Comparative study of dexmedetomidine and clonidine along with ropivacaine in epidural anaesthesia for vaginal hysterectomy

 

Jadhav Shashikant Abhimanyu¹, Kore Rahul Dharma^2*

 

^1,2Assistant Professor, Department of Anaesthesiology, Dr. V. M. Government Medical College, Solapur, Maharashtra, INDIA.

Email: rahuldkorefb@yahoo.com

 

Abstract               Background: The present randomized double blind prospective study was carried out for Comparison of Dexmedetomidine and Clonidine along with Ropivacaine in epidural anaesthesia for vaginal hysterectomy. Methods: 60 female patients of ASA grade I and II, between the age group of 45 - 60 years were randomly assigned to 2 groups. Group RD: received 17 ml of 0.75% Ropivacaine Hcl and 1µg/kg of Dexmedetomidine Hcl, Group RC: received 17 ml of 0.75% Ropivacaine Hcl and 2µg/kg of Clonidine Hcl in supine position via epidural catheter. Onset, quality, duration of sensory and motor block and hemodynamic parameters evaluated. Results: Patients from Group RD have fast sensory block onset (i.e. 9.96±0.61min), prolonged two seg. regression time (138.93±4.48) and prolonged Analgesia time ((i.e 353.9±4.03min) as compared to Group RC i.e. (12.4±0.77), (128.8±3.46),(308.06±5.47) respectively. The duration of motor blockade was prolonged in patients of group RD (242.23±5.72min) as compared to the patients in group RC (230.66±5.20min). Patients in group RD were more sedated as compared to the patients in group RC. Initial fall in heart rate was more in patients of RD group as compared to the patients of group RC but later on both the groups showed stable heart rate. Fall in systolic, diastolic and mean arterial blood pressure was more in patients of RD group (during 5 to 50- 55 min of epidural injection) as compared to the patients of group RC. Later on both the groups showed stable systolic blood pressure. Conclusion: Dexmedetomidine is better adjuvant as compared to Clonidine for providing early onset and prolonged intraoperative as well as postoperative analgesia, better sedative property Both the drugs showed bradycardia and hypotension which was clinically insignificant.

Key Words: Dexmedetomidine, Ropivacaine.

 

 

INTRODUCTION

Alpha-2 agonists like Clonidine and Dexmedetomidine have been recently added to armamentarium of the anaesthesiologists as additives in regional blocks. Analgesic and anaesthetic drug requirements get reduced to a large extent by use of Clonidine and Dexmedetomidine as adjuvants because of their analgesic properties. The affinity of Dexmedetomidine towards alpha-2 adrenoreceptors is eight times more compared to Clonidine¹ with ratio of (alpha-1: alpha-2) 1:1600.^2,3,4 They also augment local anaesthetic effect leading to stable haemodynamics and decreased oxygen demand during surgery¹. Ropivacaine, a new long-acting local anesthetic shows the differentiation between sensory and motor blocks. This differentiation is particularly useful when early mobilization is important to accelerate postoperative recovery. Addition of alpha-2 agonists to Ropivacaine improves the quality of epidural anaesthesia and postoperative analgesia^2,5,6,7. There are very few clinical trials in India which compare the effects of addition of Dexmedetomidine/Clonidine with Ropivacaine in epidural anaesthesia¹. So this prospective double blind randomized study was carried out to compare effect of Dexmedetomidine or Clonidine, as an adjuvant to Ropivacaine for epidural anaesthesia in patients undergoing vaginal hysterectomy.

 

MATERIAL AND METHODS

The present randomized double blind prospective comparative study was carried out in 60 female patients of ASA grade I and II, between the age group of 45 - 60 years scheduled electively for vaginal hysterectomy at S.R.T.R Govt. Medical College, Ambajogai, Maharashtra. After approval from the institutional ethical committee we have selected 30 patients in each group for the study. The patients were randomly allocated into two groups i.e. RD and RC. Intravenous administration of Ringer’s lactate solution was started at the rate of 8ml/kg¹. All monitors applied and basal readings noted. All patients were premedicated with IV inj. Ranitidine 1 mg/kg IV, inj, Ondansetron 0.08 mg/kg. Under all aseptic precautions, epidural catheter was inserted in L2-3 or L1-2 intervertebral space using 18 G Touhy needle and 5cm of the catheter length was kept in epidural space and after 3 - 5 minutes of administering test dose and confirming its correct placement, epidural administration of drugs was done in supine position as follows.

Group RD: received 17 ml of 0.75% Ropivacaine HCL and 1µg/kg of Dexmedetomidine HCL

Group RC: received 17 ml of 0.75% Ropivacaine HCL and 2µg/kg of Clonidine HCL

All the data was recorded in proforma. Decoding of drugs was done at the end of study. The data was analysed statistically. In this study, for quantitative data of both the groups, mean and standard deviation were calculated. To find out the significant difference between two groups unpaired t- test was used and P value calculated with 95% confidence interval (P value <0.05) using Open Epi version 2.3.1. Paired t-test was used for intra group comparison. For qualitative data, Chi square test was used and difference was considered statistically significant if P value is <0.05.

