|Year : 2020 | Volume
| Issue : 2 | Page : 116-123
Comparison of efficacy of intrathecal dexmedetomidine and magnesium sulfate as an adjuvant to 0.5% hyperbaric bupivacaine in patients undergoing infraumbilical surgeries under spinal anesthesia
Kavita Jain, Surendra K Sethi, Rahul Jain
Department of Anaesthesiology, J.L.N. Medical College and Hospital, Ajmer, Rajasthan, India
|Date of Submission||04-May-2020|
|Date of Decision||09-Jun-2020|
|Date of Acceptance||27-Jun-2020|
|Date of Web Publication||18-Jul-2020|
Dr. Surendra K Sethi
Flat No. 202, Shiv Enclave, Civil Lines, Ajmer, Rajasthan
Source of Support: None, Conflict of Interest: None
Background: Adjuvants in spinal anesthesia extends not only the duration of surgical anesthesia but also provides postoperative analgesia. This study aimed at comparing efficacy of intrathecal dexmedetomidine and magnesium sulfate as an adjuvant to 0.5% hyperbaric bupivacaine in various infraumbilical surgeries.
Materials and Methods: 120 patients belonging to American Society of Anesthesiologists (ASA) physical status I or II aged 18 to 65 years of either sex were enrolled and randomly allocated into two groups. Group D (n = 60) received intrathecal bupivacaine (hyperbaric) 0.5%, 12.5 mg (2.5 ml)+dexmedetomidine 5 μg (0.5 ml) while Group M (n = 60) received bupivacaine (hyperbaric) 0.5%, 12.5 mg (2.5 ml) + magnesium sulfate 75 mg (0.5 ml) = 3 ml. Onset of sensory and motor block, time to reach peak level of sensory block, time to two segment regression, duration of sensory and motor block, duration of analgesia, sedation score, hemodynamic changes, and side effects were noted.
Results: Onset of sensory and motor block were significantly faster in Group D (2.78 ± 0.34 min and 3.73 ± 0.43 min) compared to Group M (6.47 ± 0.43 min and 7.72 ± 0.48 min); (P < 0.05) Group D (131.70 ± 5.74 min) showed significantly prolonged time to two segment regression compared to Group M (102.78 ± 6.54 min); (P < 0.001). Duration of sensory and motor block were significantly prolonged in Group D (339.75 ± 23.57 min and 314.38 ± 14.93 min) when compared to Group M (248.18 ± 12.89 min and 228.81 ± 11.01 min); (P < 0.05). Duration of analgesia was significantly prolonged in Group D (348.26 ± 22.35 min) than Group M (268.01 ± 11.31 min); (P < 0.001). The patients remained hemodynamically stable in both groups without undue sedation and minimal side effects; (P > 0.05).
Conclusion: Dexmedetomidine (5 μg) leads to faster onset as well as prolonged duration of both sensory and motor block, prolonged duration of postoperative analgesia in comparison to magnesium sulfate (75 mg).
Keywords: Bupivacaine, dexmedetomidine, duration of analgesia, magnesium sulfate, spinal anesthesia
|How to cite this article:|
Jain K, Sethi SK, Jain R. Comparison of efficacy of intrathecal dexmedetomidine and magnesium sulfate as an adjuvant to 0.5% hyperbaric bupivacaine in patients undergoing infraumbilical surgeries under spinal anesthesia. J NTR Univ Health Sci 2020;9:116-23
|How to cite this URL:|
Jain K, Sethi SK, Jain R. Comparison of efficacy of intrathecal dexmedetomidine and magnesium sulfate as an adjuvant to 0.5% hyperbaric bupivacaine in patients undergoing infraumbilical surgeries under spinal anesthesia. J NTR Univ Health Sci [serial online] 2020 [cited 2020 Aug 10];9:116-23. Available from: http://www.jdrntruhs.org/text.asp?2020/9/2/116/289895
| Introduction|| |
Regional anesthesia (spinal or epidural) is considered to be safer than general anesthesia for lower abdominal and lower limb surgeries. It avoids general anesthesia-related problems such as airway manipulation, misplacement of endotracheal tube, hypo or hyperventilation, pulmonary aspiration and metabolic complications. It reduces surgical stress response by attenuating increase in the levels of plasma catecholamines and other hormones, reduces the risk of postoperative thromboembolic events with decreased intraoperative blood loss. In addition to this, regional anesthesia provides intra and postoperative analgesia.,
Although spinal anesthesia is easy to administer and cost effective but spinal anesthesia with local anesthetics (LAs) alone is associated with relatively shorter duration of action and inadequate postoperative analgesia leading to early rescue analgesic requirement in the postoperative period. So intrathecal adjuvants are used to improve or prolong postoperative analgesia and to decrease the adverse effects associated with high doses of a single LA agent.
