Pain, as defined by the International Association for the Study of Pain (IASP), is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.1 It results from nociception—activation of nociceptors and transmission of noxious stimuli through the nervous system, ultimately reaching the brain. While nociception conveys information about actual or impending tissue injury, pain represents the conscious perception of this sensory input and the accompanying emotional discomfort.2 Relief of pain during surgery is the fundamental goal of anaesthesia, and the skills developed intraoperatively must be continued into the postoperative period as well. Postoperative pain remains a common and distressing complication despite advancements in anaesthetic techniques.3 Although surgical anaesthesia is generally well established, postoperative pain management still lags behind, largely due to inadequate delivery or suboptimal utilization of existing analgesic agents3. Numerous strategies exist for postoperative analgesia, including systemic opioids, non-opioid analgesics, and regional anaesthesia techniques. Intravenous opioids are frequently used for moderate to severe postoperative pain, whereas neuraxial and peripheral nerve blocks provide superior analgesia with reduced systemic side effects. Spinal anaesthesia, one of the most widely practiced regional techniques, has undergone significant evolution since its introduction. Karl August Bier first successfully administered spinal anaesthesia in 1898 by injecting cocaine into the subarachnoid space. Later, lignocaine emerged in 1944 as a preferred agent due to its potency, rapid onset, diffusion characteristics, minimal toxicity, and stability.4 The introduction of bupivacaine by Ekenstam in 1957 marked another major advancement; it offered longer duration and greater potency than lignocaine.5,6 Subsequent studies confirmed its safety and effectiveness for spinal and epidural anaesthesia. Ropivacaine, a long-acting amide local anaesthetic and a pure S-enantiomer, was introduced more recently. It provides effective sensory blockade with a better safety margin because of its lower lipid solubility and reduced cardiotoxicity compared with bupivacaine7. These properties also result in enhanced sensory–motor differentiation, allowing earlier motor recovery, reduced incidence of venous thromboembolism, and shorter hospital stay8.To further enhance the quality and duration of spinal anaesthesia, several adjuvants have been investigated. These include α-2 adrenergic agonists (clonidine, dexmedetomidine), opioids (morphine, fentanyl, nalbuphine, buprenorphine), vasoconstrictors such as epinephrine, sodium bicarbonate, ketamine, and midazolam9,10. Intrathecal opioids have gained particular importance due to their synergistic action with local anaesthetics. Local anaesthetics block nerve conduction at the axonal level, while opioids act on spinal opioid receptors, enhancing analgesia11. Fentanyl, a highly lipophilic synthetic opioid, produces rapid onset of analgesia, improves intraoperative conditions, and prolongs early postoperative pain relief with fewer delayed side effects compared with morphine. Dexmedetomidine, a selective α-2 adrenergic agonist, offers analgesia, sedation, and prolongation of sensory and motor blockade with minimal respiratory depression12.Considering the pharmacological advantages of these agents, the present study aims to evaluate the anaesthetic effects of intrathecal dexmedetomidine and fentanyl as adjuvants to 0.75% isobaric ropivacaine in lower limb surgeries, focusing on the onset, duration, intensity, and recovery characteristics of sensory and motor block.13 AIM To compare the clinical and anaesthetic features of addition of Intrathecal Dexmedetomidine and Fentanyl to 0.75% Isobaric Ropivacaine in lower limb surgeries.

The present study was conducted in the Department of Anaesthesiology, S.M.S. Medical College, Jaipur. This randomized, double-blind, controlled trial included a total of 50 patients aged 20–60 years who were scheduled to undergo elective lower limb surgery. The study followed a prospective, comparative, randomized, double-blind, hospital-based interventional design. The sample size was calculated based on a standard deviation of 1.5 minutes for the onset of sensory block as reported in a seed article. To detect a mean difference of 1.6 minutes among groups with an alpha error of 0.05 and a power of 80%, a minimum of 15 subjects per group was required. For better reliability of results, 25 patients were enrolled in each group, forming Group D and Group F, comprising individuals undergoing lower limb orthopedic procedures. GROUP D GROUP F Patient received 3 ml of 0.75% isobaric ropivacaine + 5mcg dexmedetomidine in 0.5ml normal saline total volume 3.5ml intrathecal Patient received 3 ml of 0.75% isobaric ropivacaine + 0.5ml fentanyl (25mcg) total volume 3.5ml intrathecal Patients were selected according to predefined eligibility criteria. Inclusion criteria consisted of adults between 20 and 60 years of age of either sex, with a height above 145 cm and weight between 40–70 kg. Only patients classified as ASA physical status grade I or II and scheduled for lower limb orthopedic surgery lasting less than two hours were included. Exclusion criteria included a history of bleeding or coagulation disorders, chronic systemic illnesses such as hypertension, diabetes mellitus, respiratory diseases, epilepsy, cardiac disease, or mental illness, as well as chronic headache or backache. Individuals with spinal deformities, local site infections, known allergy to local anaesthetics, ASA grade III or higher, unwillingness to participate, or a history of head injury were excluded. All enrolled participants were randomized into the study groups, and both the patient and the investigator assessing outcomes remained blinded to group allocation throughout the study period.

