Pain is one of the most dreaded effects of the disease and all medical fraternity should take its relief as one of their main duties. Anesthesiologists have an important role to play in the fascinating field of pain management. 

In view of the wider application of regional anesthesia procedure in modern anesthesia practice, there is a need for local anesthetic with desirable properties like longer duration of sensory blockade and lesser duration of motor paralysis. Ropivacaine is newer amide type of local anesthetic having a lower potential for cardiac and central nervous system toxicity [1-4] shows a greater differentiation between sensory and motor blockade [5].

Adjuvant drugs are pharmacological agents possessing little pharmacological effect by themselves, but enhance or potentiate the action of other drugs when given at the same time. Adjuvant drugs modify local anesthetic effects and reduce side effects. Perioperative these drugs effect:

• Latency i.e., time of onset of local anesthetic block 

• Duration of analgesia i.e. duration of sensory and motor block 

• Quality of analgesia i.e. patient satisfaction, care provider’s impression of pain relief 

Various adjuvants that can be added to local anesthetics and administered in central neuraxial blockade are Opioids like Fentanyl [6], Sufentanyl [7], Morphine [8], Alpha2 agonists like Dexmedetomidine [9], Clonidine [10], Benzodiazepines like Midazolam [11] and other adjuvants like Neostigmine [12], Ketamine [13], Epinephrine [14], Magnesium sulphate [15].

Knowledge and use of adjuvant drug therapy has rendered neuraxial analgesia more effective in the management of both acute and chronic pain conditions. Alpha2 agonists have both analgesic and sedative properties when used as adjuvant in regional anaesthesia [16-18].

Dexmedetomidine is a new alpha2-agonist that received FDA approval in 1999 for use as short-term (less than 24 h) sedative, analgesic in the intensive care unit [19]. It causes sedation without causing respiratory depression. It has sedative, analgesic, sympatholytic and anxiolytic effect that blunt many CVS responses in perioperative period. It is an S-enantiomer of Medetomidine used in veterinary medicine. It is thought that intrathecal Dexmedetomidine produces its analgesic effect by inhibiting the release of C fibers transmitters and by hyperpolarization of post-synaptic dorsal horn neurons. The prolongation of motor effect might be caused by direct impairment of excitatory amino acid release from spinal interneurons. Alpha2 agonists produce sedative effect by acting on alpha 2-adrenergic receptors in Locus coeruleus. Alpha2 adrenoreceptors do not have an active role in the respiratory center, therefore, Dexmedetomidine throughout a broad range of plasma concentration, has minimal effects on the respiratory system.

Clonidine is imidazoline derivative with centrally acting alpha 2 adrenergic agonist activity [20]. Inhibition of substance-P release is believed to be involved in the analgesic effect. Clonidine partially inhibits voltage gated sodium and potassium channels and suppresses the generation of action potential in tonic firing spinal dorsal horn neurons. This may contribute to its analgesic effect. It stimulates central alpha2 adrenergic receptors in the brain stem, blocks the release of noradrenaline from nerve terminals leading to decreased peripheral resistance, renal vascular resistance heart rate and blood pressure.

Dexmedetomidine is a highly selective alpha2 agonist with 8 times greater affinity than Clonidine. More clinical experience has been gained with regard to usage of Clonidine compared to Dexmedetomidine by intrathecal route. There are less studies available for these drugs as adjuvants to 0.75%Ropivaciane

In our study doses of study drugs were selected based on previous study with other local anesthetics like Bupivacaine and comparative studies with plain Ropivacaine.

Thus, the present study was undertaken to evaluate clinical effects of adding 5mcg or Clonidine 15mcg to 0.75% Ropivacaine by intrathecal route to study the characteristics of the block, hemodynamic and postoperative pain relief in patients undergoing lower limb surgeries.

Hospital ethics committee clearance was obtained for this study. Informed consent was taken from all the patients. Patients who denied participation in study were treated by routine protocol of anesthesia with dignity.

