European Journal of Cardiovascular Medicine

Subarachnoid block is the anaesthesia technique of choice and is the gold standard for lower abdominal and lower extremity surgeries when compared to general and epidural anaesthesia. However spinal anaesthesia is associated with some hazards. The commonest of these being hypotension with a reported incidence greater than 80%.1 It has gained popularity due to low cost, awake patient, prompt onset, and rapid recovery and no need of airway protection.2 Presently Inj. hyperbaric Bupivacaine 0.5% is the most widely used drug for spinal anaesthesia. As it is a racemic (50:50) mixture of S and R enantiomer, it is more cardio toxic because of R enantiomer. Major limitation with the use of Bupivacaine is its CNS toxicity, cardio toxicity and prolongation of motor block. In today’s world, faster recovery along with minimal side effects and early ambulation is now in demands, especially for the day care surgeries. Due to this, there has been an ongoing search for alternative drugs with similar blocking properties of Bupivacaine but with a better margin of safety and early recovery from motor block. 3 Ropivacaine was introduced into clinical practice in 1996, and has consistently demonstrated an improved safety profile over Bupivacaine, with a reduced CNS and cardio toxic potential, together with wide clinical uses at different doses and for various indications. It has been shown to provide effective, well tolerated surgical anaesthesia via the epidural route, for major and minor nerve blocks and field blocks as well as high-quality postoperative analgesia.

Ropivacaine is enantiomerically pure (S-enantiomer) amide local anaesthetic with long-acting and with a low lipid solubility which blocks nerve fibres involved in pain transmission (Ad and C fibres) to a greater degree than those controlling motor function (Ab fibres).4 There was little difference between the Ropivacaine and Bupivacaine at different doses groups with respect to speed of onset or sensory block. The duration of analgesia was increased by increasing the concentration of both drugs, but this had minimal effect on onset time or extent of block.5 Hence this study was conducted to study and compare the effects of equal volume of 0.75% Hyperbaric Ropivacaine with 0.5% Hyperbaric Bupivacaine for lower abdominal surgeries.

A Prospective randomized double-blind study. Control study done on 60 patients in the Department of Anaesthesiology, Khaja Banda Nawaz Teaching and General Hospital, Kalaburagi for duration of 18 months i.e., from August 2022 to February 2024. Patients were randomly divided into two groups of 30 each into Group A and B by drawing out any one of the 2 labelled cards (A and B) from a sealed

Group A: Hyperbaric Ropivacaine 0.75% 3ml

Group B: Hyperbaric Bupivacaine 0.5% 3ml

Sample size: 60

Sample size calculation for 2 different groups of equal sizes for a continuous outcome measure:

n = sample size per group

α = 0.05 The probability of rejecting the null hypothesis when it is true. A level of

0.05 or 95% is most commonly used. The value was 1.96 β = 0.2 The probability of failing to reject the null hypothesis if it is false. A level of

0.2 is most commonly used. This corresponds to a study power of 0.82 or 80%.

σ 2 = population variance in mean duration of motor block in both the groups variance (standard deviation2) the SD of the study was 1.3. ⁶ in the reference study:

μ1 = Mean of onset of peak sensory block group A Ropivacaine = 7.80 μ2 = Mean of onset of peak sensory block group B Bupivacaine = 9.37

μ2 − μ1 = minimum difference was 1.57 Sample size = (Z α/2+ Z β)2 x 2σ2/(μ2-μ1)2

= (1.96 + 0.82)2 x 2 x (1.3)2/ (1.57)2

= 12.52 samples in each group

= Round figure 30 samples in each group

Sample size= Total samples 60 (30 samples were taken in each group)

Inclusion criteria:

1. Patient belonging to ASA grade I,
2. Patient undergoing elective lower abdominal surgical procedures of duration 90-120 minutes.
3. Patient of age group between 18-60 years of all

Exclusion criteria:

1. Infection at local site
2. Patient with hypersensitivity to drug
3. Addiction to opioids
4. Inadequate block
5. Bleeding disorders, cardiovascular disorders
6. History of coagulopathy or on anticoagulant treatment
7. Pregnant patient
8. Patients with neuromuscular disorders or pre-existing neurological
9. Spinal deformities

METHODOLOGY:

After obtaining the clearance and approval from Institutional Ethical Committee, patients fulfilling inclusion criteria who are willing to give written informed consent will be included in the study. Sixty patients of ASA grade I or II, aged 18-60 years of all sex scheduled for lower abdominal surgeries will be enrolled in the study. Patients will be randomly divided into two groups of 30 each into Group A and B by drawing out any one of the 2 labelled cards (A and B) from a sealed envelope. The randomization and preparation of the drug solutions will be done by a senior anaesthesiologist not involved in the study. The anaesthesiologist who will perform and observe the block characteristics will be blinded to the treatment groups and thus the study is double blinded. The composition of the drugs in various groups include:

Group A: Hyperbaric Ropivacaine 0.75% 3ml

Group B: Hyperbaric Bupivacaine 0.5% 3ml

PREOPERATIVE PERIOD: A preoperative visit was conducted on the day prior to surgery and a detailed history and presenting complaints were noted. General physical examination include height, weight and systemic examination of cardiovascular, respiratory, central nervous system and per abdomen examination was done. All patients were kept nil per oral according to ASA fasting guidelines. Routine laboratory investigations like complete haemogram, bleeding time and clotting time, random blood sugar, HIV and HBsAg were done. The patient and their attendants were briefed about the procedure and a written informed consent was taken. In the pre-operative room, a peripheral intravenous line with 18 gauge cannula was secured on opposite upper limb and crystalloid infusion was started.

