Efficacy of intrathecal Levobupivacaine with Fentanyl vs Levobupivacaine with Dexmedetomidine in patients undergoing LSCS: A prospective hospital based study

Spinal anaesthesia is the most commonly performed anaesthetic technique for caesarean section .At first lidocaine 5% was used as local anaesthetic for lscs procedure, it usage has decreased because it caused transient neurologic symptoms. After that Bupivacine 0.5% hyperbaric was used and it also has increased the duration of motor block. So Intrathecal local anesthetics alone are not enough for effective postoperative analgesia and higher doses of local anaesthetics are also associated with hemodynamic instability, which can lead to unfavorable maternal and fetal outcome. So far many adjuncts have been used to prolong the analgesia produced by intrathecal LA and to reduce their adverse effects. They are fentanyl, ketamine, dexmedetomidine, clonidine, buprenorphine midazolam and etc.

After that a new drug a levobupivacine plain was used as a local anaesthetic for caesarean section and other lower limb surgeries as it has better sensory blockade and faster regression of motor blockade compared to bupivacaine.The very latest addition to local anaesthetic used for lscs is hyperbaric levobupivacaine, which is the s enantiomer of bupivacaine and was introduced recently. Levobupivacaine seems identical to bupivacaine in potency and shows longer duration of action on neural tissue.Hyperbaric levobupivacaine has less cardiotoxicity propensity and less chance of cephalic spread, which favor particularly in LSCS. In the postoperative period prolonging the analgesia is the best way to encourage for early ambulation of patients.

Fentanyl is a lipophilic μ-receptor agonist opioid. Intrathecally, fentanyl exerts its effect by combining with opioid receptors in the dorsal horn of spinal cord and may have a supra spinal spread and action . It has been well documented that a combination of fentanyl with local anaesthetic has prolonged the sensory blockade without intensifying motor blockade.

Dexmedetomidine is a highly selective α2–adrenoceptor agonist, and recently used as an adjuvant with intrathecal local anaesthetic and found to prolong the duration of sensory and motor blockade as well as to provide hemodynamic stability during intraoperative period. It also produces dose dependent sedation, anxiolysis and analgesia (involving spinal and supraspinal sites) without respiratory depression.

Dexmedetomidine is a potent alpha 2 adregenic agonist with a half life of 2 to 3 hrs and it undergoes hepatic metabolism and excreted by kidneys. It has dose dependent action. Adverse effects are hypotension and bradycardia. Fentanyl is metabolized by N-demethylation and excreted by kidneys. Its half life is 3 to 6 hrs. Adverse are effects respiratory suppression, bradycardia , hypotension, pruritis and it should be avoided in head injury patients.

Till now studies have been conducted by using isobaric levobupivacine. But now recently hyperbaric levobupivacine is available and we are conducting a study by using hyperbaric levobupivacine.

The primary objective of the study is to compare the onset and duration of motor and sensory block and requirement of rescue analgesia for patients undergoing caesarean section under spinal anaesthesia with intrathecal fentanyl or dexmedetomiine with levobupivacaine(H)

The secondary objective of the study is to compare the haemodynamic parameters such as heart rate, non-invasive blood pressure, SpO2 between both the drugs.

Patient fullfilling the eligibility criteria will be assigned to one of two groups.

GROUP F : Patient receiving hyperbaric levobupivacine of 2.1 ml plus 0.5ml of 25mcg of fentanyl so total volume of 2.6ml .

GROUP D : Patient receiving hyperbaric levobupivacine of 2.1 ml plus 0.05ml 5mcg of dexmedetomidine plus 0.45ml of distilled water so total volume of 2.6ml

Assigning of patients into two groups was performed by anesthesiologist involved in drug preparations. Other investigator involved in the procedure and monitoring was unaware of group allocation. Patients were also blinded to the drug regimen used in spinal anesthesia. On arrival to operating room, baseline parameters recorded. Peripheral 18G cannula secured and preloading done with lactated ringer solution 10 ml/kg. Before spinal anesthesia patients were explained about the procedure and methodology of monitoring methods. In sitting position under strict aseptic precautions, using a midline approach lumbar puncture was performed at L3-L4 intervertebral space by 25G Quincke spinal needle. After confirming the free flow of cerebrospinal fluid, the studied drug solution was injected intrathecally and patients were made into supine position. Primary outcome is to determine time taken to achieve motor block and sensory block that is the duration of time taken from time of giving spinal to the onset of action of drug to produce motor and sensory block ,Duration of motor block and sensory block is that time taken from the onset of block to time when the spinal wares off and Duration of analgesia is that when the patient feels the pain and next dose of analgesic is started.Secondary outcome was to compare the hemodynamic parameters such as heart rate , blood pressure and spo2. The level of sensory block assessed, by pinprick test or cold test and dermatomes levels were tested until the highest level had stabilized by consecutive tests. The motor dermatome level was assessed using Modified Bromage scale. Bromage 0 – full flexion of knees and feet, Bromage 1 – just able to move knees, Bromage 2 – able to move feet only, Bromage 3 – unable to move feet and knees[14]. The time to reach Bromage scale 3 before surgery and Bromage 0 in post anesthesia care unit (PACU) was recorded. On achieving sensory and motor blockade and Bromage scale 3 surgery was allowed. Pain was assessed using Visual Analog Score VAS (0 to 10) scale at time of incision and at completion of surgery. VAS 0 – No pain , VAS 1 to 2 – least pain , VAS 3 to 4 – mild pain , VAS 5 to 6 – moderate pain , VAS 7 to 8 – severe pain , VAS 9 to 10 -  excruciating pain. After surgery patient shifted to PACU and observed for hemodynamic parameters, duration of sensory block, duration of motor block, degree of postoperative analgesia and need of rescue analgesic. Hypotension, defined as a decrease of systolic blood pressure by more than 30% from baseline or a fall below 90 mmHg, was treated with IV boluses of ephedrine 5 mg and IV fluid as required. Bradycardia, defined as heart rate < 60 bpm, was treated with IV atropine 0.6 mg. The incidence of adverse effects, such as nausea, vomiting, shivering, pruritus, respiratory depression, sedation, and hypotension was recorded.