in the study.
The patients with known hypersensitivity to local anesthetic agents; bleeding disorders; preexisting polyneuropathy; pregnant women; cardiorespiratory, metabolic, endocrinal, hepatic, and renal disorders; and head injury were excluded from the study.
All the patients in this study were subjected to a thorough preanesthetic checkup. Complete general physical examination and ASA grading were carried out. The purpose and procedures were explained to the patients. Visual analog scale (VAS) for pain assessment was also explained to the patients. FNB was administered by the classical approach of LABAT technique. An intravenous (IV) line was secured before performing the block. Standard monitoring was carried out using multiparameter monitor for pulse rate, noninvasive blood pressure (BP), and pulse oximetry. Under all aseptic precautions, painting and draping of the required part was carried out. The anesthesiologist stood on the same side of the fractured limb of the patient. The femoral artery was palpated immediately below the inguinal ligament. A line was drawn from the anterior superior iliac spine to the pubic symphysis to approximate the inguinal ligament. A 20G IV cannula was advanced 1–1.5 cm lateral to the femoral pulsation and 1–1.5 cm below the inguinal ligament. Direction of the cannula was kept cephalad toward the center of the inguinal ligament line at an angle of approximately 30°–45°. Two distinct “pops” felt as the fascia lata and fascia iliaca were crossed. Cannula was advanced further until paresthesia was elicited. Following negative aspiration, 16 mL of a solution containing ropivacaine combined with normal saline or dexmedetomidine as mentioned earlier was injected. Then the patients were observed and evaluated for selected parameters at specific time intervals. Onset of analgesia was recorded by the subjective feeling of heaviness, tingling, and numbness of the limb after successful deposition of local anesthetic drug. Intensity of pain was measured using a 10-cm VAS (where, 0 = no pain and 10 = worst possible pain). VAS scores were recorded before the block, just after the block at 5 min, then at an interval of 5 min up to 15 min, after that at 30 min and 60 min, and thereafter at a 60-min interval up to 360 min followed by every 120 min up to 720 min. The duration of analgesia was considered as the time from the placement of block till the administration of rescue analgesia. Pulse rate, BP level, and respiratory rate were monitored at the same time interval as the VAS score. Sedation was assessed by a modified Ramsay Sedation Scale. The degree of sedation was also recorded at the time of VAS score recording. The patients were interviewed 1 day after the procedure, and the patient acceptance and satisfaction were noted. The response of the patient to the whole procedure was graded using a three-point scale where, 1 = good, 2 = fair, and 3 = poor. All the patients were observed for side effects such as discomfort, nausea, vomiting, bradycardia, tachycardia, and hypotension, and complications such as hematoma, infection, and postblock neuropathy. Statistical analysis was performed using Student's t-test. A P value < 0.05 was considered statistically significant.
| Results|| |
The demographics of the patients, such as age, weight, and gender, were comparable in both the groups [Table 1]. No significant differences in the pre-procedural parameters of the patients between both the groups (P > 0.05) were observed [Table 2]. The onset of analgesia was earlier in group D (3.77 ± 0.84 min) as compared to group R (4.6 ± 1.1 min), and the difference was statistically significant (P < 0.05). The duration of analgesia was significantly longer in group D (744.33 ± 179.6 min) than that in group R (263.1 ± 67.24 min), and the difference was highly significant (P < 0.05). The VAS score at 5 min after the block was significantly decreased to 3.63 ± 1.04 in group D and 4.56 ± 1.33 in group R as compared to the basal value and remained low during the study period [Figure 1]. In group D, the sedation score increased to maximum mean sedation score 2.5 ± 0.5 at 60 min after the block, whereas in group R, it increased to maximum sedation score 2.0 ± 0 at 10 min after the block, which remained stable during the study period. Mean doses of rescue analgesic was much less in group D (2 ± 0.06) as compared to group R (3.3 ± 0.6), and the difference was statistically significant [Table 3]. When interviewed after 1 day of procedure, a significant number of patients graded the analgesia as good in group D in comparison to group R [Table 4]. We did not find any case of failed FNB.
Pulse rate, systolic blood pressure (SBP) level, and diastolic blood pressure (DBP) level significantly decreased in both the groups as compared to preblock. However, all the patients in both the groups remained hemodynamically stable during the study period [Figure 2], [Figure 3], [Figure 4]. During our study period, we did not observe any complications and side effects.
| Discussion|| |
Although block of femoral and sciatic nerves to produce analgesia of the lower limb was described as early as 1902 by Crile G, it was Fenwick who introduced the method at the Sydney Hospital in 1957, and since then it has gradually gained popularity. It provides adequate analgesia in the patients with the fracture of femoral shaft.
Femoral nerve analgesia has various advantages. It provides adequate pain relief and minimizes muscle spasm within a short time, decreases pain during radiological procedures, which necessitates patient movement, and the fracture can be reduced and splinted without the need for general anesthesia in the acute phase. It is quick and easy to perform with minimum equipment, and as blockade is unilateral, no risk of hemodynamic alteration is observed.
