|Year : 2020 | Volume
| Issue : 1 | Page : 8-14
Comparative study of subarachnoid injection of dexmedetomidine versus magnesium sulfate as adjuvants to bupivacaine in patients undergoing classical repair surgery
Sameh H Seyam1, Ali A Mahareak1, Eman A Salim2
1 Department of Anesthesiology and Intensive Care, Faculty of Medicine for Boys, Al-Azhar University, Cairo, Egypt
2 Department of Anesthesiology and Intensive Care, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
|Date of Submission||31-May-2018|
|Date of Acceptance||04-Feb-2019|
|Date of Web Publication||16-Apr-2020|
MD Sameh H Seyam
Khamis Mushait, Saudi Arabia, 62461-4080
Source of Support: None, Conflict of Interest: None
Background Spinal anesthesia has several benefits over general anesthesia. Addition of adjuvants to local anesthetics improves the quality of the subarachnoid block.
Objective We attempted to improve the quality of spinal anesthesia by the addition of magnesium sulfate or dexmedetomidine to intrathecal bupivacaine in patients undergoing classical repair surgery as regards primary outcome (quality of spinal anesthesia) and secondary outcomes (effect on hemodynamics and incidence of complications).
Patients and methods This prospective randomized double-blinded controlled clinical study was carried out on 75 adult female patients scheduled for classical repair surgeries under spinal anesthesia who were assigned into three equal groups. Group D: 15 mg of 0.5% hyperbaric bupivacaine plus 10 μg dexmedetomidine was given to the patients. Group M: patients received 15 mg of 0.5% hyperbaric bupivacaine plus 0.5 ml magnesium sulfate (50 mg). Group C: patients received 15 mg of 0.5% hyperbaric bupivacaine plus 0.5 ml normal saline as control. The comparison was made among the three groups in regards to onset time of sensory and motor block, degree of postoperative pain relief, effect on hemodynamic stability, and total postoperative morphine consumption, and complications were recorded.
Results There was a statistical difference among the three groups as regards the onset time of both sensory and motor block, which was faster in group D than in group C, and both were faster than group M. The duration of postoperative analgesia was significantly prolonged in D and M groups compared with the control group. The requirements of morphine sulfate in the first 24 h were significantly lower in the D and M groups compared with the control group.
Conclusion Subarachnoid dexmedetomidine supplementation of spinal block was found to be a better option than intrathecal magnesium sulfate in patients undergoing classical repair surgeries, as it provides rapid onset of sensory and motor block; also, it improves the quality of postoperative analgesia and reduces postoperative analgesic requirements.
Keywords: bupivacaine, classical repair surgery, dexmedetomidine, postoperative analgesia, subarachnoid block
|How to cite this article:|
Seyam SH, Mahareak AA, Salim EA. Comparative study of subarachnoid injection of dexmedetomidine versus magnesium sulfate as adjuvants to bupivacaine in patients undergoing classical repair surgery. Res Opin Anesth Intensive Care 2020;7:8-14
|How to cite this URL:|
Seyam SH, Mahareak AA, Salim EA. Comparative study of subarachnoid injection of dexmedetomidine versus magnesium sulfate as adjuvants to bupivacaine in patients undergoing classical repair surgery. Res Opin Anesth Intensive Care [serial online] 2020 [cited 2020 May 31];7:8-14. Available from: http://www.roaic.eg.net/text.asp?2020/7/1/8/282590
| Introduction|| |
Intrathecal anesthesia nowadays takes the upper hand in anesthesia over general anesthesia because of various benefits like less chance of airway obstacles and aspiration, facilitation of postoperative pain relief and concerns in some pre-existing medical conditions. The problem of using local anesthetics only in spinal anesthesia is brief duration of analgesia and limited postoperative pain relief, and hence early postoperative analgesia is required .
Many drugs have been used to enhance the duration and improve the quality of the spinal block; the administration of a group of drugs like opioids and others has been practiced. Intrathecal opioids produce various problems such as respiratory depression and pruritus . Dexmedetomidine, an extremely selective α2-agonist, maintains stable hemodynamics and provides the highest degree of intraoperative and postoperative analgesia with least side effects . Magnesium sulfate has analgesic effects not limited to chronic pain, but it additionally reduces duration and severity of postoperative pain. Magnesium is a noncompetitive antagonist to N-methyl-d-aspartate receptors and prevents the central sensitization due to peripheral nociceptive stimulation. Magnesium controls calcium entry into the cell .