Table 1A DEMOGRAPHIC VARIABLES (Mean ± SD) Variables Group D Group F P Value Significance Age (yrs) 33.9±11.3 37.7 ± 7.4 0.1660 N.S Weight (kg) 61.0± 5.2 61.9± 5.4 0.5512 N.S Height (cm) 163.8±4.3 163.8±4.9 1.0000 N.S Table 1A compares the demographic variables between Group D and Group F.Mean age in Group D was 33.9 ± 11.3 yrs and mean body weight was 61.0 ± 5.2 kg.Mean age in Group F was 37.7 ± 7.4 yrs and mean body weight was 61.9 ± 5.4kg.There was no statistical significant difference between the two groups regarding mean age and body weight (p > 0.05).Mean height in Group D was 163.8 ± 4.3 cm and in Group F was 163.8 ± 4.9cm.There was no statistical significant difference between the two groups regarding mean height of patients (p > 0.05). Table 1B. ASA Physical Status Distribution ASA GRADE GROUP D GROUP F P VALUE SIGNIFICANCE No. % No. % Grade I 24 96% 24 96% 1.000 N.S. Grade II 1 4% 1 4% Total 24 100% 25 100% Table 1B shows ASA physical status distribution of patients in Group D and Group F.In Group D, 24 patients were in Grade I and 1 patients in Grade II.In Group F, 24 patients were in Grade I and 1 patients in Grade II.There was no statistical significant difference in the two groups regarding ASA physical status distribution (p>0.05). Table 2 Mean duration of surgery of each group (Mean ± S.D.) Group D Group F P Value Duration of Surgery (in min.) 78±15.5 82±15.0 0.3584 It was observed that mean duration of surgery was comparable in the groups and no statistically significant difference was seen. Table 3 Onset of sensory and motor block Variables Group D Group F P Value Significance Sensory Onset Significance at T10 (min) 4.5±1.2 4.1± 1.4 0.2835 N.S Time to achieve max sensory blockade (min) 8.0± 1.5 8.3±1.9 0.5384 N.S Motor onset (min) 5.2±1.3 4.9± 1.4 0.4362 N.S Table 3 compares the mean of both sensory onset at T10 dermatome and time to achieve maximum sensory blockade between Group D and Group F. In Group D, the mean of sensory onset at T10 dermatome was 4.5 ± 1.2 minutes and In Group F, the mean of sensory onset at T10 dermatome was 4.1 ± 1.4 minutes.There was no statistical significant difference in the mean of sensory onset at T10 dermatome between the two groups (p>0.05). In Group D, the mean time to achieve maximum sensory blockade was 8.0 ± 1.5 minutes and In Group F, the mean time to achieve maximum sensory blockade was 8.3 ±1.9 minutes. There was no statistical significant difference in the meantime to achieve maximum sensory blockade between the two groups (p>0.05). In Group D, the mean onset of motor block was 5.2± 1.3 minutes and In Group F, the the mean onset of motor block was 4.9± 1.4 minutes. Between Group D and Group F, the difference in mean onset of motor block was statistically Non significant (p>0.05). Table 4 Duration of Sensory and Motor Block (Mean ± SD) Variables Group D Group F P Value Significance Duration of sensory block (min) 452.5±31.4 354.6± 14.6 <0.0001 Significant Duration of motor block (min) 421.6±26.8 305.2 ± 34.1 <0.0001 Significant Table 4 compares the mean duration of sensory and motor block between Group D and Group F.Mean duration of sensory block: Group D - 452.5 ± 354.6minutes.Group F-354.6± 14.6 minutes. Mean duration of motor block: Group D-421.6 ± 26.8 minutes. Group F-305.2 ± 34.1 minutes. Between Group D and Group F, the difference in mean duration of sensory block was statistically highly significant (p<0.0001). The difference in mean duration of the motor block was also highly significant (p<0.0001). Table 5 Time of Rescue analgesia [Mean ± SD (mins)] Group D Group F P Value Time of Rescue analgesia (min) 470.4 ± 18.3 350.8±12.4 < 0.0001 The mean time of rescue analgesia in Group D was 470.4 ± 18.3 min and in Group F was 350.8±12.4 min .The p value was <0.0001 between the Groups and found to be highly statistically significant.

