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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 3  |  Issue : 3  |  Page : 760-767

Effects of intrathecal dexmedetomidine vs intrathecal magnesium sulfate as adjuvants in spinal anesthesia


1 Department of Anesthesia, ICU and Pain Management, Faculty of Medicine for Girl Al-Azhar University, Cairo, Egypt
2 Department of Anesthesia, Intensive Care and Pain Management, Faculty of Medicine for Girls Al-Azhar University, Cairo, Egypt

Date of Submission10-Nov-2019
Date of Decision10-Nov-2019
Date of Acceptance27-Nov-2019
Date of Web Publication10-Feb-2020

Correspondence Address:
MSc, MD Amira A ElNasr Awad
Lecturer of Anesthesia, Intensive Care and Pain Management, Faculty of Medicine for Girls, AL-Azhar University, 3 Ain Shams Street, Elnaam, Cairo, 11517 Al-Abbaseya
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sjamf.sjamf_96_19

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  Abstract 


Aim Intrathecal adjuvants are used for prolongation of duration of subarachnoid block and provide adequate analgesia. This study was designed to evaluate the onset, duration, and regression of sensory and motor block of intrathecal dexmedetomidine vs magnesium sulfate as an adjuvant to 0.5% hyperbaric bupivacaine for spinal anesthesia.
Materials and methods Sixty patients aged 21–50 years, with American Society of Anesthesiologists status I, II scheduled for elective lower abdominal and lower limb surgeries, were divided into three equal groups in a randomized-controlled manner: the control group (S: n=20) received 15 mg hyperbaric bupivacaine (3 ml) and 1 ml saline, the dexmedetomidine group (DXM: n=20) received15 mg hyperbaric bupivacaine (3 ml) and 10 µg of dexmedetomidine, and the magnesium sulfate group (Mg: n=20) received 15 mg hyperbaric bupivacaine (3 ml) and 50 mg of magnesium sulfate. Hemodynamic variables such as heart rate, systolic and diastolic blood pressure, onset of sensory and motor block, regression time, time to first analgesic request, and adverse effects were recorded for each patient.
Results The onset time of sensory and motor block was rapid in the DXM group in comparison with the Mg and control groups. The onset time of sensory and motor blockade were delayed in the Mg group in comparison with the S group. The regression time of sensory and motor blockade was prolonged in the DXM group and in the Mg group compared with the S group. Demand for analgesia was significantly late in the DXM group compared with the Mg and control groups, but early in the control group.
Conclusion Dexmedetomidine had faster onset of sensory and motor blocks, and provided prolonged postoperative analgesia compared with the magnesium sulfate and control groups

Keywords: adjuvant, dexmedetomidine, magnesium sulfate, spinal anesthesia


How to cite this article:
Eloraby RM, ElNasr Awad AA, Hashim RH. Effects of intrathecal dexmedetomidine vs intrathecal magnesium sulfate as adjuvants in spinal anesthesia. Sci J Al-Azhar Med Fac Girls 2019;3:760-7

How to cite this URL:
Eloraby RM, ElNasr Awad AA, Hashim RH. Effects of intrathecal dexmedetomidine vs intrathecal magnesium sulfate as adjuvants in spinal anesthesia. Sci J Al-Azhar Med Fac Girls [serial online] 2019 [cited 2020 Oct 22];3:760-7. Available from: http://www.sjamf.eg.net/text.asp?2019/3/3/760/278059




  Introduction Top


Neuraxial anesthesia is the most preferred technique for lower abdominal and lower limb surgeries. Spinal anesthesia is considered superior to general anesthesia. It minimizes or avoids the problem associated with general anesthesia such as airway management, inhibits stress hormone release, decreases intraoperative blood loss and postoperative analgesia, and lowers the incidence of thromboembolic events [1].

Use of intrathecal adjuvants prolongs the duration of block, leads to a better success rate and patient satisfaction, and provides adequate pain management [2]. A number of adjuvants have been studied to prolong the effect of spinal anesthesia such as opioids (morphine, fentanyl, nalbuphine, buprenorphine), sodium bicarbonate, vasoconstrictors (epinephrine), N-methyl-d-aspartate antagonists (Ketamine, magnesium sulfate), centrally acting α-2 adrenoceptor agonists (clonidine and dexmedetomidine), and γ-aminobutyric acid receptor agonists (midazolam). Thus, intrathecal additive is a reliable method to prolong the duration of spinal anesthesia and prolong postoperative analgesia [3].