This study aims to evaluate the addition of dexmedetomidine versus magnesium sulfate as an adjuvant to intrathecal bupivacaine on the quality of subarachnoid block as a primary outcome (quality of spinal anesthesia) and as secondary outcomes (effect on hemodynamics and incidence of complications) in patients undergoing classical repair surgery.
| Patients and methods|| |
This was a prospective randomized double-blinded controlled clinical study, carried out in Al-Azhar University Hospitals in the period spanning from March 2015 to December 2016, to assess the effect of intrathecal dexmedetomidine or magnesium sulfate administered with 0.5% bupivacaine for a subarachnoid block in patients undergoing classical repair surgeries with regard to onset and offset of sensory and motor block and postoperative analgesia. After obtaining the approval of the Al-Azhar Faculty of Medicine Ethical Committee and the written consent of patients, this study was carried out on 75 adult female patients aged 35–50 years of American Society of Anesthesiologists (ASA) I and II physical status, BMI not more than 30 kg/m2, scheduled for classical repair surgeries under subarachnoid anesthesia. Exclusion criteria were patient refusal, coagulopathy, ASA physical status more than II, local or systemic infections or allergy to investigated drugs.
Patients were randomly divided by computer-generated next allocation. Hiding was achieved by a sequentially sealed opaque envelope. Seventy-five women scheduled for classical repair surgeries were randomly allocated to D, M, and C according to adjuvants used. In group D, patients received (15 mg) 0.5% hyperbaric bupivacaine plus (10 μg) dexmedetomidine (0.1 ml dexmedetomidine completed to 0.5 ml with normal saline). In group M, patients received 15 mg of 0.5% hyperbaric bupivacaine plus 0.5 ml magnesium sulfate (50 mg). In group C, patients received 15 mg of 0.5% hyperbaric bupivacaine plus 0.5 ml normal saline as control group.
Before shifting the patients into the operation theater, proper equipment for airway management and emergency drugs were kept ready, and all noninvasive monitors were connected to the patient. Baseline parameters involving pulse rate, blood pressure, and oxygen saturation were recorded; thereafter, 18-G intravenous cannula was inserted and secured, and the patient was preloaded with 15 ml/kg Ringer’s lactate over 15 min.
Subarachnoid anesthesia started with the patient in the sitting position, 25-G Quincke spinal needle was inserted in the L3–L4 interspinal space in the paramedian approach under strict aseptic conditions. The injected medicines were blinded from the patient and the observing anesthesia resident. Oxygen was given by a nasal cannula at the rate of 3 l/min.
As regards patients with inadequate subarachnoid anesthesia and conversion to general anesthesia, we omitted such cases from the study.
Quality of spinal anesthesia was recorded in the form of onset and duration of both sensory and motor block, block intensity, degree of postoperative pain relief, time for need of postoperative analgesia and the analgesic dose given.
Hemodynamic parameters were recorded at 1, 3, 5, and 10 min after the administration of subarachnoid block and then every 5 min after that until the end of surgery.
The estimation of sensory block level was evaluated after intrathecal block, by applying iced cubes starting after 5 min next to the subarachnoid injection and repeated every 1 min until loss of ice sensation at the T10 level, then every 5 min to recognize the highest sensory level, and then every 30 min to identify the two-segment regression time, which is the recovery time of highest achieved sensory level by two segments. The sensory block onset was described as the time that was recorded from subarachnoid injection to loss of cold sensation at T10. Motor block estimated by applying the modified Bromage scale every 1 min until the entire motor block is achieved (Bromage 0, free hip, knee and ankle movement; Bromage 1, free knee and ankle movement with no hip movement; Bromage 2, the patient is ready to move the ankle only; Bromage 3, the patient is unable to move the entire lower limb) .
The motor block onset time was considered as the time required to obtain complete motor block (Bromage grade 3) from the time of the intrathecal injection. The occurrence of side effects was recorded, such as nausea, vomiting, pruritus, and respiratory depression.
Both sensory and motor block regressions and analgesia were observed. Postoperative Analgesia was evaluated using visual analog scale (VAS) score every 1 h and detected by the first analgesic request, then every 2 h for 24 h. If VAS was more than 3 at any time, morphine sulfate 0.05 mg/kg was given intravenously and, lastly, total analgesic requirements in the first 24 h were calculated.
Sensory block duration considered as the time needed for the sensory block to return to T10 (i.e. below the umbilicus) from the highest sensory level was obtained. Motor block regression was considered when the motor block to returned to below L1, and motor block duration was considered as the time from the initiation of the subarachnoid block to return of Bromage score to grade 1.
All complications were recorded in the form of hypotension, bradycardia, sedation, or hypoventilation. Hypotension was considered if mean arterial pressure less than 60 mm Hg or systolic blood pressure (SBP) reduced to 30% or more from the baseline and was managed with intravenous fluids (Ringer’s lactate solution 250 ml) and injection of ephedrine (5 mg) in incremental injections. Bradycardia was described as heart rate (HR) less than 50 beats/min and was treated with atropine 0.6 mg intravenously. Sedation was assessed by Ramsay sedation scale, where the Ramsay sedation scale defines the conscious state from a level 1: the patient is anxious, agitated or restless, through the continuum of sedation to a level 6: the patient is completely unresponsive .
