Al-Azhar Assiut Medical Journal

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 18  |  Issue : 1  |  Page : 40--45

Intrathecal dexmedetomidine versus magnesium sulfate as adjuvant to hyperbaric bupivacaine in total abdominal hysterectomy


Abeer E Farhat1, Mona E Elkafrawy2,  
1 Lecturer of Anesthesia, Intensive Care and Pain Management, Faculty of Medicine for Girls, Al Azhar University, Cairo, Egypt
2 Assistant Professor of Obstetrics and Gynecology, Faculty of Medicine for Girls, Al Azhar University, Cairo, Egypt

Correspondence Address:
Abeer E Farhat
Helmyet Elzaitoun, Cairo 11724
Egypt

Abstract

Background Different adjuvants have been added to local anesthetics to increase the duration of regional anesthesia, delay onset of postoperative pain, and decrease pain-relieving drugs. The present study aims to compare the effect of adding dexmedetomidine versus magnesium sulfate to intrathecal hyperbaric bupivacaine in total abdominal hysterectomy regarding onset, duration of sensory and motor blockade, duration of postoperative analgesia, hemodynamic stability, and complications. Patients and methods A prospective randomized double-blind clinical study included 40 women aged 40–56 years, with American Society of Anesthesiologists physical status I and II, scheduled for total abdominal hysterectomy. They were randomly divided into two groups: group I (n=20) got 15 mg of 0.5% hyperbaric bupivacaine in addition to 10 μg dexmedetomidine, whereas group II (n=20) got 15 mg of 0.5% hyperbaric bupivacaine in addition to 100-mg magnesium sulfate, in a total volume of 4 ml in both groups. The primary outcome is onset, duration, and intensity of sensory and motor blockade. The secondary outcomes are hemodynamic stability, duration of postoperative analgesia, and complications. Results The onset of sensory and motor blockade was significantly faster and of prolonged duration in dexmedetomidine group than magnesium sulfate group (P<0.001). The duration of postoperative analgesia was significantly prolonged in dexmedetomidine group (P<0.001). Regarding hemodynamic and complications, there were no significant differences between both groups (P˃0.005). Conclusion Addition of dexmedetomidine to intrathecal bupivacaine appears to be superior to magnesium sulfate as it produce faster onset and prolongs the duration of sensory and motor blockade and postoperative analgesia.



How to cite this article:
Farhat AE, Elkafrawy ME. Intrathecal dexmedetomidine versus magnesium sulfate as adjuvant to hyperbaric bupivacaine in total abdominal hysterectomy.Al-Azhar Assiut Med J 2020;18:40-45


How to cite this URL:
Farhat AE, Elkafrawy ME. Intrathecal dexmedetomidine versus magnesium sulfate as adjuvant to hyperbaric bupivacaine in total abdominal hysterectomy. Al-Azhar Assiut Med J [serial online] 2020 [cited 2020 Jul 10 ];18:40-45
Available from: http://www.azmj.eg.net/text.asp?2020/18/1/40/281359


Full Text



 Introduction



Spinal anesthesia is usually utilized for patients who need surgical anesthesia for procedures of known duration that involve lower abdominal surgeries. It is valuable when patients wish to remain conscious or when comorbidities, for example, severe respiratory problem or a difficult airway, increase the incidence of utilizing general anesthesia [1].

Adequate postoperative pain relief can enhance recovery and increase patient satisfaction [2].

Different adjuvant have been added to local anesthetics to increase the duration of the regional anesthesia, decrease pain-relieving drugs, and delay the onset of postoperative pain [3].

Dexmedetomidine is a highly selective α2-adrenergic agonist, so it is used as an adjuvant to general anesthesia, and by acting on the intrathecal α2-adrenergic receptor, it can be used as an adjuvant in spinal anesthesia, prolonging both motor and sensory block [4].

In the spinal cord, activation of α2-receptors decreases pain transmission by hyperpolarizing spinal interneuron’s via G-protein-mediated activation of potassium channels and by decreasing the release of the neurotransmitters (substance P and glutamate) from primary afferent terminals [5].

Efficacy and safety of intrathecal magnesium as an adjuvant has been tried by several clinical trials in the past yeas [6].

Magnesium inhibits N-methyl-D-aspartate receptors and reduces pain transmission by noncompetitive mechanism and blocks central sensitization from peripheral nociceptive stimulation. It can reduce neuromuscular transmission, inhibit neuronal calcium influx, and reduce neuromuscular junction acetylcholine release, and hypermagnesemia potentiates the effects of neuromuscular blockade [7].

Magnesium sulfate affects the onset of sensory and motor block and prolongs the duration of spinal anesthesia [8].

