Bali Journal of Anesthesiology

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 5  |  Issue : 1  |  Page : 15--20

To determine the efficacy of intrathecal dexmedetomedine and fentanyl as adjuvants to spinal anesthesia for lower abdominal surgeries below the level of umbilicus - A prospective randomized controlled double blinded study


Jadi Laxmikanth, Sivakumar Segaran, Sagiev Koshy George, Ashwin John, Jemmie Rachel Johns, Nikita Mani 
 Department of Anaesthesiology and Critical Care, Pondicherry Institute of Medical Sciences, Puducherry, India

Correspondence Address:
Dr. Sivakumar Segaran
Department of Anaesthesiology and Critical Care, Pondicherry Institute of Medical Sciences, Puducherry
India

Abstract

Background: Spinal anesthesia is widely used regional anesthesia technique; however, postoperative analgesia is a major problem. The duration of analgesia can be prolonged by the addition of intrathecal adjuvants. Hence, this study is aimed to assess the characteristics of spinal block between the groups. Patients and Methods: One hundred and twenty-six adult patients were enrolled in this study. Patients were randomized into three groups of 42 in each group by the computer-generated numbers. Group A received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 25 mcg fentanyl (0.5 ml), Group B received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 5 mcg dexmedetomidine (0.1 ml) + 0.4 ml normal saline (NS), and Group C received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 0.5 ml NS. Block characteristics and hemodynamic changes were recorded between the groups. Results: Time to achieve sensory block (T10) and motor block (M1) were faster in Group B when compared to Group A and C (P < 0.001). Duration of sensory block and motor block was longer with Group B (450.12 ± 22.295 min and 390.12 ± 22.551 min) when compared to Group A (380.71 ± 13.331 min and 320.71 ± 13.403 min) and Group C (220.10 ± 14.635 min and 180.10 ± 14.355 min). Time for first rescue analgesia was also longer in Group B when compared to Groups A and C (P < 0.001). Conclusion: Intrathecal dexmedetomidine provides effective prolongation of sensory and motor block as adjuvant to hyperbaric bupivacaine in spinal anesthesia.



How to cite this article:
Laxmikanth J, Segaran S, George SK, John A, Johns JR, Mani N. To determine the efficacy of intrathecal dexmedetomedine and fentanyl as adjuvants to spinal anesthesia for lower abdominal surgeries below the level of umbilicus - A prospective randomized controlled double blinded study.Bali J Anaesthesiol 2021;5:15-20


How to cite this URL:
Laxmikanth J, Segaran S, George SK, John A, Johns JR, Mani N. To determine the efficacy of intrathecal dexmedetomedine and fentanyl as adjuvants to spinal anesthesia for lower abdominal surgeries below the level of umbilicus - A prospective randomized controlled double blinded study. Bali J Anaesthesiol [serial online] 2021 [cited 2021 Apr 22 ];5:15-20
Available from: https://www.bjoaonline.com/text.asp?2021/5/1/15/308883


Full Text



 Introduction



Spinal anesthesia is an age tested, safe, and reliable mode of anesthesia for lower limb and lower abdominal surgeries. It is a relatively easy technique, cheap, more rapid onset, fewer side effects, and produce consistent anesthesia with less failure rate.[1],[2] It has some disadvantages such as limited duration of action, dense motor blockade which makes postanesthesia ambulation difficult which is a drawback in ambulatory surgeries. It also produces post dural puncture headache in some individuals.[3],[4]

Spinal neuraxial blocks result in sympathetic, sensory, and motor blockade depending on the dose, concentration, or volume of local anesthetic injected into the subarachnoid space.[5] The use of intrathecal adjuvant has gained popularity with the aim of prolonging duration of postoperative analgesia, decrease local anesthetic dose, better success rate, patient satisfaction, and decreased stay in postanesthesia care unit.[6]

Several spinal adjuvants such as opioids (morphine, fentanyl, and sufentanil), α2 adrenergic agonists (clonidine), magnesium sulphate, neostigmine, ketamine, and midazolam have been used to improve the quality of spinal anesthesia and to prolong postsurgical analgesia.[7] However, opioids are the most frequently used intrathecal adjuvant.

Fentanyl is a synthetic opioid of the phenylpiperidine group. It is a pure μ receptor agonist and is about 100 times more potent than morphine as an analgesic. It is most commonly administered intravenously, although it is also administered epidurally and intrathecally as adjuvants.[8] Intrathecally administered opioids provide the perceived benefits of selective analgesia without motor blockade, but side effects such as delayed respiratory depression and pruritis have prompted further research to develop nonopioid analgesic with lesser side effects.

Alpha 2 adrenergic receptor agonists such as clonidine and dexmedetomidine have been the focus of interest for their sedative, analgesic, sympatholytic, and hemodynamic-stabilizing properties. Dexmedetomidine is a newer highly selective α2 receptor agonist (α2/α1 1600:1) compared with clonidine (α2/α1 200:1).[9] It is under evaluation as a neuraxial adjuvant as it provides stable hemodynamic conditions, good quality of intraoperative, and prolonged postoperative analgesia with minimal side effects.[10] Hence, this study was planned at comparing dexmedetomidine and fentanyl as adjuvants to spinal anesthesia for surgeries below the level of umbilicus.

