Spinal anesthesia is the preferred method for infra-umbilical surgeries because it provides prolonged postoperative pain relief and effective sensory and motor blockade. [1] A variety of local anesthetics can be used for spinal anesthesia, including ropivacaine, levobupivacaine, and bupivacaine. The baricity of the local anesthetic is the main physical property influencing the degree of analgesia following an intrathecal injection. [2] When performing surgeries on the lower limbs, perineum, or lower body wall, a subarachnoid (spinal) block is a safe and efficient alternative to general anesthesia. In the early 20th century, spinal anesthesia was more common than epidural anesthesia due to the technical challenges in accurately locating the epidural space and the high toxicity of the local anesthetics used for epidural anesthesia. [1] Hyperbaric bupivacaine hydrochloride (0.5%) is widely used due to its longer duration of motor and sensory blockade. Ropivacaine, part of the pipecoloxylidide class of local anesthetics, is the optically pure S-enantiomer of the parent molecule ropivacaine. [3] Compared to plain ropivacaine, hyperbaric ropivacaine has lower lipid solubility and may provide more consistent and reliable anesthesia. It block pain-transmitting A and C fibers more effectively than A fibers that control motor functions. [4,5] Ropivacaine is considered a potential substitute for lignocaine in ambulatory surgery due to its low incidence of cardiotoxicity and transient neurological symptoms. Ropivacaine has similar Pka as Bupivacaine and greater motor sensory differentiation. It is well tolerated when administered intrathecally and has a quicker onset of action compared to bupivacaine. [6] Hyperbaric local anesthetics are commonly used by modern anesthesiologists due to their short half-lives and predictable effects. Adjuvants are added to extend the duration of postoperative analgesia and enhance the characteristics of the block provided by hyperbaric ropivacaine. Intrathecal injections of plain ropivacaine at doses of 15 and 22.5 mg have shown varying degrees of sensory block, with some patients requiring general anesthesia due to insufficient block distribution. [7,8] Therefore, adjuvants like clonidine, fentanyl, or dexmedetomidine are used to improve the effectiveness of isobaric ropivacaine. [9] Dexmedetomidine, an S-enantiomer of medetomidine, has a high ratio of α2/α1 activity (1620:1) compared to clonidine (220:1) and exhibits highly selective α2-adrenergic receptor agonist activity. [1] These receptors are present in the central and peripheral nervous systems and their activation by dexmedetomidine leads to analgesia, bradycardia, hypotension, and sedation. It also reduces pain by hyperpolarizing postsynaptic dorsal horn neurons and suppressing the release of C fiber transmitters. [10,11] Due to its high lipophilicity, dexmedetomidine quickly binds to α2-adrenergic receptors in the spinal cord and is rapidly absorbed into the cerebrospinal fluid (CSF). Recent experimental studies show that dexmedetomidine, regardless of the neuraxial route of administration (epidural, caudal, or spinal), increases the duration of motor and sensory blocks induced by local anesthetics in a dose-dependent manner without causing neurotoxicity in human volunteers. [12,13] The use of intrathecal hyperbaric ropivacaine and dexmedetomidine (5 μg) for lower limb procedures is assessed in this study. Comparing the effectiveness of intrathecal hyperbaric ropivacaine and hyperbaric ropivacaine + dexmedetomidine is the goal. A highly selective α2-adrenergic receptor agonist, dexmedetomidine has sedative, analgesic, anxiolytic, hypnotic, and sympatholytic effects. There is growing interest in using it as an adjuvant to local anaesthetics due to its analgesic qualities and capacity to extend the duration of regional anaesthesia. When paired with ropivacaine, intrathecal dexmedetomidine has been shown in earlier research to extend sensory and motor blocking and lengthen the duration of postoperative analgesia. When dexmedetomidine was added to hyperbaric ropivacaine, Shashikala et al. [4] experienced sustained pain alleviation and motor block. In a similar vein, research by Ravipati and Gupta showed that adding intrathecal dexmedetomidine to ropivacaine resulted in sustained sensory and motor block. [1,3] Despite the fact that these results point to a useful function for dexmedetomidine as an intrathecal adjuvant, its effects on analgesia, sensory and motor block features, haemodynamic parameters, and side effects continue to be significant factors in clinical practice. Therefore, the present study was undertaken to evaluate and compare 0.75% hyperbaric ropivacaine alone with 0.75% hyperbaric ropivacaine combined with intrathecal dexmedetomidine in patients undergoing elective lower-limb orthopaedic surgery. AIM AND OBJECTIVE Aim To evaluate and compare the effects of intrathecal 0.75% hyperbaric ropivacaine alone versus 0.75% hyperbaric ropivacaine with dexmedetomidine as an adjuvant on analgesia and block characteristics in patients undergoing elective lower-limb orthopaedic surgery. Objectives Primary objective 1. To compare the duration of analgesia between the two groups. Secondary objectives 1. To compare sensory and motor block characteristics. 2. To compare haemodynamic parameters between the groups. 3. To assess the occurrence of adverse effects, particularly nausea and vomiting.

