INTRODUCTION:

         Spinal anaesthesia is one of the most preferred choice of anaesthesia in lower abdominal surgeries. It has got the advantage of being cost-effective, easy administration technique, rapid onset of action, with relatively less adverse effects, and most importantly patient remaining aroused throughout the procedure. Spinal anesthesia using short-duration local anesthetics poses difficulty in the management of postoperative pain; henceforth, the use of early analgesic is needed in the postoperative period. Shortcomings that were associated with this technology included a relatively short duration of anaesthesia and analgesia. To overcome this disadvantage, many kinds of adjuvants (fentanyl, sufentanil, epinephrine, etc.) were suggested to help prolong anaesthesia and analgesia. Postoperative pain management is one of the main challenges for anaesthesiologists and even with the help of multimodal analgesia techniques, patients still remain undertreated. Since no single modality for the post-operative pain relief has proven to be effective without side effects, we continue to explore modern strategies with new drug combinations. The addition of different adjuvants intrathecally is an attractive analgesic strategy due to simple and quick technique with low risk of failure and infection. Anaesthesiologists have added multiple adjuvant drugs such as epinephrine, opioids, α₂ adrenergic receptor (AR) agonists and many others to local anaesthetic agents. Intrathecal opioids are considered the gold standard in the treatment of post-operative pain with morphine as the most effective due to its potent and prolonged effect. Intrathecal morphine sulfate (ITMS) was shown to provide profound and prolonged analgesia and is now used extensively to treat acute postoperative and cancer-related pain. The analgesia produced by ITMS is adequate for pain relief after many different types of surgery in doses ranging from 0.025 to 20 mg. A single dose often suffices as the sole analgesic after surgery

Dexmedetomidine is a highly selective α₂ adrenergic receptor agonist which possesses sedative, analgesic and sympatholytic properties and gives prolonged analgesia when used intrathecally without respiratory depression. Intrathecal dexmedetomidine has been found to be ten times more potent analgesic and anaesthetic as compared to intrathecal clonidine and five times more potent than opioids like intrathecal fentanyl. Intrathecal morphine when compared to intrathecal α₂ AR agonist, clonidine proved to be better post-operative analgesic with significantly less rescue analgesic consumption, but the duration of spinal block was more with clonidine than morphine. In this study, we decided to compare intrathecal morphine with intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine in lower abdominal surgeries.

AIM: To compare the postoperative analgesic effect of intrathecal dexmedetomidine and morphine as an adjuvant to hyperbaric bupivacaine in lower abdominal surgeries and to compare the intra operative haemodynamic stability between intrathecal dexmedetomidine and morphine.

PRIMARY OBJECTIVE: To compare the postoperative analgesic effect of intrathecal dexmedetomidine and morphine as an adjuvant to hyperbaric bupivacaine.

SECONDARY OBJECTIVE: to compare the intra operative haemodynamic stability between intrathecal dexmedetomidine and morphine and the adverse effects of intrathecal dexmedetomidine with that of morphine.

ANNEXURE II

MATERIALS & METHODS:

A total of 64 patients belonging to age group 18-65 years, classified as American Society of Anaesthesiologists status I - II scheduled for lower abdominal procedures were prospectively studied. Patients will be randomly divided into two groups by sealed envelope technique: Group D receiving 15 mg of 0.5% hyperbaric bupivacaine and 5 µg dexmedetomidine Group M receiving 15 mg of 0.5% hyperbaric bupivacaine and 125 µg morphine. Sensory and motor blockade characteristics- The onset time to reach peak sensory and motor level, the regression time for sensory and motor block, time for rescue analgesia, hemodynamic changes and side-effects were recorded. Data collection was done by observation and measurement of various parameters.

SAMPLE SIZE: 64 (GROUP D - 32, GROUP M – 32)

STUDY DESIGN: Double blinded Randomized control trial.

PERIOD OF STUDY:18 months.

STUDY POPULATION: Patients undergoing lower abdominal surgeries under sub arachnoid block.

