In urological studies the central neuraxial blockade in the form of spinal anesthesia is the most widely used form of regional anesthesia. [1] Considering ambulatory day care nature of these surgeries where patients can go home on the same day, it is accepted as safer technique with its well-established safety profile. [2] .Various local anesthetic (LA) agents are being studied for their efficacy in spinal anesthesia, like lignocaine, bupivacaine, levobupivacaine, and ropivacaine [3]. Still the quest for optimal local anesthetic (LA)

agents in spinal anesthesia for urological surgeries is an ongoing area of research.

Bupivacaine, a tried-and-tested LA, has long been a mainstay, however newer contenders are emerging. Levobupivacaine and ropivacaine are amongst the rising stars being investigated for their efficacy. Isobaric ropivacaine, in particular, has generated excitement due to its close chemical resemblance to bupivacaine. It was found to be better and safe for urological surgeries due to early recovery profile that is quicker return of motor function.[4]

 When compared, the hyperbaric solutions give more predictable and controlled anesthetic effect in spinal block than isobaric preparations, potentially reducing complications. [5] As only isobaric preparations were available commertially, all studies which have used hyperbaric ropivacaine have added various concentrations of dextrose to these preparations seperately. This procedure is difficult and adds question for maintaining sterility. The aseptic technique required to create a sterile hyperbaric ropivacaine solution poses a significant hurdle to its wider adoption. [6]. Recently commercial hyperbaric preparation of ropivacaine is introduced in India. We have compared the efficacy of this hyperbaric ropivaccaine in comparison with bupivacaine for urological surgeries. The primary outcome of our study was to compare the sensory and motor spinal block characteristics of (0.75 %) hyperbaric ropivacaine with (0.5%) hyperbaric bupivacaine. Null hypothesis we have put forward was that both these drugs are similar in comparison to spinal block characteristics [7]

AIMS AND OBJECTIVES

The aim of the current study was to compare the efficacy & safety of intrathecal (0.75%) hyperbaric ropivacaine versus (0.5%) hyperbaric bupivacaine in patients undergoing elective urological surgeries.

The current study is a Prospective Randomized double blind active controlled parallel group clinical trial which was done in patients undergoing urological surgeries under Spinal anesthesia in Department of Anesthesiology, MGM Medical College & Hospital Aurangabad. The study was conducted for duration of 24 months, from June 2022 to June 2024.

SAMPLE SIZE According to study by Ghimire R et al.[8], using open epi 2.3.1 software , the mean test intervention was considered t o be 155.0±60 and mean control intervention of 190±80, with Alfa value of 0.95, the sample size was calculated to be 37 in each group.

INCLUSION AND EXCLUSION CRITERIA

Patients who belonged to age group between 18 to 70 years and patients with ASA grade 1, 2, 3 patients who undergo elective urological surgeries under spinal anaesthesia, who consented to be a part of study were included in the current study

Patients with contraindications of spinal anaesthesia such as local infection, raised intra cranial tension, coagulopathy, valvular heart disease, patients with known allergies to the study drugs, those with severe left ventricular systolic dysfunction (<30%) , pregnant and lactating women ,and those patients that required surgeries more than three hours of duration were excluded from the study.

DATA COLLECTION

All patients who met the inclusion criteria, underwent screening before enrollment in the study. Following detailed history-taking, they completed medical and laboratory examinations. Voluntary written informed consent was obtained from all eligible and willing patients, who were informed about the benefits and risks of participating in the study. Patients were randomly assigned to one of the study groups using the sealed envelope method. First group, Group R was given Intrathecal Hyperbaric Ropivacaine (0.75%) 3ml and second group, Group B was given Intrathecal Hyperbaric Bupivacaine (0.5%) 3ml.