Study Design This was a double-blind, randomized controlled study conducted to compare the effects of intrathecal 0.75% hyperbaric ropivacaine alone with 0.75% hyperbaric ropivacaine combined with dexmedetomidine in patients undergoing elective lower-limb orthopaedic surgery. Study Setting and Duration The study was conducted among patients undergoing elective lower-limb orthopaedic surgeries at the hospitals attached to Bangalore Medical College and Research Institute, Bengaluru. The study period was from August 2022 to January 2024. Study Population Patients aged 18–65 years, of either sex, scheduled for elective lower-limb orthopaedic surgery and suitable for subarachnoid block were considered for inclusion in the study. Inclusion Criteria Patients fulfilling the following criteria were included: 1. Patients willing to provide informed written consent. 2. Patients belonging to ASA physical status I or II. 3. Patients aged 18–65 years of either sex. 4. Patients weighing 40–80 kg and having a height of 140–190 cm. Exclusion Criteria Patients were excluded if they had: 1. Refusal to participate in the study. 2. Cardiovascular, renal, or hepatic disorders. 3. Contraindications to spinal anaesthesia. 4. Hypersensitivity to any of the study medications. 5. BMI >30 kg/m². Sample Size A total of 70 patients were included in the study and randomly allocated into two groups of 35 patients each. The sample size was calculated with α = 0.05 and β = 0.2, based on findings from the study by Shashikala T.K. et al. The minimum calculated sample size was 32 patients per group and was rounded to 35 patients per group. [4] Randomization and Blinding The participants were randomly divided into two groups of 35 each using a computer-generated randomization table. The study drugs were prepared in labelled syringes according to the patient's serial number and were handed over by an anaesthesiologist who was not involved in the study. Group RD Patients in Group RD (n=35) received: 0.75% hyperbaric ropivacaine 3 mL + dexmedetomidine 10 µg (0.1 mL) intrathecally. Group R Patients in Group R (n=35) received: 0.75% hyperbaric ropivacaine 3 mL + 0.1 mL normal saline intrathecally. Preoperative Preparation All patients were kept nil per oral for 8 hours before surgery. Tablet ranitidine 150 mg and tablet alprazolam 0.5 mg were administered on the night before surgery. On arrival in the operating room, intravenous access was established and patients were preloaded with Ringer lactate 10 mL/kg over 15 minutes. Standard monitoring was established using non-invasive blood pressure, pulse oximetry, and three-lead electrocardiography. Baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), and oxygen saturation (SpO₂) were recorded. Technique of Subarachnoid Block Under strict aseptic precautions, subarachnoid block was performed using a 25-G Quincke Babcock spinal needle at the L3–L4 intervertebral space, with the patient in the sitting position. After confirmation of free flow of cerebrospinal fluid, the prepared study solution was injected over 10–15 seconds. The patient was then immediately positioned supine, and the time of spinal anaesthesia was recorded. Assessment of Sensory Block Sensory block was assessed bilaterally along the midclavicular line using a cold swab. Assessment was initiated immediately after positioning the patient supine and continued until loss of sensation to pinprick at the T10 dermatome was achieved. The duration of sensory block was defined as the time from completion of injection of the study drug until the patient regained sensation at the S1 dermatome. Assessment of Duration of Analgesia The duration of analgesia, the primary outcome, was defined as the time from intrathecal administration of the