INCLUSION CRITERIA:

·   18 - 65 years of age

·   ASA I-II

·   Patients undergoing lower abdominalElective Surgeries

Willing patients.

EXCLUSION CRITERIA:

·   Emergency surgeries.

·         Patients who are not willing.

·         ASA IV graded patients.

·         Patients not fit for spinal anaesthesia.

METHODOLOGY: After obtaining the scientific committee and ethical committee clearance, informed consent written in their own language will be obtained from all the patients. Patients between the age of 18-65 years  of ASA grade I-II scheduled for elective lower abdominal surgeries under spinal anaesthesia will be selected. Preoperative evaluation will be done the day before surgery for all the patients. Fasting will be advised for 6 hours. Baseline vitals will be recorded. All the patients will be monitored with electrocardiography, pulse oximetry (SpO₂) and non invasive blood pressure (NIBP). Under aseptic precautions, sub arachnoid block will be administered using 25 gauge Quincke’s needle at L3- L4 intervertebral space by midline approach. Patients will be randomly divided into two groups by sealed envelope technique: Group D receiving 15 mg of 0.5% hyperbaric bupivacaine and 5 µg dexmedetomidine Group M receiving 15 mg of 0.5% hyperbaric bupivacaine and 125 µg morphine. The patients will be made to lie in supine position immediately after the completion of spinal injection. When the pulse oximeter decreased below 94%, oxygen(4L/min) will be administered via face mask. Hypotension, defined as a decrease of systolic blood pressure by more than 20% from baseline or a fall below 90 mm Hg, will be treated with incremental IV doses of ephedrine 5mg and intravenous fluid as required. Bradycardia, defined as a decrease of heart rate by more than 20% from baseline below 60/min, was treated with 0.3 or 0.6 mg IV atropine. The incidence of adverse effects such as nausea, vomiting, shivering, pruritus, respiratory depression and hypotension will be recorded.

Sensory level will be monitored every 2 min for initial 30 min using pin prick method. Time for onset of analgesia, time to achieve sensory level of T₈ , the highest sensory level achieved and time taken to achieve that will also be noted. After initial 30 min, sensory level will be monitored every 15 min till end of surgery.

The motor level will be assessed using modified Bromage score:

0 – Able to move the hip, knee and ankle;

1 – Unable to move the hip but is able to move the knee and ankle.

2 – Unable to move the hip and knee but is able to move the ankle.

3 – Unable to move the hip, knee and ankle.

Complete motor block recovery is assumed when modified Bromage score was 0. Time taken for onset of motor block and to achieve Bromage 3 will be noted.

Sedation score was assessed as per modified Ramsay sedation score;

1 – agitated,

2 – anxious but alert,

3 – drowsy but responding to commands,

4 – responds on glabellar tap,

5 – responds to deep, painful stimuli.

 Parameters such as the duration of time to achieve T8 sensory blockade, the time to S1 level sensory regression, the time of motor regression to Bromage 0, the time to first rescue analgesia and incidence of side effects will be recorded. All durations will be calculated considering the time of spinal injection as zero. Heart rate (HR), systolic blood pressure, diastolic blood pressure, oxygen saturation (SpO₂) and sedation score will be monitored every 5 min for initial 30 min and subsequently for every 15 min till the end of surgery.

Pain scores using Visual analogue scale (VAS) will be assessed in the postoperative period. Any patient showing VAS more than or equal to 4 or requesting for analgesia will be administered a supplemental dose of intravenous analgesics. All the patients will be monitored for presence of nausea/vomiting, pruritus, sedation, signs of respiratory depression (respiratory rate/min and SpO₂), HR and NIBP every 2 hourly for 12 h and then every 4 hourly for next 12 h.

Study will end at 24 h after induction of anaesthesia.

STATISTICAL ANALYSIS:

Data will be entered in MS Excel Spreadsheet (2010) and were analyzed using the statistical package for social sciences version 20(trial version) Descriptive statistics including proportions, measures of central tendency & measures of dispersion will be used to describe the data. Further Students t test will be used to compare the means between the groups & Chi square test to compare the proportions. A P < 0.05 will be considered to be statistically significant.