Dexmedetomidine is an agonist on the α2receptor found in the peripheral and central nervous system. Stimulation of the alpha receptors in the brain and spinal cord inhibits neuronal firing, causing hypotension, bradycardia, sedation, and analgesia. The analgesic action of the intrathecal α2-adrenoceptor agonist is depressing the release of C-fiber transmitters and by hyperpolarization of postsynaptic dorsal horn neurons. This antinociceptive effect may explain the prolongation of sensory block, but the prolongation of the motor block may result from the binding of α2 adrenoceptor agonists to motor neurons in the dorsal horn. Dexmedetomidine has high lipophilicity and facilitates rapid absorption into the cerebrospinal fluid [4].

Magnesium sulfate blocks calcium influx and noncompetitively antagonizes N-methyl-d-aspartate receptor channels and prevents central sensitization from peripheral nociceptive stimulation, leading to analgesia, and can cause side effects as nausea, vomiting, and hypotension at higher doses. The analgesic action of intrathecal Mg+2 is primarily based on the regulation of calcium influx into the cell, that is, natural physiological calcium antagonism [5].


  Materials and methods Top


This study was carried out at Al-Zahraa University Hospital on 60 patients subjected to elective lower abdominal and lower limb surgeries from July 2018 to May 2019 after approval by the Local Ethical Committee of Al-Zahraa University Hospital and after informed consent was obtained. Patients aged 21–50 years of both sexes, with American Society of Anesthesiologists status class I and II were included. Exclusion criteria included patient refusal, hypersensitivity to drugs of study, coagulopathy, history of allergy to local anesthetic drug, history of cardiac disease, hypertension, psychological disease, spinal deformities, contraindication to spinal anesthesia such as infection at the puncture site, pre-existing neurological deficits, and hemodynamic instability. Patients were divided into three equal groups (20 patients in each group). Control group: patients received 15 mg hyperbaric bupivacaine (Spinal Heavy Marcaine; 0.5% ampoule containing 20 mg in 4 ml volume; manufactured by Astra Zeneca, ABS-15185, Södertälje, Sweden) and 1 ml normal saline. Dexmedetomidine group: patients received 10 µg dexmedetomidine hydrochloride (Xamdexvail containing 100 µg in 1 ml volume, manufactured by them is Medicare Limited; BHEL, India) that was administered using an insulin syringe (10 units using an insulin syringe) diluted with normal saline 1 ml, then add to 0.5% Hyperbaric bupivacaine 15 mg (3 ml) in the same syringe to be 4 ml volume. Magnesium sulfate group: Patients received 50 mg magnesium sulfate (EIPICO, Egypt) that was administered using an insulin syringe, diluted with normal saline to 1 ml, then add to 0.5%hyperbaric bupivacaine 15 mg (3 ml)in the same syringe to be 4 ml volume.

Preoperative assessment of the patients was carried out including complete detailed history, clinical examination, and basic investigation. In the preanesthetic room, an 18 G intravenous cannula was inserted and 10 ml/kg normal saline as a preload was started. In the operating room, ECG, pulse oximetry (SpO2), and noninvasive blood pressure were monitored (base line reading); then, spinal anesthesia was started with the patient in the sitting position. Using a completely aseptic technique and infiltration of the skin by 3 ml lidocaine 2% at L3–4 or L4–5, spinal anesthesia was performed using either 25 or 22 G spinal needles (Quincke needle; Becton Dicknson, Spain). After confirmation of free flow of cerebrospinal fluid, the studied solution was slowly injected and then the patient was turned to the supine position with the head up. Patients were supplemented with oxygen of 4–6 l/min through a mask. Any hypotension episode [systolic blood pressure (SBP) <90 mmHg] was treated with ephedrine intravenous 6 mg bolus and any episode of bradycardia [heart rate (HR) <50 beats/min] was treated with 0.02 mg/kg of atropine. The level of sensory block was checked by the pin-prick method and motor block was assessed using the Modified Bromage Scale.