Randomization 

Randomization was done by using ‘Physical method’, where 60 folded papers were placed in a container, each one labeled either Group D or Group C with each label 30 in number.

Blinding 

The syringes containing the study drug were prepared by the third observer anesthesia resident to assure a proper blinding procedure. 60 patients of ASA I and II physical status aged 18-60 years scheduled to undergo elective surgery and satisfying all the inclusion criteria were enrolled in the study.

Inclusion Criteria

• Patients of either sex in age group of 18-60 yrs

• Patients with Height>140 cms and Weight less than 120 kgs

• Patients who are ASA grade I and grade II

• Posted for lower limb surgeries

• Patients who are willing to give consent for participation in the study

Exclusion Criteria

• Patient’s refusal

• Patients who are ASA III and above

• Patients who are hypersensitive to the local anesthetics

• Patients on long term analgesic therapy

• Patients with peripheral neuropathy

• Patients with local skin infections and spinal deformities

• Patients having coagulation abnormalities.

A sample size of 30 patients each randomly allocated into two groups using power analysis based on previous studies [21-22]. 

Study Procedure

A pre-anesthetic evaluation comprising of history of previous medical and surgical illnesses, previous anesthesia exposures, drug allergies; clinical examination; airway examination and baseline investigation of complete blood picture, blood sugar, serum creatinine, chest radiograph and 12 lead ECG will be done. Patients were explained about the procedure of spinal anesthesia.

• Informed/written consent was obtained from each patient before starting the study. Every patient was supplied with patient information sheet before taking the consent

• A specially designed proforma was used to collect the data including patient’s particulars, patient’s written informed consent, indication for surgery, the anesthetic details, intra-operative monitoring, post-operative follow up, etc

Anesthetic Procedure

Intraoperatively, the following protocol was followed: 

• Intravenous line was secured with 18/20 Gauge cannula. All standard monitors (NIBP, ECG, Pulse oximeter) were attached before giving spinal anesthesia

• Subarachnoid block under strict aseptic conditions was performed in sitting position at L3-L4 or L4-L5 interspines space with 27 Gauge Whitacre spinal needle and drug was administered after confirming the free flow of cerebrospinal fluid

Study groups received spinal anesthesia with:

• Group D: 3 ml of 0.75% Ropivacaine + Dexmedetomidine (5 µg) (total vol. – 3.5 ml)                                                                        

• Group C: 3 ml of 0.75% Ropivacaine + Clonidine (15 µg) (total vol.- 3.5ml)

The following parameters were observed:

Sensory Blockade

It was subjectively studied by cold swab. The patients were tested every 30 seconds at one fixed dermatome level T10 level. Then highest dermatomal level was noted. Time required for regression of level to S1 is total duration of sensory block.

Motor Blockade

It was assessed by straight leg raising while lying supine and was graded according to modified Bromage scale Table 1.

The time taken for the onset of motor blockade and the duration of motor blockade were noted. The time from injection of drug to attain bromage 3 was considered as onset of blockade and time to regain bromage score of 0 was considered as duration of motor blockade.

Hemodynamic

Heart rate and blood pressure were monitored immediately after injection and then after every 5 minutes for first 30 minutes and then every 10 minutes thereafter throughout the surgery and every hour till the complete recovery from block. The anesthesia record was maintained and changes in heart rate, blood pressure were noted. Any decrease in heart rate below 60 beats/min was considered as bradycardia and was treated with 0.3 mg of Atropine. Similarly any fall of systolic blood pressure of more than 30 % of baseline was considered as Hypotension was treated with 6 mg of ephedrine and crystalloids and oxygen as needed.

Figure 1: Visual Analogue Score

Table 1: Modified Bromage Scale

Sedation

Sedation was graded according to Modified Ramsey Sedation Scale:

• Patient is Anxious,  Agitated, Restless or both

• Patient is Cooperative, Oriented, and Tranquil

• Patient responds to commands only

• Patients exhibit brisk response to light glabellar tap or loud auditory stimulus

• Patients exhibits a sluggish response to light glabellar tap or loud auditory stimulus

• Patients exhibit no Response

Pain

Assessed by visual analogue scale at 6th hour, 12th hour, 18th hour, 24th hour. Injection tramadol 2mg/kg iv (maximum of 100mg) was given as a rescue analgesic when VAS score was greater than or equal to 4. 