An anesthesiologist administered the drug intrathecally, while another anesthesiologist (observer), blinded to the administered drug, recorded the findings. Both the patient and observer were kept unaware of the study drug used, ensuring the study was conducted double-blind. Patients had fasted for a minimum of 6 hours prior to surgery On the day of surgery in the operating theater, monitors were attached and baseline parameters such as heart rate (HR), non-invasive mean arterial pressure (MAP), oxygen saturation (SPO2), and ECG were recorded. Intravenous access was established using a 20 G intravenous cannula. Crystalloid co-loading was performed with Ringer's lactate or normal saline, and heart rate and mean blood pressure were monitored continuously. Spinal anesthesia was administered with the patient in the sitting position at the L3-L4 intervertebral space using a 23G Quincke spinal needle under strict aseptic precautions. The drug was administered according to the randomly assigned groups. After positioning the patient supine, sensory block was assessed by pinprick testing at the mid-axillary line every 3 minutes until the sensory level reached the L1 dermatome, which was considered the onset of sensory block. The peak sensory level, defined as two consecutive readings at the same dermatomal level, was recorded as the highest sensory level. Subsequently, sensory block was evaluated every 20 minutes until regression to the L1 level. The time from spinal injection (T-0) to the onset of sensory blockade reaching L1 was noted as the onset time, while the duration from T0 to regression to L1 was recorded as the total duration of sensory block. Motor block was assessed every 3 minutes using the Bromage scale from intrathecal injection until the start of surgery.

The onset of motor block was defined as the time from T-0 to achieving a motor block of grade 2. Postoperatively, motor block was evaluated every 20 minutes until complete recovery (grade 0), with the duration of motor block calculated from the onset of grade 2 motor block to complete recovery. Surgery proceeded once sensory block up to the T10 dermatome and grade 2 motor block were achieved. Failure to achieve the required block within 20 minutes was considered block failure, leading to the administration of general anesthesia to those patients. After spinal anesthesia was administered, heart rate and mean arterial pressure (MAP) were recorded every 3 minutes for the first 20 minutes. Thereafter, monitoring continued every 10 minutes until sensory block regression to the L1 level. A decrease in mean arterial pressure exceeding 20% from baseline was classified as hypotension and treated with intravenous Mephentermine 3 mg. Bradycardia, defined as heart rate less than 50 beats per minute, was managed with intravenous Atropine 0.6 mg. Intravenous Ondansetron 4 mg was administered to alleviate intraoperative nausea and vomiting. The total duration of surgery was documented for each patient

STATISTICAL ANALYSIS

The data was entered in Microsoft excel 2016 and coded and the Statistical Package for the Social Sciences Software Version 16.0 was used for

Statistical analyses. Student’s t test was used to compare the means and standard deviation, chi square test was used to assess the association. P-value less than 0.05 were considered as statistical significant.

ETHICAL CLEARANCE Institutional ethical committee clearance was obtained, with the number MGM/PHARMAC/ECRHS/2022/159.

In the current study when demographic parameters of both the groups were compared, the mean age in group R was (48.0±18.4 years) and in group B was (49.5±16.4 years). Both the groups were comparable for age, with no statistically significant difference. (P=0.714) The percentage of male patients in Group R was 75.68% and Group B was 81.09%. The percentage of female patients in Group R was 24.32% and Group B was 18.91% with χ2-Value (0.319). Both groups were statistically comparable with respect to gender distribution (P=0.572) .Maximum patients in Group R 25 were belonging to ASA II and maximum patients in Group B 27 belong to ASA II category. ASA I patients in Group B were 2 and zero in Group R. ASA III patients were equal in both groups i. e. 10 patients each. Both groups were statistically comparable in relation to ASA grade (P=0.3539) Table no 1

Spinal block characteristics have showed that the mean onset of sensory block among patients in Group R (2.89±1.13 mins) was faster than patients in Group B (3.02±0.897mins) the difference between two was statistically non-significant (P=0.570). The mean onset of motor block among patients in Group B (4.76±1.21mins) was faster than patients in Group R (4.95±1.65mins) the difference between two was statistically non-significant (P=0.576)