Although various adjuvants have been used to prolong the duration of postoperative analgesia like opioids (morphine, fentanyl, and sufentanil) and other drugs (dexmedetomidine, clonidine, magnesium sulfate, neostigmine, ketamine, and midazolam), but none of the drugs was found to be safer or effective than others in terms of their associated side effects.,,
Magnesium, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, whose efficacy or safety as an intrathecal adjuvant has been studied in recent years. Magnesium blocks calcium influx and non-competitive NMDA channel antagonism. The antinociceptive effect of magnesium seems to be effective in management of chronic and post-operative pain. The addition of magnesium as intrathecal adjuvant to LA has been reported to improve the post-operative analgesia.,
Dexmedetomidine is a highly selective α-2 adrenergic agonist which has been used as a premedication as well as an adjuvant to LA agent in spinal anesthesia and general anesthesia. Dexmedetomidine causes sedation, analgesia with minimal hemodynamic changes and respiratory depression. It decreases sympathetic tone with attenuation of the neuroendocrine and hemodynamic response to anesthesia and surgery, enhance the analgesic property of LAs along with reduced anesthetic and opioid analgesic requirement.,
Based on the earlier studies, it was hypothesized that intrathecal dexmedetomidine (5 μg) or magnesium sulfate (75 mg) with hyperbaric 0.5% bupivacaine would provide the effective spinal anesthesia in terms of prolongation of postoperative analgesia with minimal side effects. The purpose of this study was to compare the effect of intrathecal dexmedetomidine and magnesium sulfate on the various spinal block characteristics in patients undergoing infraumbilical surgeries.
| Materials and Methods|| |
After obtaining institutional ethical committee (Letter No. 2370/Acad-III/MCA/2016 Dated 18-12-2018) approval, this prospective, randomized, double-blinded study was conducted on one hundred twenty patients of ASA (American Society of Anesthesiologists) physical status I or II of either sex, aged 18–65 years scheduled for various elective infraumbilical surgeries under spinal anesthesia. The patient refusal, uncooperative patients, local pathology at the site of injection, disability limiting the performance of block, known allergy with any of the study drugs, patients having a history of significant neurological deficit, bleeding disorder, respiratory, cardiac, hepatic or renal disease, psychiatric, or neuromuscular disorders and pregnant or lactating females were excluded from our study.
The study participants were randomly allocated into two groups with 60 patients in each group using computer generated tables of random numbers. Patients in Group D (n = 60) received 0.5% hyperbaric bupivacaine 12.5 mg (2.5 ml) and dexmedetomidine 5 μg (0.5 ml) while patients in Group M (n = 60) received 0.5% hyperbaric bupivacaine 12.5 mg (2.5 ml) and magnesium sulfate 75 mg (0.5 ml). A total volume of 3 ml was administered in both groups [Figure 1]. To maintain double blinding, the individual anesthesiologists who prepared the study drug, performed the procedure, and monitored the patient thereafter as well as patient and surgeon, all were unaware of group allocation. The primary outcome measure was duration of analgesia while secondary outcome measures were onset of sensory and motor block, time to achieve highest level of sensory block, two segment regression of sensory block, duration of sensory and motor block, sedation score, hemodynamic changes, and adverse effects.
All patients had undergone a thorough preanesthetic evaluation prior to surgery. A written informed consent will obtained from all the patients prior to performing block after complete explanation about the anesthetic technique. After arrival of the patient in the operating room, an intravenous (IV) line was secured using 20G IV cannula and preloading was started with ringer lactate. The standard ASA monitoring was applied which included non-invasive blood pressure (NIBP), pulse oximetry (SpO2), and electrocardiography (ECG). The baseline parameters including heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), respiratory rate (RR), SpO2, and sedation score were recorded.