Side Effects

Intra-operative side effects like sedation, nausea, vomiting, shivering, backache, bradycardia, and hypotension requiring active treatment were noted. Following variables were observed:

• Sensory blockade – onset   and duration

• Motor blockade – onset and duration

• hemodynamic parameters

• Sedation

• Maximum level of sensory block and time to reach maximum level

• Time to reach two segment regression

• Duration of Analgesia

• Side effects

• Rescue analgesic requirement

All the parameters were recorded as per the proforma and statistically analyzed. 

Statistical Methods: Method of Statistical Analysis: The following methods of statistical analysis were used in this study. Data were expressed as Mean+Standard deviation, percentages (%) and numbers (n). The statistical analysis was performed by a statistician using Windostat version 9.2.

• Proportions were compared using chi-square test of significance

• The student t test was used to determine whether there was a statistical difference between two treatment groups in the parameters measured

• One-way analysis of variance (Anova)

Differences in parameters such as heart rate, systolic blood pressure, diastolic blood pressure, VAS score, rescue analgesics and adverse effects over time were analyzed using ANOVA (analysis of variance)

In the entire above test p value<0.05 was accepted as indicating statistical significance.

Sixty patients posted for lower limb surgeries were randomly divided into two groups:

• Group D: received 0.75%Ropivacaine with 5mcg Dexmedetomidine

• Group C: received 0.75% Ropivacaine with 15mcg of Clonidine

        Observations and results were obtained from two groups by statistical analysis and calculation the p-value.

        According to Figure 1 there is no significant difference between mean age (years) in group D and group C as p-value is>0.05.

Table 2: Comparison of Mean Age in Group D and Group C                                                             

Figure 1: Bar Diagram Showing Age Distribution

X axis – Age in years, Y axis – number of patients

According to Figure 2 there is no significant difference between proportion of gender in group D and group C as p-value is>0.05.

According to Figure 3 there is no significant difference between the mean weight (kgs.) in group D and group C, as the p-value is>0.05.

According to Figure 4 there is no significant difference in the mean weight of the group D and group C, as the p-value is>0.05.

According to Figure 5 there is no significant difference in the mean weight of the group D and group C, as the p-value is>0.05.

According to Figure 6 in our study mean duration of surgery in group D was 125.90+23.458 and group C was133.667±51.238 and p-value was 0.453, thus both groups were comparable with regards to duration of surgery.

According to Figure 7 in present study, mean time of onset of sensory block in Group D was 3.467±0.507 min and with Group C was 3.900±0.759 with a (p = 0.012).  Mean time of onset of motor block in Group D was 9.033±1.098 and in Group C was 10.00±1.66 min with (p = 0.010). This shows that the onset of sensory and motor block was faster in group D compared to group C and was statistically significant.

According to Figure 8 mean time required to reach the maximum level of sensory block in Group D was 10.600±1.037 min and in Group C was 11.413±1.15min. (p = 0.005) which was statistically significant, thus the mean time required to achieve a maximum sensory level was lower with group D compared to group C.

In our study the mean Time required for two segment regression of sensory level in group D was 135.5±7.925 min while in group C this time was 125.567±5.27 min. The p-value was 0.00 which is statistically significant (Table 1).

Graph shows that the time required for two segment regression of sensory level in group was greater in group D (Dexmedetomidine and Ropivacaine) (Table 2).

In our study, duration of sensory block in Group D was 421.133±21.968 min and in Group C was 360.600 ±23.940 min with p value of 0. 000.Thus duration of sensory block is statistically significant (p = 0.000) in Group D as compared to Group C with Dexmedetomidine group having longer total sensory blockade compared to Clonidine. 