 Patients and methods



A prospective randomized double-blind clinical study was conducted in the Department of Anesthesia and Intensive Care, Al-Zahraa University Hospital, between April 1, 2018, and September 30, 2018, after approval from the hospital ethical committee and informed written consent. The study included 40 women, between 40 and 56 years of age, with American Society of Anesthesiologists physical status I and II, planned for total abdominal hysterectomy under spinal anesthesia. Exclusion criteria include patients with uncontrolled hypertension, diabetes mellitus, cardiac disease, and any contraindication for spinal anesthesia or allergy to the study drugs. The primary outcome of the study is the efficacy of block. Secondary outcomes are hemodynamic stability, postoperative analgesia, and complications such as nausea and vomiting. Complete preanesthetic check-up was done a day before the surgical procedure. The study protocol and the spinal procedure were explained to every patient during the preoperative visit, and the patients were kept fasting overnight. No premedication was given to the patients on the earlier night of surgery. In the recovery room, after securing 18 G intravenous cannula, preloading was given with 10 ml/kg lactated ringer solution. In the operating room, patients were connected to a standard monitoring [noninvasive arterial blood pressure (BP), ECG, heart rate (HR), and pulse oximetry], and baseline readings were recorded. The patient was put in the sitting position, and under complete aseptic precaution, skin overlying L3–L4 interspace was penetrated with 2 ml of 2% lidocaine. Then lumbar puncture was done via a midline approach utilizing a 25 G spinal needle (Spinocan; B. Braun, Melsungen, Germany).

Patients were randomly divided into one of two groups using a computer-generated random numbers and closed opaque envelops. Patients and anesthesiologists who performed the block were blinded to the group allocation.Group I (n=20) received 15 mg of 0.5% hyperbaric bupivacaine plus 10 μg dexmedetomidine in preservative-free normal saline in a total volume of 4 ml.Group II (n=20) received 15 mg of 0.5% hyperbaric bupivacaine plus 100 mg magnesium sulfate in a total volume of 4 ml.

After intrathecal injection, the patients were positioned in supine position and received oxygen 4 l/min via a facemask.

The onset of sensory block was assessed by examining the adjustments in pinprick sensation, utilizing short hypodermic needle along the midclavicular line bilaterally, in every 2 min until no sensation was achieved. The onset of motor block was assessed every 2 min until complete motor block (Grade 3 modified Bromage scale in the limbs) was achieved (Bromage 0: the patient can move the hip, knee and foot; Bromage 1: the patient cannot move hip yet can move knee and foot; Bromage 2: the patient cannot move hip and knee, but ready to move the foot; and Bromage 3: the patient cannot move hip, knee, and foot) [9].

Hemodynamic monitoring (BP, HR, and pulse oximetry) was recorded at baseline and every 10 min for 30 min then every 15 min until the end of surgical procedure. Bradycardia is known as decrease in HR less than 60 beat/min and treated with intravenous atropine (0.01 mg/kg). Hypotension is known as decrease in mean BP more than 20% of baseline value and treated by intravenous fluid and ephedrine (5 mg intravenous increments). Other intraoperative adverse effects (e.g. nausea, vomiting) were recorded.

In postanesthesia care unit (PACU), the sensory level and Bromage scale were recorded every 15 min until the patient was released from the PACU. Pain in PACU was assessed on visual analog scale (VAS) between 0 and 10 (0=no pain, 10=the worst pain) at 2, 6, 12, and 24 h. VAS more than 4 or patient request analgesia was treated by intramuscular pethidine 0.5 mg/kg. Time of the first analgesic request and total dose of pethidine/24 h was recorded. The patients were discharged from PACU after complete recovery of sensory and motor functions.

Sample size was calculated expecting difference of mean detected in groups I and II was 2.45±1.33. The sample size was calculated in each group with α error 0.05 and power 80%, so for study purpose 18 patients in each group were taken.

Statistical analysis

Data were gathered, re-examined, coded, and entered to the Statistical Package for Social Science (IBM SPSS, Armonk, New York, USA) rendition 23. The quantitative data were exhibited as mean, SDs, and ranges when parametric. Likewise, qualitative variables were displayed as number and percentages. The comparison between groups regarding qualitative data was finished by utilizing c2 test. The comparison between two independent groups regarding quantitative data with parametric distribution was finished by utilizing Independent t test. The confidence interval was set to 95% and the margin of error accepted was set to 5%. Along these lines, the P value less than 0.05 was viewed as significant.

 Results



There were no statistically significant differences between the two groups regarding demographic data of the patients ([Table 1] and [Table 2]).{Table 1}{Table 2}

There were highly significant differences (P<0.001) between the two studied groups regarding the onset and regression time of sensory and motor block ([Table 3]).{Table 3}

There were no statistically significant differences between the two studied groups with respect to mean arterial pressure ([Table 4]).{Table 4}

There were no statistically significant differences between the two studied groups regarding HR ([Table 5]).{Table 5}

There were highly significant differences (P<0.001) between the two studied groups regarding the duration of analgesia ([Table 6]).{Table 6}

There were no statistically significant differences between the two studied groups regarding the complications.