Number of patients attending highest sensory level at T10 in Group R was 19 patients and Group B was 17. Number of patients attending highest sensory level at T8 in Group R was 13 patients and Group B was 18. Maximum sensory level attended in both the groups was T6. In Group R, 5 patients and Group B, 2 patients attended this T6 level. The results being statistically insignificant with χ2-value 2.203 (p =0.3323) the mean value for time to attend maximum sensory block in Group R was (14.97±3.55 mins) and Group B was (15.35±2.83 mins). The difference was statistically non-significant (P=0.614)

The mean duration of sensory block was prolonged in Group B (171.8±12.1min) than Group R (156.5±11.8 min). This difference was highly significant statistically. (P = 0.0000) Table no 2. The mean duration of motor block was prolonged in Group B (207.08±9.93 min) when compared to Group R (189.2±14.5 min), the difference was statistically highly significant (p=0.000). Table no 3.

There was no statistically significant difference in the heart rate between the two groups at various time intervals (p > 0.05). When heart rate variations as mean percentage change has been compared in both the groups, Group B shows decrease in heart rate after 2 minutes and 60 minutes onwards as compared to baseline and Group R shows increase in heart rate throughout the surgical duration as compared to baseline. when both the groups were compared for heart rate variations no statistically significant difference was noted (P value >0.05)

There was no statistically significant difference in the mean arterial pressure between the two group at various time intervals except at 200 mins after intrathecal injection when the mean arterial pressure in group B (84.86±9.52 mmHg) was less as compared to group R (90.59±6.92 mmHg) the difference being statistically significant (0.004). At the interval of 2 minutes, fall in BP noted in Group R as compared to Group B with statistically significant difference (P=0.011). Afterwards throughout the study period MAP variations remained comparable in both the groups with statistically insignificant difference. There was no incidence of bradycardia and hypotension noted in our study.

Table no 1: Showing the age distribution, gender distribution and ASA grading in the study subjects

 Students t test was used to compare the means and standard deviations, chi square test was used t asses the association, p value <0.05 was considered to be statistically significant

Table no 2 showing the distribution of onset of sensory block, time to attend maximum sensory block, duration of sensory block, highest level of sensory block.

Students t test was used to compare the means and standard deviations, p value <0.05 was considered to be statistically significant

Table 3: Showing the distribution of onset of motor block and duration of motor block

Students t test was used to compare the means and standard deviations, p value <0.05 was considered to be statistically significant

Spinal anesthesia has been found to be superior to general anesthesia in urological surgeries due to its targeted effectiveness and reduced systemic impact. LA agents used for spinal anaestheisa include lignocaine, bupivacaine, ropivacaine and levobupivacaine. The preparations of these agents are available in both isobaric and hyperbaric forms, enhancing the versatility and efficacy of these agents. Intrathecal use of hyperbaric LA agents has become more popular as they produce predictable block characteristics and reliable Spinal anaesthesia.[9] Hyperbaric lignocaine is shorter acting agent but has the problem of transient neurological symptoms, so not preferred now. While bupivacaine is known for its potent anesthetic properties, its associated cardiotoxicity and prolonged motor blockade has led to a preference for ropivacaine, and levobupivacaine as an alternative.

Ropivacaine is aminoamide local anaesthetic agent having lower potential for cardiovascular and CNS toxicity compared to other local anaesthetics. Only isobaric preparations of ropivacaine both 0.5% and 075% were available commercially for use.

Hyperbaric solutions for ropivacaine were prepared by adding dextrose separately and have tried for spinal anaesthesia by some authors [10]. These preparations have different concentrations of dextrose and variable specific gravities, preparation of these solutions again may compromise the sterility.[11]

Neon laboratories have introduced 0.75% hyperbaric ropivacaine with dextrose 80 mg as 4ml ampule ready to use for spinal anaesthesia so we have used this drug in comparison with hyperbaric bupivacaine to assess efficacy in view of spinal characteristics in urological surgeries.