Duration of motor block in Group D was 339.367±27.031 min and in Group C was 339.367±27.031 min with p value of 0.000. Thus, duration of motor block was statistically significant (p = 0.000) in Group D as compared to Group C with Dexmedetomidine group having longer duration of total motor blockade. 

Total duration of   Post - operative analgesia in Group D was 434.700±27.507 min and in Group C was 365.767±12.716 min with p value of 0.000. Thus, duration of Post - operative analgesia was statistically significant with Dexmedetomidine having longer total duration of Post - operative analgesia Table 3.

According to Figure 9 Mean sedation Group D was 1.900±0.607 and in Group C 2.167±0.699 was with p value of 0.109. Thus, the level of sedation was comparable among both groups.

According to Figure 10 The mean requirement of rescue analgesics in group D was 2.433±0.626 and in group C was 3.167±0.461 and the P value was 0.000 which shows that there was a significantly lower requirement of analgesics in group D compared to group C.

According to Figure 11 In our study, a fall in Systolic Blood Pressure of more than 30% was taken as hypotension and was treated with Inj. ephedrine 6mg iv.

In studied Groups, the mean baseline systolic blood pressure, in Group D was 125.767 mm of Hg and in Group C was 131.300 mm of Hg. (p = 0.067). Both groups were comparable. The mean systolic blood pressure was measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50 min, 60 min, 70 min, 80 min, 90min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min period. In our study the systolic blood pressure was comparable in both groups.

According to Figure 12 In studied Groups, the mean baseline diastolic blood pressure, in Group D was mm 77.333±11.595 of Hg and in Group C was 78.467±9.961 mm of Hg. (p = 0.686). Thus, both groups were comparable in baseline pressures. 

The mean diastolic blood pressure was measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min period. In our study the diastolic blood pressure was comparable in both groups.

According to Figure 13 In our study heart rate less than 60 beats per min was taken as bradycardia and was treated with Inj. Atropine. In studied Groups, the mean baseline Heart rate, in Group D is 77.500±7.375. And in Group C was79.700±6.182 with a p-value of 0.216. Baseline heart rates were comparable. The mean heart rates were measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min. In our study the Heart rate was comparable in both groups with no significant difference.

There incidence of hypotension in group D was 6.66%, the incidence of hypotension in group C was 10% which was promptly treated with Inj. ephedrine 6mg iv stat. Similarly, incidence of bradycardia in group D was 3.0 %, while the incidence of bradycardia in group C was 13.0% which was treated with Inj. Atropine 0.3 mg iv bolus. Incidence of bradycardia and hypotension were comparable among both groups. The Incidence of nausea/vomiting and shivering in group D and C was 0% Table 4.

According to Figure 14 Graph shows that the incidence of bradycardia was higher in group C but that was statistically insignificant with p-Value 0.167.

So, from our study we concluded that incidence of hypotension and bradycardia was comparable among both groups. There was no incidence of nausea/vomiting and shivering in both groups.

According to Figure 15 Mean VAS scores in group D were lower than in group C. Mean value in group D was 3.142±2.051 and in group C was 5.983±1.805 with a p value of 0.000.

Table 3: Gender Wise Distribution of Patients in Group D and Group C

Figure 2: Bar Diagram Showing Frequency Distribution of Gender

Table 4: Comparison Mean Weight (Kilograms) In Group D and Group C

Figure 3: Bar Diagram Showing Weight Distribution

There is no significant difference between the mean weight (kgs.) in group D and group C, as the p value is>0.05

Table 5: Comparison of Mean Height (Cm) In Group D and Group C

Figure 4: Bar Diagram Showing Height Distribution

There is no significant difference in the mean weight of the group D and group C, as the p value is>0.05

Figure 5: Bar Diagram Showing ASA Grade

There is no significant difference in the mean weight of the group D and group C, as the p value is>0.05

Figure 6: Bar Diagram Showing Duration of Surgery

(X axis –duration of surgery, in minutes, Y axis – number of patients)

In our study mean duration of surgery in group D was 125.90+23.458 and group C was133.667±51.238 and P value was 0.453, thus both groups were comparable with regards to duration of surgery. 