 Patients and Methods



After obtaining Institutional Ethics Committee approval (IEC: RC/16/101 dated 18/08/2016) and clinical trial registry (CTRI REF/2017/11/016086) and written informed consent, this prospective, double-blinded, randomized controlled study was conducted in 126 patients who were posted for elective surgeries below the level of umbilicus under spinal anesthesia in a tertiary care center. Patients of both sexes belonging to the American Society of Anesthesiologists physical status (ASA PS) I and II and without any exclusion criteria such as raised intracranial pressure, coagulopathy, infection at site of injection, any neurologic disease, fixed cardiac output states, previous spine surgeries, patients on anticoagulants and antiplatelet drugs, and known allergies to study drug were enrolled in the study.

Preanesthetic assessment was done in the evening before surgery for all patients, and they were explained about the procedure. Oral Lorazepam 1 mg and Ranitidine 150 mg were given the night before surgery for all patients and kept nil per oral for 8 h before the surgery. Patients were randomized into three groups of 42 each by computer-generated randomization.

Group A received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 25 mcg fentanyl (0.5 ml), Group B received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 5 mcg dexmedetomidine (0.1 ml) + 0.4 ml normal saline (NS), and Group C received 12.5 mg of 0.5% bupivacaine (2.5 ml) + 0.5 ml NS.

Patients were shifted to the operating room and noninvasive monitors such as electrocardiogram, noninvasive blood pressure, and pulse oximeter (SpO2) were connected to the patients. Intravenous access was established with 18G cannula. All patients were preloaded with 10 ml/kg of ringer lactate before spinal anesthesia. Subarachnoid block was performed by a qualified anesthesiologist at L3–L4 interspace with 12.5 mg of 0.5% hyperbaric bupivacaine along with the study drug in the sitting position. Immediately, after the drug was given patient was placed supine and that was taken as T0. After every 2 min, onset of sensory block was checked using pin-prick method and motor blockade by Modified Bromage Scale.[11]

Time to reach T10 sensory level was noted, and then, the patient was draped. Peak sensory block level (PSBL) is defined as when there is no further increase in sensory block after 4 continuous checking. Time to reach PSBL and time to achieve complete motor block (M1) were also noted. Intraoperative heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were noted for every 3 min for first 15 min, thereafter every 5 min until the end of the procedure. If there was failure of spinal anesthesia, general anesthesia would be given, and the patient would be omitted from the study.

Bradycardia which is defined as HR <50 bpm was treated with atropine 0.6 mg and hypotension which is defined as fall in MAP more than 30% from baseline or MAP <60 mmHg was treated with 6 mg ephedrine. After PSBL achieved, the patient was checked for sensory block every 15 min until there is two-segment regression of sensory block level and time for two segment regression is noted. Postoperative pain was scored according to the Visual Analog Scale (VAS) which was explained to the patient during preanesthetic check-up. When the VAS score was > 4, rescue analgesia was given with diclofenac sodium (aqueous) 75 mg in 100 ml NS dilution. Time for first rescue analgesia was noted. We also noted for complications such as nausea, vomiting, and pruritis.

Statistical analysis was performed using the Statistical package for the Social Sciences (SPSS) for Windows version 20.0 software, SPSS Inc., Chicago, USA. Data are expressed as either mean and standard deviation or numbers and percentages. Continuous variables were compared using the analysis of variance. The comparison was studied using the Chi-square test or Fisher's exact test as appropriate. P < 0.05 was considered statistically significant.

 Results



In this prospective, randomized, control, double-blinded study, all 126 patients completed the study [Figure 1]. The demographic profile which included age, sex, weight, and ASA grade were similar in all the three groups and was not statistically significant [Table 1].{Figure 1}{Table 1}

In our study, the mean duration of surgery was 126.67 ± 13.87 min in Group A, 131.31 ± 23.55 min in Group B, and 124.29 ± 14.96 min in Group C, which was not statistically significant. The mean time to achieve T10 block level in all three groups was shown in [Table 2]. Post hoc analysis revealed that the time to achieve T10 block level was significantly shorter in Group B compared to Group A and Group C.{Table 2}

The PSBL ranged from T5 to T9. A Tukey post hoc test revealed that the time to achieve PSBL was significantly lower in Group B when compared to Group A and C, and it was statistically significant.

The hemodynamic parameters such as HR, SBP, DBP, and MAP were lower in the Group B when compared to Group A and Group C at various time points during the peri-operative period, and it was statistically significant [Figure 2],[Figure 3],[Figure 4]. There are no statistically significant changes in the incidence of bradycardia and hypotension among the three groups ?[Table 2]. There is no evidence of nausea, vomiting, and pruritis in any of the groups.{Figure 2}{Figure 3}{Figure 4}

 Discussion



Spinal anesthesia is a preferred choice of anesthesia in lower abdominal surgeries as it is very economical and easy to administer, however postoperative analgesia is a major concern associated with relatively short duration of action, so early analgesic intervention is needed in the postoperative period. Various intrathecal adjuvants have been used combined with local anesthetics in spinal anesthesia to provide prolonged postoperative analgesia and to improve the quality of anesthesia.