 

Sensory block characteristics

 There is no such study which has compared the dose equivalence of Dexmedetomidine and Clonidine but the observations of various studies reveal that the dose of Clonidine is 1.5−2 times higher than Dexmedetomidine when used in epidural route^1,9,15,16. So based on these studies we used 1µg/kg of Dexmedetomidine or 2µg/kg of Clonidine as adjuvant to Ropivacaine in epidural anaesthesia as also used by Saravana Babu MS et al.¹³

Demographic profile

Table 1

P<0.05 is Significant (unpaired t-test), SD - Standard deviation, NS- Not Significant

The demographic profile of our patients was comparable with respect to mean age, body weight and duration of surgery and was statistically insignificant.

 

Sensory block characteristics

Table 2

s- Significant

Reduction in time required to achieve maximum sensory dermatomal level in patients of group RD (20.9±0.8min) as compared to the patients in group RC (24.3±0.66min).The maximum sensory dermatomal level achieved and quality of sensory and motor block were same in both the groups. The time required for two segment regression of sensory dermatomal level was more in patients of group RD (138.93±4.48min) as compared to the patients in group RC (128.8±3.46min). Bajwa SJS et al¹ observed that the onset time of sensory block in patients of group RD was 8.52 ± 2.36 minutes and it was 9.72 ± 3.44 minutes in patients of group RC. The time required to achieve maximum sensory dermatomal level in patients of group RD was 13.14 ± 3.96 minutes and it was15.80 ± 4.86 minutes in patients of group RC. They have used 1.5µg/kg of Dexmedetomidine which was more than the dose used by us (1µg/kg), so the time required for onset of sensory block and time required to achieve maximum sensory dermatomal level in patients of Bajwa’s study was earlier than observed in our study. Saravana Babu MS et al¹³ found that the time of onset of sensory block in patients of group RD was 7.33 ± 1.76 min and in patients of group RC was 8.40 ± 1.61min. The time required to achieve highest sensory dermatomal level in patients of group RD was 11.6 ± 2.05 min and in patients of group RC was 13.20 ± 2.90 min. The patients in group RD required less time to achieve maximum sensory block than patients of group RC. They have administered epidural analgesia for postoperative pain relief in patients undergoing spinal surgery under General anaesthesia. The residual effect of anaesthetic agents might be responsible for earlier onset and earlier maximum level achieved in their study as compared to our study. In our study, 26 patients in the group RD had highest dermatomal level of blockade at T6 and in group RC 23 patients achieved highest dermatomal level of blockade of T6, and the difference was statistically insignificant. None of the patient in either group showed inadequate level of sensory analgesia requiring supplementation of analgesic drugs. The present study is in accordance with observations of Bajwa SJS et al.¹ They found that the maximum sensory dermatomal level achieved in all the patients of group RD was T5-6 and that of the in group RC was T6-7. The quality of sensory block assessed in patients of both groups showed grade-4 sensory block in 26 patients and grade-3 sensory block in 4 patients of group RD. While in group RC 23 patients showed sensory block of grade-4 and 7 patients showed sensory block of grade-3. The result of the our study can be explained on the basis of observation that addition of alpha-2 agonists to local anaesthetics potentiates their action by causing hyperpolarisation of nerve tissues^3,4, giving good quality of analgesia. Bajwa SJS et al¹ observed similar results in their study. Verma J et al¹² observed that the addition of Clonidine to bupivacaine in epidural has improved the quality of sensory block with 54% of patient had sensory block of grade-3 and 35% of patient had sensory block of grade-4. Our observations are similar to above studies. Bajwa SJS et al¹ observed that the time required for two segment regression of sensory dermatomal level in patients of group RD was 136.46 ± 8.12 min and it was 128.44 ± 27.18 min in patients of group RC. The difference in two was found to be statistically significant. Thus the patients in group RC had regression of sensory dermatomal level earlier than patients of group RD.

Motor block characteristics

Table 3

 

 

Figure 2

Fall in systolic, diastolic and mean arterial blood pressure was more in patients of RD group (during 5 to 50- 55 min of epidural injection) as compared to the patients of group RC (fig.3). Later on both the groups showed stable systolic blood pressure which remained on lower side as compared to their preoperative values up to 6 hours of postoperative period. None of the patients in either group required treatment of hypotension as the fall in Blood pressure was <30% of basal value.

Saravana Babu MS et al¹³ observed that mean VAS scores were higher in RC group in comparison to RD group at different time intervals, although statistically insignificant. Duration of analgesia in patients of group RD was 407 ± 47.06 minutes and in patients of group RC was 345 ±35.02 minutes. The difference between two was found to be statistically significant. There were no postoperative complications like nausea, vomiting, respiratory depression (RR<10), hypotension, bradycardia, tachycardia, pruritus, dry mouth, drowsiness found in both the groups in recovery room.

 

CONCLUSION

We concluded that Dexmedetomidine and Clonidine both are safe and effective adjuvants to epidural Ropivacaine. Dexmedetomidine is better adjuvant as compared to Clonidine for providing early onset and prolonged intraoperative as well as postoperative analgesia, better sedative property Both the drugs showed bradycardia and hypotension which was clinically insignificant.

 

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