ABSTRACT

Corresponding Author:
Dr. Thuraganur Kapanigowda Shashikala,
Associate Professor,
Department of Anaesthesiology,
Stone Building, K R Hospital,
Mysore Medical College and Research Institute,
Mysore.
E-mail: drshi72@yahoo.com

ABSTRACT

BACKGROUND

Various adjuvants are being used with local anaesthetics intrathecally for prolongation of intraoperative and postoperative analgesia. Dexmedetomidine, the highly selective alpha-2 adrenergic agonist is a new neuraxial adjuvant gaining popularity. Fentanyl is commonly used as an opioid adjuvant to local anaesthetic for spinal anaesthesia.

AIM

The purpose of this study was to compare the onset, duration of sensory and motor block, haemodynamic effects, postoperative analgesia and adverse effects of dexmedetomidine and fentanyl used intrathecally with hyperbaric 0.5% bupivacaine for spinal anaesthesia.

METHODOLOGY

The study was conducted in prospective, double-blind manner. It included 90 American Society of Anaesthesiology (ASA) class I and II patients undergoing lower limb surgery under spinal anaesthesia. The patients were randomly allocated into three groups (30 patients each). Group C received 12.5 mg hyperbaric bupivacaine (2.5 mL) with normal saline (0. 5mL), group F received 12.5 mg bupivacaine (2.5 mL) with 25 µg fentanyl (0.5 mL) and group D received 12.5 mg bupivacaine (2.5 mL) plus 5 µg dexmedetomidine (0.5 mL). The onset time to reach peak sensory and motor level, the regression time of sensory and motor block, haemodynamic changes and side effects were studied.

RESULTS

Patients in Group D had significantly longer duration of sensory and motor block than patients in Group C and F. The mean time of two segment sensory block regression was 95.8±21 min in Group C, 130.5±17 in Group D, 131±22 in Group F (P<0.0001). The duration of motor block was 226±24.1, 626.5±48.5, 391.5±30.0 in Group C, D, and F respectively (P <0.0001). The onset time to reach maximum level of sensory block and modified Bromage 3 motor block were not significantly different between the groups. Dexmedetomidine group showed significantly less and delayed requirement of rescue analgesic.

CONCLUSION

Intrathecal dexmedetomidine is associated with prolonged motor and sensory block, haemodynamic stability and reduced demand of rescue analgesics as compared to fentanyl or lone bupivacaine.

KEYWORDS

Dexmedetomidine, Fentanyl, Bupivacaine Heavy, Spinal.

INTRODUCTION

Subarachnoid blockade is the most commonly used regional anaesthetic technique for lower limb surgery. Various adjuvants are being used with local anaesthetics for prolongation of intraoperative and postoperative analgesia.¹

NS- Not Statistically Significant

In our study there was no statistically significant difference in the adverse effects except hypotension throughout the procedure when group D and group F were compared with group C and there was no statistically significant difference when group D was compared with group F. There were 6 patients in group C, 9 patients in group D and 1 patient in group F developed hypotension which was managed with injection mephentermine 6 mg intravenously in incremental dosage.

DISCUSSION

Hypothesis Done Before the Study

We hypothesised that Dexmedetomidine when added as an adjuvant to 0.5% hyperbaric Bupivacaine intrathecally would produce a prolonged duration of sensory blockade, motor blockade and duration of analgesia when compared to Fentanyl added as an adjuvant.

Demographic Data

In our study there was no significant difference among the three groups, i.e. Control group, Dexmedetomidine group and Fentanyl group regarding the age, height and weight of the patients.

We also did not find any statistically significant difference regarding the mean duration of surgery.

In our study, the mean time taken for the onset of sensory block was 2.03±0.413, 2.23± 0.504, 2.10±0.607 min in group C, group D and group F respectively. There was no statistically significant difference in onset time of sensory blockade among the groups (p >0.314).