study solution until the first requirement for rescue analgesia. Rescue analgesia consisted of intravenous tramadol 50 mg, administered when the patient complained of pain with a VAS score of 3. Assessment of Motor Block Motor block was assessed bilaterally using the modified Bromage scale. Assessment commenced immediately after positioning the patient supine. The onset of motor block was defined as the time from intrathecal injection to achievement of a Bromage score of 3. The duration of motor block was defined as the time from intrathecal injection until return to Bromage score 0, indicating complete recovery of motor function. Assessment of Haemodynamic Parameters Heart rate, systolic blood pressure, diastolic blood pressure, and oxygen saturation were recorded after positioning the patient supine. Measurements were obtained at 1-minute intervals for the first 3 consecutive minutes, followed by 5-minute intervals for the next 15 minutes, and subsequently at 30-minute intervals until completion of surgery. The requirement for vasopressors was also recorded. Assessment of Sedation Intraoperative and postoperative sedation was assessed using the Modified Ramsay Sedation Scale. Management of Adverse Effects Hypotension was defined as a 20% fall in systolic blood pressure from baseline and was treated with intravenous fluids and intravenous ephedrine 6 mg. Bradycardia was defined as a 20% fall in heart rate from baseline and was treated with intravenous atropine 0.6 mg. Postoperative rescue analgesia was administered as slow intravenous tramadol 50 mg. Nausea and vomiting, when present, were treated with intravenous ondansetron 4 mg. Study Parameters The following parameters were assessed and compared between the two groups: 1. Onset of sensory block 2. Onset of motor block 3. Highest level of sensory block 4. Duration of sensory block 5. Duration of motor block 6. Duration of analgesia 7. Adverse effects 8. Haemodynamic parameters Statistical Analysis Data were entered into Microsoft Excel and analysed using IBM SPSS Statistics version 26. Categorical variables were expressed as frequencies and proportions. The normality of continuous variables was assessed using the Kolmogorov–Smirnov test and Shapiro–Wilk test. Continuous variables were expressed as mean and standard deviation. The Chi-square test was used for qualitative data, while Fisher's exact test was used when the assumptions for the Chi-square test were not fulfilled in 2 × 2 tables. Yates' correction was applied where appropriate. The independent Student's t-test was used to compare means between two quantitative variables, while the Mann–Whitney U test was used for comparison of medians when the data were skewed. A p-value <0.05 was considered statistically significant. Important point before we proceed For the manuscript, I recommend keeping “duration of analgesia” as the clearly stated primary outcome, because that matches your finalized title and thesis objectives. The thesis defines this specifically as the time from intrathecal injection to the first rescue analgesic requirement. Also, the thesis consistently specifies 10 µg dexmedetomidine in the actual methodology, so I have used 10 µg above.