Table 6: Distribution of Patients with Respect To ASA Grade

Table 7: Comparison of Duration of Surgery between Group D and Group C

Comparison of Study Parameters

In present study, mean time of onset of sensory block in Group D was 3.467±0.507 min and with Group C was 3.900±0.759 with a (p = 0.012).  Mean time of onset of motor block in Group D was 9.033±1.098 and in Group C was 10.00±1.66 min with (p = 0.010). This shows that the onset of sensory and motor block was faster in group D compared to group C and was statistically significant.

Mean time required to reach the maximum level of sensory block in Group D was 10.600±1.037 min and in Group C was 11.413±1.15min. (p = 0.005) which was statistically significant, thus the mean time required to achieve a maximum sensory level was lower with group D compared to group C.

In our study the mean Time required for two segment regression of sensory level in group D was 135.5±7.925 min while in group C this time was 125.567±5.27 min. The p-value was 0.00 which is statistically significant.

Figure 7: Comparison of Onset of Sensory Block

(X axis –onset of sensory block in minutes, Y axis – number of patients)

Figure 8: Comparison of Onset of Motor Block

(X axis –onset of sensory block in minutes, Y axis – number of patients)

Figure 9: Comparison of Time to Achieve Peak Sensory Level

X axis –time to achieve peak level in minutes, Y axis – number of patients

Figure 10: Comparison of 2 Segment Regression

(X axis –time for 2 segment regression in minutes, Y axis – number of patients) Graph shows that the time required for two segment regression of sensory level in group was greater in group D (Dexmedetomidine and Ropivacaine)

Figure 11: Comparison of Duration of Sensor Block

(X axis –duration of sensory block in minutes, Y axis – number of patients

Figure 12: Comparison of Duration of Motor Block

X axis –duration of motor block in minutes, Y axis – number of patients

Table 8: Onset of Sensory and Motor Blockade

Table 9: Comparison of Time to Achieve Peak Sensory Level

Table 10: Comparison of 2-Segment Regression Time

Table 11: Duration of Sensory, Motor Blockade and Duration of Analgesia

Table 12: Comparison of Level of Sedation

Table 13: Requirement of Rescue Analgesics

Figure 12: Comparison of Duration of Motor Block

X axis –duration of motor block in minutes, Y axis – number of patients

Figure 13: Comparison of Duration of Analgesia

(X axis –duration of analgesia in minutes, Y axis – number of patients)

Figure 14: Comparison of Level of Sedation

Figure 15: Comparison of Rescue Analgesic Requirement

Table 13: Requirement of Rescue Analgesics

Table 14: Comparison of Systolic Blood Pressure

Table 15: Comparison of Diastolic Blood Pressure

Figure 16: Comparison of Systolic Blood Pressure

Table 16: Comparison of Heart Rate

Figure 17: Comparison of Diastolic Blood Pressure

Figure 18: Comparison of Heart Rate

Table 17: Comparison of Side Effects

Table 18: Frequency of Side Effect

Graph shows that the time required for two segment regression of sensory level in group was greater in group D (Dexmedetomidine and Ropivacaine).

In our study, duration of sensory block in Group D was 421.133±21.968 min and in Group C was 360.600±23.940 min with p value of 0. 000.Thus duration of sensory block is statistically significant (p = 0.000) in Group D as compared to Group C with Dexmedetomidine group having longer total sensory blockade compared to Clonidine.

Duration of motor block in Group D was 339.367±27.031 min and in Group C was 339.367±27.031 min with p value of 0.000. Thus, duration of motor block was statistically significant (p = 0.000) in Group D as compared to Group C with Dexmedetomidine group having longer duration of total motor blockade. 