Various researches have been conducted for FNB with local anesthetic agents for pain relief in the fracture of femoral shaft and neck with good results, but the duration of analgesia and patient acceptance is still not sufficient to avoid the use of another modality of analgesia (opioids or nonsteroidal anti-inflammatory drugs). Various adjuvant drugs such as epinephrine, opioids, midazolam, ketamine, and neostigmine have been evaluated in conjunction with local anesthetics to prolong the duration of analgesia, but they were found to be either ineffective or to produce an unacceptably high incidence of adverse effects.
Alpha-2 adrenergic agonists have analgesic and sedative property when used as an adjuvant in regional anesthesia. The faster onset of action of local anesthetic, rapid establishment of both sensory and motor blockades, prolonged duration of analgesia, and stable cardiovascular parameters make these agents a very effective adjuvant in regional anesthesia.
Centrally mediated analgesia, α2B-adrenoceptor-mediated vasoconstrictive effects, attenuation of the inflammatory response, and direct action on a peripheral nerve are some of the proposed mechanisms for the action of α2-adrenoceptor agonist in peripheral nerve blockades.
The direct action of α2-adrenoceptor agonists on the nerve can be explained on the basis of a study by Dalle et al. on the C nerve fibers of rabbit nerves. They concluded that α2-adrenoceptor agonist enhances activity-dependent hyperpolarization by inhibiting the hyperpolarization-activated cation (Ih) current. The Ih current plays a key role in cell excitability, especially the firing frequency, in both the central and peripheral nervous systems. The Ih current is activated during the hyperpolarization phase of an action potential and normally acts to reset a nerve for subsequent action potentials. Therefore, by blocking the Ih current, α2-adrenoceptor agonist enhances hyperpolarization and inhibits subsequent action potentials.
In this study, we found a significantly rapid onset of block with longer duration of analgesia in group D as compared to group R. Sharma et al. and Helal et al. also found early onset and prolonged duration of analgesia when dexmedetomidine was added to local anesthetic in FNB.
We observed significant fall in VAS scores, which occurred after the FNB in both the groups. Similarly, Kullenberg et al. and Somvanshi et al. also found significant fall in VAS scores after FNB with ropivacaine. However, the addition of dexmedetomidine to ropivacaine caused more significant fall in VAS scores because of its analgesic action.
In our study, the sedation scores were significantly higher in group D as compared to group R. This suggests that dexmedetomidine produced good sedation in a significant number of patients, who were arousable by gentle tactile stimulation. This was in agreement with the results of the studies by Sharma et al., Memiş et al., and Kaygusuz et al., who also observed good sedation when dexmedetomidine was added to local anesthetics in peripheral nerve block.
When the patients were interviewed 24 h after the procedure, in group D, of 30 patients, 27 (90%) graded the FNB as good, whereas in group R, only 20 (66.66%) patients graded the FNB as good. Similarly, Somvanshi et al. also found 86% of patient acceptability for this technique.
We observed significant fall in the mean pulse rate, SBP, and DBP levels as compared to the basal value in both the groups, and the fall in these parameters was much more in group D than in group R. This might be due to systemic absorption of dexmedetomidine from the site of drug administration, which inhibits sympathetic activity, better analgesia over pain (low VAS score), and sedation. During the study period, all the patients in both the groups remained hemodynamically stable.
Limitation of our study was the absence of peripheral nerve stimulator (PNS) or ultrasound to perform FNB. Although PNS or ultrasound-guided FNB is reported to be safe with minimum failure rate as they provide better localization of nerve, we have used conventional blind technique of paresthesia elicitation to perform the FNB as we are not having PNS or ultrasound in our setup, and FNB is routinely administered to the patients presenting with the fracture of femoral shaft and neck at the emergency department in our institute. In spite of the use of conventional blind technique, we did not observe any failed FNB or injury to the nerve in our study.
On the basis of the results obtained from this study on FNB, we hypothesized that FNB provides almost total pain relief and abolition of muscle spasm within few minutes. Comparable analgesia could only be achieved with large dose of narcotics, which may cause respiratory depression. Least possibility of systemic reaction is observed, and it does not obscure signs and symptoms of other trauma; hence, the assessment of the patient is not interfered. Pain during radiological procedures, which necessitates patient's movement can be minimized. These patients are mostly unprepared for general anesthesia so the fracture can be reduced and splinted under nerve block analgesia without the need for general anesthesia in acute phase. It is quick and easy to perform with minimum equipment. When dexmedetomidine is added to local anesthetics in FNB, it causes early onset of analgesia, prolongs the duration of analgesia, enhances quality of analgesia, provides better hemodynamic stability leading to better patient acceptance, decreases rescue analgesic requirement in 24 h, and provides mild sedation that decreases anxiety and apprehension.
Thus, we recommend the routine use of FNB for the patients having fracture of femoral shaft and neck presenting in the emergency ward.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]