INTRODUCTION

Spinal anaesthesia is a commonly used and effective technique which provides rapid and reliable anaesthesia with muscle relaxation for patients undergoing lower abdominal and lower limb surgeries.^[1]

The advantages of spinal anaesthesia include a faster initiation of action when equated with epidural blocks, as well as the simplicity and ease of administration. The benefits are they reduce the risk of DVT, PE, coronary problems, oozing of blood, need for transfusions, and depression in respiration, provides greater relief of pain following surgery.^[2]

In the recent days, Ropivacaine is gaining increasing popularity because of reduced risk of central nervous system and cardiotoxicity, early ambulation and discharge with good quality of post-operative analgesia.^[3]

Ropivacaine is a pure S(-) enantiomer of propyl derivative of pipecoloxylidide and a new long- acting amino amide with lower lipid solubility and cardiotoxicity than Bupivacaine. ^[4,5]

Isobaric form produces variable form of sensory and motor blockade whereas hypothetically, Hyperbaric Ropivacaine produces more reliable sensory and motor blockade with faster onset, better quality of muscle relaxation than Isobaric Ropivacaine. ^[6]

Buprenorphine is an opioid of the phenanthrene morphine class with extremely high binding affinity and a partial agonist activity at the μ- and κ-receptors and partial or full agonist activity at the opioid receptor like I/nociception and λ- receptor and competitive antagonist activity at the κ- receptor. ^[7]

AIM AND OBJECTIVES

AIM:

To compare the efficacy of intrathecal Hyperbaric Ropivacaine (0.75%) and Isobaric Ropivacaine (0.75%) with Buprenorphine in patients undergoing lower abdominal and lower limb orthopedic procedures under Subarachnoid block.

OBJECTIVES:

Primary objective:

• To compare onset and duration of sensory and motor blockade.

• To assess and compare the haemodynamic parameters between both groups.

Secondary objective:

• To assess two segment sensory regression time.

• Side effects if any.

 MATERIALS AND METHODS

STUDY TYPE

Interventional

STUDY DESIGN

A prospective randomized double-blind study.

STUDY POPULATION

After Ethical Committee approval and CTRI registration, 70 patients who will undergo elective or emergency lower abdominal and lower limb surgeries at Chettinad Hospital and Research Institute, Kelambakkam, Chennai, will be taken up for study.

SAMPLE SIZE

The sample size is calculated for the two independent study group for Continuous variables for randomised control trial using the formula for Non- Inferiority design.

N=2*(Z1-  Î±+Z1- Î²/ Î´0)2*s²

•       N- size per group

•       Z- Standard normal deviate

•       δ₀- Allowable difference

•       s²- polled standard deviation of comparison groups

•       α- Type 1 error

•       β- Type 2 error 

      •       The sample size is based on the previous study in which the Mean (± SD) onset of sensory blockade (T10) was faster in patients receiving Hyperbaric Ropivacaine (0.75%) (4.42± 1.33) than in patients receiving Isobaric Ropivacaine (0.75%) (6.0± 1.03), study by Gupta et al.

     â€¢       Sample size: 70

     â€¢       Group A= 35 patients; Group B= 35 patients

     Where

•       Confidence interval 90%  Î±=0.10

•       Power (1-β)=0.30

•       Ratio of sample size, Treat/control=1

     â€¢       SD=1.3; Drop out (%)=10%

     â€¢       Allowable difference= 1.6 (Comparative study of intrathecal Hyperbaric Ropivacaine (0.75%) and Isobaric Ropivacaine (0.75%) with Buprenorphine in patients undergoing lower abdominal and lower limb procedures under Subarachnoid block)

     â€¢       The sample size calculated per group

   Group A = 35;   Group B = 35

 â€¢       Patients in each group will receive anaesthesia as follows:

•       Group A  (n= 35) :Patients will receive 3.5 ml of Hyperbaric Ropivacaine (0.75%) + 0.2 ml Buprenorphine (60mcg)

•       Group B  (n= 35) :Patients will receive 3.5 ml of Isobaric Ropivacaine (0.75%) + 0.2 ml Buprenorphine (60mcg)

Inclusion criteria

1. American Society of Anesthesiologists (ASA) grade I-III.

2. Age group between 18-60 years of both sexes.

3. Scheduled for Elective and emergency lower abdominal and lower limb surgeries under Spinal Anaesthesia.

Exclusion criteria

1. Patient refusal 

2. History of allergy to study drugs

3. Post spinal surgeries, Spinal Deformities, skin sepsis in lumbar region, patients with pre-existing neurological disorders.