Total duration of  Post - operative analgesia in Group D was 434.700±27.507 min and in Group C was 365.767±12.716 min with p value of 0.000. Thus, duration  of  Post-operative  analgesia  was  statistically Mean sedation Group D was 1.900±0.607 and in Group C 2.167±0.699 was with p value of 0.109. Thus, the level of sedation was comparable among both groups.

Figure 19: Comparison of Hypotension

Figure 20: Comparison of Bradycardia

Table 19: Comparison of Vas Score

Figure 21: Comparison of Vas Score

significant with Dexmedetomidine having longer total duration of Post - operative analgesia.

The mean requirement of rescue analgesics in group D was 2.433±0.626 and in group C was 3.167±0.461 and the p-value was 0.000 which shows that there was a significantly lower requirement of analgesics in group D compared to group C.

In our study, a fall in Systolic Blood Pressure of more than 30% was taken as hypotension and was treated with Inj. ephedrine 6mg iv.

In studied Groups, the mean baseline systolic blood pressure, in Group D was 125.767 mm of Hg and in Group C was 131.300 mm of Hg. (p = 0.067). Both groups were comparable. The mean systolic blood pressure was measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min period. In our study the systolic blood pressure was comparable in both groups.

In studied Groups, the mean baseline diastolic blood pressure, in Group D was mm 77.333±11.595 of Hg and in Group C was 78.467±9.961 mm of Hg. (p = 0.686). Thus, both groups were comparable in baseline pressures. 

The mean diastolic blood pressure was measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min period. In our study the diastolic blood pressure was comparable in both groups.

In our study heart rate less than 60 beats per min was taken as bradycardia and was treated with Inj. Atropine. In studied Groups, the mean baseline Heart rate, in Group D is 77.500±7.375. And in Group C was79.700±6.182 with a p value of 0.216. Baseline heart rates were comparable. The mean heart rates were measured at 0, 5min, 10min, 15min, 20min, 25min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min. In our study the Heart rate was comparable in both groups with no significant difference.

There incidence of hypotension in group D was 6.66%, the incidence of hypotension in group C was 10% which was promptly treated with Inj. ephedrine 6mg iv stat. Similarly, incidence of bradycardia in group D was 3.0 %, while the incidence of bradycardia in group C was 13.0% which was treated with Inj. Atropine 0.3 mg iv bolus. Incidence of bradycardia and hypotension were comparable among both groups. The Incidence of nausea/vomiting and shivering in group D and C was 0%.

Graph shows that the incidence of bradycardia was higher in group C but that was statistically insignificant with p-Value 0.167.

So, from our study we concluded that incidence of hypotension and bradycardia was comparable among both groups. There was no incidence of nausea/vomiting and shivering in both groups.

Mean VAS scores in group D were lower than in group C. Mean value in group D was 3.142±2.051 and in group C was 5.983±1.805 with a p value of 0.000.

The use of Alfa 2 agonists intrathecally are being extensively evaluated as an alternative to opioids due to opioid related side effect profile like respiratory depression, nausea, urinary retention, pruritis.

The pharmacologic properties of α-2 agonists have been extensively studied and have been employed clinically to achieve the desired effects in regional anesthesia like sedation, analgesia, anxiolysis, hypnosis and sympatholysis. Clonidine has been used successfully over the last decade for the said purpose and the introduction of dexmedetomidine has further widened the scope of α-2 agonists in regional anesthesia. The faster onset of action of local anesthetics, rapid establishment of both sensory and motor blockade, prolonged duration of analgesia into the post-operative period, dose-sparing action of local anesthetics and stable cardiovascular parameters makes these agents a very effective adjuvant in regional anesthesia. 

We have undertaken a study to evaluate the efficacy of Inj. Dexmedetomidine (5mcg) with 0.75% Ropivacaine by intrathecal route compared to Inj. Clonidine (15mcg) with 0.75% Ropivacaine by intrathecal route in patients undergoing Lower limb surgeries.

The demographic profile of our patients was comparable with respect to mean age, body weight, height, sex distribution, and duration of surgeries.