Modified Bromage Scale

  • Bromage 0–able to move the hip, knee, and ankle.
  • Bromage1–unable to move the hip, but is able to move the knee and ankle.
  • Bromage2–unable to move the hip and knee, but is able to move the ankle.
  • Bromage 3–unable to move the hip, knee, and ankle.


The primary outcome of the study was to evaluate the onset and duration of sensory and motor block in dexmedetomidine vs magnesium sulfate when used as an adjuvant.

The secondary outcomes of the study were to evaluate first request of analgesia and possible side effects.

The studied parameters

The hemodynamic parameters:
  1. HR, SBP, and diastolic blood pressure (DBP) were monitored before performing the spinal anesthesia (base line), every 5 min after spinal anesthesia, and then every 15 min till the end of surgery.


Evaluation of onset of sensory and motor blocks:
  1. Sensory block levels were assessed bilaterally by the pin-prick sensation using a blunt 27-G needle every 2 min till no sensation was achieved.
  2. Motor block were assessed every 2 min using the Modified Bromage Scale till complete motor block was achieved (Bromage 3).


Evaluation of time of sensory and motor regression:
  1. Time of sensory blockade regression (duration of sensory block) is the time of regression from no sensation to normal sensation.
  2. Time of motor blockade regression (duration of motor block) is the time of regression from modified Bromage score 3 to 0.
    • Time of first request of analgesia: the time from intrathecal injection to the first time of complaint about pain or rescue analgesia.
    • Evaluation of adverse effect: bradycardia (HR <50 beats/min).
      1. Hypotension (SBP <90 mmHg).
      2. Nausea, vomiting.
      3. Shivering.


Sample size justification

MedCalc version 12.3.0.0 program (Ostend, Belgium) was used for calculations of sample size, based on 95% confidence interval and power of the study 80% with α error 5%. According to a previous study [6], the onset time of sensory and motor blockade was significantly shortened in group D (2.53±0.57 min) and prolonged in group M (8.00±1.29 min) compared with group C (4.10±0.55 min). The dexmedetomidine group showed significantly prolonged time to two-segment regression (group D vs group M −132.33±12.51 min vs 91.83±9.69 min; P<0.001) and significantly delayed time to first analgesic request (group D vs group M −356.50±30.82 min vs 193.00±18.78 min; P<0.001).

Statistical analysis

Recorded data were analyzed using the statistical package for social sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean±SD. Qualitative data were expressed as frequency and percentage.

The following tests were carried out:
  1. A one-way analysis of variance was used to compare between more than two means.
  2. Post-hoc test: least significant difference was used for multiple comparisons between different variables.
  3. χ2-Test of significance was used to compare proportions between qualitative parameters.
  4. The confidence interval was set to 95% and the margin of error accepted was set to 5%.



  Results Top


Sixty patients were enrolled in this study and divided into three groups: DXM group, Mg group, and S group.

Demographic data did not show a statistically significant difference among the three groups with respect to age, sex, American Society of Anesthesiologists status status, and type of surgery ([Table 1]).
Table 1 Comparison between three groups according to demographic data

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There was a statistically significant difference between the three groups according to onset time of sensory and motor block. The onset time of sensory and motor block were rapid in the DXM group in comparison with the Mg and S groups .The onset time of block both sensory and motor was delayed in the Mg group in comparison with the S group ([Table 2]).
Table 2 Comparison between three groups according to onset time of sensory and motor blocks

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According to HR: There was a statistically significant difference between the three groups according to HR from 10 to 105 min; there was a significant decrease in HR in the DXM group in comparison with the Mg and S groups. HR decreased in the Mg group in comparison with the S group significantly ([Figure 1],[Figure 2],[Figure 3]).
Figure 1 Consort flow diagram.

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Figure 2 Comparison between three groups according to heart rate.

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Figure 3 Comparison between three groups according to systolic blood pressure.

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There was a statistically significant difference between the three groups according to SBP and DBP from 15 to 105 min; SBP and DBP were significantly decreased in the DXM group in comparison with the Mg group. SBP and DBP in the Mg group decreased significantly in comparison with the S group ([Figure 3] and [Figure 4]).
Figure 4 Comparison between three groups according to diastolc blood pressure.