Our study compared with the study conducted by Mahendru V et al³, who have also found statistically there was no significant difference in the mean onset of sensory block group BS (Bupivacaine+saline) 7.8±1.8, group BF (Bupivacaine+Fentanyl) 8.6±1.5, group BC (Bupivacaine+Clonidine) 8.3±2.8, group BD (Bupivacaine+Dexmedetomidine) 8.3±2.4 with p<0.113.

Our study also compared with SL Solanki et al⁴, Al-Ghanem SM et al⁵, Gupta R et al⁶ and Khan AL et al⁷, wherein the authors of these studies have not found any significant difference in the onset of sensory block in both Dexmedetomidine group and Fentanyl group.

In our study, subarachnoid block was given in sitting posture and then patients were positioned in supine posture soon after the completion of the subarachnoid injection.

In our study, mean time taken for maximum level of sensory blockade was 4.3±0.844, 4.8±0.819, 5.4±1.357 min in group C, group D, group F respectively (p<0.000). There was statistically significant difference among the groups. Our study compared with Singh et al⁸, they have found statistically significant difference among the group C and group B. In their study, the concentration of the drug used was 0.75% Bupivacaine instead of 0.5% Bupivacaine unlike our study.

In our study, maximum level of sensory blockade was not significant statistically. Our results were comparable with Mahendru V et al³, Al-Ghanem SM et al⁵, Gupta R et al⁶, Tarbeeh GA et al.⁹ They have also not found statistically significant difference between dexmedetomidine and fentanyl group. In our study, mean time taken for the sensory regression by two segments 95.8±21.3, 130±17.238, 131±22.748 min in group C, group D, group F respectively. p<0.000. Statistically, there was significant increase in mean time taken for two segment sensory regression in group D in group F as compared to group C.

Statistically, there was significant increase in time taken for sensory regression in group F when compared to group D. Our study compared with the study conducted by Gupta R et al⁶, the mean time taken for the sensory regression by two segments in group D 120±22.2 mins, group F 76±20.2 mins. The reason probably is the maximum level of sensory blockade in their study with Fentanyl group was T6 when compared to our study (T4). Our study also compared with Kanazi et al¹⁰, Khan AL et al⁷, Singh et al⁸, studies who also found significant difference in Dexmedetomidine group and fentanyl group than control group.

In our study the mean duration of rescue analgesia 235±25.675, 652±49.785, 394±28.987 in group C, group D, group F respectively. Statistically significant difference between group D compared to group F and group C and statistically significant in group F compared to group C. Our study is compared with Solanki SL et al⁴ study; in that they found group D 824±244, group C 678±178, group B 406±119 mins, which was statistically significant in group D and group C when compared to B. We also compared with Mahendru V et al³ study; in their study they also noticed statistically significant duration of rescue analgesia in group D when compared to group F and C. We also compared our study with Gupta R et al⁶; they also found significant increase in analgesia in dexmedetomidine group.

In our study time taken for onset of motor blockade 2.2±0.50 4 min, 2.3±0.614, 2.2±0.406 in group C, group D, group F respectively; p >0.419 which was not statistically significant.

In our study, the duration of motor blockade was 158±20.744, 434±63.874, 292±24.835 mins in group C, group D, group F respectively; p <0.000. Statistically, there was significant increase in mean duration of motor blockade in Group-D and Group-F as compared to Group-C. Statistically, there was significant increase in mean duration of motor blockade in Group-D as compared to Group-F. Our study compares with the study conducted by Tarbeeh GA et al⁹, who also found statistically significant difference in mean time taken for duration of motor blockade between Dexmedetomidine group and Fentanyl group compared with Bupivacaine group.

In our study, mean duration of motor blockade was prolonged in Group-D and statistically significant compared with Group-F. Our study compares with studies conducted by Al-Ghanem SM et al⁵, Gupta R et al⁶, Mahendru V et al³ and Tarbeeh GA et al⁹, who also have found statistically significant difference when Dexmedetomidine group was compared with Fentanyl group.

In our study, the mean duration of motor blockade was prolonged in Fentanyl group compared with Bupivacaine group. Our study compares with the study conducted by Mahendru V et al³, who also found statistically significant difference (Bupivacaine group - 161±19 min and Fentanyl group - 196±26 min).