REVIEW OF LITERATURE:

1.       Soumya Samal, et al., did a comparative study on Intrathecal dexmedetomidine versus morphine as adjuvant to bupivacaine in elective LSCS. This prospective comparative study was conducted on sixty parturients of ASA grade I and II scheduled for elective lower segment caesarean section under spinal anaesthesia. Cases were randomly divide into two groups: Group D received 12.5 mg of 0.5% hyperbaric bupivacaine with 5 µg dexmedetomidine and Group M received 12.5 mg of 0.5% hyperbaric bupivacaine with 125 µg morphine and concluded that : Prolong postoperative analgesia with minimal side effects makes 5 µg dexmedetomidine as an alternative to125 µg morphine as adjuvant to spinal bupivacaine in caesarean section.

2.       Pranjali kurhekar et al., did a comparative study of evaluation of intrathecal morphine and intrathecal dexmedetomidine in patients undergoing gynaecological surgeries under spinal anaesthesia. This was a prospective, randomised, double blind study involving 25 patients in each group. Group M received 15 mg of 0.5% hyperbaric bupivacaine with 250 μg of morphine while Group D received 15 mg of 0.5% hyperbaric bupivacaine with 2.5 μg of dexmedetomidine and concluded that
Intrathecal dexmedetomidine produces prolonged motor and sensory blockade without undesirable side effects but intraoperative hypotension was more frequent in dexmedetomidine group.

3.       Wasinwong et al., did a comparative study o Postoperative Analgesic Effect of Intrathecal Dexmedetomidine Compared to Morphine in Bupivacaine Spinal Block. Fifty-six patients undergoing hip or knee arthroplasty under spinal anesthesia were randomized into two groups. Each patient received a 12.5 mg dose of bupivacaine for spinal anesthesia. A 0.2 mg dose of morphine or a 5 μg dose of dexmedetomidine was diluted in an equivalent volume and administered intrathecally in the control (M) and intervention (D) group, respectively. Post-operative morphine patient control analgesia (PCA) was used in every patient. The primary objective was to determine the time to the first analgesic requirement. The time to reach the T10 sensory level, time to regression to S1 sensory level and motor levels, the 24-post-operative-hour morphine requirement, verbal numerical rating pain scale, and adverse effects were recorded and concluded that  Intrathecal dexmedetomidine provided significantly lower post-operative analgesia in 24 hours after hip or knee arthroplasty compared to morphine.

4.       Mamta Khandelwal et al., did a comparative study of morphine or dexmedetomidine as intrathecal adjuvants to 0.5% hyperbaric bupivacaine in infraumbilical surgeries.  A prospective, randomised, double-blinded study was conducted in department of anaesthesiology at a tertiary referral hospital. Eighty patients with American Society of Anaesthesiologists Status I and II were randomly allocated to receive either dexmedetomidine (5 μg) or Morphine (200 mcg) with or 0.5% hyperbaric bupivacaine and concluded that Intrathecal dexmedetomidine as compared to Morphine as an adjuvant to intrathecal bupivacaine prolonged the time to first rescue analgesia, without any significant adverse effect.

5.       Mahima gupta et al., did a comparative study of Intrathecal Dexmedetomidine with Buprenorphine as Adjuvant to Bupivacaine in Spinal Asnaesthesia. The present study included 60 patients aged between 18-60 years classified as American Society of Anesthesiologists (ASA) Physical Status (PS) I/II scheduled for elective lower abdominal surgeries. The patients were randomly allotted to two groups to receive intrathecal 3ml of 0.5% bupivacine with 60µg of buprenorphine (Group B; n=30) or 3ml of 0.5% bupivacaine with 5µg of dexmedetomidine (Group D; n=30). The onset time to peak sensory level, motor block, sedation, Haemodynamic variables, duration of motor block, analgesia and any adverse effects were noted and concluded that Intrathecal dexmedetomidine when compared to intrathecal buprenorphine causes prolonged anaesthesia and analgesia with reduced need for sedation and rescue analgesics.