Alveolar hypoventilation, defined as an elevation in partial pressure of carbon dioxide to levels more than 45 mmHg, may be associated with the development of hypoxemia.
Sample size calculation was based on previous studies; depending on the sensory onset time, we calculated that 22 patients would be required if each group were sufficient to give α of 0.05 with confidence interval 95% and actual power 85% and β of 0.15. The total sample size increased to 25 patients for each group due to assumption of possibility for patients to drop out of the study. Data were coded and entered using IBM SPSS Statistics for Windows, version 21 (IBM Corp., Armonk, N.Y., USA). Data were expressed as mean and SD for quantitative variables and as frequencies (number and percentages) for categorical variables. Comparisons among groups were achieved using analysis of variance followed by post-hoc test if there was revealed significance in normally distributed quantitative data. χ2-test was applied to compare frequency and percentage. Value of SD less than 0.05 was considered significant.
| Results|| |
All patients completed the study, with 25 patients in each group. Demographic and surgical data were similar in all groups ([Table 1]).
The sensory onset times were 3.34±1.04, 6.75±1.3, and 4.26±1.1 min in groups D, M, and C, respectively. Furthermore, motor block onset times were 3.08±0.87, 6.11±1.3, and 4.45±0.98 in groups D, M, and C, respectively. Two-segment regression times were 117.5±14.12, 104.3±12.4, and 87±10.6 min, times to L1 regression were 311.4±38.75, 252.95±58.7, and 184.82±52.2 min and motor regression times were 314±33.12, 232±48.2, and 151±27.4 min. in groups D, M, and C, respectively, as shown in [Table 2].
|Table 2 Sensory block and motor block features and postoperative analgesia|
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The duration of postoperative analgesia was 387±28.4, 214±23.7, and 151±21.2 min in groups D, M, and C, respectively.
The requirements of morphine sulfate in the first 24 h were 8.16±1.6, 12.24±2.4, and 18.48±5.1 mg in groups D, M, and C, respectively, as shown in [Table 2].
As regards postoperative pain using VAS score, pain was significantly less in groups D and M when compared with the C group at 2, 3, and 6 h time intervals (P<0.001). When group D was compared with group M, there was a significant difference only at 4 and 6 h intervals (P<0.001), as shown in [Table 3].
|Table 3 Comparison between groups according to postoperative visual analog scale|
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As regards intraoperative hemodynamics including HR and mean arterial pressure, there was no significant difference among the three groups ([Figure 1] and [Figure 2]).
|Figure 1 Comparison between groups according to changes in heart rate. C, control group; D, dexmedetomidine group; M, magnesium group. Data are represented as mean±SD.|
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|Figure 2 Comparison between groups according to changes in mean arterial blood pressure. C, control group; D, dexmedetomidine group; M, magnesium group. Data are represented as mean±SD.|
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As regards incidence of complications, there was no statistically significant difference in the incidence of complications, such as bradycardia, hypotension, and respiratory depression among study groups, as shown in [Table 4].
| Discussion|| |
There have been many studies to investigate the addition of neuraxial adjuvants involving opioids, α2-agonists, cholinergic agonists, N-methyl-d-aspartate antagonists and others to extend the duration of subarachnoid block .
This study evaluated the addition of intrathecal dexmedetomidine and magnesium sulfate combined with hyperbaric 0.5% bupivacaine in classical repair surgery to assess the extent of postoperative analgesia, onset, and offset of both sensory and motor block and the effect on hemodynamic changes.
This study showed a statistically significant difference in the onset time for both sensory and motor block among the three groups, and, for intergroup comparison, the onset time was faster in the group D and slower in the group M when compared with the control group. These results are consistent with that of Shukla et al.  who revealed that the sensory onset time was less in the dexmedetomidine group when compared with the control group. Al-Ghanem et al.  noted that the use of other doses of dexmedetomidine (5 and 10 μg) was associated with the shorter onset of sensory block.
The time to Bromage 3 in group D (3.08±0.87 min) was significantly shorter than that of group M (6.11±1.3 min) and group C (4.45±0.98 min). Shukla et al.  revealed that the time to Bromage 3 in the dexmedetomidine (3.96±0.92 min) group was statistically shorter when compared with the control group (4.81±1.03 min). Sunil et al.  who noted that Bromage 3 time in the dexmedetomidine group was shorter (3.86±1.06 min) in comparison with the fentanyl group (4.91±1.30 min), which is in agreement with our result, as regards the effect and duration of block of dexmedetomidine but not similar, because we did not use fentanyl as adjuvant.