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According to sensory and motor regression, there was a highly statistically significant difference between the three groups according to motor and sensory regression. The regression time of sensory and motor block was prolonged in the DXM and Mg groups compared with the S group. However, the duration was the longest in the DXM group among the three groups ([Table 3]).
Table 3 Comparison between three groups according to times of sensory and motor regression

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According to the time of first request of analgesia, the requirement for analgesia was significantly delayed in the DXM group in comparison with the Mg and S groups ([Figure 5]).
Figure 5 Comparison between three groups according to time of request of first analgesia.

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Postoperative adverse effects: there was no statistically significant difference between the three groups according to adverse effects ([Figure 6]).
Figure 6 Adverse effect.

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  Discussion Top


Spinal anesthesia is a popular, simple, and reliable anesthetic technique for lower limb and lower abdominal surgeries. It has been used widely in clinical practice of anesthesia because of rapid onset, high reliability, and low cost. It produces excellent operating conditions and provides effective analgesia in the postoperative period. Attempts were made to increase the duration of analgesia produced by subarachnoid block by adding various agents intrathecally. Therefore, in the present study, intrathecal dexmedetomidine and magnesium sulfate were chosen as neuraxial adjuvants.

In the current study, the onset time of sensory and motor block were rapid in the DXM group in comparison with the Mg group and the S group. However, the onset time of sensory and motor block was delayed in the Mg group in comparison with the S group. The regression time of sensory and motor block was prolonged in the DXM group and in the Mg group compared with the S group. However, the duration was the longest in the DXM group among the three groups. The requirement of analgesia was significantly delayed in the DXM group compared with the Mg group and the S group. The S group was the earliest group in requirement of analgesia.

In a study [7] and [8] using dexmedetomidine and magnesium sulfate as adjuvants showed that the onset time of sensory and motor block was rapid in the dexmedetomidine group and delayed in the Mg group in comparison with the control group and duration of anesthesia was prolonged in the DXM group in relation to the Mg and control groups. The rescue analgesic timing was significantly prolonged in the DXM group and the Mg group compared with the control groups.

Also, in agreement with our results, the Wapang et al’s [6] study compared the effect of intrathecal 10 µg of dexmedetomidine and 50 mg of magnesium sulfate with 15 mg of bupivacaine on spinal block and found that the onset time of sensory and motor blockade was significantly shortened in the DXM group (2.53±0.57 min) and prolonged in the Mg group (8.00±1.29 min) compared with the control group (4.10±0.55 min). The dexmedetomidine group showed significantly prolonged time of regression (132.33±12.51 min) vs the Mg group (91.83±9.69 min) and significantly delayed time to first analgesic request (group DXM vs Mg group −356.50±30.82 min vs 193.00±18.78 min).

Similar to our results, Regar and Kanwaria [9] compared only two groups and used the same dose as that in our study (DXM group 10 µg − Mg group 50 mg) and found that the onset time of sensory block in the DXM group was faster than the Mg group and the duration of motor block was significantly longer in the DXM group compared with the Mg group. The total duration of analgesia was significantly higher in the DXM group compare with the Mg group.

Also, Nigam et al. [10] showed that an intrathecal adjuvant of dexmedetomidine at a dose of (10 µg) (group DXM) with bupivacaine led to a significantly longer sensory block than patients in the bupivacaine group (control). The mean time of sensory regression was (323±31 min) in the DXM group and (191±15 min) in the control group. The time to rescue analgesia was significantly longer in the DXM group (383±38 min) compared with the control group (228.6±15 min).

In contrast to our study, Hastir and Samuel [11] compared the control group (bupivacaine) and two different doses of dexmedetomidine (5 and 10 µg), and found that the time of sensory block to reach the T10 dermatome was similar in all groups, there was a dose-dependent prolongation of the duration of sensory, motor block, and the time to rescue analgesic were in the order, it was prolonged in DXM(10 µg)>DXM(5 µg)>control.