Under all aseptic precautions spinal anesthesia was performed in sitting position at the level of L3-L4 or L4-L5 intervertebral space through a midline approach using a 25-gauge Quincke spinal needle. After confirming free flow of cerebrospinal fluid (CSF), the drug was injected as per group allocation. Immediately after the injection of drug, the patients were laid in supine position. The level of sensory block was assessed bilaterally by pin-prick sensation using a blunt 25-gauge needle along the midclavicular line every two minutes. The sensory block was graded as (normal sensation - 0; blunted sensation - 1; no sensation - 2). Grade 2 was taken as onset of sensory block. Onset of sensory block was the time from intrathecal injection to the time taken to achieve T10 dermatomal level while T6 was the highest level of sensory block achieved. Two segment regression was the time taken by sensory block to regress up to two segment of spinal cord level from highest level of sensory block. Duration of sensory block was the time taken to regress sensory block up to S1 dermatome from the highest level achieved.
Onset of motor block was assessed every two minutes and it was graded according to modified bromage scale (Grade 0 - no motor block; Grade 1 - inability to raise extended legs; Grade 2 - inability to flex knees; Grade 3 - inability to flex ankle joints). Grade 3 was taken as complete motor block. Onset of motor block was the time from intrathecal injection to the time taken to achieve Grade 3 of modified bromage scale and duration of motor block was the time taken to regress from maximum modified bromage scale (Grade 3) to complete recovery of motor block (Grade 0).
Pain was assessed using a standard 10 cm visual analog scale (VAS), with 0 corresponding to no pain and 10 designating the worst possible pain. Duration of analgesia was defined as the time from intrathecal injection to the time when VAS score >3 or when patient demands for analgesia (rescue analgesic).
The level of sedation was assessed using Ramsay Sedation Scale (RSS):
Ramsay 1- Anxious, agitated, restless
Ramsay 2- Cooperative, oriented, tranquil
Ramsay 3- Responsive to commands only
Ramsay 4- Brisk response to light glabellar tap or loud auditory stimulus
Ramsay 5- Sluggish response to light glabellar tap or loud auditory stimulus
Ramsay 6- No response to light glabellar tap or loud auditory stimulus
Intraoperatively, the various hemodynamic parameters (HR, SBP, DBP, MAP, and SpO2) were noted every two min for first ten min, every five min for next 30 min and every 15 min till the completion of surgical procedure. Incidence of hypotension, bradycardia, nausea or vomiting, pruritus, drowsiness, respiratory depression, urinary retention, were observed, recorded, and treated accordingly. Hypotension will be defined as fall in baseline blood pressure of more than 20% or a SBP <90 mm Hg and treated with intravenous fluids and/or mephentermine 6 mg IV. Bradycardia was defined as HR <60/min and treated with atropine 0.6 mg IV. Ondansetron 0.1 mg/kg was given to treat nausea or vomiting. Desaturation was defined as SpO2<90% and managed by O2 supplementation at the rate of 4–5 L/min using facemask.
A total sample size of 120 patients was calculated using power and sample size calculator (PS version 22.214.171.124), alpha error of 0.05 and power of 80%. Standard qualitative and quantitative tests were used to compare the data (e.g., paired or unpaired student t-test, ANOVA, Chi-square test). Descriptive statistics included computation of percentages, means and standard deviations. The data were checked for normality before statistical analysis using Shapiro–Wilk test. The data was coded and entered into Microsoft excel spreadsheet. Analysis was done using SPSS version 20 (IBM SPSS Statistics Inc., Chicago, Illinois, USA) windows software program. A P value of <0.05 was considered to be significant.
| Results|| |
The demographic data including mean age, sex, weight, and ASA physical status classification were comparable in both groups; P > 0.05 [Table 1].
The mean time for onset of sensory block in Group D and Group M were 2.78 ± 0.34 min and 6.47 ± 0.43 min, respectively. Onset of sensory block was significantly earlier in Group D as compared to Group M; P < 0.001. Similarly, the mean time for onset of motor block in Group D and Group M were 3.73 ± 0.43 min and 7.72 ± 0.48 min, respectively. Onset of motor block in Group D was significantly earlier as compared to Group M; P < 0.001 [Table 2].