Hypotension was treated by intravenous fluid and ephedrine (5 mg intravenous increments).

Bradycardia was treated by intravenous atropine (0.01 mg/kg). Nausea and vomiting was treated by metoclopramide 10 mg intravenous ([Figure 1]).{Figure 1}

 Discussion



In the present study, we compared the effect of adding intrathecal dexmedetomidine versus magnesium sulfate as an adjuvant to hyperbaric bupivacaine on the efficacy of block (onset, intensity, and regression time of sensory and motor blockade) as well as hemodynamic stability, the duration of postoperative analgesia, and complications on 40 women scheduled for total abdominal hysterectomy.

Regarding the onset time of sensory and motor blockade, it was earlier in dexmedetomidine group in contrast with magnesium sulfate group. The study results are similar to the study of Shukla et al. [10]; they studied 90 patients scheduled for lower abdominal and lower limb procedures who were randomly allocated into three groups to get intrathecal 15 mg hyperbaric bupivacaine plus either 10 μg dexmedetomidine (group D), 50 mg magnesium sulfate (group M), or 0.1 ml saline (group C). They found that onset time of sensory and motor blockade was rapid and of prolonged duration in dexmedetomidine group in comparison with magnesium sulfate group.

On the contrary, Farooq and Gupta [11] studied the effect of adding (50 mg) magnesium VS (10 μg) dexmedetomidine intrathecal as adjuvant to bupivacaine on efficacy of block on 90 patients undergoing lower abdominal and lower limb surgeries. They founded that onset time of sensory and motor block was shorter in dexmedetomidine group when compared with the other group, but the difference was statistically insignificant, which is not consistent with our results.

Regarding the duration of sensory and motor blockade, our results agree with Regar and Kanwaria [12]. They studied 50 patients undergoing lower limb and lower abdominal surgeries who were randomly allocated into two groups that received 3 ml of 0.5% hyperbaric bupivacaine plus either 10 μg of dexmedetomidine (group A) or 0.1 ml (50 mg) magnesium sulfate (group B) and found that duration of sensory and motor blockade was significantly prolonged in dexmedetomidine group compared with magnesium sulfate group.

Regarding hemodynamic, there were no statistically significant differences between the two studied groups. Our study results went in line with the study conducted by Talaat et al. [13], who studied 90 patients scheduled for elective cesarean section and were randomly divided into three groups that received intrathecal hyperbaric bupivacaine 12.5 mg plus either (5 μg) dexmedetomidine in (group D) or (50 mg) magnesium sulfate (group M), or 0.5 ml saline (group C) and found that no significant differences regarding mean arterial pressure and HR.

Our results disagree with Abdel Hamid and El-Lakany [14], who studied the effect of dexmedetomidine on 62 patients, who were randomly allocated into two groups. Group D got 3.5 ml volume of 0.5% hyperbaric bupivacaine in addition to 5 μl dexmedetomidine intrathecal, and group P got 0.5 ml normal saline added to the same dose of 0.5% hyperbaric bupivacaine and served as placebo for lower abdominal surgeries. They found that bradycardia (considered when HR<50 beat/min) occurred in eight cases in dexmedetomidine group compared with none in the other group. Bradycardia may be owing to activation of central postsynaptic α 2 adrenoceptors leading to sympatholytic effect (hypotension and bradycardia) [15].

The duration of analgesia, which was defined as the time between the onset of spinal analgesia and the first request of analgesia was significantly prolonged in dexmedetomidine group in comparison with the magnesium sulfate group. Similar results were observed by Regar and Kanwaria [12]. They found that the duration of analgesia was significantly prolonged in dexmedetomidine group. In addition, Gupta et al. [16] and Mahendru et al. [17] got similar results.Total analgesic consumption in the initial 24 h postoperatively was less in dexmedetomidine group than in the other group, and the first rescue analgesia was delayed in dexmedetomidine group in contrast with the other group.

Postoperative VAS score in the initial 6 h was less in dexmedetomidine group than the other group.

Regarding the complications, there were no statistically significant differences between both groups. Our results agree with Magdy et al. [18]; who reported the addition of low-dose dexmedetomidine intrathecal (5 μg) or intravenous (0.5 μg /kg/h) to spinal anesthesia for cesarean section attenuates maternal hemodynamic and the hormonal response to cesarean section without adverse effects.

 Conclusion



Addition of dexmedetomidine as an adjuvant to intrathecal bupivacaine in total abdominal hysterectomy appears to be superior to mg sulfate as it produces rapid onset and prolongs the duration of both sensory and motor blockade and postoperative analgesia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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