A double blinded randomized control trial of the effects pf differences in epidural needle entry point and angle of rotation of needle hub on the duration of sensory blockade in lower limb orthopaedic surgeries

70 patients who meet the Inclusion criteria will be randomly allocated into 2 groups of 35 each(Control group or Rotation group).Monitors (non-invasive arterial blood pressure, pulse oximetry and electrocardiography) will be attached for all patients upon arrival to the operating room.

Each patient will receive 500 ml of 0.9% NS intravenously before initiating the block procedure. Patients will be then placed in the sitting position. After sterilization and preparation of the site, the skin will be anesthetized by subcutaneous injection of 3ml 2% lidocaine.

An experienced Anesthesiologist will perform the procedure. An 18-gauge,3.5 inch, Tuohy needle will be inserted at the level of L4-5 intervertebral space and pushed forward till the epidural space is attained by the loss-of-resistance technique. Confirmation of the catheter tip position will be done using C Arm

In control group (midline approach) the needle will enter the midline of the spine and the tip will be placed in the usual cephalad direction i.e. 90 degrees and then the catheter will be inserted.

For the rotation group (paramedian approach), the needle will enter the paramedian point and on reaching the epidural space, the tip will be rotated 45 degrees towards the operating side. The catheter will be inserted thereafter.

After the catheter gets inserted 5 cm, the needle will be removed, and the catheter will be secured to the skin. A test dose of 3 ml of Inj.Lignocaine 2% with 1:2,00,000 adrenaline will be injected

The method of securing the catheter with plasters against the patient’s back will be uniform between the groups. Patients will be placed in supine position following which 12 mL of bupivacaine 0.5% will be injected epidurally

The evolution of sensory and motor blocks on both sides will be observed every 5 min till the maximum sensory level is attained. The sensory block level will be evaluated based on pinprick test. Motor block level will be evaluated using Bromage Scale. Readiness for surgery was defined as complete loss of pinprick sensation up to T10 with a Bromage scale of 3 on the surgical side.

Hemodynamic parameters (HR, MAP, and SPO2) will be recorded at baseline and then every 5 minutes during the first 30 min of the operation and subsequently at 15 min intervals until the end of surgery. Complications (hypotension, bradycardia) will be recorded in case of happening and will be managed according to the protocol.

Hypotension will be considered significant if decrease in the systolic arterial blood pressure ≥30% from the baseline, and will be treated with intravenous (IV) crystalloid infusion. If volume expansion was not effective, Inj Ephedrine 6mg IV will be administered. Bradycardia (≥30% decrease from the baseline) will be managed with Inj. Atropine 0.6mg IV. At the end of surgery, patients will be transferred to PACU for epidural infusion and total volume of local anesthetic injected epidurally up to 24 hrs in the post-operative period will be recorded.

Inadequate surgical anaesthesia will be documented as a failure and the patient will be subjected to General anesthesia

BROMAGE SCALE

SCORE 0 (none) – Full flexion of knees and feet

1(partial)-Just able to move knees

2(almost complete)-Able to move feet only

3 (complete)- Unable to move feet or knees

After regression of the sensory level to T12, the epidural infusion comprising of 0.125% Bupivacaine with 2mics/ml Fentanyl will be started at 4ml/hr in both the groups.

If the patients complain of pain, the existing infusion rate will be given as bolus as rescue analgesic & the infusion rate will be stepped up by 1ml increments. The maximum allowed infusion rate is 7ml/hr. If the patient still complains of pain Inj Morphine will be administered intravenously in 3mg increments and the total volume of local anesthetic given epidurally for 24hrs in the post operative period will be noted in both the groups.