The highest level (T6) of sensory block achieved was significantly earlier in Group D (9.98 ± 0.54 min) as compared to Group M (17.35 ± 0.52 min); P < 0.001. Two segment regression was significantly prolonged in Group D (131.70 ± 5.74 min) when compared to Group M (102.78 ± 6.54 min); P < 0.001 [Table 2].
The duration of sensory block in Group D and Group M were 339.75 ± 23.57 min and 248.18 ± 12.89 min, respectively. The mean duration of sensory block was significantly prolonged in Group D as compared to Group M; (P < 0.001). Similarly. the duration of motor block in Group D and Group M were 314.38 ± 14.93 min and 228.81 ± 11.01 min respectively and the mean duration of motor block was also significantly prolonged in Group D as compared to Group M; (P < 0.001). The mean duration of analgesia was significantly prolonged in Group D (348.25 ± 22.34 min) when compared to Group M (268.01 ± 11.30 min); (P < 0.001) [Table 2].
The mean sedation score in Group D was found to be significantly higher at time interval from 25 min to 60 min as compared to Group M. The difference in sedation score was statistically significant with a maximum sedation score being 2.86 ± 0.34 in Group D at 45 min intraoperatively; (P < 0.001) [Figure 2].
|Figure 2: Comparison of sedation score (RSS) in two groups. Group M - Magnesium sulfate; Group D – Dexmedetomidine. RSS – Ramsey sedation score|
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A decrease in mean HR was noted in both Group D and M but difference in mean HR was found to be statistically insignificant at various time intervals; (P > 0.05) [Figure 3]. Similarly, decrease in SBP, DBP, and MAP were noted in both the groups but the difference between the means of the two groups was not statistically significant at various time intervals; (P > 0.05) [Figure 4], [Figure 5], [Figure 6]. Similar trends were noted for SpO2 and it remained comparable at all time intervals in both groups; (P > 0.05).
No significant adverse effects or complications were observed in any of the group during both intraoperative and postoperative period. Nausea and vomiting occurred in 1 (1.6%) patient in Group M while 2 (3.3%) patients in Group D. Bradycardia was observed in 4 (6.3%) patients in Group M while 2 (3.3%) patients in Group D. Bradycardia (<60/min) was managed by a bolus dose of atropine 0.6 mg IV. Hypotension (decrease in SBP >20% of baseline or <90 mm Hg) was observed in 2 (3.33%) patients in both Group M and Group D. Hypotension was managed by fluid administration or mephentermine 6 mg IV boluses. Shivering was observed in 4 (6.6%) patients in Group M whereas 6 (10%) patients in Group D; (P > 0.05) [Table 3].
| Discussion|| |
The present study was conducted to compare intrathecal 0.5% bupivacaine with either dexmedetomidine or magnesium sulfate in patients undergoing infraumbilical surgeries under spinal anesthesia. The intrathecal dose of dexmedetomidine (5 μg) was chosen based on previous study by Al-Mustafa et al. where in no neurotoxic effects have been observed or reported in their study. Similarly the dose of intrathecal magnesium sulfate (75 mg) in our study was based on previous studies like Kathuria B et al. and Jabalameli M et al. that the use of this particular dose could prolong the duration of analgesia without added side effects.
The mean time for onset of both sensory and motor block were found to be significantly faster in dexmedetomidine group when compared to magnesium sulfate group. Wapang A et al. had conducted a study to compare dexmedetomidine (10 μg) and magnesium sulfate (50 mg) with intrathecal bupivacaine (12.5 mg) for various block characteristics under spinal anesthesia and found that mean onset time of sensory block was significantly faster in the Group D (2.53 ± 0.57 min) compared to Group M (8.00 ± 1.29 min) which concurs with our study. The onset of sensory block was found to be faster in dexmedetomidine group which might be due to higher dose of dexmedetomidine (10 μg) used in their study compared to our study (5 μg). The onset was delayed in magnesium group that could be because of lower dose (50 mg) of magnesium used in their study compared to our study (75 mg). Deepa G et al. reported that mean time of onset of motor block (time to reach Grade 1) was significantly shorter in Group D (4.97 ± 1.1 min) when compared to Group M (12.3 ± 1.36 min) in gynecological surgeries under subarachnoid block.