In our study, mean sedation score was assessed using Ramsay sedation scale. There was no statistical significant difference among the groups (p=0.155).

Our study compares with the studies conducted by Mahendru V et al³, who also found no statistical significant difference among three groups.

In our study, there was no statistically significant difference in the haemodynamic parameters like heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure throughout the surgery when Group-D and Group-F was compared with Group-C and also there is no statistical significant difference when Group-D compared with Group-F.

In our study, there was no statistically significant difference in the adverse effects throughout the procedure when Group-D and Group-F compared with group-C and also there was no statistical significant difference when Group-D was compared with Group-F.

CONCLUSION

From the present study, we conclude that both Fentanyl and Dexmedetomidine will delay the onset of sensory and motor block, prolong the time of regression by two segments, prolong the duration of sensory block, motor block and duration of analgesia compared to bupivacaine alone.

However, Dexmedetomidine as an adjuvant produces more prolonged duration of sensory block and motor block and duration of analgesia compared to Fentanyl as an adjuvant.

Both Fentanyl and Dexmedetomidine as adjuvants do not produce significant haemodynamic changes with minimal effects on ventilation and oxygenation. They produce lesser incidence of pruritus and postoperative nausea and vomiting. Hence, it is concluded that Dexmedetomidine is better than Fentanyl as an adjuvant to 0.5% hyperbaric bupivacaine for spinal anaesthesia.

REFERENCES

1. Cousins MJ. Neural blockade in clinical anaesthesia and pain medicine. 4^th edn. Philadelphia: Lippincott Williams and Wilkins 2009:p 213.
2. Corby MP, Bach AB. Transient radicular irritation (TRI) after spinal anaesthesia in day-care surgery. Acta Anaesthesiol Scand 1998;42(4):425-9.
3. Mahendru V, Tewari A, Katyal S, et al. A comparison of intrathecal dexmedetomidine, clonidine, and fentanyl as adjuvants to hyperbaric bupivacaine for lower limb surgery: a double blind controlled study. J Anaesthesiol Clin Pharmacol 2013;29(4):496-502.
4. Solanki SL, Bharti N, Batra YK, et al. The analgesic effect of intrathecal dexmedetomidine or clonidine, with bupivacaine, in trauma patients undergoing lower limb surgery: a randomised, double-blind study. Anaesth Intensive Care 2013;41(1):51-6.
5. Al-Ghanem SM, Massad IM, Al-Mustafa MM, et al. Effect of adding dexmedetomidine versus fentanyl to intrathecal bupivacaine on spinal block characteristics in gynaecological procedure: a double blind controlledstudy. American Journal of Applied Science 2009;6(5):882-7.
6.  Gupta R, Verma R, Bogra J, et al. A comparative study of intrathecal dexmedetomidine and fentanyl as adjuvants to Bupivacaine. Journal of Anaesthesiol Clinical Pharmacolol 2011;27(3):339-43.
7. Khan AL, Singh RB, Tripathi RK, et al. A comparative study between intrathecal dexmedetomidine and fentanyl as adjuvant to intrathecal bupivacaine in lower abdominal surgeries: a randomized trial. Anaesthesia: Essays and Researches 2015;9(2):139-48.
8. Singh R, Shukla A. Randomized, controlled study to compare the effect of intrathecal clonidine and dexmedetomidine on sensory analgesia and motor block of hyperbaric bupivacaine. Indian Journal of Fundamental and Applied Life Sciences 2012;2(4):24-33.
9. Tarbeeh GA, Mohamed AA. Effect of intrathecal bupivacaine-fentanyl versus bupivacaine dexmedetomidine in diabetic patients. Egyptian Journal of Anaesthesia 2013;29(1):13-8.
10. Kanazi GE, Aouad MT, Jabbour-Khoury SI, et al. Effect of low-dose dexmedetomidine or clonidine on the characteristics of bupivacaine spinal block. Acta Anaesthesiol Scand 2006;50(2):222-7.