Two-segment regression time, time to L1 regression and motor regression time were significantly lower in group D when compared with the other two groups. Group M block regression times were significantly prolonged in comparison with group C; these results mean that intrathecal dexmedetomidine and magnesium prolong the motor and sensory block time. These results are consistent with that of Kanazi et al.  who noticed that the addition of intrathecal dexmedetomidine (3 µg) to bupivacaine (12.0 mg) significantly decreased the onset of motor block, and it prolonged sensory and motor block with maintained hemodynamic stability.
Results of Kim et al.  revealed that regression time to S1 was 268.9±15.84 min in the dexmedetomidine group and 122.9±10.42 min in the fentanyl group, and regression time to Bromage 0 was 221.1±1.37 min in the dexmedetomidine group and 103.2±3.33 min in the fentanyl group; these results are in agreement with that of this study but not similar.
As regards postoperative analgesia using VAS score, the VAS was significantly less in groups D (0.85±0.29, 1.23±0.56, and 1.36±0.88) and M (1.12±0.64, 2.46±1.58, and 3.52±1.74) at 2, 4, and 6 h time intervals when compared with the control group (3.47±0.88, 3.44±0.73, and 3.93±1.06), respectively (P<0.001). When group D was compared with group M, VAS was significantly short for D than M at 4 and 6 h intervals (P<0.001).
In agreement with our study, Sunil et al. , found that, in group M, VAS started to increase at 4 h, but the patient requested the first dose of analgesia at 5 h postoperatively. Thereafter, VAS score started to increase again and the second dose of analgesia was given at 10 h. VAS started to increase again, and the third dose of analgesia was given at 18 h. Finally, the fourth dose of analgesia was given at 24 h. In that study, the whole duration of analgesia was measured from the zero time until the patient requested first analgesic dose when the VAS was more than 3. Total analgesia given was more in group M when compared with group D, which was statistically significant .
The times for the first analgesic requirement and duration of postoperative analgesia were 387±28.4, 214±23.7, and 151±21.2 min. in groups D, M, and C, respectively; significantly prolonged in adjuvant groups compared with the control group; within the adjuvant groups there was significant increase in duration of postoperative analgesia in group D compared with group M. The requirements of morphine sulfate in the first 24 h were 8.16±1.6, 12.24±2.4, and 18.48±5.1 mg in groups D, M, and C, respectively, significantly lower in the studied groups compared with the control group; within the studied groups, there was significant increase in the requirements of postoperative analgesia in group M compared with group D. These results were consistent with that of Shukla et al.  who compared addition of dexmedetomidine or magnesium sulfate to subarachnoid bupivacaine for surgeries of the lower abdomen.
Ashraf et al.  noted a significantly prolonged time to first analgesic demand in the dexmedetomidine group as opposed to the control group. Their study included 90 patients who were allocated to take subarachnoid 10 mg bupivacaine 0.5% or 10 mg bupivacaine 0.5% plus 5 µg dexmedetomidine. Subarachnoid injection of α2 adrenergic agonists provides effective antinociceptive results by modifying spinal neurotransmitter discharge and efficiently decreases acute pain .
As regards HR and mean arterial pressure alterations in this study, there was no statistical difference among the studied groups. These results are in agreement with that of Leelavathy et al.  who performed a comparison between dexmedetomidine and fentanyl as adjuvants to subarachnoid bupivacaine for surgeries of the lower abdomen, and they noticed that there were no significant changes in hemodynamics. Kanazi et al.  showed the insignificant effect of dexmedetomidine on SBP when added to intrathecal bupivacaine. Moreover, Al-Mustafa et al. , using 5 and 10 µg dexmedetomidine, found a dose-dependent decrease in the SBP when compared with the bupivacaine (control) group, but it was still not significant.
Against the current results, Joshi and Sriramamurthy  revealed a significant decline in hemodynamics when 15 µg dexmedetomidine was added to subarachnoid bupivacaine; this may be due to increasing dexmedetomidine dose to 15 μg against 10 μg of our study.
In this study, hypotension and bradycardia were more in the dexmedetomidine group than in the other two groups, but it was not statistically significant. Respiratory depression was not detected in any group.
| Conclusion|| |
It became clear that adding dexmedetomidine as adjuvant to bupivacaine to spinal block has better results than magnesium sulfate or bupivacaine alone in patients undergoing classical repair surgeries, as it provides rapid onset of sensory and motor block and lengthens the duration of sensory block and motor block. It improves the quality of postoperative analgesia and reduces postoperative analgesic requirements; no complications were recorded.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]