DOSE OF DRUG SELECTED

The equipotent ratio between bupivacaine and ropivacaine is 2:3. It has shown in some dose finding studies that using this ratio (2:3), bupivacaine and ropivacaine have similar profiles and at equal doses (1:1), anaesthesia was less intense using ropivacaine.[9], Considering this we in the current study have compared 3ml hyperbaric ropivacaine 0.75 % (22.5mg) with 3ml hyperbaric bupivacaine 0.5% (15mg).

SENSORY BLOCK CHARACTERISTICS

Onset of sensory blockade

In our study onset of sensory block was defined as the time of intrathecal injection to time taken to achieve L1 level. In the present study, the mean onset of sensory block among patients in Group R (2.89±1.13 mins) was faster than patients in Group B (3.02±0.897mins) but the difference between two values was statistically nonsignificant with P=0.570.

Kulkarni et al. [9] studied hyperbaric ropivacaine versus hyperbaric bupivacaine in patients undergoing lower-abdominal, perineal or lower-limb surgery under spinal anesthesia the mean onset of sensory block was faster in Group R (3.2 ±1.5mins), than in Group B (4.3 ± 3.5mins) which was similar with our study.

Gohil et al. [12] observed anesthetic efficacy and safety of ropivacaine 0.75% versus bupivacaine 0.5% for spinal anesthesia in patients undergoing lower limb orthopedic surgery and found that ropivacaine (2.6±0.53 min) produced faster onset of sensory block than bupivacaine (3±0.56 min) (P<0.006), this finding was also in agreement with our study.

In another study by Ghimre et al.[8], who studied the effectiveness of hyperbaric ropivacaine over hyperbaric bupivacaine in spinal anaesthesia, the time to onset of maximum sensory block level was faster in bupivacaine (9.10±3.90min) than in ropivacaine (10.87±5.37min) with statistically not significant difference. Though the difference is nonsignificant they have noted faster onset of bupivacaine than that of ropivacaine. This is not similar to our study may be due to the different definition of onset of sensory block in their study, where they have considered the time of onset of sensory block as time taken to achieve maximum sensory height.

Maximum height of sensory block:

In our study, number of patients attending highest sensory level at T10 in Group R was 19patients and Group B was 17. Number of patients attending highest sensory level at T8 in Group R was 13 patients and Group B was 18. Maximum sensory level attended in boththe groups was T6 with Group R, 5 patients and Group B, 2 patients. The results being statistically insignificant with χ2-value 2.203 (p=0.3323). In the current study we found that, the mean value for time to attend maximum sensory block in Group R was (14.97±3.55 mins) and Group B was (15.35±2.83 mins). The difference between two values was statistically non-significant (P=0.614) . In a study by Fetts et al.[13] who compared plain and hyperbaric solutions of ropivacaine for spinal anaesthesia, the authors observed that the maximum block height was T8 as median in hyperbaric group. Ghimre et al.[8] noted the the time taken to achive maximum height for hyperbaric ropivacaine as 13.4±4.40 mins which correlates with our findings.

Duration of Sensory Block

In the current study we defined the duration of sensory blockade as the time taken from intrathecal injection of drug till the L1 regression. The mean duration of sensory block was prolonged in Group B (171.8±12.1mins) than in Group R (156.5±11.8 min). This difference was highly significant statistically. (P = 0.0000). Kulkarni et al.[9], observed that mean duration of sensory block was shorter in hyperbaric ropivacaine (155 ±60 mins) than bupivacaine (190.5±80 mins) (P = 0.028, P < 0.05). this finding correlates with our study.

Dar et al.[10] compared hyperbaric bupivacaine and ropivacaine for lower limb surgeries and also found that sensory block duration is significantly more in bupivacaine than ropivacaine. Total duration of sensory block in bupivacaine was 260 min and in ropivacaine was 160min P<0.001 .In a meta-analysis by Khaleel et al.[14], for comparison between intrathecal ropivacaine versus bupivacaine in a non-obstetric population, the authors found that the duration of the sensory block was longer in the bupivacaine group compared to the ropivacaine group. Duration of sensory block in 30 studies with 2168 participants have shown standard mean difference of −0.76 (−1.08–−0.45) with p value <0. 001.All these studies correlates with our study.