The mean age of patients in Group D and Group F were 33.9±11.3 and 37.7±7.4 years respectively which were comparable in all the groups. Weight distribution in both the Groups was comparable with mean weight being 61.0±5.2 kg and 61.9±5.4 kg in Group D and Group F respectively. All the patients selected in the study were of height >145cm. In our Mean height in Group D-163.8 (+4.3) cm Mean height in Group F-163.8 (± 4.9) cm.So the patient height was also identical in all the groups. This has helped us to eliminate the possibility of variations in spread of local anaesthetic intrathecally as the highest level of block achieved is affected by height of the patient. All the patients studied were from the orthopaedic department coming after traumatic injury of the lower limbs. No statistical significance was noted between the groups regarding duration of surgery. The mean onset of sensory block was seen, In Group D at 4.5±1.2 minutes. In Group F at 4.1±1.4 minutes. The mean onset of motor block was seen In Group D at5.2 ±1.3 minutes. In Group F at 4.9±1.4 minutes. So in our study we concluded that there was no significant difference be- tween Groups D and F in the onset of sensory block or in the time for the onset of motor block (p>0.05). Our results coincide with Gupta et al study14 . In our study, the mean duration of sensory block was Group D-452.5±31.4 minutes, Group F-354.6±14.6 minutes In our study, the mean duration of motor block was Group D-421.6±26.8 minutes, Group F-305.2+34.1 minutes, Our study has shown that the sensory block regression was significantly slower with the addition of intrathecal dexmedetomidine as compared with fentanyl, as both time for two segment regression and till S1 regression were significantly more with intrathecal dexmedetomidine (p<0.0001). Addition of fentanyl also prolonged the time to two segment regression and duration of sensory block as compared to control group. In our study we conclude that the addition of 5ug dexmedetomidine with isobaric ropivacaine significantly prolonged the duration of motor block com- pared with 25 μg fentanyl (p<0.0001).This result is consistent with Y. Y. Lee et al15 (2005) and Rajni Gupta et al16 (2011). In our study, mean duration of analgesia was Group D-470.4±18.3 minutes, Group F-350.8±12.4 minutes, Our study has shown that the addition of 5ug dexmedetomidine to 0.75% isorbaric ropivacaine significantly prolongs the duration of anal compared to fentanyl group (p<0.0001). In 2011, Hala E A Eid et al17 performed a study to compare the effect of addition of 10μg and 15μg dexmedetomidine to 3ml of 0.5% hyperbaric bupivacaine. They found that dexmedetomidine significantly prolonged time to two segment regression, sensory regression to S1, regression of motor block to modified Bromage 0 and time to first rescue analgesic. In addition, it significantly decreased postoperative pain scores. The effects were greater with 15μg dexmedetomidine than with 10μg dexmedetomidine. Our study demonstrated no clinically significant difference in the haemodynamic parameters among the two groups. The incidence of adverse effects was also the same among the 2 groups. In our study hypotension and bradycardia were more in the dexmedetomidine group than in the fentanyl but it was not statistically significant. Pruritus after intrathecal fentanyl is known but it was not significant in our study. Nausea and vomiting were observed in 4%, and 8% patients in Groups D and F respectively. This suggested that the incidence of nausea and vomiting was not changed significantly among different groups. No patient had residual neurological deficit, post-dural puncture headache or transient neurological symptom. Our results coincide with Rajni Gupta et al study.18 Our study demonstrated no clinically significant difference in the haemodynamic parameters among both the groups. The incidence of adverse effects was also the same among both the groups.

Intrathecal 5μg dexmedetomidine seems to be an attractive alternative to adjuvant to 0.75% isobaric ropivacaine in spinal anesthesia25ug fentanyl as lower limb surgeries. It is associated with prolonged motor and sensory block, provides good quality of intraoperative analgesia and excellent quality of postoperative analgesia as compared to fentanyl.

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