The time to achieve highest level of sensory block was significantly shorter in dexmedetomidine group. Swarup VP et al. reported a significantly faster time required to achieve the highest sensory level with Group D (4.2 ± 0.4 min) than Group M (6.3 ± 0.6 min) in patients who had undergone lower abdominal and lower limb surgeries under spinal anesthesia. In our study, two segment regression was significantly prolonged in dexmedetomidine group; (P < 0.001). Swarup VP et al. found that two segment regression was significantly prolonged in dexmedetomidine group when compared to magnesium sulfate group however the doses of magnesium sulfate (50 mg) and dexmedetomidine (10 μg) with bupivacaine (15 mg) were different from our study. Our results were supported by this study.
The mean duration of sensory and motor block were significantly prolonged in Group D compared to Group M. Shukla et al. found that patients in Group D had significantly longer sensory and motor block times than patients in Group M. The regression of sensory block up to T10 dermatome and motor block to bromage 3 scale, was prolonged in demedetomidine group (352 ± 45 min and 331 ± 35 min) than magnesium sulfate group (265 ± 65 min and 251 ± 51 min) which supports our study however they had used different doses of magnesium sulfate (50 mg) and dexmedetomidine (10 μg) with bupivacaine 15 mg.
Very few studies had assessed the duration of analgesia while comparing intrathecal dexmedetomidine and magnesium sulfate in various infraumbilical surgeries under spinal anesthesia. In present study, mean duration of analgesia was also significantly prolonged in dexmedetomidine group. Wapang A et al. showed a significantly delayed time to first analgesic request in Group D (356.50 ± 30.82 min) when compared to Group M (193.00 ± 18.78 min). Swarup VP et al. also reported a significantly prolonged duration of analgesia in dexmedetomidine group (361.9 ± 18.4 min) than magnesium group (251.9 ± 30.4 min). Our results were in concordance with these studies.
Alpha-2-receptor agonists like dexmedetomidine have antinociceptive action for both somatic and visceral pain. Intrathecal dexmedetomidine used as an adjuvant with hyperbaric bupivacaine prolongs the duration of sensory block by depressing the release of C-fiber transmitters and by hyperpolarization of post-synaptic dorsal horn neurons. The prolongation of duration of motor block may result from binding of alpha-2 receptor agonists to motor neurons in the dorsal horn of the spinal cord. Magnesium acts on voltage-dependent N-Methyl-D-Aspartate (NMDA) receptor channels which blocks calcium influx and noncompetitively antagonizes NMDA receptor channels. The glutamate and aspartate neurotransmitters are released after noxious stimuli which bind to the NMDA receptor and activation of these receptors leads to calcium influx followed by central sensitization in the spinal cord.,
The mean sedation score remained in clinically acceptable range (RSS <3) in both the groups which showed that both of the drugs did not cause undue sedation in any patient. Sunil BV et al. also showed that RSS was 2 in all the patients during both intraoperative and postoperative period. A decrease in mean HR was observed in both the groups. Bradycardia is a known side effect of dexmedetomidine and magnesium sulfate which is due to their central action whereby decreasing sympathetic outflow and norepinephrine release. Both SBP and DBP decreased from the baseline in the both the groups Although patients in both groups had hypotension but it was found to be clinically insignificant and managed by intravenous fluid administration and vasopressors only. Sunil BV et al. found HR and MAP comparable in both groups which supports our study.
No significant complications were observed in both the groups. Wapang A et al. reported side effects like nausea, vomiting, hypotension, bradycardia, and shivering after addition of dexmedetomidine and magnesium sulfate to spinal anesthesia but found to be not significant.
| Conclusion|| |
Dexmedetomidine (5 μg) leads to faster onset and prolonged duration of both sensory and motor block, prolonged duration of analgesia with minimal hemodynamic changes and side effects in comparison to magnesium sulfate (75 mg) when used as an adjuvant with hyperbaric bupivacaine in spinal anesthesia. So, dexmedetomidine (5 μg) seems to be a safe and effective alternative to magnesium sulfate (75 mg) that can be used as an adjuvant with hyperbaric bupivacaine in spinal anesthesia for infraumbilical surgeries.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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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], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]