4. Coagulopathy, Dysrhythmia  

5. Major Hepatic, Renal and Cardiovascular Dysfunction

6. BMI >35, Height <140cm

7. Surgeries involving major blood loss

METHODOLODY

The enrolled subjects will be randomized into the 2 study groups using computer generated randomization code. 

All the patients will receive Tab Alprazolam 0.5mg HS and Tab Ranitidine 150mg HS and 6am in the morning of surgery. On arrival in Pre-op area an IV access with 18G IV cannula will be secured and RL will be started.

Establishment of proper standard monitoring systems (pulse oximetry, continuous electrocardiography and non-invasive blood pressure monitoring and SpO₂). 

Sitting position is recommended for all patients included in this study. Under all aseptic precautions L3-L4 inter-space will be infiltrated with 2ml of 2% Inj. Lignocaine.

Study drug will be prepared by the person not involved in the study. The subarachnoid space will be entered at L3-L4 intervertebral-space via the midline approach using 26-Gauge Quincke spinal needle. The correct needle placement will be identified by free flow of cerebrospinal fluid and 3.7 ml of study drug will be injected by the anesthesiologist.

The patient will be placed in supine position to carry over the initial assessment. The onset of sensory and motor blockade will be assessed at baseline and 3 min interval up to 15 min.

The onset of sensory blockade will be considered as loss of cold sensations at T10 level and the highest level of sensory blockade will also be noted.The onset of motor blockade will be evaluated using Modified Bromage score of 2.Two segment sensory blockade and the regression of Motor Blockade to score of 0 will be noted at the end of the procedure.

The duration of sensory blockade is taken as the two segment regression and the duration of motor block is taken Modified Bromage score of 0.

The duration of analgesia is taken as the time taken for the first analgesic need for the patient. 

Continuous Vital monitoring includes patient’s HR, NIBP, RR and SpO2 will be monitored at 3 min interval up to 15 minutes then every 5 minutes up to 30 minutes.

The Modified Bromage score and level of sensory blockade will be noted for every 30 min up to 5 hrs.

 POST- OPERATIVE PAIN AND SIDE EFFECTS

• Post-surgery, the time for request of first rescue analgesia will be noted from the time of administration of spinal anaesthesia to complain of pain VAS score of >/=3 (i.e. 0=No Pain, 10=worst imaginable pain).

• In case of Pain Inj. Tramadol 50 mg will be given intravenously.

• Side effects such as nausea and vomiting will be treated using Inj. Ondensetron 4mg IV, Bradycardia by Inj. Atropine 0.6mg and Hypotension by adequate fluids or if required Inj. Ephedrine 6mg.

REFERENCES

1. O’Connor PJ, Hanson J, Finucane BT. Induced hypotension with epidural/general anesthesia reduces transfusion in radical prostate surgery. Can J Anaesth 2006;53:873‑80.

2. Mattoo P, Chowdhary A, Mehta N, Chopra V. Comparison of the effect of intrathecal 0.5% isobaric bupivacaine and 0.5% isobaric levobupivacaine in patients undergoing lower abdominal and lower limb surgeries. JOURNAL OF EVOLUTION OF MEDICAL AND DENTAL SCIENCES-JEMDS. 2016 Sep 26;5(77):5668-72.

3. Sultan MA, Ali Shams TM, Mageed NA, El‑ebidy MG. Intrathecal hyperbaric ropivacaine versus hyperbaric bupivacaine in geriatric hypertensive patients. Benha M. J. 2005;22:479.

4. Rattenberry W, Hertling A, Erskine R. Spinal anaesthesia for ambulatory surgery. BJA Educ. 2019 Oct;19(10):321-328. doi: 10.1016/j.bjae.2019.06.001. Epub 2019 Aug 13. PMID: 33456853; PMCID: PMC7807930.

5. Latwal BS, Singam A, Shrey S, et al. A comparative study of intrathecal 0.5% hyperbaric bupivacaine & intrathecal 0.75% isobaric ropivacaine in lower abdominal surgeries. J. Evolution Med. Dent. Sci. 2020;9(05):256-261, DOI: 10.14260/jemds/2020/58

6. Gupta R, Bogra J, Singh PK, Saxena S, Chandra G, Kushwaha JK. Comparative study of intrathecal hyperbaric versus isobaric ropivacaine: A randomized control trial. Saudi J Anaesth 2013;7:249-53.

7. Singh AP, Kaur R, Gupta R, Kumari A. Intrathecal buprenorphine versus fentanyl as adjuvant to 0.75% ropivacaine in lower limb surgeries. J Anaesthesiol Clin Pharmacol 2016;32:229-33.