INTRAOPERATIVE PERIOD

On arrival to the operating room standard ASA monitors - Non-Invasive Blood Pressure (NIBP), Electrocardiogram(ECG) and Pulse oximeter (SpO2) were attached. Injection Ondansetron 0.1 mg/kg intravenous was given. Baseline Pulse Rate (PR), Systolic blood pressure, Diastolic blood pressure, Mean blood pressure, Respiratory rate and Oxygen Saturation (SpO2%) was noted & monitored.

Using Quincke-Babcok needle Subarachnoid Block at L3-L4 is given under strict aseptic precautions and patients will receive either of the study drug mentioned above. At the end study will be decoded.

The following parameters will be measured-

1. Dermatomes of T8 nerve will be checked for sensory

Quality of sensory block will be graded as:

• Sharp pain, that is normal sensation to pin prick
• Analgesia, only touch felt, but not pin prick
• Anaesthesia, no response to pin

The onset of sensory block is defined as time from injection of drug till no response to pin prick test.

Duration of sensory block is defined as time interval between complete sensory block till first postoperative pain.

1. Motor blockade will be determined according to Modified Bromage Scale for Lower extremity on a 4point scale.

Quality of motor block will be graded as:

0: No motor block.

1: Inability to raise extended leg; able to move knees and feet.

2: Inability to raise extended leg and move knee; able to move Feet. 3: Complete block of motor limb.

The onset of motor blockade is defined as time from injection of drug till Modified Bromage scale 3.

The duration of motor block is defined as the time interval between complete paralysis to Bromage scale 0.

The sensory & motor blockade will be assessed every 3 minutes for 30 minutes after injection of drug & at 60, 120, 240 and 360 minutes.

The block will be considered as failed if complete sensory and motor block will not be achieved after 30 minutes and the failed block will be converted to general anaesthesia and excluded from the study.

1. Measurements of blood pressure, heart rate and oxygen saturation will be recorded at 0,1,3,5,10 minutes and at every 15 minutes till the surgery gets

Any adverse effects such as hypotension (<20% decrease in systolic blood pressure), Nausea and Vomiting, Pruritis, Shivering and bradycardia will be noted and treated.

Statistical Analysis: Data was analyzed by IBM SPSS 25.0 version software. Collected data were spread on excel sheet and prepared master chart. For quantitative data analysis of descriptive statistics were done mean, standard deviation initially; independent samples “t-” test was used to compare the mean values between two variables for statistical significant. For quantitative data analysis chi-square test and Fisher exact probability tests were applied for statistically significant. P ≤ 0.05 was considered statistically significant for all comparisons

Study observes that, maximum number of patients in the two groups 19 (31.7%) cases were belongs to the age group of 21—30 years, followed by 17 (28.3%) were belongs to 31—40 years and 11 (18.3%) cases were belongs to the age groups of 51-60. But there was statistically no significant difference of mean age between the groups Group-A and Group-B (P>0.05)

Study observed that; in the group-A Male cases were 26 (86.7%) and in Group-B male cases were 21 (70.0%) and Female cases in Group-A were 4 (13.3%) and Group- B were 9 (30.0%). There was statistically no significant difference of distribution of gender between the Groups A and Group B (P>0.05)

The mean weight of Group-A was 68.23 kg and group-B was 64.10 kg, mean weight was statistically not significant difference between Group-A and Group-B (P>0.05)

Table No.1: ASA status wise distribution of cases in the groups

                  NS= not significant, S=significant, HS=highly significant

ASA status I in Group-A were 20 (66.7%) cases in Group-B were 24 (80.0%) cases. There was statistically not significant difference in the distribution of ASA status between Group-A and Group-B (P>0.05)

Table No.2: Diagnosis wise distribution of cases

                             NS= not significant, S=significant, HS=highly significant

Majority of cases were diagnosed 27 (45.0%) were acute appendicitis, followed by 14 (23.3%) of cases were diagnosed Inguinal hernia and 9 (15.0%) of cases were diagnosed hydrocele. There was statistically not significant difference of distribution of diagnosis between Group-A and Group-B (P>0.05).