Onset of Sensory and Motor Blockade

Onset of sensory block is the time lapse between drug administration and loss of cold sensation at T10 dermatome tested by cold swab. Onset of motor block is the time lapse between drug administration and attainment of Bromage 3.

In our study the mean time of onset of sensory block in group D is (3.467±0.507) and group C is (3.900±0.759) with a p value of 0.012.

Mean time for the onset of motor block in group D is 9.033±1.098, group C 10.00±1.66 with a p value of 0.010, thus indicating a faster onset of sensory and motor block in group D compared to group C.

[24] Conducted a double-blind randomized control study of intrathecal ropivacaine 7.5mg with dexmedetomidine 5mcg versus ropivacaine 7.5mg with clonidine 15 mcg in patients undergoing TURP. The study showed an earlier onset of sensory and motor blockade.

In another study conducted by [25] a Comparative evaluation of dexmedetomidine and fentanyl for epidural analgesia in lower limb orthopedic surgeries, Onset of sensory analgesia at T10 was earlier in dexmedetomidine group (7.12±2.44min) compared to fentanyl group (9.14±2.94min). 

Peak sensory level and two segment regression:

In our study the mean peak sensory level achieved is comparable in both groups but the mean time to reach the peak sensory level is significantly shorter in group D (10.600±1.037) than in group C (11.413±1.150) with a p value of 0. 005. The mean two segment regression time is also prolonged in group D. 

[26] Conducted a randomized, prospective, double-blind study of intrathecal hyperbaric ropivacaine with Dexmedetomidine 5 mcg and hyperbaric ropivacaine with clonidine 50 mcg in lower abdominal surgeries. They concluded that time to two segment regression was significantly greater with dexmedetomidine group (148.16+14.42 min) compared to clonidine group (102.16 +14.69 min) with a p value of<0.001.

Duration of Sensory and Motor Blockade:               

Mean duration of sensory block in group D is (421.133±21.968) and in group C is (360.600±23.940) with a p value of 0.000. Mean duration of motor block in group D is (339.367±27.031) and group C is (306.600±23.940) with a p value of 0.000. Thus, the duration of both sensory and motor block is significantly prolonged in group D compared to group C.

Similar prolongations were observed in a study conducted by [27]. Who compared dexmedetomidine, clonidine, fentanyl as adjuvants to hyperbaric bupivacaine. They concluded that intrathecal dexmedetomidine as adjuvant was associated with a prolonged motor and sensory blockade with a better postoperative analgesia and reduced requirement of rescue analgesia in first 24 hrs.  Compared to clonidine and fentanyl groups.

In another study conducted by [21] they observed that the total duration of motor blockade was prolonged in dexmedetomidine group as compared to fentanyl group (421±21 min vs. 149.3±18.2 min, p-value˂0.0001).

[28], conducted a randomized, prospective study between intrathecal isobaric ropivacaine 0.75% plus dexmedetomidine and isobaric ropivacaine 0.75% plus fentanyl for lower limb surgeries. They concluded that dexmedetomidine at dose of 5 mcg prolonged the duration of motor blockade (136.733 min) as compared to fentanyl (94.866 min) with p value of 0.00.

Duration of Analgesia and Rescue Analgesia

In our study mean duration of analgesia in group D is 434.700±27.507 and group C is 365.767±12.716 with a p value of 0.000. The mean VAS scores were lower in group D compared to group C. The mean requirement for rescue analgesia in group D is (2.433±0.626) and in group C is (3.167±0.461) with a p value of 0.000. Thus, the duration of analgesia is statistically significantly prolonged in group D with a significant lower requirement of rescue analgesia.

[29] Studied the effect of intrathecal ropivacaine and dexmedetomidine and demonstrated that dexmedetomidine significantly prolongs the sensory motor blockade and provides a better analgesia with reduced requirement of analgesics.

[30] Conducted a prospective study of ropivacaine with dexmedetomidine versus clonidine by epidural route and concluded that dexmedetomidine is a better neuraxial adjuvant compared to clonidine in providing early blockade and prolonged postoperative analgesia with stable cardiorespiratory parameters.