A total of 70 patients undergoing elective lower-limb orthopaedic surgery under spinal anaesthesia were included and randomized equally into two groups: Group RD (0.75% hyperbaric ropivacaine with intrathecal dexmedetomidine, n=35) and Group R (0.75% hyperbaric ropivacaine alone, n=35). The two groups were comparable with respect to baseline demographic and clinical characteristics. Table 1: Baseline demographic and clinical characteristics of the study participants Characteristic Group RD (n=35) Group R (n=35) p-value Age (years), mean ± SD 39.69 ± 11.54 40.26 ± 12.30 0.842 Age group, n (%) 0.756 18–30 years 8 (22.9) 10 (28.6) 31–45 years 17 (48.6) 14 (40.0) 46–60 years 10 (28.6) 11 (31.4) Gender, n (%) 0.621 Male 21 (60.0) 23 (65.7) Female 14 (40.0) 12 (34.3) ASA physical status, n (%) 0.780 ASA I 27 (77.1) 26 (74.3) ASA II 8 (22.9) 9 (25.7) Values are expressed as mean ± SD or n (%). Statistical tests: Independent t-test for age; Chi-square test for categorical variables. The baseline characteristics were comparable between the two groups. The mean age was 39.69 ± 11.54 years in Group RD and 40.26 ± 12.30 years in Group R, with no statistically significant difference (p=0.842). The majority of participants belonged to the 31–45-year age group. Males constituted 60.0% of Group RD and 65.7% of Group R, while females accounted for 40.0% and 34.3%, respectively (p=0.621). ASA I patients predominated in both groups (77.1% vs. 74.3%), with no significant difference in ASA distribution (p=0.780). Thus, the two groups were well balanced at baseline. Table 2: Comparison of sensory block characteristics between the groups Sensory block parameter Group RD (n=35) Mean ± SD Group R (n=35) Mean ± SD p-value Onset of sensory block (min) 2.69 ± 0.53 3.31 ± 0.63 <0.001* Time to highest sensory level (min) 4.49 ± 0.66 5.57 ± 0.61 <0.001* Duration of sensory block (min) 259.03 ± 15.40 165.31 ± 19.48 <0.001* Statistical test: Independent t-test. *Statistically significant. Sensory block characteristics differed significantly between the two groups. The onset of sensory block was significantly faster in Group RD than in Group R (2.69 ± 0.53 vs. 3.31 ± 0.63 min; p<0.001). The time to achieve the highest sensory level was also shorter in Group RD (4.49 ± 0.66 vs. 5.57 ± 0.61 min; p<0.001). Importantly, the duration of sensory block was substantially prolonged with dexmedetomidine, measuring 259.03 ± 15.40 minutes in Group RD compared with 165.31 ± 19.48 minutes in Group R (p<0.001). Table 3: Comparison of motor block characteristics between the groups Motor block parameter Group RD (n=35) Mean ± SD Group R (n=35) Mean ± SD p-value Onset of motor block (min) 4.54 ± 0.95 5.37 ± 0.88 <0.001* Time to maximum motor block (min) 5.01 ± 0.55 6.00 ± 0.54 <0.001* Duration of motor block (min) 202.40 ± 17.73 148.31 ± 10.99 <0.001* Statistical test: Independent t-test. *Statistically significant. The addition of intrathecal dexmedetomidine significantly altered motor block characteristics. The onset of motor block was faster in Group RD than in Group R (4.54 ± 0.95 vs. 5.37 ± 0.88 min; p<0.001). Similarly, the time to maximum motor block was shorter in Group RD (5.01 ± 0.55 vs. 6.00 ± 0.54 min; p<0.001). The duration of motor block was significantly longer in the dexmedetomidine group, at 202.40 ± 17.73 minutes compared with 148.31 ± 10.99 minutes in the ropivacaine-only group (p<0.001). Table 4: Comparison of duration of analgesia between the groups Analgesic parameter Group RD (n=35) Mean ± SD Group R (n=35) Mean ± SD p-value Duration of analgesia (min) 324.03 ± 19.81 234.80 ± 17.90 <0.001* Time to rescue analgesia (min) 350.80 ± 25.70 255.00 ± 19.65 <0.001* Statistical test: Independent t-test. *Statistically significant. The primary outcome, duration of analgesia, was significantly prolonged in patients receiving intrathecal dexmedetomidine. The mean duration of analgesia was 324.03 ± 19.81 minutes in Group RD compared with 234.80 ± 17.90 minutes in Group R (p<0.001). Similarly, the time to administration of rescue analgesia was significantly longer in Group RD than in Group R (350.80 ± 25.70 vs. 255.00 ± 19.65 minutes; p<0.001). These findings demonstrate a significant prolongation of postoperative analgesia with the addition of dexmedetomidine to hyperbaric ropivacaine.