Table 3: Procedure of surgery wise distribution of cases

                  NS= not significant, S=significant, HS=highly significant

27 (45.0%) of cases surgery procedure was appendectomy, followed by 14 (23.3%) of cases surgery procedure was hernioplsty and 9 (15.0%) of cases procedure of surgery was Jaboulay’s procedure. There was statistically not significant difference of distribution of surgery procedure among Group-A and Group- B (P>0.05)

Table 4: Comparison of mean Time to Onset of Sensory block (TOS), Time to Peak Sensory block (TPSL) and Time to Complete Motor block (TOM) (in minutes) between the groups

There was statistically highly significant mean difference of time to onset of sensory block between Group-A and Group-B (P<0.001).

There was statistically highly significant mean difference of time to Peak sensory block between Group-A and Group-B (P<0.001).

There was statistically highly significant mean difference of time to complete motor block between Group-A and Group-B (P<0.001).

Table 5: Comparison of mean duration of sensory block and motor block (in minutes) between the groups A and B

There was statistically highly significant mean difference of duration of sensory block and duration of motor block between Group-A and Group-B (P<0.001). 

Most of the patients in Group-A had the mean pulse rate ranging from 85.00 bpm to 96.00 bpm between preoperative and at 1 minutes to 120 minutes. Similarly patients in Group-B had the mean pulse rate. There was statistically significant difference of mean PR between group-A and Group-B (P<0.05), (P<0.001). In Group-A seen higher mean pulse rate as compare to Group-B

Early studies with isobaric ropivacaine reported to have variable or inadequate block patterns for surgery and confirmed that the addition of glucose to the solution of ropivacaine has better effects as with other drugs used for Spinal anaesthesia. It reduces the proportion of a limited block or more extensive block which has been previously reported from studies on both tetracaine and bupivacaine. It is known that ropivacaine is 30- 40% less potent and effects are short lived than bupivacaine making it advantageous for short to intermediate duration of surgeries or ambulatory surgeries.

We observed that ropivacaine significantly produced slower onset but shorter time to peak effect (4.01 ± 0.83, 13.43 ± 0.77) than bupivacaine (3.06 ± 0.69, 14.36 ± 0.99); however, level of sensory block achieved was similar and duration of sensory block was significantly lesser with ropivacaine (154.93 ± 6.45 min). The onset of pinprick analgesia at T10 was more rapid in bupivacaine Group B than in ropivacaine Group A. (P <0.001) However, the time to (peak) maximum extent of cephalad spread and the level achieved were similar in both groups. The mean duration of sensory block was shorter in Group A (154.93 ± 6.45) than in Group B (190.00 ± 7.20). (P <0.001) The time to maximum motor blockade was statistically similar (P 0.05).

No significant difference in the incidence of bradycardia was observed in two groups and they responded easily to injection atropine. 3 patients in Group B and 3 patients in Group A developed shivering which was managed conservatively. The findings were similar to the study carried out in elective surgeries under Spinal Anaesthesia by Whiteside7 and others who observed onset time of 5 and 2 min with 3 ml of 0.5% hyperbaric ropivacaine and bupivacaine in 5% and 8% glucose respectively. We observed that ropivacaine has a less potent effect on motor nerves and the degree of sensory-motor separation is more as compared with bupivacaine, but can produce reliable Spinal Anaesthesia, which has been supported by similar observations of other studies.

The findings were similar to the study carried out by Whiteside7 and others, who observed mean onset time of motor blockade of 15 min and 10 min and total duration of around 90 min and 180 min with similar dose of hyperbaric ropivacaine and bupivacaine respectively. Luck et al8 also observed less degree and duration of motor blockade, lower incidence of bromage score of grade III in 63% with hyperbaric 0.5% ropivacaine as compared to 90% with 0.5% bupivacaine, with the similar dose of 3 ml with 30 mg/ml of glucose.

We also noted that compared to bupivacaine ropivacaine group had good sensory blocks, favourable recovery profile of sensory/motor blockade and shorter time to first micturition. These features of ropivacaine are beneficial for ambulatory surgery. We found no evidence of any late sequelae such as backache or other transient symptoms in this study as with previous studies of ropivacaine. Hence, ropivacaine can be a safer alternative for ambulatory surgeries. In this study we have used equal volume of Injection 0.75% hyperbaric ropivacaine and 0.5% hyperbaric bupivacaine, dose of a Injection 0.75% hyperbaric ropivacaine and 0.5% hyperbaric bupivacaine would vary i.e., 22.5mg and 15mg respectively.

Duration of sensory block and motor block in patients receiving 0.75 % hyperbaric Ropivacaine was less when compared to the patients receiving 0.5 % hyperbaric bupivacaine. The onset of sensory and motor block was nearly same in both the groups. Incidence of Complications like hypotension and bradycardia were less in Ropivacaine group. Ropivacaine is comparable to the hyperbaric 0.5% bupivacaine in terms of quality of block, but with a shorter recovery profile, it is a useful agent for Spinal Anaesthesia for intermediate duration of surgeries.

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