[31] Conducted a randomized double-blind study on the effects of adding intrathecal dexmedetomidine to hyperbaric bupivacaine for saddle spinal block in adults undergoing Peri-anal surgeries. They concluded that the duration of analgesia was significantly prolonged and analgesic consumption was significantly reduced in group with dexmedetomidine (501.35+63.90) with a p value of 0.001.

Sedation Score:

Sedation in our study was assessed by Ramsay sedation scale.  The mean Ramsay sedation (RSS) score of Group D was comparable to Group C with p value of 0.109 showing no statistical significance between the two groups.

[27], who compared dexmedetomidine, clonidine, fentanyl as adjuvants to hyperbaric bupivacaine showed no significant difference in the sedation scores. 

Hemodynamic Parameters and Side Effects:

Average mean systolic blood pressure in group D (dexmedetomidine and ropivacaine) was115.852+9.154 and group C (clonidine and ropivacaine) was 115.424+9.076 with a p value of 0.335. Average mean diastolic blood pressure in group D (dexmedetomidine and ropivacaine) was 71.650+7.397 and group C was 72.224+7.074 with a p value of 0.133. Average mean heart rate in group D (dexmedetomidine and ropivacaine) 73.380+6.543and group C was 73.138+ 6.206 with a p-value of 0.469.

In our study hemodynamic parameters and side effects are comparable in both the groups.

[21] Conducted a study of Dexmedetomidine as an intrathecal adjuvant for postoperative analgesia and demonstrated a no significant change in haemodynamic parameters.             

[27] Who compared dexmedetomidine, clonidine, fentanyl as adjuvants to hyperbaric bupivacaine showed no significant changes in hemodynamic parameters and side effects both were comparable intraoperatively and postoperatively.

[32] Conducted study on Effect of low-dose dexmedetomidine or clonidine on the characteristics of bupivacaine spinal blockade divided 60 patients into 3 groups. Group B received 12 mg of hyperbaric bupivacaine, group D received 12 mg of bupivacaine supplemented with 3 µg of dexmedetomidine and group C received 12 mg of bupivacaine supplemented with 30 µg of clonidine. He observed that the mean arterial pressure, heart rate and level of sedation were similar in the three groups intra-operatively and post-operatively.

[24] Conducted a double-blind randomized control study of intrathecal ropivacaine 7.5mg with dexmedetomidine 5mcg versus ropivacaine 7.5mg with clonidine 15 mcg by intrathecal route in patients undergoing TURP.

From the present study, we draw the following conclusion:

Dexmedetomidine as an adjuvant with ropivacaine intrathecally as compared to clonidine 

• Shortens the onset of sensory and motor block

• Prolongs the duration of sensory and motor blockade

• Provides effective postoperative analgesia and prolongs the duration for first rescue analgesia 

• Provides desirable sedation intraoperatively 

• Does not result in any major adverse effects 

Thus, intrathecal Dexmedetomidine in a dose of 5mcg as an adjuvant to ropivacaine increases postoperative analgesia without any significant adverse effects.

Recommendations

Adjuvants used in neuraxial blockade with local anaesthetics prolong the duration of analgesia into postoperative period. Complications associated with neuraxial blockade can be avoided if the adjuvant added to intrathecal local anaesthetic provides adequate analgesia for prolonged periods.

Our experience with dexmedetomidine as an adjuvant to ropivacaine have been very satisfactory in terms of blockade characteristics, post-operative analgesia and smooth and stable maintenance of hemodynamic with no significant side effects as compared to clonidine. So, we recommend the use of dexmedetomidine in a dose of 5 mcg as an adjuvant to ropivacaine for prolonged duration surgeries and those with significant post-operative pain. Further ropivacaine has an added advantage of less cardio toxicity and better differential sensory and motor blockade.

We recommend further studies to evaluate dexmedetomidine as a smaller number of studies are available.

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