The present randomized double-blind study evaluated the effect of adding intrathecal dexmedetomidine to 0.75% hyperbaric ropivacaine for spinal anaesthesia in patients undergoing elective lower-limb orthopaedic surgery. The study was conducted on patients undergoing elective lower limb orthopedic surgeries in hospitals affiliated with Bangalore Medical College & Research Institute (BMCRI) from August 2022 to January 2024. The research employed a double-blinded randomized comparative study design to assess the efficacy of Ropivacaine combined with Dexmedetomidine versus Ropivacaine alone. The sample consisted of 70 patients aged 18 to 65 years, divided into two groups of 35 each. The study targeted individuals within a weight range of 40-80 kg and a height range of 140-190 cm, with ASA grades I and II, excluding those with specific health conditions or hypersensitivities. Baseline characteristics In the present study, the two groups were comparable with respect to age, sex and ASA physical status. The mean age was 39.69 ± 11.54 years in Group RD and 40.26 ± 12.30 years in Group R, with no statistically significant difference (p=0.842). Males made up 60.0% and 65.7% of Groups RD and R, respectively, according to a similar gender distribution (p=0.621). The distribution of ASA physical status was likewise comparable, with ASA I patients making up 77.1% of Group RD and 74.3% of Group R (p=0.780) (Table 1). These results show sufficient baseline comparability and provide credence to the hypothesis that variations in block and analgesic results were more closely associated with the administration of dexmedetomidine than with variations in preoperative or demographic factors. Previous randomised trials comparing intrathecal dexmedetomidine with ropivacaine have likewise revealed similar baseline characteristics. In a randomised double-blind research, Gupta et al. showed that dexmedetomidine was effective in extending spinal analgesia and block duration in lower-limb surgery patients receiving 0.75% ropivacaine with or without 5 µg dexmedetomidine. [1] Sensory block characteristics The substantial improvement in sensory block after adding dexmedetomidine was one of the study's main conclusions. Group RD experienced sensory block much more quickly than Group R (2.69 ± 0.53 vs. 3.31 ± 0.63 min; p<0.001). Additionally, Group RD had a substantially shorter time to reach the maximum sensory level (4.49 ± 0.66 vs. 5.57 ± 0.61 min; p<0.001). (Table 2). The current study's earlier onset is in line with earlier clinical findings. In their investigation of 0.75% isobaric ropivacaine and dexmedetomidine in lower limb surgery, Ravipati et al. found that dexmedetomidine considerably longer sensory block and caused earlier sensory blockade. [2] Similarly, when 5 µg dexmedetomidine was given to 0.75% ropivacaine for lower-limb surgery, Mohanty et al. observed much faster sensory and motor block and delayed remission. [13] Meta-analytic data also supports the significant duration of sensory block in this investigation. According to Niu et al., intrathecal dexmedetomidine considerably extended sensory block as compared to a placebo, with a pooled mean difference of almost 74 minutes. [14] Intrathecal dexmedetomidine significantly prolonged postoperative analgesia, according to a later comprehensive analysis that included 24 randomised studies and 1,460 patients.[15] Dexmedetomidine's effect on spinal α2-adrenergic receptors, especially in the dorsal horn, may account for the increased sensory blockage. When these receptors are activated, nociceptive neurotransmission is reduced and local anaesthetics' antinociceptive effects are strengthened. Therefore, ropivacaine-induced neuronal blockage may be facilitated and prolonged by dexmedetomidine. [1,16] Motor block characteristics The present study also demonstrated significant differences in motor block characteristics. Dexmedetomidine caused a faster start of motor block (4.54 ± 0.95 vs. 5.37 ± 0.88 min; p<0.001) and a shorter duration to maximum motor block (5.01 ± 0.55 vs. 6.00 ± 0.54 min; p<0.001). Additionally, there was a substantial increase in the length of motor block from 148.31 ± 10.99 minutes in Group R to 202.40 ± 17.73 minutes in Group RD (p<0.001) (Table 3). These results are consistent with those of Singh et al., who examined patients having elective lower-limb orthopaedic surgeries and compared ropivacaine alone with ropivacaine with 5 µg dexmedetomidine. They concluded that dexmedetomidine offered a quicker start and longer duration of sensory and motor blockage. In a similar vein, Ravipati et al. found that intrathecal dexmedetomidine considerably prolonged the duration of motor block during lower limb surgery [17], [2] The meta-analysis of Niu et al., which showed a substantial extension of motor block with intrathecal dexmedetomidine, further supports the current findings. [14] When compared to a placebo, dexmedetomidine dramatically increased the duration of both sensory and motor blocks and accelerated their onset, according to another comprehensive study. [18] As a result, the results of this study are in line with the larger body of research showing that intrathecal dexmedetomidine increases the degree and duration of spinal blockage. Postoperative analgesia