Limbu et al. [12] compared two groups [Mg 50 mg and control group (bupivacaine)] of patients undergoing lower extremity surgery and found that the onset of sensory and motor block was similar. Duration of sensory and motor block was prolonged in patients of the magnesium group, but this was not statistically significant.Also, Singh et al. [13] compared Mg 50 mg vs the control group (bupivacaine) among patients requiring spinal anesthesia; their results showed that intrathecal magnesium prolonged the duration of spinal analgesia, but with a delayed onset. The time to first analgesic request in the Mg group was delayed compared with the C group.

In our study, in terms of hemodynamics changes and adverse effects, there was a statistically significant difference between the three groups according to HR and SBP and DBP from 10 to 105 min; there was a significant decrease of hemodynamics parameters in the DXM group in comparison with the Mg group and the S group. Hemodynamics parameters decreased in the Mg group in comparison with the S group.

There was no statistically significant difference between the three groups according to adverse effects (bradycardia, hypotension, nausea and vomiting, shivering).

These results are in agreement with the research of Regar and Kanwaria [9], who compared only two groups (DXM 10 µg and Mg 50 mg) and found that no significant difference was observed according to the mean difference in pulse rate in both groups, but the incidence of bradycardia was significantly higher in the DXM group compared with the Mg group and there was greater decrease in SBP and DBP in the DXM group in comparison with the Mg group.

In agreement with the current study, Wapang et al. [6] compared the effect of intrathecal dexmedetomidine and magnesium sulfate on the characteristics of bupivacaine spinal they found that the number of patients with hypotension was higher in the DXM group than the Mg and control groups, and hypotension was more prevalent in the control group in relation to the Mg group.


  Conclusion Top


Use of DXM as an adjuvant to spinal bupivacaine in lower limb and lower abdominal surgeries is a good alternative to intrathecal Mg as it produces earlier onset and prolonged duration of sensory and motor block and provides excellent quality of postoperative analgesia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Ko SH, Lim HR, Kim DC, Han YJ, Choe H, Song HS. Magnesium sulfate does not reduce postoperative analgesic requirements. Anesthesiology. 2001; 95:640–646.  Back to cited text no. 5
    
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Wapang A, Singh NR, Singh SS, Nado H, Fatima N. Effect of intrathecal dexmedetomidine and magnesium sulphate on the characteristics of bupivacaine spinal block-a comparison. ‏Int J Health Sci Res 2014; 4:169–177.  Back to cited text no. 6
    
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Farooq Z, Gupta N. Magnesium sulphate and dexmedetomidine used intrathecally as adjuvant to bupivacaine. Int J Med Res Health Sci 2017; 6:42–46.  Back to cited text no. 7
    
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Deepa G, Narayanan VK. An experimental study comparing intrathecal dexmedetomidine with intrathecal magnesium sulphate as bupivacaine adjuvants for spinal anaesthesia in majorgynaecological surgery. J Evol Med Dent Sci 2017; 6:1133–1142.  Back to cited text no. 8
    
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Regar S, Kanwaria LM. A comparative study of intrathecal dexmedetomidine with intrathecal magnesium sulfate used as adjuvants to bupivacaine. Global J Res Anal 2017; 6:48–50.  Back to cited text no. 9
    
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Nigam R, Murthy M, Debbarma M. Effects of intrathecal dexmedetomidine on bupivacaine spinal anesthesia in patients undergoing lower limb surgery. J Evid Based Med Healthcare 2015; 2:XX.  Back to cited text no. 10
    
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Hastir S, Samuel M. To study the dose related efficacy of intrathecal dexmedetomidine for prolongation of spinal anaesthesia when added to hyperbaric bupivacaine in complex lower limb orthopedic surgeries. Int J Sci Res 2019; 8:2.  Back to cited text no. 11
    
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Limbu PM, Sindhu K, Singh SN, Pokharel K, Maharjan R. Intrathecal magnesium sulfate as analgesic and anaesthetic adjunct to bupivacaine in patients undergoing lower extremity orthopaedic surgery. J Soc Anesthesiol Nepal 2017; 4:74–80.  Back to cited text no. 12
    
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Singh NR, Wapang AO, Singh SS. Evaluation of intrathecal magnesium sulphate as adjuvant in bupivacaine spinal anesthesia − a study. Int J Health Sci Res 2015; 5:XX.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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