Addition of fentanyl with local anesthetics increases the quality of the regional block and the duration of the block.[12] The effects of intrathecal fentanyl can be attributed to its action on opioid receptors in the dorsal horn of the spinal cord.[13] Alpha 2 receptor agonists produce analgesia by the suppression of C fiber transmission, thereby causing hyperpolarization of postsynaptic neurons of the posterior horn. It is probable that prolonging the motor block of the spinal anesthetics results from the binding of the alpha 2 receptor agonists to the motor neurons in the posterior horn.[14]

In our study, the time taken to achieve sensory block to T10 level was significantly faster in Group B when compared to Group A and Group C (P < 0.001) and time taken to achieve T10 sensory block in Group A was faster than Group C. Our results were similar to the studies where they compared intrathecal dexmedetomidine and fentanyl as additives to bupivacaine and concluded that dexmedetomidine has faster sensory onset compared with fentanyl and local anesthetic alone when injected intrathecally.[15],[16]

Gupta et al.[17] compared intrathecal dexmedetomidine and fentanyl as adjuvants to bupivacaine. They observed that the maximum height of sensory block achieved was T5 with dexmedetomidine and T6 with fentanyl as adjuvant to local anesthetic. In our study, the PSBL achieved in dexmedetomidine group was T5 in 15 patients and in fentanyl group T5 was achieved by 10 patients.

In our study, the time taken for the onset of motor block (M1) in dexmedetomidine group was faster when compared with fentanyl group and NS group. Similarly, Safari et al.[18] conducted a study on intrathecal dexmedetomidine and fentanyl as adjuvants to bupivacaine on the duration of spinal block in addicted patients where they found that onset of motor block was significantly faster in the dexmedetomidine group when compared to fentanyl group which was statistically significant. This finding also shared the results by other studies.[19],[20]

In our study, the time taken for two segment regression was longer in dexmedetomidine group when compared to fentanyl group and NS group. Similarly, Kurhekar et al.[21] have conducted a study on the effect of adding dexmedetomidine and morphine to intrathecal bupivacaine in gynecological procedures and found out that dexmedetomidine group took longer time for two segment regression when compared to morphine and NS group. Similar results were also reported by other studies.[15],[17]

In our study, the mean duration of sensory block and motor block was longer for dexmedetomidine group when compared to fentanyl and NS groups. Al-Ghanem et al.[22] had studied the effect of addition of 5 mcg dexmedetomidine or 25 mcg fentanyl intrathecal to 10 mg isobaric bupivacaine in vaginal hysterectomy and concluded that 5 mcg dexmedetomidine produces more prolonged motor and sensory block as compared with 25 mcg fentanyl. In a comparative study conducted by Leelavathy et al.[23] between intrathecal bupivacaine with dexmedetomidine and intrathecal bupivacaine with fentanyl for lower abdominal surgeries and found out that the duration of sensory and motor blockade was more in dexmedetomidine group compared to fentanyl group, which was statistically significant.

Our results were similar to other studies[13],[14],[15],[24] who reported that intrathecal dexmedetomidine is associated with prolonged sensory block when compared to fentanyl and NS group, but they did not find any significant changes in the duration of motor block which is different from our study where we found prolongation of both sensory and motor block.

In our study, the hemodynamic parameters such as HR, SBP, DBP, and MAP were lower in the dexmedetomidine group when compared to fentanyl and NS group. Our results were different from the results published in previous reports where they did not find statistically significant changes in hemodynamic between the groups.[17],[21],[25]

In our study, two patients in fentanyl group and one in dexmedetomidine group had bradycardia and one patient in dexmedetomidine group had hypotension. Other adverse effects such as nausea, vomiting, and pruritis were not seen. Similar study by Routray et al.,[26] on the effect of intrathecal dexmedetomidine and fentanyl as adjuvants to hyperbaric bupivacaine for orthopedic lower limb and lower abdominal procedures and found out that in there study the incidence of bradycardia, hypotension, nausea, vomiting, pruritis, and urine retention was not statistically significant.

Some limitations arose from our study. The study was done on ASA 1 and ASA 2 patients only which cannot be extrapolated for higher ASA grades and pediatric age groups. We also did not measure the sedation score in our patients.

 Conclusion



From this study, we conclude that both fentanyl and dexmedetomidine are effective adjuvants to spinal bupivacaine with better block characteristics than plain bupivacaine. Intrathecal dexmedetomidine has longer sensory analgesia and motor block with rapid onset when compared to intrathecal fentanyl and NS as adjuvants to hyperbaric bupivacaine in spinal anesthesia without significant side effects.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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