The study's most noteworthy finding was that intrathecal dexmedetomidine significantly prolonged postoperative analgesia. In Group RD, the mean duration of analgesia was 324.03 ± 19.81 minutes, while in Group R, it was 234.80 ± 17.90 minutes. This is an increase of around 89 minutes (p<0.001). In a similar vein, Group RD had a considerably longer time to rescue analgesia than Group R (350.80 ± 25.70 vs. 255.00 ± 19.65 minutes; p<0.001) (Table 4). Since the main goal of the current study was to extend postoperative analgesia, these findings are very pertinent. According to Gupta et al., the duration of analgesia increased from around 242 minutes to 478 minutes when 5 µg intrathecal dexmedetomidine was added to 0.75% ropivacaine. [1] The direction and size of the impact were consistent, indicating a significant prolonging of analgesia with dexmedetomidine, even though the absolute length varied from the current research. Additionally, Mohanty et al. showed that the duration of analgesia with 0.75% ropivacaine with 5 µg dexmedetomidine was substantially longer than with ropivacaine alone (348.00 ± 23.02 vs. 207.60 ± 17.23 min). [13] The current observation of persistent analgesia after dexmedetomidine treatment is strongly supported by this discovery. Systematic reviews also provide strong evidence. Intrathecal dexmedetomidine increased postoperative analgesia duration by a pooled mean difference of 191.3 minutes when compared to placebo, according to Paramasivan et al.'s analysis of 24 randomised controlled studies including 1,460 patients. [15] More recently, a meta-analysis that specifically examined the combination of ropivacaine and dexmedetomidine discovered that, in comparison to ropivacaine alone, the combination considerably extended postoperative analgesia as well as sensory and motor block. [19] Dexmedetomidine's analgesic effects are probably caused by activation of spinal α2-adrenergic receptors, which results in antinociception and decreases the transmission of pain signals in the dorsal horn. The extended duration of analgesia seen in the current research may be explained by this mechanism working in concert with ropivacaine-induced sodium-channel blockage. [1,16] When combined, these results show that intrathecal dexmedetomidine, when given as an adjuvant to 0.75% hyperbaric ropivacaine, consistently has a positive impact. Improved block characteristics are indicated by significantly shorter sensory and motor block onset times as well as longer sensory and motor block durations (Tables 2 and 3). More significantly, a clinically significant increase in postoperative pain management is shown by the about 89-minute extension in analgesic duration and the roughly 96-minute delay in rescue analgesia (Table 4). The results are in line with larger systematic reviews and meta-analyses of intrathecal dexmedetomidine as well as earlier lower-limb investigations employing ropivacaine and dexmedetomidine.[1-15, 17-19] The evidence that dexmedetomidine is a useful intrathecal adjuvant for extending spinal anaesthesia and postoperative analgesia is strengthened by the consistency across investigations.

This randomized double-blind study demonstrates that the addition of 10 µg intrathecal dexmedetomidine to 0.75% hyperbaric ropivacaine significantly improves the characteristics of spinal anaesthesia in patients undergoing elective lower-limb orthopaedic surgery. When compared to ropivacaine alone, dexmedetomidine generated a much longer duration of both sensory and motor blockade, as well as a much quicker onset and accomplishment of maximal sensory and motor block. Most notably, the dexmedetomidine group experienced considerably longer postoperative analgesia and a longer time to first rescue analgesia. These results suggest that intrathecal dexmedetomidine is a useful adjuvant to 0.75% hyperbaric ropivacaine, offering improved block characteristics and extended analgesia. The combination seems to be a helpful spinal anaesthetic method for elective lower-limb orthopaedic surgeries, within the constraints of this study. LIMITATIONS OF THE STUDY This study has several limitations. First, the sample size was relatively small, with only 70 patients, which may limit the statistical power and generalizability of the findings to a broader surgical population. Second, the results might not be directly relevant to other surgical procedures or higher-risk patient populations because the study was carried out in a small institutional environment and only comprised patients undergoing elective lower-limb orthopaedic surgery. Third, long-term postoperative pain outcomes and functional recovery were not investigated because the study focused on the duration of analgesia and block features during the perioperative period. Fourth, even though the trial was randomised and double-blind, each patient may react differently to spinal anaesthesia and the need for postoperative analgesics. Lastly, as the study only looked at one intrathecal dosage of dexmedetomidine, it was unable to identify the ideal dose and dose-response relationship. It is necessary to conduct larger multicenter trials with longer follow-up periods and to evaluate various dosages of dexmedetomidine.

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