CHARACTERISTICS OF MOTOR BLOCKADE

Onset of motor block

We defined onset of motor blockade as the time taken from intrathecal injection of the study drug till the achievement of grade II 2 motor block. In the current study, the onset of motor block among patients in Group B (4.76±1.21mins) was faster than patients in Group R (4.95±1.65mins) but the difference between two values were statistically non-significant (P=0.576). Ghimre et al.[8] also presented similar results as in our study. Onset of motor blockade was statistically significant (ropivacaine 13.10±4.40 mins, and bupivacaine 8.70±3.19min; p value of <0.05). Dar et al.[10] in their study compared spinal characteristics of hyperbaric ropivacaine and bupivacaine and noted onset of motor blockade earlier in bupivacaine than in ropivacaine (Group B: 9 mins, Group R: 13 mins P<0.001) with statistically significant difference. Both these studies have similar findings as our study. The actual values for each group in both these studies were more than our study because they have considered onset of motor block as achieving complete grade III motor blockade as per Bromage scale.

Duration of motor block

In our study, duration of motor block was taken as the time from intrathecal injection of study drug till complete motor recovery. The mean duration of motor block was prolonged in Group B (207.08±9.93min) when compared to Group R (189.2±14.5min), the results were statistically highly significant (p=0.000). Naren CK et al. [15] studied the clinical efficacy and safety of subarachnoid block with 0.5% hyperbaric ropivacaine compared with 0.5% hyperbaric bupivacaine in elective gynaecological surgeries. Their study observed that the duration of motor block was longer with bupivacaine 162.8 min than with ropivacaine 131.7 min ( p value <0.05) , which was statistically significant. Dar FA et al. [10] found that the mean duration of motor block was shorter in ropivacaine group (126±9.2min) compared to bupivacaine group (174±12.6min) with p value <0.05. The findings in both studies were similar to our study. Khaleel et al. [14] their meta-analysis found that the duration of the motor block was significantly longer with bupivacaine than with ropivacaine in various studies. Duration for motor block in 31 studies with 2289 participants, standard mean deviation was −1.85 (−2.48–−1.22) with p value <0.001.

INTRAOPERATIVE HAEMODYNAMIC PARAMETERS

There was no statistically significant difference in the heart rate between the two groups at various time. There were no incidences of bradycardia in any of the study subjects at any given point of time during the study. Findings from our study correlate with various other studies with statistically insignificant difference between like Kulkarni KR et al.[9], P. D. W. Fettes et al.[13], Naren CK et al.[15], Dar FA et al.[10].

Mean arterial pressure: There was no statistically significant difference in the mean arterial pressure between the two groups at various time intervals except at 200 mins after intrathecal injection when the mean arterial pressure in Group B (84.86±9.52 mmHg) was less as compared to Group R (90.59±6.9 mmHg) the difference being statistically significant (0.004). This is the time interval at which there was complete recovery from motor blockade in Group R where as it was not in Group B. These findings can be correlated with studies by Kulkarni KR et al.[9], Upadya M et al.[16], Waris I et al.[17], Ghimire R et al.[8]. There were no incidences of hypotension in any of the study subjects at any given point of time during the study.

The intrathecal hyperbaric ropivacaine (3ml 0.75%) when compared with hyperbaric bupivacaine (3ml 0.5%) for urological surgeries shows faster recovery from sensory as well as motor block. Other Spinal characterstics like onset of sensory and motor block , maximum height of sensory block and haemodynamic variations were comparable in both drugs at given dosages and concentrations .Thus considering the surgical level of duration 0.75% hyperbaric ropivacaine is an good alternative for 0.5 % bupivaccaine in urological procedures.

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