COMPARING EFFICACY OF INTRATHECAL BUPIVACAINE AND FENTANYL AS A PREMIXTURE VERSUS SEQUENTIAL ADMINISTRATION IN LOWER LIMB SURGERIES": RANDOMIZED CONTROL TRIAL

RESEARCH QUESTION    Is efficacy of intrathecal injection of bupivacaine and fentanyl as sequential administration from separate syringes better, as compared to from a single syringe?  

AIM

To study and compare efficacy of intrathecal injection of 2.8 ml bupivacaine and 25 mcg of fentanyl in a single syringe versus sequential administration in separate syringes, in lower limb surgeries.

This is a prospective randomised double-blind study which will be performed in

a tertiary care hospital over a period of 7 months. After obtaining institutional ethical committee approval,40 patients aged 18–60years, American Society of Anaesthesiologists (ASA) grade I and II scheduled for unilateral lower limb surgery under subarachnoid block will be enrolled in this study. After written informed consent patients will be allocated into two groups of 20 patients each according to computer generated random numbers before the commencement of study. Group A patients will receive premixed 0.5% hyperbaric bupivacaine 2.8 ml(14 mg) and 0.5 ml (25 microgram) of fentanyl in a single 5.0 ml syringe.  Group B will receive 0.5% hyperbaric bupivacaine 2.8 ml (14 mg) in a 5 ml syringe followed by 0.5 ml (25 microgram) of fentanyl in a 1ml tuberculin syringe.

Patients will undergo a thorough preanesthetic check-up a day before surgery and an informed consent will be taken.

Patients will be NPO 6 hours for solid food and 2hours for clear fluid before surgery. They will be familiarized with the concept of visual analogue scoring (VAS). Anaesthesia machine will be checked, drugs and equipment’s necessary for emergency resuscitation will be kept ready.

Intraoperative monitoring for heart rate, non-invasive blood pressure, electrocardiography, oxygen saturation (Spo2) will be connected and base line parameters will be recorded. Venous access will be established with 18-gauge cannula and Ringer lactate will be started as the maintenance fluid at rate of 10ml/kg/hour.

The drug codes sealed in envelopes numbered 1–40 will be opened by the designated anaesthesiologist of the work area just before the administration of anaesthesia and

drug prepared using sterile technique according to group allocated. The drug will then be handed over to the attending anaesthesiologist in a coded form who was unaware about the study design and the study groups. Also, the patients will be blinded to the group they belong.

Observer will not present while subarachnoid block Is administered. Twenty-six-gauge Quincke spinal needle will be used in all the cases. Patient will be placed in sitting position, back painted and draped under aseptic precautions. L4-L5 intervertebral space will be located and 26-gauge Quincke’s needle introduced. In Group A patient 5ml syringe containing 2.8ml of 0.5% bupivacaine and 0.5 ml of fentanyl will be introduced in subarachnoid space after observing free flow of CSF on aspiration. In group B patients 2.8 ml of 0.5% of bupivacaine in 5ml syringe will be introduced first in subarachnoid space after observing free flow of CSF on aspiration followed immediately by administration of 0.5ml fentanyl through a 1 ml tuberculin syringe without aspiration into the subarachnoid space. Both group patients will receive spinal injection at same rate. After the procedure patients will be placed in supine position.  Sensory block will be assessed by a sterile pin prick every 2 min till 20 min

and then after every 10 min till the highest level was achieved. Time to onset of sensory block is defined as time taken to achieve the loss of sensation at T10 dermatome. The time to onset of motor block is defined as time taken to reach Bromage score of 3. Time of sensory block regression is assessed from maximal block height attained to regression till two dermatomal level. Time of regression of motor block is assessed from Bromage score of 3 to score of 0. Vital parameters like Blood pressure, Heart rate will be assessed every 5 minutes for initial 30 min and then every15 minutes till end of surgery.  Hypotension is defined as decrease of systolic blood pressure to 80% of baseline or less and will be treated with 6 mg ephedrine given intravenously.

Bradycardia defined as HR <60 beats per minute and will be corrected using 0.6 mg of intravenous atropine sulphate. Postoperative analgesia in the form of diclofenac75mg will be given if the visual analogue score is 5 and the study will be concluded at this point.